Barley: Omics approaches for abiotic stress tolerance

Abiotic stresses such as frost, drought, salinity, hypoxia, and mineral deficiency or toxicity frequently limit growth and productivity of temperate cereal crops, for which barley (Hordeum vulgare L. ssp. vulgare) could represent a model. Improving barley resistance to such constraints is thus fundamental in view of the expected climate change for minimizing the gap between potential and actual yield (the so-called yield gap), increasing the yield stability, and guaranteeing the sustainability of the crop. As different omics technologies have been developed during the past few decades, they enabled systematic analysis of changes that occur in plants in response to abiotic stresses. In this chapter, we focus on the omics contribution to the improvement of abiotic stress tolerance in barley. After a brief summary of the most relevant abioticstresses that limit the crop yields worldwide, successful genomics approaches have been described, starting from the exploitation of germplasm resources. Structural and functional approaches that helped in understanding the mechanisms and the genetic bases of abiotic stress tolerance, when applied to barley and model species(mainly Arabidopsis, rice, and Brachypodium), have been reviewed as an important step toward crop tolerance improvement. Quantitative genetics and genetical genomics of abiotic stress tolerance have been discussed, as they represent both a huge source of information and a challenge for future holistic approaches. Then, we present an overview of the contribution of other omics sciences (e.g., proteomics, epigenomics, metabolomics, ionomics, and phenomics). In the last section, integrative (systems) biology, together with a series of strategies for the future, is proposed and discussed.