Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm.

Xinyao He,Philomin Juliana,Arun K Joshi,Muhammad R Kabir,Aakash Chawade,Felix Marza,Rabiul Islam,Ravi P Singh,Pawan K Singh,Gary Peterson,Gary Peterson,Gyanendra P Singh,Krishna K Roy

doi:10.3389/fgene.2021.679162

Abstract

Wheat blast (WB) is a destructive disease in South America and its first outbreak in Bangladesh in 2016 posed a great risk to food security of South Asian countries. A genome wide association study (GWAS) was conducted on a diverse panel of 184 wheat genotypes from South Asia and CIMMYT. Phenotyping was conducted in eight field experiments in Bolivia and Bangladesh and a greenhouse experiment in the United States. Genotypic data included 11,401 SNP markers of the Illumina Infinium 15K BeadChip and four additional STS markers on the 2NS/2AS translocation region. Accessions with stable WB resistance across experiments were identified, which were all 2NS carriers. Nevertheless, a dozen moderately resistant 2AS lines were identified, exhibiting big variation among experiments. Significant marker-trait associations (MTA) were detected on chromosomes 1BS, 2AS, 6BS, and 7BL; but only MTAs on 2AS at the 2NS/2AS translocation region were consistently significant across experiments. The resistant accessions identified in this study could be used in production in South Asian countries as a preemptive strategy to prevent WB outbreak.

Highlights

Bread wheat grown in tropical and subtropical regions is subjected to a range of diseases, among which is wheat blast (WB)
The objectives of the current study were designed with this aim and includes (1) screen a panel of CIMMYT and South Asian bread wheat germplasm for adult plant Wheat blast (WB) resistance and (2) identify molecular markers associated with WB resistance via genome-wide association study (GWAS)
It is noteworthy that the model mixed linear model (MLM) did not fit Jash18a; but multilocus mixed model (MLMM) and fixed and random model circulating probability unification (FarmCPU) that fitted this experiment were not able to identify a stably expressed marker-trait associations (MTA) locus either

Summary

Introduction

Bread wheat grown in tropical and subtropical regions is subjected to a range of diseases, among which is wheat blast (WB). The disease had been endemic in four South American countries, Brazil, Bolivia, Paraguay, and Argentina, before its outbreak in Bangladesh in 2016, affecting 15,000 ha wheat fields with yield losses of 5–51% (Islam et al, 2016; Malaker et al, 2016). Soon thereafter, this disease was identified in the Muchinga Province of Zambia during the 2017–2018 rainy season, indicating its introduction into the African continent (Tembo et al, 2020). Leaf infection is less prominent than spike infection and usually does not lead to severe yield loss; but the fungal conidia produced on leaves could be an important source of inoculum for spike infection (Cruz et al, 2015)

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