| 1. |
- Andreasen, Katarina, et al.
(författare)
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Genetic identity of putative Linnaean plants : Successful DNA amplification of Linnaeus's crab apple Malus baccata
- 2014
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 63:2, s. 408-416
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Advancements in molecular techniques enable us to extract DNA from historic herbarium specimens and facilitate genetic comparisons between herbarium material and living plant collections. These recent advances offer an exciting opportunity for identifying extant Linnaean plants by genetic comparisons of Linnaeus's own herbarium specimens with potentially remnant plants from his cultivations. DNA from the lectotype of Malus baccata (L.) Borkh. in the Linnaean Herbarium was successfully extracted and amplified for five of twelve loci of microsatellites. Results of genetic comparisons with M. baccata trees from Linnaeus's Hammarby, Sweden, show that the trees at Hammarby are closely related to each other, but not to the lectotype, which is closer to material from Russia. This suggests that Linnaeus received M. baccata from more than one source. Although not close to the lectotype and not represented by a specimen in the Linnaean Herbarium, the extant M. baccata at Hammarby may still represent Linnaean plants, that were grown by Linnaeus himself, or the descendants to such plants. Future studies on the almost 50 living, potential Linnaean plants may reveal an invaluable biological, scientific and cultural heritage from the era that saw the rise of systematic biology.
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| 2. |
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| 3. |
- Crespo, Leonardo, et al.
(författare)
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A systematic review of rye (Secale cereale L.) as a source of resistance to pathogens and pests in wheat (Triticum aestivum L.)
- 2017
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 154, s. 1-9
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Forskningsöversikt (refereegranskat)abstract
- Wheat is globally one of the most important crops. With the current human population growth rate, there is an increasing need to raise wheat productivity by means of plant breeding, along with development of more efficient and sustainable agricultural systems. Damage by pathogens and pests, in combination with adverse climate effects, need to be counteracted by incorporating new germplasm that makes wheat more resistant/tolerant to such stress factors. Rye has been used as a source for improved resistance to pathogens and pests in wheat during more than 50 years. With new devastating stem and yellow rust pathotypes invading wheat at large acreage globally, along with new biotypes of pest insects, there is renewed interest in using rye as a source of resistance. Currently the proportion of wheat cultivars with rye chromatin varies between countries, with examples of up to 34%. There is mainly one rye source, Petkus, that has been widely exploited and that has contributed considerably to raise yields and increase disease resistance in wheat. Successively, the multiple disease resistances conferred by this source has been overcome by new pathotypes of leaf rust, yellow rust, stem rust and powdery mildew. However, there are several other rye sources reported to make wheat more resistant to various biotic constraints when their rye chromatin has been transferred to wheat. There is also development of knowledge on how to produce new rye translocation, substitution and addition lines. Here we compile information that may facilitate decision making for wheat breeders aiming to transfer resistance to biotic constraints from rye to elite wheat germplasm.
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| 4. |
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| 5. |
- Crespo, Leonardo, et al.
(författare)
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Mapping resistance to the bird cherry-oat aphid and the greenbug in wheat using sequence-based genotyping
- 2014
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Ingår i: TAG Theoretical and Applied Genetics. - : Springer Science and Business Media LLC. - 0040-5752 .- 1432-2242. ; 127, s. 1963-1973
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Tidskriftsartikel (refereegranskat)abstract
- Identification of novel resistance QTL against wheat aphids. First QTL-resistance report for R. padi in wheat and chromosome 2DL for S. graminum . These sources have potential use in wheat breeding.The aphids Rhopalosiphum padi and Schizaphis graminum are important pests of common wheat (Triticum aestivum L.). Characterization of the genetic bases of resistance sources is crucial to facilitate the development of resistant wheat cultivars to these insects. We examined 140 recombinant inbred lines (RILs) from the cross of Seri M82 wheat (susceptible) with the synthetic hexaploid wheat CWI76364 (resistant). RILs were phenotyped for R. padi antibiosis and tolerance traits. Phenotyping of S. graminum resistance was based on leaf chlorosis in a greenhouse screening and the number of S. graminum/tiller in the field. RILs were also scored for pubescence. Using a sequence-based genotyping method, we located genomic regions associated with these resistance traits. A quantitative trait locus (QTL) for R. padi antibiosis (QRp.slu.4BL) that explained 10.2 % of phenotypic variation was found in chromosome 4BL and located 14.6 cM apart from the pubescence locus. We found no association between plant pubescence and the resistance traits. We found two QTLs for R. padi tolerance (QRp.slu.5AL and QRp.slu.5BL) in chromosomes 5AL and 5BL, with an epistatic interaction between a locus in chromosome 3AL (EnQRp.slu.5AL) and QRp.slu.5AL. These genomic regions explained about 35 % of the phenotypic variation. We re-mapped a previously reported gene for S. graminum resistance (putatively Gba) in 7DL and found a novel QTL associated with the number of aphids/tiller (QGb.slu-2DL) in chromosome 2DL. This is the first report on the genetic mapping of R. padi resistance in wheat and the first report where chromosome 2DL is shown to be associated with S. graminum resistance.
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| 6. |
- Edin, Eva, et al.
(författare)
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Genetic diversity and occurrence of the F129L substitutions among isolates of Alternaria solani in south-eastern Sweden
- 2016
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- Background: Early blight, caused by the fungus Alternaria solani, occurs on potato mainly in the south-eastern part of Sweden, but also in other parts of the country. The aim of this study was to investigate the genetic diversity of A. solani populations from different potato growing regions in south-eastern Sweden using AFLP marker analysis. In addition, the cultured isolates were examined for substitutions in the gene encoding cytochrome b, associated with loss of sensitivity against QoI fungicides.Results: Nei's gene diversity index for the Swedish populations of A. solani revealed a gene diversity of up to 0.20. Also genetic differentiation was observed among populations of A. solani from different locations in south-eastern Sweden. The mitochondrial genotype of the isolates of A. solani was determined and both known genotypes, GI (genotype 1) and GII (genotype 2), were found among the isolates. The occurrence of the F129L substitution associated with a loss of sensitivity to strobilurins was confirmed among the GII isolates. In vitro conidial germination tests verified that isolates containing the F129L substitution had reduced sensitivity to azoxystrobin and, at a lower extent, to pyraclostrobin.Conclusions: Genetic diversity was relatively high among isolates of A. solani in south-eastern part of Sweden. F129L substitutions, leading to reduced sensitivity to strobilurins, have been established in field populations, which may have implications for the future efficacy of QoI fungicides.
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| 7. |
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| 8. |
- Elsafy, Mohammed, et al.
