Association Mapping of Drought Tolerance Indices in Ethiopian Durum Wheat (Triticum turgidum ssp. durum)

Abstract

Ethiopia is a major producer of durum wheat in sub-Saharan Africa. However, its production is prone to drought stress as it is fully dependent on rain, which is erratic and unpredictable. This study aimed to detect marker-trait associations (MTAs) and quantitative trait loci (QTLs) related to indices. Six drought tolerance indices, i.e., drought susceptibility index (DSI), geometric mean productivity (GMP), relative drought index (RDI), stress tolerance index (STI), tolerance index (TOL), and yield stability index (YSI) were calculated from least-square means (lsmeans) of grain yield (GY) and traits significantly (p < 0.001) correlated with grain yield (GY) under field drought stress (FDS) and field non-stress (FNS) conditions. GY, days to grain filling (DGF), soil plant analysis development (SPAD) chlorophyll meter, seeds per spike (SPS), harvest index (HI), and thousand kernel weight (TKW) were used to calculate DSI, GMP, RDI, STI, TOL, and YSI drought indices. Accessions, DW084, DW082, DZ004, C037, and DW092 were selected as the top five drought-tolerant based on DSI, RDI, TOL, and YSI combined ranking. Similarly, C010, DW033, DW080, DW124-2, and C011 were selected as stable accessions based on GMP and STI combined ranking. A total of 184 MTAs were detected linked with drought indices at –log10p ≥ 4.0,79 of which were significant at a false discovery rate (FDR) of 5%. Based on the linkage disequilibrium (LD, r2 ≥ 0.2), six of the MTAs with a positive effect on GY-GMP were detected on chromosomes 2B, 3B, 4A, 5B, and 6B, explaining 14.72, 10.07, 26.61, 21.16, 21.91, and 22.21% of the phenotypic variance, respectively. The 184 MTAs were clustered into 102 QTLs. Chromosomes 1A, 2B, and 7A are QTL hotspots with 11 QTLs each. These chromosomes play a key role in drought tolerance and respective QTL may be exploited by marker-assisted selection for improving drought stress tolerance in wheat.

Genome-wide association mapping for component traits of drought and heat tolerance in wheat

“…For the identification of genes/QTLs based on the linkage disequilibrium (LD), GWAS is one of the effective methods. For the prediction of candidate genes, GWAS has been widely used in several crops using genome-wide dense markers (Liu et al, 2018;Srivastava et al, 2020;Alseekh et al, 2021;Tiwari et al, 2022), including wheat (Negisho et al, 2022;Zhang et al, 2022). Advantages of GWAS is, QTLs for several traits can be found with high resolution in one go.…”

Genome-wide association study of yield-related traits in common wheat (Triticum aestivum L.) under normal and drought treatment conditions

“…Therefore, these seven co-located QTL can be used to synergistically improve the yield and drought resistance of wheat. To the best of our knowledge, only a few QTL for STI, which was calculated from TGW, have been detected in wheat ( Negisho et al., 2022 ). Nevertheless, they were located at different chromosomal regions with these QTL for STI detected in this study.…”

Genetic variation, population structure, and marker-trait association of rice (Oryza sativa L.) cultivars using morphological characteristics and molecular markers

“…Similarly, another study identi ed several markers associated with yield contributing traits in crops(Anandan et al 2016). Beside rice, this associations have been discussed in many other crops (Negisho et al 2022…”