Ripening Physiology of Fruit from Transgenic文档.pdf

Plant Physiol. (1993) 102: 911-916 Ripening Physiology of Fruit from Transgenic Tomato (Lycopersicon esculentum) Plants with Reduced Ethylene Synthesis Harry J. Klee* Monsanto Company, Chesterfield, Missouri 63198 titative correlation between ethylene synthesis and the rate l h e physiological effects of reduced ethylene synthesis in a of fruit ripening; as ethylene synthesis is lowered, ripening is transgenic tomato (Lycopersicon esculentum) line expressing 1- progressively delayed. There is also evidence that many aminocyclopropane-1-carboxylic acid (ACC) deaminase enzyme aspects of ripening are ethylene independent. For example, have been examined. Fruit from the transgenic line 5673 ripen PG mRNA accumulates to a high level even when ethylene significantly slower than control fruit when removed from the vine synthesis has been reduced greater than 100-fold (Oeller et early in ripening. In contrast, fruit that remain attached to the al., 1991). A significant problem with a11 of the results ob- plants ripen much more rapidly, exhibiting little delay relative to tained to date, however, is that a low level of ethylene the control. Ethylene determinations on attached fruit revealed that there was significantly more interna1 ethylene in attached than synthesis persists and as little as 0.1 parts per million of detached fruit. l h e higher ethylen