Genomics and Molecular Breeding for Improving Tolerance to Abiotic Stress in Barley (Hordeum Vulgare L.)

Barley is one of the most important cereal crop in the world, in terms of harvested area, trade value, cattle feed and human nutrition. It is one of the most adapted plant species to marginal environments, where abiotic stresses, such as drought, heat, cold, low fertility and salinity, are prevalent and limit crop productivity. Due to its wide adaptability, barley is often the only crop that can be grown in many countries of West Asia and North Africa, thus representing a very important resource for farmers and the principal feed for livestock in these areas. To cope with these adverse conditions, the selection for barley cultivars with stable and economic yield under variant environments is a primary requirement of any breeding program. Recently, new genomic and molecular tools have increased the number of genes identified in the barley gene pool, involved in abiotic stress tolerance and in the adaptation to unfavorable environments. The complementation of traditional breeding approaches with new analytical selection methodologies is required for future yield gains to meet the global food/feed and industrial demand as well as to cope up with the effects of climate changes. Therefore, exploiting new genomics- and molecular-based breeding strategies to increase barley yield as well as the development of new varieties with improved adaptation to abiotic stresses is crucial. In this chapter, the utilization of genomics- and molecular-based tools and their integration with classical breeding approaches is presented to improve the tolerance to abiotic stresses in barley. Major challenges in breeding for tolerance to major abiotic stresses are described in the beginning, followed by the exploitation and utilization of different genomics and genetic resources, and breeding approaches currently used to produce tolerant varieties. The application of marker-assisted selection and markers discovery using quantitative genetics, association mapping and bioinformatics approaches for abiotic stress tolerances in barley are also highlighted. Furthermore, comparative and functional genomics approaches used to understand abiotic stress tolerance mechanisms in plants and their potential application for improving tolerance to abiotic stresses in barley have been discussed. Finally, challenges and future perspectives for the application of genomics- and molecular-based breeding strategies for barley crop improvement under abiotic stress conditions are overviewed.