Effects of the silencing of sorbitol dehydrogenase on sugar partitioning in vegetative sinks in apple.

摘要

The major aim of this study was to determine the effect of the modulation of sorbitol dehydrogenase activity on sugar partitioning in apple leaves at different developmental stages. Transgenic plants with regulated sorbitol dehydrogenase (SDH) activity were obtained using transgenic sense and antisense technology. Plants were analyzed using native polyacrylamide gel electrophoresis assay and western blotting. Sugar levels (glucose, fructose, sorbitol and sucrose) were determined in leaves at different developmental stages. The two antisense lines (A090802-1 and A011803/A) showed reduced SDH activity in immature leaves while the sense lines (S071502 and S091202) showed similar SDH activity to untransformed controls. Western blot analysis partially correlated with activity assays implying the possibility of post-transcriptional regulation. Differences in SDH activity were associated with an altered fructose sorbitol ratio in immature leaves of transgenic plants. Increased levels of glucose in immature and middle stage leaves were observed in antisense line A011803/A. Differences in fructose:sorbitol and sorbitol:sucrose ratios among transformants were not significant in mature, fully expanded leaves. These results suggest that the differential regulation of SDH activity in immature leaves could have dramatic consequences on the sugar partitioning between sink and source vegetative tissues and consequently on the vegetative growth of apple plants.