Increased potato tuber size resulting from apoplastic expression of a yeast invertase

The role of sucrose cleavage in determining sink strength in potato was investigated by generating transgenic potato plants that expressed a yeast invertase in either the cytosol or apoplast of tubers. Cytosolic localization gave rise to a reduction in tuber size and an increase in tuber number per plant whereas apoplastic targeting led to an increase in tuber size and a decrease in tuber number per plant. Sink organ size can be manipulated through modification of sucrose metabolism. © 1997 Nature Publishing Group.