(författare)
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Elucidating the genetic diversity of farmer cultivars of female date palms (Phoenix dactylifera L.) from Sudan by microsatellite markers
- 2016
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Ingår i: Genetic Resources and Crop Evolution. - : Springer Science and Business Media LLC. - 0925-9864 .- 1573-5109. ; 63, s. 975-986
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity in female date palms for a total of 89 tree samples, representing 18 cultivar groups, was investigated using 10 loci of microsatellite (SSR) primers. The microsatellites examined showed high polymorphism, a total of 126 for the 10 microsatellite loci, giving an average of 12.6. Low F-ST values were observed among different fruit classification groups of Sudanese date palms (soft, semi-soft and dry) suggesting that the observed high genetic variability is maintained locally within cultivars. Across all genetic parameters, in comparison among the cultivar groups, the Jaw group was consistently highly variable followed by Korsha, Gondela and Barakawi, respectively. Multivariate analysis of the 89 date palms showed some strong relationships with some mixed grouping, showing a tendency of relate fruit classification and related genotypes. Dry dates almost grouped together while the soft and semi-soft were mixed and somewhat related to genotypes. The effect of genotype was highly supported by the relationship of 14 cultivar groups, in which similar cultivars were associated regardless of the state to which they belong. Further detailed analyses of female date palm populations from different geographic locations represented by a minimum of five plants per cultivar is necessary to provide the basis for understanding of the date palm genomes, revealing the true extent of gene flow between farmer cultivars.
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| 9. |
- Elsafy, Mohammed, et al.
(författare)
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Phenotypic Diversity of Date Palm Cultivars (Phoenix dactylifera L.) from Sudan Estimated by Vegetative and Fruit Characteristics
- 2015
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Ingår i: International Journal of Biodiversity. - : Hindawi Limited. - 2314-4149 .- 2314-4157.
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to apply some of the vegetative and fruit traits which are easily recognised to identify the variation and the diversity level of the most famous Sudanese date palm cultivars grown on farm in the northern region of Sudan. Sixteen phenotypic traits consisting of ten quantitative and six qualitative characteristics were used for describing the vegetative and fruit characteristics. The principal components analysis (PCA) and UPGMA clustering were used to analyse the data set. The results revealed high variability among the cultivars according to PCA. Fourteen out of the sixteen quantitative and qualitative traits investigated showed a strong discriminating factor suggesting their possible uses in the initiation of Sudanese date palm morphological descriptor list. UPGMA clustering exhibited strong relationship between some cultivars according to their fruit and vegetative characteristics similarity. Based on morphological traits, cultivars Wad-laggi (Lag) and Wad-khateeb (Kha) formed a distinct group suggesting their close relatedness. Similarly, the cultivars sharing the dry fruit texture such as Gondaila (Gon), Tamoda (Tam), Kolmah (Kol), and Barkawi (Bar) were grouped together according to their vegetative traits. Further investigations on Sudanese date palm using more phenotypic characteristics are recommended in order to shape and complete the set of the morphological descriptor list.
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| 10. |
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| 11. |
- Ghasemkhani, Marjan, et al.
(författare)
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Assessment of diversity and genetic relationships of Neonectria ditissima: the causal agent of fruit tree canker
- 2016
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 153, s. 11-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Neonectria ditissima is one of the most important fungal pathogens of apple trees, where it causes fruit tree canker. Information about the amount and partitioning of genetic variation of this fungus could be helpful for improving orchard management strategies and for breeding apple cultivars with high levels of genetically determined resistance. In this study single-spore Neonectria isolates originating from both the same and from different perithecia, apple cultivars and apple orchards in Sweden and Belgium, were evaluated for AFLP- and SSR-based genetic similarity and for mating system.Results: Seven SSR loci produced a total of 31 alleles with an average of 4 alleles per locus, while 11 AFLP primer combinations produced an average of 35 fragments per primer combination and 71 % polymorphic fragments. An AFLP-based analysis of molecular variance (AMOVA) revealed that 89 % of the variation was found within orchards and 11 % between orchards. Genetic similarity among the studied isolates was illustrated with a principal coordinate analyseis (PCoA) and a dendrogram. AFLP-based Jaccard's similarity coefficients were the highest when single-ascospore isolates obtained from the same perithecium were compared, medium-high for isolates from different perithecia on the same tree, and lowest when isolates from different trees were compared.Conclusions: Based on the results of PCoA and AMOVA analysis, isolates from the same or geographically close orchards did not group together. Since AFLP profiles differed also when single-ascospore isolates from the same perithecium were compared, the mating system of N. ditissima is most likely heterothallic.
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| 12. |
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| 13. |
- Ghasemkhani, Marjan, et al.
(författare)
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Real-time PCR for detection and quantification, and histological characterization of Neonectria ditissima in apple trees
- 2016
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Ingår i: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 30, s. 1111-1125
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Tidskriftsartikel (refereegranskat)abstract
- Neonectria ditissima, the causal pathogen of fruit tree canker, is a sordariomycete fungus that affects apple orchards, especially in north-western Europe. To prevent serious disease epidemics, an accurate, rapid, and sensitive method for detection of N. ditissima is needed for pathogen identification. A quantitative real-time PCR (qPCR) assay was developed for both detection and quantification of this pathogen in infected apple cultivars. Several primer sets were designed from regions of the β-tubulin gene. One primer set passed several validation tests, and the melting curve confirmed species-specific amplification of the correct product. In addition, the N. ditissima biomass could be detected at variable amounts in samples from the infection sites of six different cultivars, with ‘Aroma' having the lowest amount of N. ditissima biomass and ‘Elise' the highest. To complement the qPCR results, tissue from detached shoots and 1-year-old trees of ‘Cox's Orange Pippin' (susceptible) and ‘Santana' (partially resistant) was used in a histopathology study. In both detached shoots and trees, fungal hyphae were found in cells of all tissues. No qualitative differences in the anatomy of the infected samples were observed between the cultivars. In the detached shoot experiment, both cultivars were affected but differences in the rate of disease progression suggest that the partially resistant cultivar could resist the fungus longer. The qPCR assay developed in our study produced reproducible results and can be used for detection of N. ditissima in infected trees.
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| 14. |
- Ghasemkhani, Marjan, et al.
