Poster: Regulation of gene expression

Abs # 753: Differential expression of three catalase isozymes under abiotic stresses in Capsicum annuum L. and functional analysis of CaCat1

Presenter:	Lee, Sang Ho
Authors	Lee, Sang Ho  (A)   An, Chung Sun  (A)
Affiliations:	(A): Department of Biological Sciences, Seoul National University

Three catalase genes (CaCat1, CaCat2 and CaCat3) were isolated from hot pepper and their expression patterns were analyzed. The CaCat1 and CaCat2 were differentially expressed in various organs and their patterns were also regulated by different circadian rhythms. But, CaCat3 transcripts were equally accumulated with the basal level in all organs. In situ hybridization showed the preferential localization of CaCat1 in vascular system and in response to wounding and paraquat treatment, CaCat1 transcript was significantly increased only in the paraquat-treated systemic leaves. In the protein activity, Ca²⁺/CaM activated only CAT1 isozyme, whereas activities of CAT1 and CAT2 were nonselectively inhibited by salicylic acids. Additionally, transgenic Arabidopsis overexpressing CaCat1 showed an enhanced resistance to paraquat, while it was not tolerant to wounding stress. Finally, microarray analysis revealed the changes of transcriptome in hot pepper suffering from paraquat stress. These results suggest a new perspective for possible roles of CaCat1 catalase group remained speculative until now.