Poster: Hormones

Abs # 638: Expression patterns of a cytochrome P450 (CYP71A1) in avocado cell suspension cltures

Presenter:	Li, Rui , rl38500@yahoo.com
Authors	Li, Rui  (A)   Bozak, Kristin  (A)
Affiliations:	(A): California polytechnic university, Pomona, CA 91768

Ethylene regulates a specific set of genes that encode proteins with specific functions in plant growth and developmental processes. One of these genes has been identified as a cytochrome P450 monooxygenase enzyme, and designated Cyp71A1 in Avocados. However, the role of this protein in plant growth and development remains unknown. Our previous results showed that wounding stress induced the accumulation of Cyp71A and the production of ethylene in Avocados. In establishing a cell suspension culture of avocado to study expression patterns of P450, we found that constant shaking (shearing stress) induced the expression of P450, and released ethylene (92.0 ppm/d/g fresh cell) during culture. The induction of the gene was intensified when cells were exposed to 50 M jasmonic acid, 100 M salicylic acid, and fungal elicitor (100 g/ml of P. cinnamomi) for 6 h. Application of AVG (amino-ethoxy-vinyglycine), an ethylene synthesis inhibitor, reduced the production of ethylene, but did not affect the induction of P450 at the transcriptional level. These results are consistent with the preliminary results obtained from transgenic Arabidopsis harboring a chimera with the reporter gene GUS under control of a 1 kb promoter from Cyp71A. Our results implicate that the effect of shearing should be considered if using a cell suspension culture as model system to study gene expression. This work was supported by an NIH-MBRS grant to KRB.