(författare)
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Screening for Partial Resistance to Fruit Tree Canker in Apple Cultivars
- 2015
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1099, s. 687-690
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Konferensbidrag (refereegranskat)abstract
- Fruit tree canker in apple, caused by the fungus Neonectria ditissima, is considered as a serious economic problem in apple orchards, especially in northwestern Europe. This fungus produces cankers on the wood of branches and trunks, and severe attacks can result in the loss of limbs or whole trees. The fungus produces conidia and ascospores, both of which are dispersed and cause infection during prolonged periods of rainy weather. Apple cultivars show variable levels of partial resistance to the fungus, whereas complete resistance has not yet been reported. Therefore, apple genotypes with high levels of genetically determined resistance should be identified for use in apple breeding. In this study, ten apple cultivars were screened for resistance to N. ditissima. For each cultivar, both potted trees and cut-off shoots in glass bottles were inoculated in a greenhouse. The resulting lesions were measured and disease progression curves were calculated; AUC (area under curve) was used for comparisons of infection severity. Significant differences between cultivars were observed in both experiments. The cultivar 'Rodluvan' showed the highest degree of resistance in both experiments, while the most susceptible were 'Jonathan'(cut shoots) and 'Akero' (potted trees).
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| 15. |
- Gustavsson, Larisa
(författare)
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A high-density, multi-parental SNP genetic map on apple validates a new mapping approach for outcrossing species
- 2016
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Ingår i: Horticulture Research. - : Oxford University Press (OUP). - 2052-7276. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative trait loci (QTL) mapping approaches rely on the correct ordering of molecular markers along the chromosomes, which can be obtained from genetic linkage maps or a reference genome sequence. For apple (Malus domestica Borkh), the genome sequence v1 and v2 could not meet this need; therefore, a novel approach was devised to develop a dense genetic linkage map, providing the most reliable marker-loci order for the highest possible number of markers. The approach was based on four strategies: (i) the use of multiple full-sib families, (ii) the reduction of missing information through the use of HaploBlocks and alternative calling procedures for single-nucleotide polymorphism (SNP) markers, (iii) the construction of a single backcross-type data set including all families, and (iv) a two-step map generation procedure based on the sequential inclusion of markers. The map comprises 15 417 SNP markers, clustered in 3 K HaploBlock markers spanning 1 267 cM, with an average distance between adjacent markers of 0.37 cM and a maximum distance of 3.29 cM. Moreover, chromosome 5 was oriented according to its homoeologous chromosome 10. This map was useful to improve the apple genome sequence, design the Axiom Apple 480 K SNP array and perform multifamily-based QTL studies. Its collinearity with the genome sequences v1 and v3 are reported. To our knowledge, this is the shortest published SNP map in apple, while including the largest number of markers, families and individuals. This result validates our methodology, proving its value for the construction of integrated linkage maps for any outbreeding species.
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| 16. |
- Gustavsson, Larisa, et al.
(författare)
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Approaches for evaluation of resistance to European canker (Neonectria ditissima) in apple
- 2016
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1127, s. 75-81
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- European canker is caused by the fungus Neonectria ditissima (Neonectria galligena, formerly Nectria galligena). The disease causes significant losses to apple production in Sweden and many other countries with a temperate wet climate. Application of fungicides and good horticultural practices do not prevent canker damage in nurseries and orchards. Disease outbreaks damage and even completely destroy trees. To date, complete resistance to N. ditissima is not known in apple, but cultivars differ considerably in their level of partial resistance. To be able to conduct breeding for resistance to European canker, reliable plant tests are urgently needed. Differences in resistance to N. ditissima (colonization rate; CR) in apple cultivars were evaluated by wound inoculations with a standardized number of conidia on cut shoots from mature trees placed in a climate chamber and on potted trees in an unheated greenhouse. Infection percentage (Inf%) was assessed by 'natural' inoculations in leaf scars under high infection pressure in the field. All the experiments were carried out over 2 years. Lengths of lesions were measured at regular time intervals on five occasions for shoots and seven occasions for trees. Considerable differences in CR and Inf% were found among the cultivars. The relative levels of resistance obtained are consistent with previous reports for most cultivars. Assessment of CR (area under curve) and Inf% thus proved to be useful tools for evaluation of resistance to European canker. Also, some potentially new sources of resistance were identified.
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| 17. |
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| 18. |
- Gustavsson, Larisa, et al.
(författare)
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Do we preserve unique apple germplasm?
- 2011
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 918, s. 661-666
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Konferensbidrag (refereegranskat)
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| 19. |
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| 20. |
- Gustavsson, Larisa
(författare)
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Evaluation of the Carbohydrate Composition of Crabapple Fruit Tissues Native to Northern Asia
- 2023
-
Ingår i: Plants. - 2223-7747. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- A comprehensive comparative analysis of the carbohydrate composition (soluble sugars and pectins) of fruit tissues of Malus baccata, Malus mandshurica, Malus chamardabanica, and Malus sachalinensis, characteristic of the vast territory of Eastern Siberia and the Far East, was carried out. It was shown that a large part of the soluble carbohydrates of the studied species were represented by transport sugars-sorbitol and sucrose. These compounds also provided the main variability in the carbohydrate composition of fruits in the studied material. The polymers pectins and protopectins isolated from the studied fruits were highly methoxylated (up to 60-70%), and their content averaged about 6% of dry weight. The greatest length of pectin polymers was found in the fruit tissues of M. chamardabanica and M. sachalinensis. Data on elemental analysis of fractions of pectins and protopectins of all studied species showed the absence of potentially toxic concentrations of heavy metals. Of note is the rather high content of calcium in both polymer fractions of the four studied species, while its content in protopectin is significantly higher. In addition, in all cases, the presence of low-molecular-weight oligosaccharide molecules with a low-dispersed linear structure was revealed in the tissues of the fruits. It is worth noting that the high content of ascorbic acid was observed in the fruits of all studied species. In addition to being of fundamental interest, information about the carbohydrate composition of the wild Malus species can be useful for apple breeding when choosing sources of genes underlying useful traits.
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| 21. |
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| 22. |
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| 23. |
- Gustavsson, Larisa, et al.
(författare)
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Genetic diversity in Swedish and Finnish heirloom apple cultivars revealed with SSR markers
- 2013
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Ingår i: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 162, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- A set of 85 heirloom apple cultivars aimed for long-term preservation in two germplasm collections in Sweden and Finland was evaluated with 8 SSR primer pairs to evaluate genetic diversity and genetic relatedness. An additional set of 16 European cultivars was included for comparison. The eight SSR primer pairs amplified 9 loci and 105 alleles. Genetic analyses performed by MDS indicated some differentiation between Swedish and Finnish cultivars, with European cultivars intermixed with the Swedish. The existence of three groups was, however, indicated by a Bayesian model-based clustering. One of the groups was clearly dominated by Swedish cultivars and another by Finnish. The third group included almost equal proportions of representatives from all three areas. The obtained results confirmed the genetic distinctness of Finnish apple cultivars, which can be explained by climate adaptation and admixture with a Russian gene pool. (C) 2013 Elsevier B.V. All rights reserved.
