| 1. |
- Albertsson, Johannes, et al.
(författare)
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Effects of competition between short-rotation willow and weeds on performance of different clones and associated weed flora during the first harvest cycle
- 2014
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 70, s. 364-372
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the ability of willow clones to compete with weeds, willow shoot biomass and plant mortality were measured over the first harvest cycle for 10 commercial and two breeding clones at three different sites in southern Sweden. Two levels of weed pressure (weeded and not weeded) were employed and the effects of cutback or not after the first growing season were compared for willow clones under weed pressure. There were significant differences between clones in their ability to compete with weeds, measured as willow shoot growth reduction in plots with weeds, at two of the three sites. However, shoot biomass reduction due to weeds was large in all the clones, with Stina and SW Inger among the least affected. Mean shoot growth reduction after the first harvest cycle for the commercial clones was 68.3%, 91.2% and 94.3% at the three sites and the corresponding plant mortality was 9.8%, 57.3% and 56.2% under weed pressure. Significant clonal differences in yield, under weed-free conditions, were found at all three sites. Significant clonesite interactions were found for both growth reduction and biomass production. Cutting back shoots after the establishment season, under weed pressure, resulted in higher mean plant mortality and lower mean willow shoot biomass after one harvest cycle at two of the three sites. The weed flora was initially dominated by annuals, but became dominated by perennial weeds during the first harvest cycle. (C) 2014 Elsevier Ltd. All rights reserved.
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| 2. |
- Albertsson, Johannes, et al.
(författare)
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Effects of mechanical weed control or cover crop on the growth and economic viability of two short-rotation willow cultivars
- 2016
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 91, s. 296-305
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Tidskriftsartikel (refereegranskat)abstract
- Willow grown as short rotation coppice (SRC) is sensitive to weed competition, so herbicide treatment combined with mechanical weed control is recommended when establishing a plantation. This study compares that practice with two mechanical, row crop cultivator (RC) and row crop cultivator with torsion weeder (RCT), and two cultural treatments, cover crop (CC) and cut cover crop (CCC), to control weeds. Willow responses to these treatments were compared during the first three years after planting using two cultivars, Gudrun and Tordis with broad and narrow leaves, respectively. At harvest, the RCT treatment had produced 27% more biomass than the RC treatment (13.9 vs 11.0 Mg ha(-1) dry matter) and approximately three times more than the cultural treatments. However, the standard control treatment, herbicides and row crop cultivator (HRC), produced more than all other treatments (17.3 Mg ha(-1) dry matter). The two cultural treatments had higher plant mortality (CC 26.2% and CCC 32.8%) than the other treatments (HRC 2.7%, RC 7.0% and RCT 7.0%) after the first harvest cycle. No interaction between cultivar and treatment was found for willow shoot biomass, weed biomass or plant mortality. Overall, however, Gudrun had lower plant mortality and less weed biomass after the first harvest cycle than Tordis. All treatment and cultivar combinations gave positive financial annual returns when the whole life-span of the plantation was considered. This study suggests that without using herbicides, it is possible to establish a willow SRC plantation that produce enough to be economically viable. (C) 2016 Elsevier Ltd. All rights reserved.
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| 3. |
- Albertsson, Johannes, et al.
(författare)
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Site-related set-back by weeds on the establishment of 12 biomass willow clones
- 2014
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Ingår i: Weed Research. - : Wiley. - 0043-1737 .- 1365-3180. ; 54, s. 398-407
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Tidskriftsartikel (refereegranskat)abstract
- Ten commercial clones of willow and two breeding clones were studied for their ability to compete with weeds during the establishment year at three different sites in southern Sweden. Cuttings were planted according to commercial practice in April, and the two treatments, 'Weeded' and 'Unweeded', were laid out in a strip-plot design. Weeds in the 'Weeded' treatment were removed mechanically and by hand hoeing. Willow plant shoot weight and plant mortality were measured after the first growing season to evaluate the initial effect of weeds. In addition, weed flora, weed aboveground biomass, soil properties, shoot damage and soil moisture were assessed during the growing season. Plant mortality was <1% in the 'Weeded' treatment at the three study sites, while in 'Unweeded' it was significantly higher, 2.7%, 24.6% and 37.4%. Weeds reduced willow plant shoot weight by 93.4%, 94.0% and 96.1% at the three sites. Only one site showed clonal differences in shoot growth reduction, as well as in plant mortality. These results show the importance of weed control in willow plantations, as growth of all clones tested were dramatically hampered by weeds during the first growing season, regardless of trial site conditions. Moreover, conditions at certain sites, such as soil properties in combination with weed cover, may cause high plant mortality during the establishment year in this perennial biomass crop.
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| 4. |
- Bengtsson, Therese, et al.
