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Fusarium head blight (FHB), caused by the fungus Fusarium graminearum Schwabe is an important disease of wheat that causes severe yield losses along with serious quality concerns. Incorporating the host resistance from either wild relatives, landraces, or exotic materials remains challenging and has shown limited success. Therefore, a better understanding of the genetic basis of native FHB resistance in hard winter wheat (HWW) and combining it with major quantitative trait loci (QTLs) can facilitate the development of FHB-resistant cultivars. In this study, we evaluated a set of 257 breeding lines from the South Dakota State University (SDSU) breeding program to uncover the genetic basis of native FHB resistance in the US hard winter wheat. We conducted a multi-locus genomewide association study (ML-GWAS) with 9,321 high-quality single-nucleotide polymorphisms (SNPs). A total of six distinct marker-trait associations (MTAs) were identified for the FHB disease index (DIS) on five different chromosomes including 2A, 2B, 3B, 4B, and 7A. Further, eight MTAs were identified for Fusarium-damaged kernels (FDK) on six chromosomes including 3B, 5A, 6B, 6D, 7A, and 7B. Out of the 14 significant MTAs, 10 were found in the proximity of previously reported regions for FHB resistance in different wheat classes and were validated in HWW, while four MTAs represent likely novel loci for FHB resistance. Accumulation of favorable alleles of reported MTAs resulted in significantly lower mean DIS and FDK score, demonstrating the additive effect of FHB resistance alleles. Candidate gene analysis for two important MTAs identified several genes with putative proteins of interest; however, further investigation of these regions is needed to identify genes conferring FHB resistance. The current study sheds light on the genetic basis of native FHB resistance in the US HWW germplasm and the resistant lines and MTAs identified in this study will be useful resources for FHB resistance breeding via marker-assisted selection. [ABSTRACT FROM AUTHOR]

Wheat blast, caused by the Triticum pathotype of Pyricularia oryzae , is an emerging disease that threatens the global supply of wheat. The pathogen was first reported in Brazil and subsequently spread to the neighboring countries of Argentina, Bolivia, and Paraguay. More recently, wheat blast was reported in Asia and Africa, having been observed in Bangladesh and Zambia. The transcontinental spread of the pathogen has heightened awareness of the disease and has underscored the need to prepare for potential introductions into major wheat production regions. To this end, we have conducted greenhouse evaluations of the 2017 - 2020 hard winter wheat ( Triticum aestivum L.) entries of the USDA-coordinated Northern and Southern Regional Performance Nurseries (NRPN and SRPN, respectively) of the U.S. Great Plains using an aggressive isolate of the pathogen, B-71, collected in Bolivia in 2012. Based on molecular marker analysis, all potentially resistant entries in both the NRPN and SRPN were in possession of the distal chromosomal translocation of 2N V S from Aegilops ventricosa , which has previously been associated with wheat blast resistance. No potentially new sources of resistance were evident in the 2017 - 2020 regional performance nurseries, which highlights the need for the continued use of 2N V S donor lines in Great Plains wheat breeding programs.

The National Agrobiodiversity Center of the RDA, Korea, has more than 22,700 accessions of global wheat genetic resources, including Korean wheat cultivars and landraces. Despite the numerous efforts to develop high-quality, hard winter wheat, the employment of new genetic resources into Korean wheat breeding programs is still hampered by the different growing environments. To overcome this limitation, 200 germplasms that were screened using the Genebank Management System (GMS) were evaluated in three different regions in Korea. In the 2018–2019 trial, 55 lines that showed superior field performance and high protein content were selected from among the 200 germplasms. These lines were re-evaluated in the 2019–2020 trial, and 24 lines that had suitable traits for growth, grain yield, and grain protein content in three locations were finally selected. These winter wheat germplasms also showed high yield stability throughout the three different environments in Korea. Preliminary screening using GMS information, consecutive regional tests, and quality tests could be effective procedures for the development of hard winter wheat in Korea. Therefore, introduction breeding could be a favorable breeding method aiming to improve quality, where useful genetic resources are limited. [ABSTRACT FROM AUTHOR]

The article describes the parameters of ecological plasticity and stability of characteristic "productivity" in hard winter wheat. Under conditions of the Rostov region hard winter wheat varieties breeding All-Russian Research Institute of Grain Crops: Donskoy Yantar’, Aksinit, Kurant, Agat donskoy, Amazonka, Lazurit, Kristella, Kiprida, Oniks were studied with green manure fallow predecessor in 2010...2015. Variety Donchanka was used as standard. The studies revealed that the average yield in the trials ranged from 5.9 t/ha at variety Donchanka up to 7.2 t/ha at variety Lazurit. The maximum yield for the period of studies was observed at Aksinit (9.8 t/ha). The most stable variety is Kurant which has a low coefficient of variation (CV = 7.8%), and regression coefficient (bi = -1.4). A Kristella had the highest coefficient of variation among the studied varieties (CV = 23.9%). We define a linear regression coefficient (bi) which is less than 1. These genotypes form stable yields under adverse growing conditions. By the method of two-way analysis of variance on parameter "productivity" it was found that the dispersion of "genotype -environment" significantly exceeds the variance of error. Ffactual > Ftheoretical at the sources of variation "variety", "conditions" and "variety-condition". This suggests that varieties respond differently to changes in climatic conditions. In our experiment variety Donchanka was the least responsive; most responsive - variety Lazurit. Varieties Lazurit and Kurant are recommended to growing on the extensive background. Here the highest return could be obtained at the lowest cost.

