R. Zrenner et al., ANALYSIS OF THE EXPRESSION OF POTATO URIDINEDIPHOSPHATE-GLUCOSE PYROPHOSPHORYLASE AND ITS INHIBITION BY ANTISENSE RNA, Planta, 190(2), 1993, pp. 247-252
The expression of the enzyme UDP-glucose pyrophosphorylase (UGPase; EC
2.7.7.9) from potato (Solanum tuberosum L.) was analysed with respect
to sink-source interactions and potato tuber storage. The highest lev
el of expression was found in developing tubers, the strongest sink ti
ssue. Storage of mature tubers at low temperatures led to an increase
of the steady-state level of UGPase mRNA, implicating a role of this e
nzyme in the process of ''cold-sweetening''. Transgenic plants were cr
eated expressing UGPase antisensee RNA under the control of the 35S pr
omoter of the Cauliflower Mosaic Virus with the polyadenylation signal
of the octopine-synthase gene. Regenerated plants were tested for red
uction of UGPase at the RNA, protein and activity levels. Plants with
a 95%-96% reduction of UGPase activity in growing tubers showed no cha
nge in growth and development. Also, carbohydrate metabolism in tubers
of these plants was not substantially affected, indicating that only
4% of the wild-type UGPase activity is sufficient for the enzyme to fu
nction in plant growth and development.