9604115 Giovannoni Dr. Giovannoni treats ripening of the tomato fruit as a developmental program - in contrast to most of other analyses in which the tomato fruit is studied as an example of plant senescence. Some ethylene-insensitive tomato mutants, indeed, indicate that the senescence-specific hormone ethylene can be modulated in a developmental fashion. His group has isolated from tomato genes homologous to components of the ethylene signal transduction pathway detected in other plants. In combination with his mutant collection and the detection of fruit-specific transcripts that do not respond to ethylene but are under other developmental control, the project develops. It includes the characterization and transgenic manipulation of the CTR1 ethylene signal transduction modulator as one aspect. Secondly, constitutive ethylene responding mutants are characterized physiologically and with respect to the expression of developmentally-regulated transcripts. Finally, non-ethylene responsive, developmentally induced transcripts will be functionally characterized. The work is expected to provide an integrative view of different gene expression programs regulating fruit ripening in general.
