ISOLATION OF THE TOMATO AGAMOUS GENE TAG1 AND ANALYSIS OF ITS HOMEOTIC ROLE IN TRANSGENIC PLANTS

To understand the details of the homeotic systems that govern flower d evelopment in tomato and to establish the ground rules for the judicio us manipulation of this floral system, we have isolated the tomato AGA MOUS gene, designated TAG1, and examined its developmental role in ant isense and sense transgenic plants. The AGAMOUS gene of Arabidopsis is necessary for the proper development of stamens and carpels and the p revention of indeterminate growth of the floral meristem. Early in flo wer development, TAG1 RNA accumulates uniformly in the cells fated to differentiate into stamens and carpels and later becomes restricted to specific cell types within these organs. Transgenic plants that expre ss TAG1 antisense RNA display homeotic conversion of third whorl stame ns into petaloid organs and the replacement of fourth whorl carpels wi th pseudocarpels bearing indeterminate floral meristems with nested pe rianth flowers. A complementary phenotype was observed in transgenic p lants expressing the TAG1 sense RNA in that first whorl sepals were co nverted into mature pericarpic leaves and sterile stamens replaced the second whorl petals.