Genetic Dissection of Drought Tolerance of Elite Bread Wheat (Triticum aestivum L.) Genotypes Using Genome Wide Association Study in Morocco

Abstract

Drought is one of the most important yield-limiting factors in Morocco. Identification and deployment of drought-tolerant wheat varieties are important to cope with the challenge of terminal moisture stress and increase wheat productivity. A panel composed of 200 elite spring bread wheat genotypes was phenotyped for yield and agronomic traits for 2 years (2020 and 2021) in Morocco under rainfed and irrigated environments. The panel was genotyped using 20K SNPs and, after filtration, a total of 15,735 SNP markers were used for a genome-wide association study (GWAS) using a mixed linear model (MLM) to identify marker-trait associations (MTA) and putative genes associated with grain yield and yield-related traits under rainfed and irrigated conditions. Significant differences were observed among the elite genotypes for grain yield and yield-related traits. Grain yield performance ranged from 0.97 to 6.16 t/ha under rainfed conditions at Sidi Al-Aidi station and from 3.31 to 9.38 t/h under irrigated conditions at Sidi Al-Aidi station, while Grain yield at Merchouch station ranged from 2.32 to 6.16 t/h under rainfed condition. A total of 159 MTAs (p < 0.001) and 46 genes were discovered, with 67 MTAs recorded under rainfed conditions and 37 MTAs recorded under irrigated conditions at the Sidi Al-Aidi station, while 55 MTAs were recorded under rainfed conditions at Merchouch station. The marker ‘BobWhite_c2988_493’ on chromosome 2B was significantly correlated with grain yield under rainfed conditions. Under irrigated conditions, the marker ‘AX-94653560’ on chromosome 2D was significantly correlated with grain yield at Sidi Al-Aidi station. The maker ‘RAC875_c17918_321’ located on chromosome 4A, associated with grain yield was linked with the gene TraesCS4A02G322700, which encodes for F-box domain-containing protein. The markers and candidate genes discovered in this study should be further validated for their potential use in marker-assisted selection to generate high-yielding wheat genotypes with drought tolerance.

Genome-wide association mapping of genomic regions associated with drought stress tolerance at seedling and reproductive stages in bread wheat

“…Wheat is affected by drought stress at all growth stages. Even though most earlier studies focused on aboveground adult plant traits (El Gataa et al, 2022), seedling traits are equally important since the seedling stage is the most vulnerable stage in warm and dry regions, and their trait values may differ significantly from those of adult plants (Harrison and Laforgia, 2019). This study evaluated a bread wheat panel systematically assembled from the CIMMYT gene bank for seedling traits (viz., CL, SLT, RLT, SWT, and RWT) under hydroponics conditions.…”

“…Drought tolerance is a complex quantitative trait governed by many genes, some of which have minor effects while others have major effects (Kumar et al, 2012). Further, it has low heritability owing to its polygenic inheritance and significant genotype by environment interaction (Sukumaran et al, 2018;El Gataa et al, 2022;Rabieyan et al, 2022). Drought tolerance can be improved genetically by identifying sources of stress-tolerant traits and/or genotypes, and introgressing and mobilizing the genomic regions controlling these traits into locally adapted cultivars (Shelake et al, 2022).…”

“…Several earlier GWAS studies have detected the genomic regions associated with traits contributing to drought stress tolerance in wheat either at seedling (e.g., Maulana et al, 2020;Danakumara et al, 2021;Sallam et al, 2022) or at reproductive stage (e.g., Gataa et al, 2021;El Gataa et al, 2022), however, only a few studies identified genomic regions for traits recorded on both seedlings and reproductive stages (e.g., Rufo et al, 2020). The establishment of seedlings is believed to have significant effects on crop stand and therefore crop yield.…”

Drought Stress and its Tolerance Mechanism in Wheat

“…These QTLs were associated with [i] root and shoot attributes during the seedling stage and [ii] canopy temperature during the grain-filling stage. El Gataa et al [65] revealed noteworthy single-nucleotide polymorphisms [SNPs] among candidate genes associated with plant abiotic stress responses. These findings have the potential to facilitate marker-assisted selective breeding aimed at enhancing drought resistance at the seedling stage.…”

Plant Tolerance to Drought Stress with Emphasis on Wheat

“…Some QTLs of wheat detected by Maulana et al [49] co-localized with previously reported QTLs (i) for root and shoot traits at the seedling stage and (ii) for canopy temperature at the grain-filling stage. Some significant single-nucleotide polymorphisms (SNPs) were identified in candidate genes involved in plant abiotic stress responses, which will allow marker-assisted selective breeding for drought tolerance at the seedling stage [50].…”