(författare)
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A Novel QTL for Powdery Mildew Resistance in Nordic Spring Barley (Hordeum vulgare L. ssp. vulgare) Revealed by Genome-Wide Association Study
- 2017
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The powdery mildew fungus, Blumeria graminis f. sp. hordei is a worldwide threat to barley (Hordeum vulgare L. ssp. vulgare) production. One way to control the disease is by the development and deployment of resistant cultivars. A genome-wide association study was performed in a Nordic spring barley panel consisting of 169 genotypes, to identify marker-trait associations significant for powdery mildew. Powdery mildew was scored during three years (2012-2014) in four different locations within the Nordic region. There were strong correlations between data from all locations and years. In total four QTLs were identified, one located on chromosome 4H in the same region as the previously identified mlo locus and three on chromosome 6H. Out of these three QTLs identified on chromosome 6H, two are in the same region as previously reported QTLs for powdery mildew resistance, whereas one QTL appears to be novel. The top NCBI BLASTn hit of the SNP markers within the novel QTL predicted the responsible gene to be the 26S proteasome regulatory subunit, RPN1, which is required for innate immunity and powdery mildew-induced cell death in Arabidopsis. The results from this study have revealed SNP marker candidates that can be exploited for use in marker-assisted selection and stacking of genes for powdery mildew resistance in barley.
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| 5. |
- Bengtsson, Therese, et al.
(författare)
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Genetic diversity, population structure and linkage disequilibrium in Nordic spring barley (Hordeum vulgare L. subsp vulgare)
- 2017
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Ingår i: Genetic Resources and Crop Evolution. - : Springer Science and Business Media LLC. - 0925-9864 .- 1573-5109. ; 64, s. 2021-2033
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Tidskriftsartikel (refereegranskat)abstract
- Genetic diversity, population structure and genome-wide linkage disequilibrium (LD) was estimated in Nordic spring barley (Hordeum vulgare L. subsp. vulgare) by genotyping 180 breeding lines with 48 SSR markers and 7842 high-confidence SNPs using the Illumina Infinium 9K assay. In total 6208 SNPs were polymorphic and selected for further statistical analysis. A Mantel test revealed a strong positive correlation with a Pearson's correlation coefficient (r) of 0.86, between the estimates of genetic distances based on SSR and SNP data. Population structure analysis identified two groups with a clear ancestry and one group with an admixed ancestry. The groups were primarily separated based on row-type and geographical origin. Average LD for the whole population decayed below a critical level of r(2) = 0.20 within a range of 0-4 cM. To avoid confounding effects of the strong population structure, LD decay for the different groups was analysed separately and ranged from 0 to 12 cM. A slower LD decay was found within the two-rowed lines compared to the six-rowed lines and the two-rowed lines originating from the northern part, which could be the result of strong selection for malting quality and yield in the southern part. No large difference in genetic diversity was observed between population sub-groups, but differences at certain chromosomal regions were evident.
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| 6. |
- Berlin Kolm, Sofia, et al.
(författare)
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Genetic diversity, population structure and phenotypic variation in European Salix viminalis L. (Salicaceae)
- 2014
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Ingår i: Tree Genetics & Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 10:6, s. 1595-1610
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the potential of association genetics for willow breeding, Salix viminalis germplasm was assembled from UK and Swedish collections (comprising accessions from several European countries) and new samples collected from nature. A subset of the germplasm was planted at two sites (UK and Sweden), genotyped using 38 SSR markers and assessed for phenological and biomass traits. Population structure, genetic differentiation (F-ST) and quantitative trait differentiation (Q(ST)) were investigated. The extent and patterns of trait adaptation were assessed by comparing F-ST and Q(ST) parameters. Of the 505 genotyped diploid accessions, 27 % were not unique. Genetic diversity was high: 471 alleles was amplified; the mean number of alleles per locus was 13.46, mean observed heterozygosity was 0.55 and mean expected heterozygosity was 0.62. Bayesian clustering identified four subpopulations which generally corresponded to Western Russia, Western Europe, Eastern Europe and Sweden. All pairwise F-ST values were highly significant (p<0.001) with the greatest genetic differentiation detected between the Western Russian and the Western European subpopulations (F-ST = 0.12), and the smallest between the Swedish and Eastern European populations (F-ST = 0.04). The Swedish population also had the highest number of identical accessions, supporting the view that S. viminalis was introduced into this country and has been heavily influenced by humans. Q(ST) values were high for growth cessation and leaf senescence, and to some extent stem diameter, but low for bud burst time and shoot number. Overall negative clines between longitudinal coordinates and leaf senescence, bud burst and stem diameter were also found.
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| 7. |
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| 8. |
- 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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| 9. |
- Crespo, Leonardo, et al.
