TIE1Is Involved In Regulation Of Leaf Senescence In Arabidopsis

Leaf is the major place to assimilate through photosynthesis. In higher plant, leaf senescence play a critical role for their survival, development and productivity. Different kinds of phytohormones and genes are involved in leaf aging. However, the molecular mechanisms of plant branching are still not well understood. In order to identify genes involved in leaf aging, we focus on a transcription repressor TIE1which regulates leaf development.We showed that the semi-dominant mutant tiel-D, which is overexpression of TIE1in Arabidopsis, leads leaf early aging. Yeast two-hybrid analysis found that TIE1interacted with the TCP20transcription factor. Bimolecular fluorescence complementation (BiFC) and genetic analysis confirmed the interactions. TCP20is a key regulator in leaf development, and TCP20may be involved in regulation of leaf senescence, according to previous reports. We fused the TCP20to3’-end region of TIE1and the construct was transformed to wild type plants. The same phenotype of tiel-D found in these transgenic lines. This indicated TIE1was involved in the same pathway of senescence as TCP20.To further confirm TIE1which regulates leaf senescence, an activation domain VP16was fused to TIE1, in which the EAR motif was mutated or deleted, and the construct was transformed to wild-type Arabidopsis. These transgenic lines showed late senescence.To summarize, this analysis suggest TCP20may participate in the regulation of leaf senescence, and TIE1cooperates with TCP20to modulate leaf development.