Identification of QTLs/Defense Genes Effective at Seedling Stage Against Prevailing Races of Wheat Stripe Rust in India

Abstract

Resistance in modern wheat cultivars for stripe rust is not long lasting due to the narrow genetic base and periodical evolution of new pathogenic races. Though nearly 83 Yr genes conferring resistance to stripe rust have been cataloged so far, few of them have been mapped and utilized in breeding programs. Characterization of wheat germplasm for novel sources of resistance and their incorporation into elite cultivars is required to achieve durable resistance and thus to minimize the yield losses. Here, a genome-wide association study (GWAS) was performed on a set of 391 germplasm lines with the aim to identify quantitative trait loci (QTL) using 35K Axiom® array. Phenotypic evaluation disease severity against four stripe rust pathotypes, i.e., 46S119, 110S119, 238S119, and 47S103 (T) at the seedling stage in a greenhouse providing optimal conditions was carried out consecutively for 2 years (2018 and 2019 winter season). We identified, a total of 17 promising QTl which passed FDR criteria. Moreover these 17 QTL identified in the current study were mapped at different genomic locations i.e. 1B, 2A, 2B, 2D, 3A, 3B, 3D, 4B, 5B and 6B. These 17 QTLs identified in the present study might play a key role in marker-assisted breeding for developing stripe rust resistant wheat cultivars.

Meta-QTLs and candidate genes for stripe rust resistance in wheat

“…The yield losses due to stripe rust can be upto 70% under severe epidemic conditions, adversely affecting grain-filling duration, leading to poor grain yield and quality 3 . Under severe conditions, the yield losses may approach 100%, when the infection occurs at the seedling stage and environmental conditions are conducive for the pathogen to persist until maturity 4 , 5 .…”

“…At least 140 stripe rust pathotypes are known globally; of these, ~ 28 pathotypes occur in India alone 5 – 7 . Transcaucasia including the border of Eastern Europe and Western Asia was initially suggested to be the centre of origin of this pathogen 8 , 9 .…”

“…In India, it is a major disease in the North West Plain Zones (NWPZ) including Punjab, Haryana, and Western Uttar Pradesh, which are the major wheat growing areas. A major outbreak of this disease in India was witnessed in NWPZ during 2006 and in the Northern Hills Zone (NHZ) during 2012–2013 5 , 15 , 16 .…”

Meta-QTL Analysis for Stripe Rust Resistance in Wheat

“…The yield losses can be up to 70% under severe epidemic conditions, adversely affecting grain-lling duration, thus leading to poor grain yield as well as grain quality (Vikram et al 2021). Under severe conditions, the yield losses may go up to 100% when the infection occurs at the seedling stage and environment conditions conducive to the pathogen persist until maturity (Afzal et al 2007; Pradhan et al 2020). In India, it is a major disease in the North West Plain Zones (NWPZ) especially in the sub-mountainous parts of Punjab, Haryana, and Western Uttar Pradesh, which are the major wheat growing areas.…”

“…In India, it is a major disease in the North West Plain Zones (NWPZ) especially in the sub-mountainous parts of Punjab, Haryana, and Western Uttar Pradesh, which are the major wheat growing areas. In fact, a major outbreak of this disease was witnessed in NWPZ during 2006 and in the Northern Hills Zone (NHZ) during 2012-13, leading to severe yield losses (Prashar et al 2007; Saharan et al 2013;Pradhan et al 2020). As many as 83 Yr genes have already been identi ed globally, which are distributed on all the 21 wheat chromosomes (McIntosh et al 2014).…”