Loci Controlling Adaptation to Heat Stress Occurring at the Reproductive Stage in Durum Wheat

Khaoula El Hassouni,Amadou Tidiane-Sall,Bouchra Belkadi,Miloudi Nachit,Abdelkarim Filali-Maltouf,Ayed Al-Abdallat,Filippo M Bassi

doi:10.3390/agronomy9080414

Abstract

Heat stress occurring during the reproductive stage of wheat has a detrimental effect on productivity. A durum wheat core set was exposed to simulated terminal heat stress by applying plastic tunnels at the time of flowering over two seasons. Mean grain yield was reduced by 54% compared to control conditions, and grain number was the most critical trait for tolerance to this stress. The combined use of tolerance indices and grain yield identified five top performing elite lines: Kunmiki, Berghouata1, Margherita2, IDON37-141, and Ourgh. The core set was also subjected to genome wide association study using 7652 polymorphic single nucleotide polymorphism (SNPs) markers. The most significant genomic regions were identified in association with spike fertility and tolerance indices on chromosomes 1A, 5B, and 6B. Haplotype analysis on a set of 208 elite lines confirmed that lines that carried the positive allele at all three quantitative trait loci (QTLs) had a yield advantage of 8% when field tested under daily temperatures above 31° C. Three of the QTLs were successfully validated into Kompetitive Allele Specific PCR (KASP) markers and explained >10% of the phenotypic variation for an independent elite germplasm set. These genomic regions can now be readily deployed via breeding to improve resilience to climate change and increase productivity in heat-stressed areas.

Highlights

IntroductionTerminal heat stress is defined as a rise in temperature that occurs between heading and maturity
Heat stress is a major environmental constraint to crop production
The yield performance of the genotypes across environments averaged 2171 kg ha−1 and ranged from 352 kg ha−1 obtained under heat stress conditions for the lowest yielding line DWAyT-0215, to 4658 kg ha−1 under normal conditions for the highest yielding line DWAyT-0217

Summary

Introduction

Terminal heat stress is defined as a rise in temperature that occurs between heading and maturity When this stress matches with the reproductive phase of the wheat plant, it affects anthesis and grain filling, resulting in a severe reduction in yield [1]. High temperatures at the time of flowering cause floret sterility via pollen dehiscence [2], decrease photosynthetic capacity by drying the green tissues, and reduce starch biosynthesis [1,3]. These in turn result in a negative effect on grain number and weight [4,5,6,7]. Breeding selection would benefit by a better understanding of traits associated with tolerance to high temperatures, as well as the identification of the genomic regions controlling these traits

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Results

Conclusion