(författare)
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Field population development of bird cherry-oat aphid and greenbug (Hemiptera: Aphididae) on wheat-alien substitution and translocation lines
- 2015
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Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 203, s. 249-260
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Tidskriftsartikel (refereegranskat)abstract
- The aphids Rhopalosiphum padi L. and Schizaphis graminum (Rondani) are destructive pests of wheat (Triticum aestivum L.). In field trials in north-west Mexico, we examined the development of R. padi and S. graminum populations on six wheat genotypes that had previously been assessed for aphid resistance under controlled conditions. Five of these wheat genotypes carried different alien translocations in the genetic background of the spring wheat cultivar Pavon F76, which was used as the control. The trials were established in a randomized complete block design and repeated in three successive sowings. Aphids were sampled weekly from tillering stage until collapse of the aphid populations in the control. Number of aphid-days (i.e. the area under the curve of aphids per tiller) was calculated to compare population sizes. Genotypes 1AL.1RS(e) and (1D)1R(pr) significantly reduced R. padi populations across all sowing dates, by 32.8 and 24.1 %, respectively, compared with the control. Interaction between the wheat genotypes and sowing had a significant effect on the aphid-days of S. graminum. Genotype 7A.7S-L5 with Aegilops speltoides Tausch chromatin significantly reduced the S. graminum population by between 48.5 and 74.8 % in the three sowings compared with the control. These three wheat genotypes were also previously characterized as resistant in laboratory trials and can be considered promising resistance sources to R. padi and S. graminum in wheat breeding programs.
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| 10. |
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| 11. |
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| 12. |
- 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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| 13. |
- Crespo, Leonardo, et al.
(författare)
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Resistance to multiple cereal aphids in wheat-alien substitution and translocation lines
- 2013
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Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 7, s. 535-545
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Tidskriftsartikel (refereegranskat)abstract
- Rhopalosiphum padi, Schizaphis graminum, and Sitobion avenae are three of the most destructive aphid species of wheat (Triticum aestivum L.). They can significantly reduce wheat yields directly by feeding and indirectly by transmitting viruses. This study aimed to search for resistance to these aphid species among lines derived from different rye (Secale cereale) origins and from Aegilops speltoides, all in the genetic background of the wheat cultivar Pavon F76. Resistance was quantified as aphid weight (R. padi, S. avenae, and S. graminum) and the number of aphids and percentage of infested leaf area exhibiting chlorosis (S. graminum). The most resistant genotypes reduced R. padi and S. avenae weight by 24.2 and 34.3 %, respectively, at the seedling stage, compared with Pavon F76 control plants. Strong S. graminum resistance was found only in A. speltoides-derived lines, the most resistant of which (7A.7S-L5) sustained just 3 % chlorosis and reduced S. graminum colony weight by 67.7 %. One line carrying the 1AL.1RS(am) wheat-rye translocation from Amigo wheat (originally from Insave rye) reduced S. avenae weight by 23.2 and 21.8 % in seedling and adult plants, respectively. Single genotypes carrying the complete 1R chromosome or the 1RS chromosome arm derived from E12165 wheat and Presto triticale proved to be resistant to both R. padi and S. avenae at the seedling stage. Further research should be conducted to unravel the genetic basis of resistance to these aphids in 1RS genotypes. The sources of resistance identified here may be useful for incorporating multiple aphid species resistance in wheat breeding programs, particularly for R. padi and S. avenae, to which no resistant wheats have been bred.
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| 14. |
- Delp, Gabriele, et al.
(författare)
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Microarray analysis of the interaction between the aphid Rhopalosiphum padi and host plants reveals both differences and similarities between susceptible and partially resistant barley lines
- 2009
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Ingår i: Molecular Genetics and Genomics. - : Springer Science and Business Media LLC. - 1617-4615 .- 1617-4623. ; 281:3, s. 233-248
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Tidskriftsartikel (refereegranskat)abstract
- The bird cherry-oat aphid (Rhopalosiphum padi L.) is an important pest on cereals causing plant growth reduction without specific leaf symptoms. Breeding of barley (Hordeum vulgare L.) for R. padi resistance shows that there are several resistance genes, reducing aphid growth. To identify candidate sequences for resistance-related genes, we performed microarray analysis of gene expression after aphid infestation in two susceptible and two partially resistant barley genotypes. One of the four lines is a descendant of two of the other genotypes. There were large differences in gene induction between the four lines, indicating substantial variation in response even between closely related genotypes. Genes induced in aphid-infested tissue were mainly related to defence, primary metabolism and signalling. Only 24 genes were induced in all lines, none of them related to oxidative stress or secondary metabolism. Few genes were down-regulated, with none being common to all four lines. There were differences in aphid-induced gene regulation between resistant and susceptible lines. Results from control plants without aphids also revealed differences in constitutive gene expression between the two types of lines. Candidate sequences for induced and constitutive resistance factors have been identified, among them a proteinase inhibitor, a serine/threonine kinase and several thionins.
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| 15. |
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| 16. |
- Kellner, Martin, et al.