Spot blotch (SB) caused by Cochliobolus sativus (anamorph: Bipolaris sorokiniana) is an economically important disease of wheat worldwide. Under a severe epidemic condition, the disease can cause yield losses up to 70%. Previous approaches like bi-parental mapping for identifying SB resistant genes/QTLs exploited only a limited portion of the available genetic diversity with a lower capacity to detect polygenic traits, and had a lower marker density. In this study, we performed genome-wide association study (GWAS) for SB resistance in hard winter wheat association mapping panel (HWWAMP) of 294 genotypes. The HWWAMP was evaluated for response to B. sorokiniana (isolate SD40), and a range of reactions was observed with 10 resistant, 38 moderately resistant, 120 moderately resistant- moderately susceptible, 111 moderately susceptible, and 15 susceptible genotypes. GWAS using 15,590 high-quality SNPs and 294 genotypes we identified six QTLs (p =

Spot blotch (SB) caused by Cochliobolus sativus (anamorph: Bipolaris sorokiniana) is an economically important disease of wheat worldwide. Under a severe epidemic condition, the disease can cause yield losses up to 70%. Previous approaches like bi-parental mapping for identifying SB resistant genes/QTLs exploited only a limited portion of the available genetic diversity with a lower capacity to detect polygenic traits, and had a lower marker density. In this study, we performed genome-wide association study (GWAS) for SB resistance in hard winter wheat association mapping panel (HWWAMP) of 294 genotypes. The HWWAMP was evaluated for response to B. sorokiniana (isolate SD40), and a range of reactions was observed with 10 resistant, 38 moderately resistant, 120 moderately resistant- moderately susceptible, 111 moderately susceptible, and 15 susceptible genotypes. GWAS using 15,590 high-quality SNPs and 294 genotypes we identified six QTLs (p = <0.001) on chromosomes 2D, 3A, 4A, 4B, 5A, and 7B that collectively explained 30% of the total variation for SB resistance. Highly associated SNPs were identified for all six QTLs, QSb.sdsu-2D.1 (SNP: Kukri_c31121_1460, R2 = 4%), QSb.sdsu-3A.1 (SNP: Excalibur_c46082_440, R2 = 4%), QSb.sdsu-4A.1 (SNP: IWA8475, R2 = 5.5%), QSb.sdsu-4B.1 (SNP: Excalibur_rep_c79414_306, R2 = 4%), QSb.sdsu-5A.1 (SNP: Kukri_rep_c104877_2166, R2 = 6%), and QSb.sdsu-7B.1 (SNP: TA005844-0160, R2 = 6%). Our study not only validates three (2D, 5A, and 7B) genomic regions identified in previous studies but also provides highly associated SNP markers for marker assisted selection. In addition, we identified three novel QTLs (QSb.sdsu-3A.1, QSb.sdsu-4A.1, and QSb.sdsu-4B.1) for SB resistance in wheat. Gene annotation analysis of the candidate regions identified nine NBS-LRR and 38 other plant defense-related protein families across multiple QTLs, and these could be used for fine mapping and further characterization of SB resistance in wheat. Comparative analysis with barley indicated the SB resistance locus on wheat chromosomes 2D, 3A, 5A, and 7B identified in our study are syntenic to the previously identified SB resistance locus on chromosomes 2H, 3H, 5H, and 7H in barley. The 10 highly resistant genotypes and SNP markers identified in our study could be very useful resources for breeding of SB resistance in wheat. [ABSTRACT FROM AUTHOR]

Abstract: Field experiments were conducted in the 2005/2006 and 2006/2007 crop seasons to evaluate the tolerance of hard winter wheat (HWW) and soft winter wheat (SWW) varieties to post-emergence mesosulfuron-methyl treatment. The application of mesosulfuron-methyl at 11.25g a.i.ha−1 plus a noninonic surfactant at 252g a.i.ha−1 to three HWW and three SWW varieties in either autumn (Zadoks stage 14–15) or spring (Zadoks stage 24–25) resulted in visible injury, including chlorisis, stunting and leaf deformities. The greatest injury occurred at fourteen days after treatment (DAT) for all wheat varieties. All varieties showed the same initial sensitivity to herbicide treatment, but differed significantly in their recovery from plant damages. The HWW varieties recovered more successfully from spring-applied herbicide than the SWW varieties; conversely, the SWW varieties recovered more rapidly from damage caused by autumn-applied herbicide than the HWW varieties. Normalized Difference Vegetative Index (NDVI) values were severely affected by autumn herbicide application for HWW varieties and spring application for SWW varieties. Autumn herbicide application for SWW varieties and spring herbicide application for HWW varieties produced higher grain yields. Based on these data, we conclude that applying mesosulfuron-methyl plus a noninonic surfactant in autumn for SWW varieties and in spring for HWW varieties is optimal, and that application timing has profound implications for herbicide tolerance and production of wheat. [Copyright &y& Elsevier]