scholarly journals Field-based screening identifies resistance to Sunn pest (Eurygaster integriceps) feeding at vegetative stage in elite wheat genotypes

2017 ◽  
Vol 68 (2) ◽  
pp. 126 ◽  
Author(s):  
Livinus Emebiri ◽  
Mustapha El Bousshini ◽  
Mui-Keng Tan ◽  
Francis C. Ogbonnaya

Sunn pest (Eurygaster integriceps Puton) is currently widely distributed in West and Central Asia and Eastern Europe, but has not been found in Australia, Western Europe or North America. Climate warming is known to promote the expansion of its range of distribution, and it is expected that the insect could spread into new territories. Varieties of wheat (Triticum aestivum) carrying resistance remain an important component of managing the biosecurity risk of any potential incursion. Previous studies have identified sources of Sunn pest resistance in wheat, but there is little information on the genes that confer the resistance. This research used field-based, artificial infestation cages to evaluate 204 elite wheat varieties for Sunn pest resistance, at Terbol, Lebanon. A significant (P < 0.001) difference in resistance was observed among the wheat germplasm, with 19 varieties rated as resistant to moderately resistant and 17 as highly susceptible. Three of the elite varieties showed very little damage, a status similar to that of the resistant check, ICBW-209273. In parallel, the research carried out a genome-wide scan with single-nucleotide polymorphism (SNP) markers to identify chromosome regions and putative genes associated with resistance. Association mapping identified SNP markers with significant associations on chromosomes 2D, 4B and 5B. When these markers were projected onto the wheat population sequencing-based (POPSEQ) reference map, they tended to map close to the location of wheat height-reducing genes. The phenotypic variation explained by the identified markers ranged from 7% to 11%, and collectively, they explained 23.9% of the variation or 45% of the generalised heritability. Marker-trait association was confirmed in two independent, doubled-haploid wheat populations, derived from crosses involving wheat landraces from Afghanistan, where Sunn pest is recognised as an endemic problem. In the two wheat populations, the analyses validated the strong association between wsnp_BF483640B_Ta_2_2 and resistance to Sunn pest damage at the vegetative stage. This study demonstrates existence of genetic resistance to Sunn pest feeding at the vegetative stage in elite wheat germplasm. The study also identified and validated SNP markers that could be useful tools for transfer of resistance into new wheat cultivars.


2019 ◽  
Vol 109 (7) ◽  
pp. 1208-1216 ◽  
Author(s):  
Lei Wu ◽  
Yu Zhang ◽  
Yi He ◽  
Peng Jiang ◽  
Xu Zhang ◽  
...  

Improving resistance to Fusarium head blight (FHB) in wheat is crucial in the integrated management of the disease and prevention of deoxynivalenol (DON) contamination in grains. To identify novel sources of resistance, a genome-wide association study (GWAS) was performed using a panel of 213 accessions of elite wheat germplasm of China. The panel was evaluated for FHB severity in four environments and DON content in grains in two environments. High correlations across environments and high heritability were observed for FHB severity and DON content in grains. The panel was also genotyped with the 90K Illumina iSelect single nucleotide polymorphism (SNP) array and 11,461 SNP markers were obtained. The GWAS revealed a total of six and three loci significantly associated with resistance to fungal spread and DON accumulation in at least two environments, respectively. QFHB-2BL.1 tagged by IWB52433 and QFHB-3A tagged by IWB50548 were responsible for resistance to both fungal spread and DON accumulation. In summary, this study provided an overview of FHB resistance resources in elite Chinese wheat germplasm and identified novel resistance loci that could be used for wheat improvement.



2020 ◽  
Vol 21 (13) ◽  
pp. 4706
Author(s):  
Irina N. Leonova ◽  
Ekaterina S. Skolotneva ◽  
Elena A. Orlova ◽  
Olga A. Orlovskaya ◽  
Elena A. Salina

