Physiological and Molecular Responses to Controlled Severe Drought in Two Barley (Hordeum Vulgare L.) Genotypes

Drought is a major abiotic stress that restricts growth and productivity of many crops. The objectives of this study were to assess the morphological and physiological responses of barley plants at the vegetative stage to controlled severe drought, and to test the expression of drought-responsive genes (HvHsdr4, HvNCED2, HvDHN1, HvDHN9, and HvCBF3) in a time course of drought treatment. Barley plants of two genotypes (Rum and Yarmouk) were exposed to controlled severe drought (25% field capacity) in a greenhouse experiment. The two genotypes showed a similar and significant reduction in net photosynthetic rate and plant height. At the molecular level, a differential gene expression of drought-responsive genes was shown between the two genotypes. The results indicate that drought-responsive genes can be useful marker genes to study the differential response of barley genotypes to drought stress conditions.