| 1. |
- Bertholdsson, Nils-Ove, et al.
(författare)
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QTL for chlorophyll fluorescence of barley plants grown at low oxygen concentration in hydroponics to simulate waterlogging
- 2015
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Ingår i: Euphytica. - : Springer Science and Business Media LLC. - 0014-2336 .- 1573-5060. ; 201, s. 357-365
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Tidskriftsartikel (refereegranskat)abstract
- Waterlogging is a major factor limiting barley grain yield worldwide. Climate change will likely increase this water stress in Northern Europe. Breeding for waterlogging tolerance (WLT), as for other abiotic stresses, is difficult, but identification of genetic markers linked to genes affecting WLT could facilitate the breeding process. To identify a suitable marker population, parents of 14 double-haploid (DH) barley populations were tested for segregation of biomass growth reduction in waterlogged soil. The most interesting was found in the offspring from crossing cv. Psaknon and breeding line (SLUdt1398 x Mona(4)). Hence, 120 DH-lines derived from this cross were phenotyped for the chlorophyll fluorescence parameter quantum yield (QY) of electron transport of PSII from leaves of hypoxia-stressed plants and further genotyped with 384-SNP Illumina GoldenGate Bead Array. Five quantitative trait loci (QTL) for QY, with a narrow sense heritability of 0.87, were identified on chromosomes 4, 6 and 7H. They had additive effects ranging from 0.74 to 1.35 % with LOD scores from 3 to 12 and explained variance from 6 to 29 %. The major alleles for high QY were from cv. Psaknon; i.e., QY was low if the alleles from cv. Psaknon were not present. Based on leaf necrosis and residual biomass data, the four most interesting QTL may be also in two other populations with completely different progeny, which shows a certain stability of these QTL. The possibility of using marker assistant selection for WLT is discussed, as is possible concurrent improvement of drought tolerance and grain yield.
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| 2. |
- 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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| 3. |
- 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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| 4. |
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| 5. |
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| 6. |
- 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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| 7. |
- Crespo, Leonardo
(författare)
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Multiple Aphid resistance from alien sources and its chromosomal location in bread wheat
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wheat (Triticum aestivum) is a very important cereal crop and is cultivated worldwide on more than 200 million hectares annually, with an average grain yield of about 3 t/ha. A number of diseases and pests are known to affect wheat production, with aphids being important insect pests. The aphid species that commonly attack wheat are Schizaphis graminum, Rhopalosiphum padi, Sitobion avenae, Diuraphis noxia and Metopolophium dirhodum. These aphids can reduce wheat yields by up to 40% solely due to feeding and by over 60% when their feeding transmits viral diseases. One way to reduce aphid damage is through plant breeding and growing resistant varieties. The aims of this thesis were to: 1) identify novel sources of resistance to multiple aphid species in a wheat-alien genetic stock; 2) determine the utility of those resistance sources in the field; 3) review the utility of rye as a source of resistance to biotic stresses in wheat; and 4) locate genomic regions associated with aphid resistance in a synthetic hexaploid wheat (SHW). Under laboratory conditions, certain wheat genotypes carrying the 1R chromosome from rye reduced both R. padi and S. avenae growth, the most resistant ones by 24 and 34% relative to the control, respectively. Certain Aegilops speltoides-derived wheat lines displayed hardly any chlorosis due to S. graminum and reduced aphid colony weight by up to 68% compared with the control. The results of laboratory and field evaluations were in good agreement. The most resistant wheat-rye genotype reduced R. padi field population development by 33% relative to the control, while the A. speltoides-derived line reduced S. graminum field population development by up to 75%. Certain rye-derived genotypes carrying resistance to one or two aphid species also showed resistance to fungal diseases such as powdery mildew and Septoria tritici blotch. Five quantitative trait loci (QTL) associated with aphid resistance were found in the SHW mapping population. One QTL for R. padi antibiosis is located on chromosome arm 4BL, two QTL for R. padi tolerance on 5AL and 5BL, and two QTL for S. graminum resistance on 2DL and 7DL. An epistatic interaction that enhanced R. padi tolerance was also detected. The sources of resistance identified here have potential applications in wheat breeding programmes aiming to incorporate aphid resistance.
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| 8. |
- Crespo, Leonardo
(författare)
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Resistance to aphids in wheat : from a plant breeding perspective
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Wheat is one of the main staple foods in the world. Among the many constraints there are for wheat production, aphids cause severe damage by their feeding, and by virus transmission. The current document summarizes the available information regarding wheat resistance to aphids. The text is divided into four sections. The first section “Plant resistance to insects: from a historical perspective” serves as an introduction, where some important factors shaping Plant Resistance to insects as a discipline are presented. The section “Categories of resistance and plant defenses to aphids”, presents the concepts of Plant Resistance to insects, with wheat-aphid examples. The methods to assess the categories of resistance are briefly discussed in this section as well. “Genetic resources for resistance to aphids in wheat”, the third part of the document, is focused on the wheat relatives in which resistance to biotic stresses and to aphids in particular can be found. The aim of this section is to describe the resistance donors in relation to each of the main aphid species that attack wheat. Finally, some aspects on how to improve wheat for resistance to aphids are discussed in the fourth section, “Considerations for wheat breeding”.
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| 9. |
- 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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| 10. |
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