Poster: Hormones

Abs # 615: Functional Analysis of DREB/ERF Transcription Factors Involved in Expression of Melon ACC Synthase gene(CMe-ACS2)

Presenter:	Shinji, Mizuno , mizuno@graduate.chiba-u.jp
Authors	Shinji, Mizuno  (A)   Yosuke, Hirasawa  (A)   Hiroki, Nakagawa  (B)   Tetsuo, Hirabayashi  (C)   Takahide, Sato  (A) (B)
Affiliations:	(A): Graduate School of Science and Technology, Chiba Univ. (B): Faculty of Horticulture, Chiba Univ. (C): Japan Horti. Produc. Inst.

A melon ACC synthase gene(CMe-ACS2) is highly homologous in amino acid level to At-ACS6 which is known as a multi-responsive ACC synthase gene in Arabidopsis. Therefore, CMe-ACS2 may also be induced by various environmental stimuli. We investigated expression pattern of CMe-ACS2 gene in melon leaves under various stress conditions and chemical/hormone treatments. CMe-ACS2 was increased by wounding, and under stress conditions such as cold and high salt in melon leaves. The promoter region of CMe-ACS2 contained a DRE/CRT cis-acting element(GCCGAC) that was involved in gene expression responsive to drought, high salt and cold stress. By using the yeast one-hybrid screening system, we isolated three cDNAs encoding DREB/ERF transcription factors. Their deduced amino acid sequences were including single AP2/ERF DNA binding domain. One of them was classified into DREB subfamily, and the others were classified into ERF subfamily based on the AP2/ERF domain amino acid sequence. Gel mobility shift assay and yeast one-hybrid b-galactosidase reporter assay showed that these transcription factors bound to not only DRE/CRT sequence, but also mutant sequence which substitude DRE/CRT for GCC box core sequence(GCCGCC) that was involved in ethylene responsive pathway. we discuss whether these transcription factors play roles in stress-related gene expression of CMe-ACS2.