(författare)
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Plant volatile-induced aphid resistance in barley cultivars is related to cultivar age
- 2010
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Ingår i: TAG Theoretical and Applied Genetics. - : Springer Science and Business Media LLC. - 0040-5752 .- 1432-2242. ; 121, s. 1133-1139
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that volatile chemical interaction between certain barley (Hordeum vulgare) cultivars can cause reduced host plant acceptance by the aphid Rhopalosiphum padi, and that certain cultivars can induce this effect while others can respond. In this study, we tested whether inducing and responding capabilities are linked to year of release in Swedish two-rowed spring barley. Eighteen cultivars released between 1897 and 1992 were tested in randomly selected subsets with pairwise combinations of volatile emitters and receivers. Significantly reduced aphid acceptance as a result of exposure to volatiles from plants of a different cultivar were found in 24% of the cultivar combinations. In general, older cultivars had a higher degree of aphid resistance after barley volatile treatment than did younger cultivars. The inducing effect of the emitter was also related to date of emitter cultivar release but the time relationship was reversed. Combinations with a younger volatile emitter and an older volatile receiver gave the strongest reduction in aphid acceptance of treated plants. Linear relationships between microsatellite diversity of emitting cultivars and their efficiency as inducers indicated that younger cultivars might have a more unique odour, whereas older cultivars may be more sensitive to induction.
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| 17. |
- Kim, Sung-Yong, et al.
(författare)
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Mutations in Two Aphid-Regulated β-1, 3-Glucanase Genes by CRISPR/Cas9 Do Not Increase Barley Resistance to Rhopalosiphum padi L
- 2020
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Callose deposition is induced in plants by various stress factors such as when plants are attacked by herbivores and pathogens. In the case of aphids, callose plugging of aphid-damaged phloem sieve tubes is expected to reduce aphid access to the phloem sap, while aphid-induced upregulation of callose-degrading beta-1,3-glucanase genes in the host plant might counteract this negative effect on aphid performance. We have tested this hypothesis with barley mutants in which one or both of two beta-1,3-glucanase genes (1636 and 1639) have been mutated by CRISPR/Cas9 technique in cv. Golden Promise. These two genes were previously found to be upregulated by the cereal pestRhopalosiphum padiL. in susceptible barley genotypes. Four 1636/1639 double mutant, three 1636 single mutant and two 1639 single mutant lines were tested for aphid resistance along with control lines. All mutant lines had single base insertions, causing frame shifts and premature stop codons. Three of the four double mutant lines showed significantly reduced beta-1,3-glucanase activity, and bacterial flagellin-induction resulted in significantly more callose formation in the leaves of double mutant compared to control and single mutant lines. However, we found no effect of these modified plant traits on barley resistance toR. padi. Both genes were confirmed to be upregulated byR. padiin Golden Promise. The gene 1637 is another beta-1,3-glucanase gene known to be upregulated byR. padiin barley and was here found to be higher expressed in a double mutant line when compared with a control line. If this can compensate for the general reduction of beta-1,3-glucanase activity in the double mutants is difficult to discern since phloem concentrations of these proteins are unknown.
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| 18. |
- Kushwaha, Sandeep Kumar, et al.
(författare)
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ResCap: plant resistance gene prediction and probe generation pipeline for resistance gene sequence capture
- 2021
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Ingår i: Bioinformatics Advances. - : Oxford University Press (OUP). - 2635-0041. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- The discovery of novel resistance genes (R-genes) is an important component in disease resistance breeding. Nevertheless, R-gene identification from wild species and close relatives of plants is not only a difficult but also a cumbersome process. In this study, ResCap, a support vector machine-based high-throughput R-gene prediction and probe generation pipeline has been developed to generate probes from genomic datasets. ResCap contains two integral modules. The first module identifies the R-genes and R-gene like sequences under four categories containing different domains such as TIR-NBS-LRR (TNL), CC-NBS-LRR (CNL), Receptor-like kinase (RLK) and Receptor-like proteins (RLPs). The second module generates probes from extracted nucleotide sequences of resistance genes to conduct sequence capture (SeqCap) experiments. For the validation of ResCap pipeline, ResCap generated probes were synthesized and a sequence capture experiment was performed to capture expressed resistance genes among six spring barley genotypes. The developed ResCap pipeline in combination with the performed sequence capture experiment has shown to increase precision of R-gene identification while simultaneously allowing rapid gene validation including non-sequenced plants.
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| 19. |
- Mehrabi, Sara, 1982-
(författare)
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Candidate genes for resistance and susceptibility to the bird cherry-oat aphid (Rhopalosiphum padi L.) in barley (Hordeum vulgare L.)