Stem rust caused by Puccinia graminis f. sp. tritici Eriks. is a dangerous disease of common wheat worldwide. Development and cultivation of the varieties with genetic resistance is one of the most effective and environmentally important ways for protection of wheat against fungal pathogens. Field phytopathological screening and genome-wide association study (GWAS) were used for assessment of the genetic diversity of a collection of spring wheat genotypes on stem rust resistance loci. The collection consisting of Russian varieties of spring wheat and introgression lines with alien genetic materials was evaluated over three seasons (2016, 2017 and 2018) for resistance to the native population of stem rust specific to the West Siberian region of Russia. The results indicate that most varieties displayed from moderate to high levels of susceptibility to P. graminis; 16% of genotypes had resistance or immune response. In total, 13,006 single-nucleotide polymorphism (SNP) markers obtained from the Infinium 15K array were used to perform genome-wide association analysis. GWAS detected 35 significant marker-trait associations (MTAs) with SNPs located on chromosomes 1A, 2A, 2B, 3B, 5A, 5B, 6A, 7A and 7B. The most significant associations were found on chromosomes 7A and 6A where known resistance genes Sr25 and Sr6Ai = 2 originated from Thinopyrum ssp. are located. Common wheat lines containing introgressed fragments from Triticum timopheevii and Triticum kiharae were found to carry Sr36 gene on 2B chromosome. It has been suggested that the quantitative trait loci (QTL) mapped to the chromosome 5BL may be new loci inherited from the T. timopheevii. It can be inferred that a number of Russian wheat varieties may contain the Sr17 gene, which does not currently provide effective protection against pathogen. This is the first report describing the results of analysis of the genetic factors conferring resistance of Russian spring wheat varieties to stem rust.



2016 ◽  
Vol 106 (11) ◽  
pp. 1352-1358 ◽  
Author(s):  
Jayaveeramuthu Nirmala ◽  
Shiaoman Chao ◽  
Pablo Olivera ◽  
Ebrahiem M. Babiker ◽  
Bekele Abeyo ◽  
...  

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, can cause severe yield losses on susceptible wheat varieties and cultivars. Although stem rust can be controlled by the use of genetic resistance, population dynamics of P. graminis f. sp. tritici can frequently lead to defeat of wheat stem rust resistance genes. P. graminis f. sp. tritici race TKTTF caused a severe epidemic in Ethiopia on Ug99-resistant ‘Digalu’ in 2013 and 2014. The gene Sr11 confers resistance to race TKTTF and is present in ‘Gabo 56’. We identified seven single-nucleotide polymorphism (SNP) markers linked to Sr11 from a cross between Gabo 56 and ‘Chinese Spring’ exploiting a 90K Infinium iSelect Custom beadchip. Five SNP markers were validated on a ‘Berkut’/‘Scalavatis’ population that segregated for Sr11, using KBioscience competitive allele-specific polymerase chain reaction (KASP) assays. Two of the SNP markers, KASP_6BL_IWB10724 and KASP_6BL_IWB72471, were predictive of Sr11 among wheat genetic stocks, cultivars, and breeding lines from North America, Ethiopia, and Pakistan. These markers can be utilized to select for Sr11 in wheat breeding and to detect the presence of Sr11 in uncharacterized germplasm.





2020 ◽  
Author(s):  
Rajiv Sharma ◽  
Salar Shaaf ◽  
Kerstin Neumann ◽  
Yu Go ◽  
Martin Mascher ◽  
...  

AbstractIn barley, the transition from the vegetative to reproductive phase is complex and under the control of photoperiodic and temperature conditions. One major gene involved is PPD-H1, a PSEUDO-RESPONSE REGULATOR 7 (PRR7) that encodes a component of the circadian clock. Mutation at PPD-H1 resulted in the photoperiod non-responsive ppd-H1 alleles that are beneficial under high latitudinal environments as they allow vegetative growth during the long-day summer conditions whereby higher yields are harvested by farmers. Utilizing a diverse GWAS panel of world-wide origin and a genome-wide gene-based set of 50K SNP markers, a strong association of days to heading with the PPD-H1 gene was detected in multi-location field trials. Re-sequencing of the gene spanning putative causative SNPs, SNP22 (Turner et al. 2005) and SNP48 (Jones et al. 2008), detected recombination between the two, previously reported to be in complete LD. Phenotyping of the recombinants and phylogenetic relationships among haplotypes supported the original conclusion of Turner et al. (2005) that SNP22, present in the CCT domain, is the most likely causative SNP. To infer the origin of non-responsiveness, the PPD-H1 gene was re-sequenced in a geo-referenced collection of 2057 wild and domesticated barleys and compared with the allelic status of the 6000-year-old barley sample from the Yoram cave in the Masada cliff. A monophyletic and post-domestication origin in the Fertile Crescent was found in contrast to the pre-domestication origin proposed by Jones et al. (2008). We show that the photoperiod non-responsiveness originated from Desert type wild barley in the Southern Levant.



