My lab has developed a biochemical assay that we hope will allow us to define a mechanism by which the ethylene receptors control CTR1 activity, both in the presence and absence of ethylene binding. Additionally, using this assay, we hope to identify other factors that are involved in CTR1 regulation, with the goal of fully elucidating the upstream events in ethylene signal transduction. A second project involves using a molecular genetic approach to identify new factors involved in ethylene signaling. We are presently using a map-based cloning approach to isolate genes from two Arabidopsis mutants that have increased sensitivity to ethylene. Chromosome walking has placed the eer1 locus in a 1 cM window on chromosome 1.
Work is also underway to characterize a second mutant with increased ethylene sensitivity.
We are presently initiating map-based cloning for this mutant and examining crosses with other ethylene mutants to identify the gene of interest and determine its role in ethylene signaling. Finally, my lab is also interested in how ethylene-dependent physiological processes are manifested, specifically the mechanisms that are responsible for the progression of fruit ripening and flower senescence. Pollination and fertilization lead to dramatic changes in the flower including senescence of tissues such as the petals and styles and at the same time growth of the ovary and developing ovules. Interestingly, in carnation flowers, each physiological process features a burst in ethylene production, yet in one case, ethylene initiates senescence and in the other it promotes growth. It is unclear as to how ethylene can cause such different phenotypes, but such differential responsiveness to ethylene occurs throughout a plant's life cycle.