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bird cherry-oat aphid (Rhopalosiphum padi L.) is an important pest on spring-sown cereals. The aphid reduces yield and can act as a vector of barley yellow dwarf virus. R. padi does not give visible symptoms, but heavy infestation can reduce the yield substantially. R. padi is one of the most important pests of barley, which has the fourth rank among the cereals in global production. In order to overcome this problem, the plants are treated with pesticides. However, some of the pesticides are no longer permitted to use due to their negative environmental effects. Another problem is that the aphids develop resistance against them. Therefore, a new approach is to identify genetic factors that could be used in breeding host plants for resistance. There are many examples of successful plant breeding for resistance to aphids, but in the case of R. padi and barley, no resistant cultivar is commercially available. The aim of this thesis was to identify and characterise aphid resistance and susceptibility factors in barley. This was done using two major approaches. Firstly, constitutive and aphid-induced gene expression was studied in a large number of barley genotypes with known levels of resistance. Secondly, two cDNAs putatively adding to aphid resistance were transformed to Arabidopsis and barley and the effect of transformation on aphid performance and behaviour was evaluated. The study of constitutive transcript abundance in 23 barley genotypes gave suggestive evidence that two genes might be related to aphid resistance; a thionin and a proteinase inhibitor gene, and that a lipoxygenase gene might be related to aphid susceptibility.The study of both constitutive and aphid-induced transcript abundances of three glucanase genes, gave support to the idea that two of them might be susceptibility factors. The cDNA of the proteinase inhibitor mentioned above was expressed in Arabidopsis, under control of either a constitutive or a phloem-specific promoter and the effects were evaluated using the green peach aphid, Myzus persicae Sulzer. This aphid is a generalist, feeding on many different plant species, both monocot (such as barley) and dicot (such as Arabidopsis). The results showed lower settling and fecundity on some of the transgenic lines as compared to on controls. In conclusion, the thesis suggests a role in resistance against R. padi in barley for two genes encoding a thionin and a proteinase inhibitor. It has also given support for a role in susceptibility against R. padi of genes encoding a lipoxygenase and two glucanases. The work further shows that a cDNA from barley, selected based on the interaction between a monocot plant and an essentially monocot specialist aphid, affected the resistance of the dicot Arabidopsis against a generalist aphid.
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| 20. |
- Mehrabi, Sara, 1982-, et al.
(författare)
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The constitutive expression and induction of three β-1,3-glucanases by bird cherry-oat aphid in relation to aphid resistance in 15 barley breeding lines
- 2016
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Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 10:2, s. 101-111
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Tidskriftsartikel (refereegranskat)abstract
- In this study, 15 closely related barley genotypes were analyzed for the abundance of three β-1,3-glucanase transcripts immediately before and during infestation by the bird cherry-oat aphid (Rhopalosiphum padi L.). The barley lines are doubled haploid lines in backcross (BC) generations BC1 and BC2 from a cross between cultivar Lina and a wild barley accession. Previously, they have been characterized as susceptible (S) or resistant (R) to R. padi based on their ability to support nymphal growth. Here we also tested whether resistance was manifested as reduced aphid settling on the plants. Indeed, aphid numbers were lower on R than on S lines in all cases where there were significant differences between R and S lines. The choice of β-1,3-glucanase sequences is based on earlier results comparing two S and two R genotypes, suggesting that at least two of the three studied sequences are susceptibility factors. The comparisons of transcript abundance in plants with aphids showed for two of the β-1,3-glucanase sequences that there were several cases where an S genotype had significantly higher abundance than an R genotype, and in no case did an R line have significantly higher abundance than an S line. Thus, there was some support for the idea that β-1,3-glucanase sequences are susceptibility factors in the interaction between barley and R. padi.
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| 21. |
- Mehrabi, Sara, et al.
(författare)
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Transcript abundance of resistance- and susceptibility-related genes in a barley breeding pedigree with partial resistance to the bird cherry-oat aphid (Rhopalosiphum padi L.)
- 2014
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Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 198:2, s. 211-222
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Tidskriftsartikel (refereegranskat)abstract
- Aphids such as the bird cherry-oat aphid (Rhopalosiphum padi L.) are serious pests in agriculture worldwide. Partially resistant barley genotypes have been produced in a breeding program for resistance to R. padi. The resistance is manifested as smaller aphids after a certain period of nymphal growth on the test plants. A large number of doubled haploid breeding lines thereby characterized as partially resistant or susceptible to R. padi are available from this breeding program. In the present study a selection of these lines, spanning four generations and 23 genotypes, was used for the evaluation of the constitutive transcript abundance of gene sequences in young barley plants. The genes were selected from an earlier microarray study where they had been identified as being up-regulated by aphids in all four barley genotypes studied or differentially up-regulated or constitutively expressed in the two resistant as compared to the two susceptible barley genotypes. The prediction for constitutive transcript abundance across the selection of genotypes was here confirmed for five out of eight investigated genes. Two of these were, as predicted, expressed at equal levels in all genotypes. Two gene sequences exhibited higher transcript abundance in resistant than in susceptible offspring; one coding for a thionin and another for a proteinase inhibitor. A lipoxygenase gene had higher transcript abundance in the susceptible lines. The study thus gives further support for putative constitutive roles of three genes previously identified as significant in the barley-R. padi interaction.
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| 22. |
- Nicolia, Alessandro, et al.
