Genetic Engineering of Acidity in Tomato Fruit I Characterization of Genes for NADP-Malic Enzyme in Tomato Fruit

9362031番茄果实中的邓斯穆尔风味与高水平的糖和酸有关。已知随着果实成熟，果实中苹果酸的含量下降50%，这种下降被认为是由胞质NADP依赖的苹果酸酶(NADP-ME)介导的。利用玉米NADP-ME的异源探针，分离和鉴定成熟过程中番茄果皮中表达的NADP-ME基因。一旦被分离，番茄基因将被用于基因工程实验，以便减少或抑制成熟过程中发生的NADP-ME的诱导，更高的苹果酸水平将在成熟的果实中持续存在。同时，为了深入了解调节水果中酸水平的机制，将对水果中更高水平的同一种酶进行改造。这项研究的预期结果将是能够直接控制水果中的酸水平，这可能会在加工番茄的处理中显著影响番茄的味道。***

9362031 Dunsmuir Flavor in tomato fruit is associated with high levels of both sugars and acids. It is known that the level of malic acid in the fruit declines by 50% with fruit ripening and that this reduction is thought to be mediated by a cytosolic NADP dependent malic enzyme (NADP-ME). The tomato NADP-ME genes which are expressed in the pericarp during ripening by using a heterologous probe for NADP-ME from maize will be isolated and characterized. Once isolated, the tomato genes will be used in genetic engineering experiments so that the induction of NADP-ME which occurs during ripening would be reduced or inhibited and higher malic acid levels would persist within the ripe fruit. In parallel higher levels of the same enzyme in the fruit will be engineered in order to gain insight into mechanisms which regulate acid levels in the fruit. %%% The anticipated outcome of this research would be the ability to directly engineer the acid levels in fruit which could significantly affect the flavor of tomatoes in the treatment of processing tomatoes. ***