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| 24. |
- Gustavsson, Larisa
(författare)
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Genetic diversity of pear germplasm in Bosnia and Herzegovina, as revealed by SSR markers
- 2021
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Ingår i: Zemdirbyste-Agriculture. - : Lithuanian Research Centre for Agriculture and Forestry. - 1392-3196. ; 108, s. 71-78
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Tidskriftsartikel (refereegranskat)abstract
- Bosnia and Herzegovina (BIH) pear germplasm in the ex situ field collection at the University of Banja Luka was characterised with simple sequence repeat (SSR) markers in order to reveal redundancies, determine genetic diversity and confirm uniqueness. European pear (Pyrus communis L.) 67 accessions of the BIH collection and 7 reference cultivars of the ex situ collection at SLU in Balsgard, Sweden were analysed using a set of 10 SSR markers. All markers resulted in good amplification and easy scoring of marker alleles One-third of accessions appeared to be triploid. A total of 112 alleles were amplified in unique diploid genotypes with on average 11.2 alleles per marker. Mean observed heterozygosity (Ho) was 0.72, mean expected heterozygosity (He) - 0.80 and mean Shannon index (I) - 1.96. Inbreeding coefficient (F-IT) for diploid accessions ranged from -0.06 to 0.28 (mean 0.02) and Wright's inbreeding coefficient (F-IS)- from -0.27 to 0.17 (mean -0.03). In the BIH pear collection, mean value of genetic differentiation (F-ST) between the reference cultivars and pear accessions was 0.05. Principal coordinate analysis (PCoA) divided the 74 pear accessions into three groups. The first group consisted of diploid, reference and possible triploid pear accessions, while the second and third groups contained only BIH possible triploid accessions. Overall, the results revealed high levels of polymorphism and uniqueness, indicating that BIH pear germplasm represents very diverse and valuable material for future breeding programmes.
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| 25. |
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| 26. |
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| 27. |
- Gustavsson, Larisa, et al.
(författare)
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Odla blåbär i trädgården
- 2009
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Ingår i: Fakta. Trädgård / fritid. - 1102-1969.
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Annan publikation (populärvet., debatt m.m.)
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| 28. |
- Gustavsson, Larisa, et al.
(författare)
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Resistance to Neonectria ditissima in apple : insights from metabolomics and lipidomics analyses
- 2023
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Ingår i: Xxxi international horticultural congress (ihc2022). - : International Society for Horticultural Science. - 9789462613614 ; , s. 329-335, s. 329-336
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Konferensbidrag (refereegranskat)abstract
- European canker, caused by the necrotrophic fungus Neonectria ditissima, is the most serious disease in apple production in Sweden. The disease is favored by a relatively cool and rainy climate. The canker damages have a significant economic impact due to reduced bearing surface and increased orchard management costs. The possibilities for chemical and biological control are very limited. Therefore, directed breeding for new resistant cultivars is urgently needed. Knowledge of inheritance of canker resistance and understanding of molecular mechanisms involved in resistant and susceptible responses to fungal attacks would facilitate breeding. In this study, we evaluated the tempo-spatial differences in plant-pathogen interactions in a set of partially resistant and susceptible cultivars by conducting metabolomic and lipidomic analyses. The major trends in metabolomics and lipidomic profiles were common among cultivars, irrespective of the degree of susceptibility. Several metabolites and lipids varied with time point and cultivar under N. ditissima infection. Putative key metabolites such as suberic acid and jasmonic acid were upregulated in all cultivars upon infection. Additionally, several lipids exhibited changes 30 to 45 days post-inoculation. Thus, the approach used seems to have resulted in a rich data set to be further analyzed in light of ongoing QTL-mapping efforts.
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| 29. |
- Gustavsson, Larisa, et al.
(författare)
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Screening of Apple Cultivars for Resistance to European Canker, Neonectria ditissima
- 2013
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 976, s. 529-536
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Konferensbidrag (refereegranskat)abstract
- European canker, caused by the fungus Neonectria ditissima, is a severe problem in apple production both in Sweden and in many other northern European countries. Even when applying fungicides and good horticultural practices, canker damage occurs almost yearly in nurseries and orchards. Some years, devastating outbreaks destroy numerous trees. To date, complete resistance to N. ditissima is not known in apple. For further research and plant breeding, heritable variation in quantitative resistance should be investigated by phenotyping large sets of cultivars. In the present project, 55 apple cultivars were screened for resistance to N. ditissima. One-year-old shoots from mature trees were inoculated in the greenhouse with a standardized volume and concentration of conidia suspension using different inoculation methods. Two-year-old trees of five cultivars were inoculated in the field. Length of the occurring cankers was measured at regular intervals throughout a period of up to three months. The investigated cultivars showed considerable differences in colonization rate. In cultivars known to be highly resistant, i.e., 'Santana', lesions progressed much slower compared to susceptible cultivars like 'Cox's Orange Pippin' and 'James Grieve'. Since the inoculation-based phenotyping is demanding in labour and time (duration), especially when the test is performed on grafted trees, qPCR-based assessment of fungal biomass at early stages of infection was explored as an alternative or complementary approach for phenotyping.
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| 30. |
- Gustavsson, Larisa, et al.
(författare)
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Varför äpplen på banken?
- 2011
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Ingår i: Pomologen. - 1650-9455. ; 11, s. 10-15
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 31. |
- Hegay, Sergay, et al.
(författare)
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Comparing genetic diversity and population structure of common beans grown in Kyrgyzstan using microsatellites
- 2012
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Ingår i: Scientific Journal of Crop Science. - 2322-1690. ; 1, s. 63-75
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Tidskriftsartikel (refereegranskat)abstract
- Common bean (Phaseolus vulgaris L.) is an important export crop in Kyrgyzstan. The aim of this study was to assess the extent of genetic diversity, determine the population structure, and relate to the main gene pools grown in Kyrgyzstan. Twenty-eight common bean accessions (including five Kyrgyz cultivars, and main references from the Mesoamerica and South America) were evaluated with microsatellites. Nine polymorphic microsatellites were used to estimate genetic diversity and heterozygosity. The number of alleles per microsatellite locus ranged from 2 to 4 and there were a total of 24 alleles. The observed heterozygosity of each accession over all loci ranged from 0 to 0.11 (with an average of 0.01), while the expected average heterozygosity was 0.05, which could reflect the self-pollinating breeding behavior of common beans. The analysis of molecular variance further revealed that 94.71% of the total variation was accounted by differences among accessions (Fst =0.947; p<0.001). Cluster analysis grouped accessions in two gene pools: 16 belong to the Andean and 12 to the Mesoamerican gene pool. The microsatellites separated accessions in Mesoamerican gene pool from Durango and Jalisco races, which were grouped together. We also observed that the most divergent accessions were the Kyrgyz cultivars, which may be related to the Mesoamerican races. Andean accessions were less diverse than Mesoamerican accessions in this study. This research confirms the ability of microsatellites to differentiate common bean accessions, even using a small sample size, and to be able to assign modern cultivars to their gene pools or races.
