Project Number: 5335-21430-006-00
Project Type: Appropriated

Start Date: Apr 01, 2006
End Date: Mar 31, 2011

Objective:
OBJECTIVE: 1. To determine the ethylene biosynthetic capacity of the tomato plant. We will determine whether the tomato ACS isozymes have the capacity to heterodimerize using functional intermolecular complementation and Bimolecular Fluorescence Complementation (BiFC) in E.coli. We will also determine the biochemical properties of the active homo- and heterodimeric isozymes. We will focus our studies on the heterodimeric forms of the fruit, and also perhaps of senescing vegetative tissues. 2. To determine some of the molecular details of the regulation of the tomato genes by the hormone auxin. The Auxin Response Factors (ARF) that regulate their auxin-inducibility will be identified and tested whether affect plant senescence. Our studies will be focused on the ARFs and auxin-ethylene interactions in fruit and abscission zones.

Approach:
Ethylene is a unique plant signaling molecule. The hydrocarbon gas, known as the fruit ripening hormone, controls many aspects of plant growth and development, and its synthesis is highly regulated. Recent experimental evidence indicates that the key enzyme in the ethylene biosynthetic pathway,1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) is encoded by a highly divergent multigene family in various mono and dicotyledonous plants. The members of each family are differentially regulated by various inducers and developmental stages. Studies on the heterodimerization properties of the various ACS isozymes are proposed in order to determine the biochemical capacity of the ACC gene family. Functional intermolecular complementation and biomolecular fluorescence complementation (BiFC) experiments will be carried to achieve this objective. Furthermore, molecular experiments are proposed to determine which of the Auxin Response Factor (ARF) gene family members regulates the various ACS genes in tomato. REPLACES 5335-21430-005-00D (4/06). BSL 1; 2/19/08.