Identification of Main-Effect and Environmental Interaction QTL and Their Candidate Genes for Drought Tolerance in a Wheat RIL Population Between Two Elite Spring Cultivars.

S M Hisam Al Rabbi,Ajay Kumar,Suraj Sapkota,Shahryar Kianian,Mohamed Mergoum,Shyam Solanki,Sepehr Mohajeri Naraghi,Ali Missaoui,Raed Seetan,Mohammed S Alamri,Elias M Elias

doi:10.3389/fgene.2021.656037

Abstract

Understanding the genetics of drought tolerance can expedite the development of drought-tolerant cultivars in wheat. In this study, we dissected the genetics of drought tolerance in spring wheat using a recombinant inbred line (RIL) population derived from a cross between a drought-tolerant cultivar, ‘Reeder’ (PI613586), and a high-yielding but drought-susceptible cultivar, ‘Albany.’ The RIL population was evaluated for grain yield (YLD), grain volume weight (GVW), thousand kernel weight (TKW), plant height (PH), and days to heading (DH) at nine different environments. The Infinium 90 k-based high-density genetic map was generated using 10,657 polymorphic SNP markers representing 2,057 unique loci. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. One novel QTL for drought tolerance was identified on chromosome 2D. In silico expression analysis of candidate genes underlaying the exclusive QTLs associated with drought stress identified the enrichment of ribosomal and chloroplast photosynthesis-associated proteins showing the most expression variability, thus possibly contributing to stress response by modulating the glycosyltransferase (TraesCS6A01G116400) and hexosyltransferase (TraesCS7B01G013300) unique genes present in QTL 21 and 24, respectively. While both parents contributed favorable alleles to these QTL, unexpectedly, the high-yielding and less drought-tolerant parent contributed desirable alleles for drought tolerance at four out of six loci. Regardless of the origin, all QTL with significant drought tolerance could assist significantly in the development of drought-tolerant wheat cultivars, using genomics-assisted breeding approaches.

Highlights

Hard red spring wheat (HRSW), comprising about 25% of the total United States wheat production, is unique for its high protein content (Vocke and Ali, 2013)
We only found one gene in QTL-24 annotated to encode for a hexosyltransferase (TraesCS7B01G013300), a homolog of TraesCS2A01G097400, a gene we proposed to be important for grain volume weight (GVW) and thousand kernel weight (TKW) traits controlled by QTL-3
A population developed from a cross between elite lines was used to elucidate the genetic factors involved in the control of drought tolerance in HRSW in northern United States

Summary

Introduction

Hard red spring wheat (HRSW), comprising about 25% of the total United States wheat production, is unique for its high protein content (Vocke and Ali, 2013). This important crop often experiences drought, which is one of the main natural hazards harming wheat production worldwide (Araus et al, 2008). It regularly affects about 50% of wheat-producing areas (Pfeiffer et al, 2005). Drought tolerance enables plants to yield satisfactorily under limited or periodic water-deficient conditions (Turner, 1979). Developing wheat cultivars with improved drought tolerance is the key to reduce yield loss due to water stress

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