2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdulsalam Dakouri ◽  
Mebarek Lamara ◽  
Md. Masud Karim ◽  
Jinghe Wang ◽  
Qilin Chen ◽  
...  

AbstractGenetic resistance is a successful strategy for management of clubroot (Plasmodiophora brassicae) of brassica crops, but resistance can break down quickly. Identification of novel sources of resistance is especially important when new pathotypes arise. In the current study, the reaction of 177 accessions of Brassica napus to four new, virulent pathotypes of P. brassicae was assessed. Each accession was genotyped using genotyping by sequencing to identify and map novel sources of clubroot resistance using mixed linear model (MLM) analysis. The majority of accessions were highly susceptible (70–100 DSI), but a few accessions exhibited strong resistance (0–20 DSI) to pathotypes 5X (21 accessions), 3A (8), 2B (7), and 3D (15), based on the Canadian Clubroot Differential system. In total, 301,753 SNPs were mapped to 19 chromosomes. Population structure analysis indicated that the 177 accessions belong to seven major populations. SNPs were associated with resistance to each pathotype using MLM. In total, 13 important SNP loci were identified, with 9 SNPs mapped to the A-genome and 4 to the C-genome. The SNPs were associated with resistance to pathotypes 5X (2 SNPs), 3A (4), 2B (5) and 3D (6). A Blast search of 1.6 Mb upstream and downstream from each SNP identified 13 disease-resistance genes or domains. The distance between a SNP locus and the nearest resistance gene ranged from 0.04 to 0.74 Mb. The resistant lines and SNP markers identified in this study can be used to breed for resistance to the most prevalent new pathotypes of P. brassicae in Canada.



2019 ◽  
Vol 46 (2) ◽  
pp. 307-314
Author(s):  
Yu-Qing ZHANG ◽  
Juan ZOU ◽  
Yi-Ke LIU ◽  
Wei-Jie HE ◽  
Zhan-Wang ZHU ◽  
...  


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vladimir V. Strelnikov ◽  
Ekaterina B. Kuznetsova ◽  
Alexander S. Tanas ◽  
Viktoria V. Rudenko ◽  
Alexey I. Kalinkin ◽  
...  

AbstractCell transmembrane receptors and extracellular matrix components play a pivotal role in regulating cell activity and providing for the concerted integration of cells in the tissue structures. We have assessed DNA methylation in the promoter regions of eight integrin genes, two nidogen genes, and the dystroglycan gene in normal breast tissues and breast carcinomas (BC). The protein products of these genes interact with the basement membrane proteins LAMA1, LAMA2, and LAMB1; abnormal hypermethylation of the LAMA1, LAMA2, and LAMB1 promoters in BC has been described in our previous publications. In the present study, the frequencies of abnormal promoter hypermethylation in BC were 13% for ITGA1, 31% for ITGA4, 4% for ITGA7, 39% for ITGA9, 38% for NID1, and 41% for NID2. ITGA2, ITGA3, ITGA6, ITGB1, and DAG1 promoters were nonmethylated in normal and BC samples. ITGA4, ITGA9, and NID1 promoter hypermethylation was associated with the HER2 positive tumors, and promoter hypermethylation of ITGA1, ITGA9, NID1 and NID2 was associated with a genome-wide CpG island hypermethylated BC subtype. Given that ITGA4 is not expressed in normal breast, one might suggest that its abnormal promoter hypermethylation in cancer is non-functional and is thus merely a passenger epimutation. Yet, this assumption is not supported by our finding that it is not associated with a hypermethylated BC subtype. ITGA4 acquires expression in a subset of breast carcinomas, and methylation of its promoter may be preventive against expression in some tumors. Strong association of abnormal ITGA4 hypermethylation with the HER2 positive tumors (p = 0.0025) suggests that simultaneous presence of both HER2 and integrin α4 receptors is not beneficial for tumor cells. This may imply HER2 and integrin α4 signaling pathways interactions that are yet to be discovered.



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