Strategies of Barley Improvement under water stress: Responses, ‎Approaches and Management ‎

Plants use a variety of strategies to cope with abiotic stress, depending on the species and the growth of the plant. Abiotic stresses such as drought is the most important stress that affects yield of agricultural products. In addition, drought stress is one of the main limiting factors in plant growth, it can also inhibit respiration, photosynthesis, and thus affects the growth and physiological metabolism of plants. Plants activate several mechanisms such as morphological and structural changes as well as the expression of drought-resistant genes, the synthesis of hormones and osmotic regulators to reduce drought stress. Drought accelerates grain leaf senescence, altering the expression of thousands of genes and ultimately affecting grain protein content and grain yield. However, the genotypic variability exists for drought induced disruption and tolerance in barley. In this review, the approaches can help for improving barley genotypes in response to drought stress through breeding and physiological traits, genetic engineering, and marker-assisted selection (MAS). We detected genes and proteins involved in response to drought-tolerance using proteomics, transcriptomics and metabolomics approaches. Also, the introduced Quatitatives Traits Loci (QTLs) related to yield and Stay green and physiological traits found in this study can be used for MAS in barley improvement for drought tolerance in the future. In particular, comparative studies of genetically diverse germplasm exposed to adverse conditions such as drought provide valuable insights into plant responses to stress and create information on biochemical pathways involved in adaptation to environmental limitations. Proper evaluation of omics data can help the biomarker discovery.