|Manoharan, Muthusamy - UNIVERSITY OF ARKANSAS|
Submitted to: In Vitro Cellular and Developmental Biology - Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2007
Publication Date: December 1, 2007
Citation: Dahleen, L.S., Manoharan, M. 2007. Recent advances in barley transformation. In Vitro Cellular and Developmental Biology - Plants. 43:493-506. Interpretive Summary: The science of barley transformation has shown many advances in the last eight years. New methods to improve gene insertion have been tested and gene expression is being targeted to specific barley tissues. Genes are now being inserted to increase disease and stress resistance, improve malting quality, nutrient content, feed quality, and produce feed enzymes and pharmaceutical compounds. Transformation also is being used as a tool to identify the effects of isolated genes and to develop new methods to identify genes. This review article describes the newest advances in barley transformation and points out some of the needs for future research.
Technical Abstract: Barley, an important member of the cereals, has been successfully transformed through various methods such as particle bombardment, Agrobacterium-tumefaciens, DNA uptake, and electroporation. Initially, the transformation in barley concentrated on developing protocols using marker genes such as gus, bar, and hpt. Immature embryos and callus derived from immature embryos were targeted for transformation. Subsequently, genes of agronomic and malting importance have been deployed in barley. Particle bombardment appears to be the preferred choice for barley transformation in the majority of the reports, although Agrobacterium-mediated transformation is being used more often. The current review focuses on the challenges encountered in barley transformation such as somaclonal variation, development of transformation system for commercial cultivars, gene expression, stability and inheritance, and gene flow. Newer markers such as the green fluorescent protein (gfp), firefly luciferase, and phosphomannose isomerase were found to be useful in the selection of transgenic plants. Tissue-specific promoters such as those for B1-hordein and D-hordein genes as well as spike-specific promoters are increasingly used to drive gene expression. The review also describes recent research on gene tagging through transformation, insertion of disease resistance and abiotic stress resistance genes, transformation with genes for improved malting quality, nutrient content, feed quality and production of feed enzymes and pharmaceutical compounds.