Efficient generation of transgenic barley: The way forward to modulate plant–microbe interactions

Stable genetic transformation represents the gold standard approach to the detailed elucidation of plant gene functions. This is particularly relevant in barley, an important experimental model widely employed in applied molecular, genetic and cell biological research, and biotechnology. Presented are details of the establishment of a protocol for Agrobacterium-mediated gene transfer to immature embryos, which enables the highly efficient generation of transgenic barley. Advancements were achieved through comparative experiments on the influence of various explant treatments and co-cultivation conditions. The analysis of representative numbers of transgenic lines revealed that the obtained T-DNA copy numbers are typically low, the generative transmission of the recombinant DNA is in accordance with the Mendelian rules and the vast majority of the primary transgenics produce progeny that expresses the respective transgene product. Moreover, the newly established protocol turned out to be useful to transform not only the highly amenable cultivar (cv.) ‘Golden Promise’ but also other spring and winter barley genotypes, albeit with substantially lower efficiency. As a major result of this study, a very useful tool is now available for future functional gene analyses as well as genetic engineering approaches. With the aim to modify the expression of barley genes putatively involved in plant–fungus interactions, numerous transgenic plants have been generated using diverse expression cassettes. These plants represent an example of how transformation technology may contribute to further our understanding of important biological processes.     

Sequence comparison of glyceraldehyde-3-phosphate dehydrogenases from the three urkingdoms: evolutionary implication

The primary structure of the glyceraldehyde-3-phosphate dehydrogenase from the archaebacteria shows striking deviation from the known sequences of eubacterial and eukaryotic sequences, despite unequivocal homologies in functionally important regions. Thus, the structural similarity between the eubacterial and eukaryotic enzymes is significantly higher than that between the archaebacterial enzymes and the eubacterial and eukaryotic enzymes. This preferred similarity of eubacterial and eukaryotic glyceraldehyde-3-phosphate dehydrogenase structures does not correspond to the phylogenetic distances among the three urkingdoms as deduced from comparisons of ribosomal ribonucleic acid sequences. Indications will be presented that the closer relationship of the eubacterial and eukaryotic glyceraldehyde-3-phosphate dehydrogenase resulted from a gene transfer from eubacteria to eukaryotes after the segregation of the three urkingdoms.