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

番茄果实中的风味与高糖和高酸含量有关。众所周知，果实中苹果酸的水平随着果实成熟而下降50%，这种下降被认为是由细胞质内NADP依赖的苹果酸酶（NADP- me）介导的。利用玉米NADP-ME异源探针对番茄成熟过程中果皮中表达的NADP-ME基因进行了分离和鉴定。一旦分离出来，番茄基因将用于基因工程实验，以减少或抑制在成熟过程中发生的NADP-ME的诱导，并在成熟的果实中保持较高的苹果酸水平。与此同时，为了深入了解调节水果中酸水平的机制，将在水果中设计更高水平的相同酶。这项研究的预期结果将是能够直接设计水果中的酸水平，这可能会在番茄加工过程中显著影响番茄的风味。＊＊＊

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. ***