(författare)
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Targeted gene mutation in tetraploid potato through transient TALEN expression in protoplasts
- 2015
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 204, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Potato is the third largest food crop in the world, however, the high degree of heterozygosity, the tetrasomic inheritance and severe inbreeding depression are major difficulties for conventional potato breeding. The rapid development of modern breeding methods offers new possibilities to enhance breeding efficiency and precise improvement of desirable traits. New site-directed mutagenesis techniques that can directly edit the target genes without any integration of recombinant DNA are especially favorable. Here we present a successful pipeline for site-directed mutagenesis in tetraploid potato through transient TALEN expression in protoplasts. The transfection efficiency of protoplasts was 38-39% and the site-directed mutation frequency was 7-8% with a few base deletions as the predominant type of mutation. Among the protoplast-derived calli, 11-13% showed mutations and a similar frequency (10%) was observed in the regenerated shoots. Our results indicate that the site-directed mutagenesis technology could be used as a new breeding method in potato as well as for functional analysis of important genes to promote sustainable potato production. (C) 2015 Elsevier B.V. All rights reserved.
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| 23. |
- Ninkovic, Velemir, et al.
(författare)
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Aphid acceptance of Hordeum genotypes is affected by plant volatile exposure and is correlated with aphid growth
- 2009
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Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 169, s. 177-185
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Tidskriftsartikel (refereegranskat)abstract
- Nineteen genotypes of Hordeum vulgare (L.) were screened and characterized as partially resistant or susceptible regarding growth of the bird cherry-oat aphid (Rhopalosiphum padi L.). In a separate test, these same genotypes were treated with volatiles from undamaged plants of barley cultivar Alva. As a result of this treatment, aphid host acceptance (AHA) was significantly affected in seven genotypes, and the magnitude of the effect was positively correlated with aphid growth (AG) in the independent resistance screening test. Changes in AHA induced by volatiles from the same genotype as the volatile receiver were also positively correlated with AG. All the 19 genotypes were also tested as inducers with cultivar Kara as the receiver of volatiles. Five genotypes induced significant reductions in AHA of Kara. The results show that aphids are able to detect changes in responding plants induced by volatiles from another plant. Plant volatile interactions may thus be a component of induced resistance to aphids. These interactions could influence the results of experiments used to select for insect-resistant plants in plant breeding programmes, where normally plant genotypes are mixed at testing.
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| 24. |
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| 25. |
- Nur, Ahmed, et al.
(författare)
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Effect on radish pests by application of insecticides in a nearby spring oilseed rape field
- 2011
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 135, s. 168-176
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Tidskriftsartikel (refereegranskat)abstract
- Chemical control of insect pests is often necessary to ensure high yields of field crops. The aim of the present study was to study whether field pesticide use influences amount of pest damage in neighbouring garden crops. Spring oilseed rape, OSR (Brassica napus L.), was established in Southern Sweden as an example of an agricultural field crop. One half of the OSR field was treated with insecticides to control flea beetles (Phyllotreta spp., Chrysomelidae) and pollen beetle (Meligethes aeneus Fab., Nitidulidae). Radish (Raphanus sativus L.) was used as an example of a common garden crop and it was sown as four replications at three different distances and on four occasions during the season. Care was taken to protect the radish plots from pesticide due to wind drift during applications. Damage to the radish by flea beetle and cabbage root fly (Delia radicum L., Anthomyiidae) along with unspecified leaf damage was recorded. Significantly lower damage by flea beetles was found on cotyledons of radish adjacent to the insecticide treated side of the OSR field compared to the untreated side in radishes from the first sowing. Unspecified damage to true leaves was also less abundant on radishes at the treated side of the OSR field as compared to the untreated side, in all three of the radish harvests analysed. However, radish plot distance from the OSR field did not influence leaf damage. Root fly damage rates in radish did not differ significantly between those adjacent to the treated and untreated sides of the OSR. Damage rates were, however, higher in the radish plots closest to the OSR field in the first sowing, which coincides with the appearance of the first ovipositing females after overwintering as pupae elsewhere. Generally, insecticide treatment in the agricultural field appeared to influence overall damage in the neighbouring garden crop, despite the fact that the garden crop was protected against wind drift of the insecticides during applications.
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| 26. |
- Nur, Ahmed, et al.
(författare)
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Perception of pesticide use by farmers and neighbors in two periurban areas
- 2011
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 412, s. 77-86
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Tidskriftsartikel (refereegranskat)abstract
- Public concern about pesticide use is high although varying with social factors. Individual differences in 'perception' and attitude to pesticide use might be particularly evident in periurban regions where farmers and other people live together. This was investigated using a questionnaire sent to 600 farmers and 600 non-farmers in two periurban areas of Sweden. 'Neighbors'(1) were found to have a more negative attitude to pesticides than farmers, who were slightly positive to the use. Neighbors perceived pesticide use in agriculture to be more harmful to the environment than did farmers and also to reduce the quality of products. Both farmers and neighbors thought that farmers are the predominant users of pesticides. However, reported pesticide users within the home setting were just as common among the neighbors as among the farmers. Perceptions of pesticide use were also found to differ between periurban regions within the country. Attitudes and perceptions of pesticide use, as well as of who is the user, differ based on the group of people in a periurban environment and between different regions. Such differences might play a role for tensions and conflicts in the periurban area of a society and also for regulations of pesticide use. (C) 2011 Elsevier B.V. All rights reserved.
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| 27. |
- Stenberg, Johan A, et al.
