Bacterial thermostable beta-glucanases as a tool for plant functional genomics.

A new strategy for creating experimental models for functional genomics has been proposed. It is based on the expression in transgenic plants of genes from thermophilic bacteria encoding functional analogues of plant proteins with high specific activity and thermal stability. We have validated this strategy by comparing physiological, biochemical and molecular properties of control tobacco plants and transgenic plants expressing genes of beta-glucanases with different substrate specificity. We demonstrate that the expression of bacterial beta-1,3-1,4-glucanase gene exerts no significant influence on tobacco plant metabolism, while the expression of bacterial beta-1,3-glucanase affects plant metabolism only at early stages of growth and development. By contrast, the expression of bacterial beta-1,4-glucanase has a significant effect on transgenic tobacco plant metabolism, namely, it affects plant morphology, the thickness of the primary cell wall, phytohormonal status, and the relative sugar content. We propose a hypothesis of beta-glucanase action as an important factor of genetic regulation of metabolic processes in plants.