Enhanced desiccation survival by engineering osmolyte biosynthesis in plants.
Palva, E. T.; Holmstrom, K. O.; Mantyla, E.; Welin, B.; Mandal, A.; Tunnela, O. E.; Londesborough, J.;
Physical stresses in plants: genes and their products for tolerance. Proceedings of a workshop held at Maratea, Italy, 24-27 September 1995. Year: 1996 Pages: 187-198
1996
บทคัดย่อ
Plant growth, productivity and distribution are severely limited by environmental stress factors such as drought, salinity and freezing temperatures, all of which disturb the water balance of the cell. Plants have evolved different strategies to alleviate the adverse effects of these stresses. A common adaptive response to stresses that results in water deficit is the accumulation of osmolytes or osmoprotectants that help cells to maintain their water balance and, in addition, protect macromolecules in stressed cells. The simplicity of the metabolic pathways leading to osmolyte biosynthesis makes them amenable to genetic engineering. Here, the potential for engineering the biosynthetic pathways of two different types of osmoprotectants, the quarternary ammonium compound glycine betaine and the non-reducing disaccharide trehalose, is discussed. Biosynthesis of both compounds is a two-step process in prokaryotes as well as in eukaryotes. For biosynthesis of glycine betaine, the bacterial genes bet
A and betB, encoding choline dehydrogenase and betaine aldehyde dehydrogenase, respectively, were used. These genes were expressed in transgenic tobacco plants which were subsequently shown to produce glycine betaine. For biosynthesis of trehalose, the TPS1 gene from yeast encoding the first enzyme of the pathway, trehalose-6-phosphate synthase, was used. Transgenic tobacco plants expressing TPS1 were shown to produce active TPS1 and to accumulate trehalose in their leaves. Production of trehalose was associated with enhanced desiccation survival both in primary transformants and TPS1-positive progeny. The results suggested that engineering osmolyte biosynthesis may provide an efficient strategy to generate crop plants with enhanced tolerance of water deficit as well as improved postharvest storage properties.