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| 32. |
- Hegay, Sergay, et al.
(författare)
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Genetic diversity analysis in Phaseolus vulgaris L. using morphological traits
- 2014
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Ingår i: Genetic Resources and Crop Evolution. - : Springer Science and Business Media LLC. - 0925-9864 .- 1573-5109. ; 61, s. 555-566
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Tidskriftsartikel (refereegranskat)abstract
- Common bean (Phaseolus vulgaris) is an important export crop in Kyrgyzstan since the end of the twentieth century. Genetic diversity analysis of common bean populations is useful for breeding programs, as it helps to select genetic material to be used for further crossing. Twenty-seven common bean accessions were analyzed using 13 qualitative morphological traits. In some cases, obtained morphological data were combined with previously published results based on microsatellite markers. The similarity matrices generated from the molecular and morphological data were significantly correlated (r = 0.49, P < 0.01). Cluster analyses based on Dice's similarity coefficient were constructed based on morphological data and the combined data set of morphology and microsatellite, and both grouped the 27 accessions according to their origin: 15 belonged to the Andean and 12 to the Mesoamerican gene pool. On average, the Andean accessions were less diverse than the Mesoamerican accessions. The average diversity based on the Shannon diversity index for the 13 qualitative morphological traits was 0.05. Overall, this study revealed that qualitative morphological markers are efficient in assigning modern cultivars to their gene pools of origin.
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| 33. |
- Hegay, Sergay, et al.
(författare)
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Introducing host-plant resistance to anthracnose in Kyrgyz common bean through inoculation-based and marker-aided selection
- 2014
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Ingår i: Plant Breeding. - : Wiley. - 0179-9541 .- 1439-0523. ; 133, s. 86-91
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Tidskriftsartikel (refereegranskat)abstract
- Common bean (Phaseolus vulgaris L.) is one of the most important legume crops for human consumption. However, its grain yield can be reduced by up to 90% by the seedborne disease, anthracnose. Fungicide treatment is costly and time-consuming. The introduction of host plant resistance against this disease appears, therefore, to be crucial for enhancing the productivity of this crop in Kyrgyzstan. The use of DNA-based markers in backcrossing programmes may help speed up the breeding for resistance. In this study, we used a combination of inoculation tests and a DNA marker (SCAreoli marker) to track the transfer of host-plant resistance (Co-2 gene) from two donor cultivars, Vaillant' and Flagrano', to susceptible Kyrgyz cultivars Ryabaya', Kytayanka' and Lopatka', which are widely grown in the country. The segregating offspring were evaluated to test the reliability of the SCAreoli marker as selection aid for host-plant resistance to anthracnose. Our study showed that a co-dominant DNA marker can successfully be used in backcross breeding to distinguish segregating material in different market classes of common bean.
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| 34. |
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| 35. |
- Husenov, Bahromiddin, et al.
(författare)
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Breeding for wheat quality to assure food security of a staple crop: the case study of Tajikistan
- 2015
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Ingår i: Agriculture and Food Security. - : Springer Science and Business Media LLC. - 2048-7010. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background: This study evaluated options and obstacles to strengthening food security through breeding a staple crop in a developing country, using the case of quality of bread wheat in Tajikistan as an example. Methods: Three wheat varieties and 19 breeding lines were collected from two field trial locations included in the Tajik wheat breeding programme. Grain protein composition as a measure of quality was determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Payne scores were calculated in order to predict quality. Results: There was high variation between and high heterogeneity within several lines and varieties in relation to protein composition. Differences between the same varieties/lines at different locations were also observed. The number of grains analysed from each variety/line allowed prediction of quality, and the majority of materials analysed showed high Payne scores. Based on Payne scores and cluster analyses, a group of varieties/lines with high quality was identified as interesting for further breeding. Conclusions: This study demonstrated the importance of improving wheat maintenance breeding and early generation seed production and of developing suitable screening methods for quality to secure food supply in developing countries such as Tajikistan.
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| 36. |
- Husenov, Bahromiddin, et al.
(författare)
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Constraints and Perspectives for Sustainable Wheat Production in Tajikistan
- 2020
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Ingår i: Frontiers in sustainable food systems. - : Frontiers Media SA. - 2571-581X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Wheat is a major crop with a key role for food security in Tajikistan, contributing 60% of daily calorie intake for the Tajik population. A clear understanding of the major constraints and opportunities relating to wheat production and sustainability in farmers' fields is therefore required. A survey of 210 different wheat fields of different sizes, located in different agricultural zones in Tajikistan and at different altitudes, was conducted during three consecutive years (2012–2014). A questionnaire on wheat production and sustainability, seeking overall information about farms and specific data on crop management practices, was applied. It was accompanied by surveillance of field status concerning diseases, pests, weeds, and influence of abiotic stresses. In addition, a screening was carried out on major Tajik wheat varieties and advanced breeding lines, to assess their resistance to important diseases. The results showed that the agronomic knowledge of Tajik farmers was generally poor and that wheat yield was low, affecting social, economic, and environmental sustainability. The farms surveyed were generally small, growing winter wheat for human consumption year after year. Seeds were hand-broadcast at the optimal sowing time, without chemical treatments and either wheat or technical crops were used as preceding crops. Most farmers used nitrogen fertilizer and irrigation but no weed treatment. The low knowledge status of wheat farmers influenced crop performance and were correlated with lack of crop rotation, while the lack of pest management resulted in high levels of weeds and severe insect damage. While some similarities were shared by most wheat fields surveyed, there was also some variation in wheat crop performance among farms in relation to their size, year of study, agricultural zone, and altitude. Wheat production on small farms still relied heavily on manual labor, while larger farms used more machinery. However, larger farms were not more successful wheat producers than small farms. Most of the Tajik wheat varieties and lines screened were found to be susceptible to at least one of the diseases screened for, i.e., stripe rust, leaf rust, and common bunt. Our findings demonstrate a need for concerted action to overcome wheat yield constraints and achieve sustainability in crop production in Tajikistan. Education of farmers appears key to improving social, economic, and environmental sustainability. Use of certified seed of suitable wheat varieties and appropriate crop management practices, including weed control while also taking biodiversity into consideration, are other important measures for increasing wheat yield and improving sustainability.
