乙烯对高等植物的叶片衰老起重要的正向调控作用，但由于衰老中的叶片担负着支持新生器官生长发育的“源器官”功能，为保证从“源”向“库”的营养物质外运具有一定的持续性、适宜的速度和效率，叶片衰老过程中乙烯合成的时序和水平要被严格和精细地调控，但目前人们对这其中的分子机制还知之甚少。本项目利用模式植物拟南芥，从筛选鉴定乙烯合成限速酶ACS基因家族中参与催化衰老乙烯合成的关键成员入手，综合利用多种分子生物学和生物化学手段，解析叶龄信号和乙烯信号对不同ACS基因的调控差异；借助三种不同类型ACS基因转录后调控靶序列缺失与互换、相关早衰与晚衰突变体、乙烯合成与信号传递突变体、关键控制基因的功能分析等，深入解析在转录和转录后水平调控这些关键ACS基因、使叶片发育过程中的乙烯合成适时、适量以契合衰老进程需要的分子机制，具有重要的科学意义和创新性。

Ethylene is a well-known positive regulator of leaf senescence. The rate or the progression of senescence is tightly linked to the efficiency of nutrient remobilization in senescing leaves, which is important for the growth and development of other parts of the plant. Both the timing of the onset of ethylene production and its level during leaf senescence are fine-tuned and adjusted to meet the demands of the senescence progression. Aminocyclopropane-1-carboxylate synthase (ACC synthase, ACS), the key enzyme for ethylene biosynthesis, is encoded by a multiple gene family. Based on their C-terminal sequences, ACS proteins can be divided into three main groups. Although ethylene biosynthesis pathway has been elucidated by the Yang Cycle, it is still at early stage to understand how different type ACS genes are harmoniously regulated at both transcriptional and post-transcriptional levels to meet the requirement for the level of ethylene production needed in a given cellular environment. This project deals with an investigation of the complex network which optimizes the expression of distinct subsets of ACS genes during Arabidopsis leaf senescence. Molecular biological and molecular genetic tools will be used.