Detailed Genetic Analysis for Identifying QTLs Associated with Drought Tolerance at Seed Germination and Seedling Stages in Barley

Abstract

Drought induces several challenges for plant development, growth, and production. These challenges become more severe, in particular, in arid and semiarid countries like Egypt. In terms of production, barley ranks fourth after wheat, maize, and rice. Seed germination and seedling stages are critical stages for plant establishment and growth. In the current study, 60 diverse barley genotypes were tested for drought tolerance using two different treatments: control (0-PEG) and drought (20%-PEG). Twenty-two traits were estimated for seed germination and seedling parameters. All traits were reduced under drought stress, and a significant variation was found among genotypes under control and stress conditions. The broad-sense heritability estimates were very high under both control and drought for all traits. It ranged from 0.63 to 0.97 under the control condition and from 0.89 to 0.97 under drought, respectively. These high heritabilities suggested that genetic improvement of drought tolerance in barley at both stages is feasible. The principal component analysis revealed that root-related parameters account for the largest portion of phenotypic variation in this collection. The single-marker analysis (SMA) resulted in 71 quantitative trait loci (QTLs) distributed across the seven chromosomes of barley. Thirty-three QTLs were detected for root-length-related traits. Many hotspots of QTLs were detected for various traits. Interestingly, some markers controlled many traits in a pleiotropic manner; thus, they can be used to control multiple traits at a time. Some QTLs were constitutive, i.e., they are mapped under control and drought, and targeting these QTLs makes the selection for drought tolerance a single-step process. The results of gene annotation analysis revealed very potential candidate genes that can be targeted to select for drought tolerance.

High-LD SNP markers exhibiting pleiotropic effects on salt tolerance at germination and seedlings stages in spring wheat

“…Germination is a sensitive growth stage to salt stress and is considered an important growth stage in the plant's life (Feizi and Aghakhani 2007;Moursi 2014;Wu et al 2019). Therefore, evaluating genotypes at this stage is very effective in abiotic stress studies to develop tolerant cultivars (Sallam et al 2019).…”

Identification and Validation of High LD Hotspot Genomic Regions Harboring Stem Rust Resistant Genes on 1B, 2A (Sr38), and 7B Chromosomes in Wheat

“…Therefore, phenotypic selection at the seedling stage alone can be misleading due to plant development and genotype × environment interaction. Phenotypic selection along with molecular genetic tools will lead to genetic improvement and a better understanding of stem rust resistance in wheat (Mourad et al, 2019;Dawood et al, 2020;Moursi et al, 2020;Ghazy et al, 2021). Moreover, selection at the seedling stage for stem rust resistance is very important as it is an efficient assay for advancing lines to the next generation.…”

Contribution of functional genomics to identify the genetic basis of water‐deficit tolerance in barley and the related molecular mechanisms

“…In that case, it can be hypothesized that sensitive genotypes display damage not occurring in tolerant genotypes, thus leading to earlier expression of the AP2 TF to limit the consequences of cell dehydration. In other respects, AP2 and other TFs such as bHLH, MYB and ABI5 were identified as candidate genes in genomic regions associated with drought tolerance traits at germination, seedling or reproductive stages among large collections of Egyptian and worldwide genotypes (Moursi et al., 2020; Thabet et al., 2020). Recently, Luo et al.…”

“…(2019) determined QTL associated with peroxidase and catalase activity under drought stress, and identified six genes encoding peroxidases close to the markers associated with better tolerance. H 2 O 2 scavenging appears as a key process conferring drought tolerance since two genes coding for catalases were identified as candidates in QTL associated with tolerance traits at germination and seedling stages when testing 60 Egyptian contrasted genotypes (Moursi et al., 2020). DHAR , which encodes dehydroascorbate reductase the enzyme allowing ascorbate regeneration for H 2 O 2 elimination, exhibits sequence variation associated with adaptation to bioclimatic arid conditions, based on the analysis of the genomes of 803 contrasted barley landraces (Lei et al., 2019).…”

“…Four SNPs in this sHSP gene were found associated with important agronomic traits in conditions of water shortage and could be thus considered as markers for improving drought tolerance in barley (Xia et al., 2013). Another gene coding for one HSP70 isoform was found as a marker for QTL associated with drought tolerance at germination and seedling stages in 60 Egyptian genotypes (Moursi et al., 2020).…”