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| 37. |
- Husenov, Bahromiddin, et al.
(författare)
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Evaluation and managing wheat seed-borne diseases: options and suggestions from the case of Tajikistan.
- 2017
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Ingår i: Cereal Research Communications. - : Springer Science and Business Media LLC. - 0133-3720 .- 1788-9170. ; 45, s. 124-138
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Tidskriftsartikel (refereegranskat)abstract
- Wheat seed-borne diseases are among the major constraints reducing crop yield and the quality of seed and grain. In this study we aimed to evaluate the type and prevalence of fungal seed-borne diseases in Tajik wheat seed samples. Particular emphasis was given to common bunt resistance in advanced wheat breeding materials. Furthermore, we aimed to identify options for improving the seed quality. Seed samples collected from two different locations in Tajikistan were tested by conventional seed-health testing methods for presence of seed-borne diseases. Nineteen advanced wheat breeding lines and three varieties collected from the Tajik wheat breeding program were screened using an artificial inoculation test for their response to common bunt. Significant differences were found between the locations and genotypes concerning presence of common bunt and black point. Fourteen fungal species, where most of them are pathogenic for wheat, were identified in the seed samples. Tilletia laevis, T. tritici, Bipolaris sorokiniana, Stemphylium spp., and Drechslera spp. were the major pathogenic fungi observed in collected wheat samples. Common bunt was predominantly represented by T. laevis. No strong resistance was found in the studied Tajik wheat material, although a low percentage of infection was found in one line (SHARK/F4105W2.1), while the material was evaluated for common bunt resistance. In managing seed-borne diseases, breeding of resistant varieties should be given a priority, while cultural practices such as preventing contamination and monitoring seed health status should also be considered, as a last resort the use of chemical seed treatments are advised.
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| 38. |
- Husenov, Bahromiddin, et al.
(författare)
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Sustainable Wheat Production and Food Security of Domestic Wheat in Tajikistan: Implications of Seed Health and Protein Quality
- 2021
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Ingår i: International journal of environmental research and public health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Staple crop yield, quality and sustainable production are critical for domestic food security in developing countries. In Tajikistan, both seed-borne diseases and protein quality impair the yield and the quality of the major staple crop, wheat. Here, we used a detailed two-year survey of fields on 21 wheat-producing farms in Tajikistan, combined with lab analyses on seed health and protein quality, to investigate the presence of seed-borne diseases and bread-making quality in Tajik wheat. Seed samples were collected for the analysis of: (i) the presence of common bunt (Tilletia spp.) using the centrifuge wash test, (ii) the major pathogenic fungi on/in the seed using the agar plate test and (iii) the protein amount and size distribution using size-exclusion high-performance liquid chromatography (SE-HPLC). Field occurrence of common bunt and loose smut was generally low (3 farms in year one (14%) showed common bunt occurrence), but the presence of fungi was observed microscopically on most seed samples (on seeds from 19 out of 21 farms = 91%). Tilletia laevis was the dominant agent in common bunt (present in 19 farms compared to T. tritici present in 6 farms). Altogether, 18 different fungi were identified from seed samples by microscopy. Protein composition, measured with high-performance liquid chromatography as protein amount and size distribution (known to correlate with bread-making quality), differed significantly between samples from different farms and years, although the farm type and land elevation of the farm were not the determinants of the protein composition. The presence of certain fungi on the seed correlated significantly with the protein quality and could then have an impact on the bread-making quality of the Tajik wheat. The presence of seed-borne diseases, a low protein content and weak gluten were the characteristics of the majority of the grain samples, mostly irrespective of farm type and farmer's knowledge. For sustainable development of the Tajik farming systems, and to strengthen the food security of the country, the knowledge of Tajik farmers needs to be increased independently of farm type; in general, plant breeding is required and certified seeds need to be made available throughout the country.
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| 39. |
- Loots, Sonja, et al.
(författare)
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Distribution, habitat profile and genetic variability of Namibian succulent Lithops ruschiorum
- 2019
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Ingår i: Bothalia - African Biodiversity and Conservation. - : South African National Biodiversity Institute. - 0006-8241 .- 2311-9284. ; 49
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Tidskriftsartikel (refereegranskat)abstract
- Background: The species-rich flora of southern Africa comprises a high number of endemics, including succulents such as the flowering stones in the genus Lithops, but conservation status for these species is not well underpinned because detailed field data and assessments of genetic diversity are lacking.Objectives: We wanted to assess plant abundance and identify factors that may affect survival in Lithops ruschiorum through carefully conducted field surveys, and to determine amount and partitioning of genetic variation by amplified fragment length polymorphism (AFLP) analysis.Method: Field surveys were carried out in nine populations in Namibia. The most meticulously studied population was divided into 51 sites, while another 43 sites were recognised in the remaining eight populations. At each site, occupied area and number of plants were recorded as well as altitude, aspect, slope, soil texture and substrate. Amplified fragment length polymorphism markers were employed to study 52 individuals from seven populations. Results: In total, 8465 individuals were recorded. Plant density and/or plant number was associated with aspect, slope, soil texture, substrate and geographic distance from the coast. Analysis of molecular variation showed that 95% of the variability occurs within populations. Genetic and geographic distances among populations were correlated suggesting an isolation-by-distance pattern.Conclusion: Results are concordant with a strong impact of fog-based precipitation on plant density in the coastal populations, whereas rain probably is more important at one population which is situated further inland. Within-population genetic variation was medium high as usually reported for perennial, outcrossing species, but the low population differentiation implies considerable gene flow and/or population fragmentation.
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| 40. |
- Mujaju, Claid, et al.
