Poster: Hormones

Abs # 601: Profiling ethylene-regulated gene expression in Arabidopsis thaliana by microarray analysis

Presenter:	Zhong, Guangyan , zhong@lal.ufl.edu
Authors	Zhong, Guangyan  (A)   Burns, Jacqueline K. (A)
Affiliations:	(A): University of Florida

Ethylene regulated gene expression in leaves of Arabidopsis thaliana was investigated using an expressed sequence tag-based microarray containing approximately 6000 unique genes. Comparing expression profiles of the ethylene-insensitive mutant etr1-1, the ethylene constitutive mutant ctr1-1, ethylene-treated wild type and untreated wild type plants identified a total of approximately 8% of the investigated genes with a greater than 2.5 fold change. Ctr1-1 and exogenous ethylene treatment had similar changes in gene expression, but differences were noted. Ethylene up-regulated several genes involved in its own biosynthesis and signal transduction pathway. A large number of transcription factors and some putative signaling components were highly regulated by ethylene. One transcription factor gene, AtEBP, had the largest induction in ctr1-1 and ethylene-treated wild type when compared with etr1-1. Putative signaling components, the heterotrimeric G protein b subunit AGB1 and the small GTPase gene Rab18 were down-regulated by ethylene, whereas expression of phosphatase 2C was induced. Chloroplast structural protein and photosynthetic genes were generally down-regulated. Ethylene appeared to regulate other primary metabolic pathways. Plant defense and PR?protein genes were differentially regulated, with some genes within this class highly up-regulated. Other ethylene-regulated genes identified were known sugar-, auxin-, wounding- and jasmonic acid-related genes, suggesting the existence of coordinated interactions of ethylene with other hormonal and defense signaling pathways. Although hundreds of potentially important transcriptome changes were identified, the functions of many ethylene-regulated genes remain unknown.