Seclection And Mechanism Preliminary Studies Of ERF On Regulation Of Petunia Floral Scent Synthesis

Petunia(Petunia hybrida) is a model plant, which can be used to study of ethylene signaling and flower scent. Ethylene response factor(ERF), which has AP2/ERF domain, is the last component of the ethylene signal transduction pathways. ERF has an important role in fruit ripening, flower senescence, plant growth and development, stress responses and hormonal regulation. On the basis of previous studies, we know that petunia aroma sharply reduced and ethylene has increased dramatically after pollination. It is indicated that ethylene can regulate petunia floral scent biosynthesis. To understand the mechanism of ERF in regulation floral scent synthesis, the effects of ERF transcription factors on the expression of floral scent genes in getting several subfamily of ? ERF genes from petunia were analyzed. The regulatory relationships of ERF on floral genes, the expression characteristics of Ph ERF6 during the day, the transcription levels of floral transcription factors and floral synthase genes after silencing Ph ERF6 and Ph ERF30 mediated by VIGS and the subcelluar location of Ph ERF30 were examined. Results were as follows:1 Using the dual-luciferase detection system, the effects of Ph ERF6, Ph ERF25 and Ph ERF30 transcription factors on the expression of ODO1, EOBI, EOBII, PAAE, BPBT, PAL were analyzed. Results showed that overexpression of Ph ERF6 has a significant negative effect on the expression of ODO1, BPBT and PAL. However, silencing of Ph ERF30 significantly increased the expression of EOBII, EOBI and ODO1. Similarly, silencing of Ph ERF25 significantly increased the expression of EOBI. It is indicated that Ph ERF6, Ph ERF25 and Ph ERF30 may inhibit the expression of floral gene to influence the synthesis of floral scent.2 The proteins physically interacting with Ph ERF6 were obtained through the yeast two-hybrid screening. Yeast two-hybrid analysis showed that full length of Ph ERF6 physically interacted with ODO1 and EOBI. The N-Terminal of EOBI is the core domain of interaction. It is indicated that Ph ERF6 physically interacted with ODO1 and EOBI, which are key transcription fators of floral scent synthesis pathway, confirming that Ph ERF6 was related to the synthesis of floral scent.3 Quantitive real-time PCR assay showed that the diurnal expression pattern of Ph ERF6 was found to be rhythmic, which coordinated the pattern of volatile emissions. It is showed that Ph ERF6 had different expression patterns in volatile emissions stage and Ph ERF6 involved in the synthesis of floral scent. After silencing Ph ERF6 and Ph ERF30 respectively mediated by VIGS, the transcription levels of several transcription factors and floral scent synthase genes were increased. These results indicated that Ph ERF6 and Ph ERF30 have positive effect on the expression of these genes and the synthesis of floral scent.4 Subcellular localization analysis showed that the Ph ERF30 exclusively localized in the nucleus.