(författare)
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Genetic diversity among and within watermelon (Citrullus lanatus) landraces in Southern Africa
- 2011
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Ingår i: Journal of Horticultural Science and Biotechnology. - : Informa UK Limited. - 1462-0316 .- 2380-4084. ; 86, s. 353-358
-
Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity in watermelon (Citrullus lanatus) was estimated among 213 seedlings from 22 accessions collected in Botswana, Namibia, South Africa, Zambia, and Zimbabwe. The accessions consisted of two types of watermelon landraces: sweet watermelon (C. lanatus var. lanatus) and cow-melon (C. lanatus var. citroides), also known as citron melon. In addition, three commercial varieties of C. lanatus var. lanatus from the USA were included for comparison. Ten simple sequence repeat (SSR; microsatellite) loci detected a total of 153 alleles. The polymorphic information content (PIC) ranged from 0.833 - 0.963, suggesting sufficient discriminatory power. Both a cluster analysis and a principal co-ordinate analysis produced two major clusters, one with the 13 cow-melon accessions and the other with the 12 sweet watermelon accessions. Within the sweet watermelon cluster, the three US cultivars grouped together with the Botswana accessions. Some of the other accessions also grouped according to their country of origin, but others did not. Within-accession diversity parameters showed that those sweet watermelon accessions found in traditional agrosystems were just as genetically variable as the cow-melon accessions.
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| 41. |
- Mujaju, Claid, et al.
(författare)
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Genetic diversity in watermelon (Citrullus lanatus) landraces from Zimbabwe revealed by RAPD and SSR markers
- 2010
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Ingår i: Hereditas. - : Springer Science and Business Media LLC. - 0018-0661 .- 1601-5223. ; 147, s. 142-153
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Tidskriftsartikel (refereegranskat)abstract
- Low polymorphism in cultivated watermelon has been reported in previous studies, based mainly on US Plant Introductions and watermelon cultivars, most of which were linked to breeding programmes associated with disease resistance. Since germplasm sampled in a putative centre of origin in southern Africa may harbour considerably higher variability, DNA marker-based diversity was estimated among 81 seedlings from eight accessions of watermelon collected in Zimbabwe; five accessions of cow-melons (Citrullus lanatus var. citroides) and three of sweet watermelons (C. lanatus var. lanatus). Two molecular marker methods were used, random amplified polymorphic DNA (RAPD) and simple sequence repeats (SSR) also known as microsatellite DNA. Ten RAPD primers produced 138 markers of which 122 were polymorphic. Nine SSR primer pairs detected a total of 43 alleles with an average of 4.8 alleles per locus. The polymorphic information content (PIC) ranged from 0.47 to 0.77 for the RAPD primers and from 0.39 to 0.97 for the SSR loci. Similarity matrices obtained with SSR and RAPD, respectively, were highly correlated but only RAPD was able to provide each sample with an individual-specific DNA profile. Dendrograms and multidimensional scaling (MDS) produced two major clusters; one with the five cow-melon accessions and the other with the three sweet watermelon accessions. One of the most variable cow-melon accessions took an intermediate position in the MDS analysis, indicating the occurrence of gene flow between the two subspecies. Analysis of molecular variation (AMOVA) attributed most of the variability to within-accessions, and contrary to previous reports, sweet watermelon accessions apparently contain diversity of the same magnitude as the cow-melons.
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| 42. |
- Mujaju, Claid, et al.
(författare)
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Molecular and farmer-based comparison of a wild-weed and landrace complex of watermelon in Zimbabwe
- 2012
-
Ingår i: Australian Journal Of Crop Science. - 1835-2693 .- 1835-2707. ; 6, s. 656-661
-
Tidskriftsartikel (refereegranskat)abstract
- Traditional farming systems have been associated with the occurrence of intervarietal and interspecific natural crosses in many crop plants, thus contributing to the genetic diversity of the crop through genetic exchange. In this study, a combination of farmerpreferred morphological traits and RAPD markers were used to evaluate the dynamics of genetic diversity in 43 watermelon accessions collected at a single village level with a traditional farming system. The molecular variability assessed with RAPD markers and analyzed with multidimensional scaling and cluster analysis, demonstrated a substantial differentiation among the accessions. Population structure analysis also demonstrated the existence of three major forms of watermelon, identified by a set of alleles predominant within each form. Dendrograms based on RAPD data and on farmer-preferred traits data were positively correlated according to a Mantel test. Although cultivated cow-melons were genetically most similar to wild-weedy plants at molecular level, they grouped more similar to sweet watermelons based on farmer-preferred traits. The present study revealed limited gene flow between three forms of watermelon and provides insight into how the genetic differentiation corresponds to farmers’ classification of watermelons
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| 43. |
- Mujaju, Claid, et al.
(författare)
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Variationsrika vattenmeloner i södra Afrika
- 2012
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Ingår i: LTJ-fakultetens faktablad.
-
Annan publikation (populärvet., debatt m.m.)abstract
- På soliga semesterresor till varmare länder, har allt fler svenskar lärt sig att uppskatta de stora, läskande vattenmelonerna. Ingenting släcker törsten bättre, och säkrare, än en generös skiva saftig vattenmelon med sitt karaktäristiska spröda och rosaröda fruktkött. Tillgången är inget problem; det finns knappast något tropiskt eller subtropiskt land (vattenmelon växer bäst vid 20–30 °C) som inte kan erbjuda lokalodlade vattenmeloner. Minst 55 länder producerar vattenmeloner, och den samlade produktionen beräknas till över 100 millioner ton per år. I odlingsanalyser betraktas vattenmelon som en grönsak, och den odlas på drygt 10% av den areal som används till grönsaker
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| 44. |
- Nordlander, Josefine, et al.
(författare)
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Genetic diversity in gooseberry (Ribes uva-crispa), as estimated with SSR markers
- 2022
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Ingår i: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 306
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Tidskriftsartikel (refereegranskat)abstract
- European gooseberry (Ribes uva-crispa L.) is a popular berry crop in many European countries, including Sweden, Denmark and Ukraine. There is no active gooseberry breeding programme in either Sweden or Denmark, but a successful programme is operating in Ukraine. In Sweden and Denmark, research on gooseberries is primarily focused on collection and phenotypic evaluation of genetic resources. As part of these activities, a large number of inventory finds have been collected but have not yet been characterised morphologically or molecularly. The goal of this study was thus to characterise gooseberry germplasm with 15 simple sequence repeat (SSR) markers. From 242 accessions analysed, 153 unique genotypes were identified. Cultivars that have been in widespread cultivation in Sweden, such as the Finnish cultivars ‘Hinnonmäen Keltainen’ and ‘Hinnonmäen Punainen’, had relatively large numbers of synonymous samples. While many inventory finds were identifiable as synonyms of known cultivars, several were found to constitute unique genotypes within the germplasm studied. The studied genotypes clustered relatively well in three posterior groups, consisting of cultivars originating before and after the American gooseberry mildew (Sphaerotheca mors-uvae) outbreak around 1900 and cultivars originating from the territory of the former Soviet Union. A fourth genetic cluster consisting mainly of inventory finds from central and northern Sweden was also identified. In addition, it was possible to verify recorded and stipulated parentages for some of the cultivars studied and to identify three likely parent-parent-child trios. Thus, inventories of local gooseberry germplasm and a subsequent genotyping proved successful in finding unique local genotypes, with potential local adaptation. The data obtained provide a foundation for future studies of gooseberry genetic resources, while also illustrating the importance of a well-curated and phenotypically characterised set of reference cultivars for future studies.