(författare)
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Optimizing Crops for Biocontrol of Pests and Disease
- 2015
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 20, s. 698-712
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Forskningsöversikt (refereegranskat)abstract
- Volatile compounds and extrafloral nectar are common defenses of wild plants; however, in crops they bear an as-yet underused potential for biological control of pests and diseases. Odor emission and nectar secretion are multigene traits in wild plants, and thus form difficult targets for breeding. Furthermore, domestication has changed the capacity of crops to express these traits. We propose that breeding crops for an enhanced capacity for tritrophic interactions and volatile-mediated direct resistance to herbivores and pathogens can contribute to environmentally-friendly and sustainable agriculture. Natural plant volatiles with antifungal or repellent properties can serve as direct resistance agents. In addition, volatiles mediating tritrophic interactions can be combined with nectar-based food rewards for carnivores to boost indirect plant defense.
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| 28. |
- Åhman, Inger
(författare)
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Aktuellt om bladlussituationen
- 2012
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Ingår i: Medd. från Södra jordbruksförsöksdistriktet, Sveriges lantbruksuniversitet. - 0282-180X. ; 65, s. 11:1-11:1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 29. |
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| 30. |
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| 31. |
- Åhman, Inger
(författare)
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Breeding for inducible resistance
- 2013
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Ingår i: IOBC-WPRS Bulletin. - 1027-3115. ; 89, s. 311-317
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 32. |
- Åhman, Inger
(författare)
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Genrevolution i växtförädlingspraktiken
- 2013
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Ingår i: Sveriges utsädesförenings tidskrift. - 0039-6990. ; 122, s. 26-28
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 33. |
- Åhman, Inger, et al.
(författare)
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Impact of herbivory and pollination on performance and competitive ability of oilseed rape transformed for pollen beetle resistance
- 2009
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Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 3, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- Competitive ability of transgenic oilseed rape transformed with a pea lectin gene was estimated by comparisons of its performance when grown in a mixture with its non-transgenic counterpart and when grown singly, with and without pollen beetles present. The experiments were carried out in cages, once with bumblebees as pollinators and once without. In the absence of herbivory but with the presence of bumblebees, singly grown plant lines without lectin generally performed better than lines with lectin. Pollen beetles affected plant growth and reproduction, but there were no consistent differences between the lectin and non-lectin plant lines indicating that the transgenic trait did not protect plants from pest attack. Herbivory reduced the number of seeds when bumblebees were present. In the absence of bumblebees, however, plants produced more seeds with pollen beetles than without, indicating that some pollination was carried out by the beetles. Efficient pollination affected the competitive abilities of the lines; lectin lines were more competitive with bumblebees present and the reverse was true when bumblebees were absent. In the presence of bumblebees, lectin lines gained from being grown mixed with its non-transgenic counterpart. Because the transgenic plants expressed pea lectin in developing pollen it is possible that pollen quality in those plants was reduced, which may explain why the lectin lines had an advantage over non-lectin lines when exchange of pollen between the two plant types was facilitated by bumblebees.
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| 34. |
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| 35. |
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| 36. |
- Åhman, Inger, et al.
(författare)
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Introgression of resistance to Rhopalosiphum padi L. from wild barley into cultivated barley facilitated by doubled haploid and molecular marker techniques
- 2019
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Ingår i: TAG Theoretical and Applied Genetics. - : Springer Science and Business Media LLC. - 0040-5752 .- 1432-2242. ; 132, s. 1397-1408
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Tidskriftsartikel (refereegranskat)abstract
- Key messageLong-term pre-breeding using Hordeum vulgare ssp. spontaneum as a donor of bird cherry-oat aphid resistance has resulted in agronomically improved resistance sources of barley along with easy-to-use molecular markers.AbstractBird cherry-oat aphid (Rhopalosiphum padi L.) is a pest and a virus vector in barley to which there are no bred-resistant cultivars. The present study describes how resistance from Hordeum vulgare ssp. spontaneum has been introgressed in cultivated barley via five successive crosses with the same cultivar Lina (BC) and in parallel with other more modern barley cultivars. Most of the selections for resistance are based on measurements of individual aphid growth in the laboratory. This very slow phenotyping method has been complemented by molecular marker evaluation and application in part of the breeding material. Doubled haploid production in each generation has been crucial for more precise selection of lines with the quantitatively expressed resistance. A field trial of selected BC3-generation lines essentially confirmed the laboratory results, so did genotyping of the whole pedigree of parents and selected BC2 and BC4 offspring lines. The Infinium iSelect 50K SNP assay confirmed relationships between lines and discerned several new markers for a resistance QTL on chromosome 2H.
