ASPB President's Symposium
Klee, Harry , Kevany, Brian , Tieman, Denise , Dal Cin, Valeriano .
Ethylene mediates tomato fruit ripening by receptor turnover.
Fruit ripening in tomato requires the coordination of both developmental cues and the phytohormone ethylene. The multigene ethylene receptor family negatively regulates ethylene signal transduction by suppressing ethylene responses in the absence of the hormone. We have used tomato as a model system for ethylene action because of the many ethylene dependent responses, most notably fruit ripening. Our results indicate that a reduction in the levels of either of two receptors, LeETR4 or LeETR6, causes an early ripening phenotype. We had previously demonstrated that there is an approximately ten-fold increase in overall receptor mRNA levels associated with ripening. This result is puzzling since the receptors are negative regulators of ethylene responses and fruit ripening is dependent upon ethylene action. However, analysis of receptor proteins during ripening revealed that there is rapid degradation of receptor proteins in the presence of ethylene and that degradation likely occurs through the 26S proteasome-dependent pathway. Ethylene exposure of immature fruits depletes receptor proteins and brings about earlier ripening. The results are consistent with a model in which receptor levels modulate timing of the onset of fruit ripening by measuring cumulative ethylene exposure.
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1 - University of Florida, Plant Molecular and Cellular Biology Program, Horticultural Sciences, PO Box 110690, Gainesville, FL, 32611-0690, USA
2 - University of Florida, Plant Molecular and Cellular Biology Program
Presentation Type: ASPB Major Symposium
Location: International Ballroom North/Hilton
Date: Wednesday, July 11th, 2007
Time: 4:30 PM