Minisymposium 11: Reproductive Development

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Abs # M1102: New clothes for COI1: insights into cell separation, abscission, apical dominance, epinasty and meristem arrest

Presenter:	Kim, Joonyup       Contact Presenter
Authors	Kim, Joonyup  (A) (B)  Dotson, Bradely  (A) (C)  Rey, Camila  (A) (C)  Patterson, Sara E (A) (B)
Affiliations:	(A): University of Wisconsin - Madison (B): Program in Cellular and Molecular Biology (C): Department of Horticulture
Web Site:	http://www.hort.wisc.edu/Patterson/Frameset.html

Although remembered as one of the earliest traits selected by human being, it is not until recently that abscission has been recognized as a model for cell separation process. Abscission is the developmental process that includes a series of programmed events resulting in detachment of organs. We have been characterizing a novel floral organ abscission mutant, dab4-1 (delayed abscission) in Arabidopsis. This mutant has several unique phenotypes including delayed floral organ abscission, lack of anther dehiscence, delayed meristem arrest, epinastic leaf growth and strong apical dominance. Recent observations indicate that dab4-1 has altered responses to several phytohormones. To further understand the hormone interactions in dab4-1, expression of more than 20 plant hormone response genes were examined. Many of these genes were differently regulated in the mutant background. Levels of auxin in dab4-1 were measured both in the shoot apex and stem. In addition, the levels of methyl jasmonate (meJA) and jasmonic acid (JA) were measured for both in dab4-1 and wild type. Genetic interactions with other hormone response mutants have also been observed and will be discussed. We have cloned DAB4 using map-based cloning and it is an F-BOX gene, COI1. Previous reports on this gene indicate that it is involved in the JA pathway and characterized for its mutants insensitivity to meJA, male sterility and mostly disease resistance. Here, we will demonstrate that dab4-1 has new additional phenotypes in specific ecotype indicating novel roles of DAB4/COI1 during plant development. We are continuing further studies on protein-protein interactions along with downstream targets for DAB4 and believe this data will further elucidate novel functions of original DAB4 in plant development.