Morphological, physiological and metabolic responses of diverse barley inbreds to dry down and moderate drought stress

Drought stress alters the metabolic activity, physiological processes, and plant growth and such responses might differ with the intensity of stress. We evaluated the genotypic diversity on plant morphology, photosynthetic responses, metabolite shift and their relationship in diverse barley inbreds under dry down (DD) and moderate drought (MD) stress using 23 genetically diverse parental inbreds of genetic mapping population of barley. MD stress caused a strong growth reduction, while DD stress triggered inhibition of photosynthetic health. We observed that the induced changes occurred in a genotype-dependent manner. Compared to control conditions, the metabolism of simple sugars and polyhydroxy acids increased in MD and DD, while the maximum accumulation of amino acid, lipids and phosphates occurred in DD stress. Accumulation of hexose and metabolites with unknown classification was the metabolic signature of drought tolerant inbreds. The inbreds tolerant to MD originated from the temperate regions while those tolerant to both MD and DD came from semi-arid regions. Low stomata density, reduced water loss and retarded growth under drought stress were the key features of inbreds with better survival capacity under severe dehydration. We identified drought tolerant barley inbreds and our study offers resources for future genetic research on various drought tolerance strategies.