Barley

Barley (Hordeum vulgare L.) is a widely adapted cereal crop with an extremely wide geographic distribution throughout the world. It finds great use for animals as a feed and for humans as a grain, especially as the source for malt for the brewing industry. In recent times, there is considerable interest in the nutritional properties of barley due to the discovery of the cholesterol-lowering effect of β-glucan, a cell wall polysaccharide. Exploitation of genetic diversity in the primary and secondary gene pool of barley using DNA-based technologies has yielded interspecific crosses with improved grain properties, malting quality and resistance to biotic and abiotic stresses. The significant achievements regarding introgression of alien genes include the genes Rym14(Hb), Rym16(Hb) and Ryd4(Hb) which were introgressed from Hordeum bulbosum conferring resistance to BaMMV, BaYMV and BYDV in barley. Significant advances in genetic engineering of barley have been obtained, and strategies for establishment of regenerative cell and tissue culture systems as well as for development of DNA delivery techniques have been formulated. Lately, a huge potential has been realised in barley grains to produce pharmaceutical proteins like oral vaccines, growth supplements and food additives which are being exploited in a commercial scale. Nevertheless, several problems still remain like the strong genotype dependency of barley transformation protocols, transformation efficiency, transgene stability and public acceptance. The review focuses on all these issues and elaborates achievements made in the last two decades in genetic enhancement of barley using different alien gene transfer approaches.