探討阿拉伯芥中CONSTANS-Like 9/10調控開花時間及植物發育之特性與功能性分析

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Flowering time is controlled by several pathways including photoperiodic, autonomous, vernalization and GAs pathway. In the photoperiodic pathway, CONSTANS (CO) plays a central role to regulate flowering in Arabidopsis. It is well-characterized that AtCO promotes flowering in Arabidopsis under long-day conditions. Furthermore, AtCO is the first B-box protein identified in Arabidopsis. In addition to AtCO, there are 16 other CONSTANS-Like（COL） proteins contained one or two B-box domains and one CCT domain at the N terminus and C terminus, respectively. AtCOL9 has been reported as a repressor in modulating the flowering time of Arabidopsis. In this study, functional analysis of the AtCOL9 and its closest related gene AtCOL10 was performed. The flowering time was delayed in 35S::AtCOL9 / AtCOL9-SRDX transgenic plants whereas 35S::AtCOL9-VP16 and 35S::AtCOL10-VP16 caused early flowering. This indicated that AtCOL9 and AtCOL10 may act as a repressor in controlling flowering time. In addition, anther indehiscence was found in 35S::AtCOL9-VP16 and 35S::AtCOL10-VP16 transgenic plants and concerted with the down-regulation of NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1 (NST1) and NAC SECONDARY WALL THICKENING PROMOTING FACTOR 2 (NST2) expression that associated with secondary thickening in the anther endothecium. Our results indicated that amino acid sequence of AtCOL9 shares highly similarity with AtCOL10, thus both of them may regulate flowering time and anther development in the same way. Interestingly, this result is opposite to that observed for OnCOL9/10, the AtCOL9/10 orthologs in Oncidium Gower Ramsey. Our previous study indicated that OnCOL9 and OnCOL10 may act as an activator in controlling flowering time and indirectly repress anther endothecium development. As results aforementioned, COL9/10 genes in monocots and eudicots may behave divergently in regulating flowering time and plant development during evolution.