Association mapping unravels the genetic basis for drought related traits in different developmental stages of barley.

Drought stress significantly reduces crop yields at all stages of plant development. Barley, known for its abiotic-stress adaptation among cereals was used to examine the genetic basis of drought tolerance. A population of 164 spring barley lines was subjected to polyethylene glycol (PEG) induced drought stress during germination and seedling development. Six traits were measured, including germination percentage and rate, seedling length and weight, and root-to-shoot ratios. Seedling area, volume, and root and shoot diameter was acquired with a flatbed scanner. This population was also subjected to short-term drought during the heading stage in the greenhouse. Root and shoot weight and grain yield data were collected from well watered and droughted plants. Significant variation within traits were observed and several of them exhibited strong correlations with each other. In this population, two genotypes had 100% germination under PEG-induced drought and drought tolerance throughout the heading stage of plant development. A genome-wide association scan (GWAS) revealed 64 significant marker-trait associations across all seven barley chromosomes. Candidate genes related to abiotic stress and germination were identified within a 0.5Mbp interval around these SNPs. In silico analysis indicated a high frequency of differential expression of the candidate genes in response to stress. This study enabled identification of barley lines useful for drought tolerance breeding and pinpointed candidate genes for enhancing drought resiliency in barley.