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| 45. |
- Nybom, Hilde, et al.
(författare)
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Analysis of the genetic diversity and structure across a wide range of germplasm reveals prominent gene flow in apple at the European level
- 2016
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: The amount and structure of genetic diversity in dessert apple germplasm conserved at a European level is mostly unknown, since all diversity studies conducted in Europe until now have been performed on regional or national collections. Here, we applied a common set of 16 SSR markers to genotype more than 2,400 accessions across 14 collections representing three broad European geographic regions (North + East, West and South) with the aim to analyze the extent, distribution and structure of variation in the apple genetic resources in Europe.Results: A Bayesian model-based clustering approach showed that diversity was organized in three groups, although these were only moderately differentiated (F-ST = 0.031). A nested Bayesian clustering approach allowed identification of subgroups which revealed internal patterns of substructure within the groups, allowing a finer delineation of the variation into eight subgroups (F-ST = 0.044). The first level of stratification revealed an asymmetric division of the germplasm among the three groups, and a clear association was found with the geographical regions of origin of the cultivars. The substructure revealed clear partitioning of genetic groups among countries, but also interesting associations between subgroups and breeding purposes of recent cultivars or particular usage such as cider production. Additional parentage analyses allowed us to identify both putative parents of more than 40 old and/or local cultivars giving interesting insights in the pedigree of some emblematic cultivars.Conclusions: The variation found at group and subgroup levels may reflect a combination of historical processes of migration/selection and adaptive factors to diverse agricultural environments that, together with genetic drift, have resulted in extensive genetic variation but limited population structure. The European dessert apple germplasm represents an important source of genetic diversity with a strong historical and patrimonial value. The present work thus constitutes a decisive step in the field of conservation genetics. Moreover, the obtained data can be used for defining a European apple core collection useful for further identification of genomic regions associated with commercially important horticultural traits in apple through genome-wide association studies.
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| 46. |
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| 47. |
- Nybom, Hilde, et al.
(författare)
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Assessment of fire blight tolerance in apple based on plant inoculations with Erwinia amylovora and DNA markers
- 2012
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Ingår i: Trees - Structure and Function. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 26, s. 199-213
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Tidskriftsartikel (refereegranskat)abstract
- Fire blight (Erwinia amylovora) causes serious damage to pome fruit orchards, and identification of germplasm with heritable disease resistance is therefore crucial. Two dominant SCAR (sequence characterised amplified region) marker alleles (AE10-375 and GE-8019), flanking a previously identified QTL (quantitative trait locus) for resistance to fire blight on ‘Fiesta’ linkage group 7 in apple cultivars related to ‘Cox’s Orange Pippin’, were screened on 205 apple cultivars. Both marker alleles were present in 22% of the cultivars, indicating presence of the QTL allele for tolerance, and both were lacking in 25%, indicating homozygosity for absence of the QTL tolerance allele. However, 33% had only the marker allele AE10-375, while 20% had only GE-8019, suggesting that some cultivars with the dominant alleles for both of the flanking markers can carry these on separate chromosomes and may lack the QTL allele for tolerance. In 2009 and 2010, terminal shoots of greenhouse-grown grafted trees of 21 cultivars (only 20 in 2010) were inoculated with Erwinia amylovora. ‘Idared’ (susceptible) and ‘Enterprise’ (tolerant) were included as controls. Disease severity for each cultivar was expressed as percentage of necrosis in relation to entire length of shoot, and the ranking of cultivars in 2009 and 2010 was compared with a Spearman rank correlation test,P<0.01. A relationship between presence of both flanking marker alleles for tolerance and level of fire blight tolerance was confirmed with a Mann–Whitney U-test,P<0.01 in 2009, andP<0.05 in 2010. A PCO (principal coordinate) analysis based on band profiles obtained with 12 SSR (simple sequence repeat) loci produced three loose clusters, two of which contained known offspring of ‘Cox’s Orange Pippin’, and one with cultivars that were either unrelated or had an unknown origin. Cases where DNA markers did not predict level of fire blight damage as expected, were, however, as common among descendants of ‘Cox’s Orange Pippin’ as among apparently unrelated cultivars. Obviously the ‘Fiesta’ LG 7 QTL has some predictive value, both for known ‘Cox’ relatives and others, but more efficient markers would be desirable for marker-assisted selection.
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| 48. |
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| 49. |
- Nybom, Hilde, et al.
(författare)
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Genome-Wide Association Mapping of Flowering and Ripening Periods in Apple
- 2017
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Deciphering the genetic control of flowering and ripening periods in apple is essential for breeding cultivars adapted to their growing environments. We implemented a large Genome-Wide Association Study (GWAS) at the European level using an association panel of 1,168 different apple genotypes distributed over six locations and phenotyped for these phenological traits. The panel was genotyped at a high-density of SNPs using the Axiom (R) Apple 480 K SNP array. We ran GWAS with a multi-locus mixed model (MLMM), which handles the putatively confounding effect of significant SNPs elsewhere on the genome. Genomic regions were further investigated to reveal candidate genes responsible for the phenotypic variation. At the whole population level, GWAS retained two SNPs as cofactors on chromosome 9 for flowering period, and six for ripening period (four on chromosome 3, one on chromosome 10 and one on chromosome 16) which, together accounted for 8.9 and 17.2% of the phenotypic variance, respectively. For both traits, SNPs in weak linkage disequilibrium were detected nearby, thus suggesting the existence of allelic heterogeneity. The geographic origins and relationships of apple cultivars accounted for large parts of the phenotypic variation. Variation in genotypic frequency of the SNPs associated with the two traits was connected to the geographic origin of the genotypes (grouped as North+East, West and South Europe), and indicated differential selection in different growing environments. Genes encoding transcription factors containing either NAG or MADS domains were identified as major candidates within the small confidence intervals computed for the associated genomic regions. A strong microsynteny between apple and peach was revealed in all the four confidence interval regions. This study shows how association genetics can unravel the genetic control of important horticultural traits in apple, as well as reduce the confidence intervals of the associated regions identified by linkage mapping approaches. Our findings can be used for the improvement of apple through marker-assisted breeding strategies that take advantage of the accumulating additive effects of the identified SNPs.
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| 50. |
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