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| 37. |
- Åhman, Inger
(författare)
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Kapitel 13. Växtförädling
- 2015
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Ingår i: Vår Mat - Odling av åker- och trädgårdsgrödor - Biologi förutsättningar och historia. - 9789144092805 ; , s. 505-526
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 38. |
- Åhman, Inger
(författare)
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Mapping resistance to the bird cherry-oat aphid (Rhopalosiphum padi) in barley
- 2010
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Ingår i: Plant Breeding. - : Wiley. - 0179-9541 .- 1439-0523. ; 129, s. 637-646
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Tidskriftsartikel (refereegranskat)abstract
- P>Aphid resistance is a desirable trait in barley to combat the spread of the barley yellow dwarf virus and also to reduce the direct damage that aphids can inflict on cereals. A significant quantitative trait locus (QTL) on barley chromosome 3H was mapped based on a doubled-haploid population derived from F1 of the cross 'Lina' x '5172-28:4' that showed segregation for resistance to bird cherry-oat aphid. This QTL explained 9% of the variance in aphid growth and is a novel QTL for aphid resistance to bird cherry-oat aphid. Combining this QTL on chromosome 3H with another major QTL on chromosome 2H would potentially provide a more durable and higher level of resistance. Depending on the prevalent species in the cultivated areas, pyramiding resistance to other aphid species such as the corn leaf aphid and the Russian wheat aphid will provide greater protection to the plant in the field against both aphids and barley yellow dwarf virus.
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| 39. |
- Åhman, Inger, et al.
(författare)
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Plant Genes Benefitting Aphids-Potential for Exploitation in Resistance Breeding
- 2019
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Aphids are phloem sap-feeding insects common as pests in various crops. Here we review 62 omics studies of aphid/plant interactions to search for indications of how aphids may manipulate the plants to make them more suitable as hosts, i.e. more susceptible. Our aim is to try to reveal host plant susceptibility (S) genes, knowledge which can be exploited for making a plant more resistant to its pest by using new plant breeding techniques to knock out or down such S genes. S genes may be of two types, those that are involved in reducing functional plant defense and those involved in further increasing plant factors that are positive to the aphid, such as facilitated access to food or improved nutritional quality. Approximately 40% of the omics studies we have reviewed indicate how aphids may modify their host to their advantage. To exploit knowledge obtained so far, we suggest knocking out/down candidate aphid S genes using CRISPR/Cas9 or RNAi techniques in crops to evaluate if this will be sufficient to keep the aphid pest at economically viable levels without severe pleiotropic effects. As a complement, we also propose functional studies of recessively inherited resistance previously discovered in some aphid-crop combinations, to potentially identify new types of S genes that later could be knocked out or down also in other crops to improve their resistance to aphids.
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| 40. |
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| 41. |
- Åhman, Inger
(författare)
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Quantitative trait locus for resistance to the aphid Rhopalosiphum padi L. in barley (Hordeum vulgare L.) is not linked with a genomic region for gramine concentration
- 2020
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Ingår i: Arthropod-Plant Interactions. - : Springer Science and Business Media LLC. - 1872-8855 .- 1872-8847. ; 14, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- Gramine is an indole alkaloid found in certain grass species. Results of previous studies have diverged as to whether this compound might cause resistance to aphids or not. In a breeding program aiming to introduce resistance to the cereal pest Rhopalosiphum padi L. in barley, a cultivar has been crossed with the progenitor of cultivated barley, Hordeum vulgare ssp. spontaneum, and an F-1-derived population of doubled haploid (DH) lines was screened both for seedling gramine concentration and resistance to R. padi. The resistance was measured as individual aphid growth in the laboratory. The present study aims to determine if there is a genetic relationship between aphid growth retardation and gramine concentration. To do so, the lines were genotyped with a 384 SNP oligonucleotide pool assay and QTL analyses were performed for both traits. A previously identified aphid resistance locus on the distal part of chromosome 2HS was thereby confirmed, with resistance inherited from H. v. ssp. spontaneum, whereas one or more QTL for gramine concentration were potentially indicated on chromosome 3H, thus corroborating that the two traits are not linked genetically.
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| 42. |
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| 43. |
- Åhman, Inger
(författare)
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Skador på salixodlingar
- 2009
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Ingår i: Skador på skog. ; :12, s. 136-139
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 44. |
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| 45. |
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| 46. |
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| 47. |
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| 48. |
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| 49. |
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| 50. |
- Åhman, Niclas, et al.
(författare)
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In-service science teacher professional development
- 2015
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Ingår i: NorDiNa. - : University of Oslo Library. - 1504-4556 .- 1894-1257. ; 11:2, s. 207-219
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to explore teachers’ professional development when using the tool Content Representations (CoRe) to plan a learning study in chemistry, which they also implemented and analysed. The work of six experienced science teachers, all teaching at the 6th to 9th year (age 13 to 16 years), was followed at eight group meetings during one year. The teachers’ discussions during the group meetings were audio and/or video recorded. Recordings were transcribed and a thematic analysis was performed. The results show that two main approaches to teaching emerged in the teachers’ discussions, a pragmatic and a reflective approach, respectively. During the investigation period, the focus of the teachers’ discussions changed, from a predominantly pragmatic approach to a predominantly reflective approach. The results indicate that the work with CoRe and learning study stimulated the teachers to express and discuss their knowledge, beliefs and attitudes towards teaching, i.e. promoted their professional development.
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