MANIPULATION OF SINK-SOURCE RELATIONS IN TRANSGENIC PLANTS

Since 1980, the use of transgenic plants in modern plant science has b ecome a powerful tool to study whole plant physiology. In this review, we try to summarize the data obtained in the field of photoassimilate partitioning. Attempts to study sink-source interactions concern fact ors which might limit sink strength and source capacity. Transgenic pl ants have been used to manipulate the sucrose to starch ratio in order to produce plants with higher sucrose levels in their source leaves. Alterations in partitioning were achieved by manipulating Calvin cycle enzymes, transport proteins and sucrose biosynthetic enzymes. The abi lity of sink tissues to attract photoassimilates has been altered by e ither increasing or decreasing sucrose hydrolytic activities. The incr ease of sucrose hydrolysis was achieved by creating transgenic potato plants with tuber specific yeast-derived invertase. Decreased sucrose utilization was achieved by antisense inhibition of sucrose synthase i n potato tubers.