乙烯是调节植物生长发育的重要荷尔蒙之一，它积极参与影响叶器官萌出、生长、衰老等阶段。乙烯对茎弯曲、开花和叶片发育过程的细胞分裂和扩张有着正负两种调控作用，如低浓度乙烯促进乙烯生物合成缺陷突变体acs叶片扩张，而高浓度抑制其扩张。为进一步了解乙烯调控叶细胞分裂和扩张的机理，本项目将用拟南芥acs植株作材料，利用定量蛋白组学方法挖掘鉴定、配合生物学功能分析对乙烯调控的翻译后修饰（PTM）网络-磷酸化蛋白质组和蛋白降解组进行研究。采用多步纯化、质谱鉴定、定量分析来挖掘大量磷酸化位点与泛素修饰的目标蛋白，探索由乙烯诱导的磷酸化蛋白组与泛素-26S蛋白酶体介导的降解蛋白组在乙烯信号调控叶器官细胞分裂和扩张中的作用。揭示乙烯在植物叶器官细胞分裂和扩张中的多重和双互抗作用以及PTM网络所介导的信号通道是如何调控细胞周期中的重要节点。这一研究成果及研究方法将广泛服务于农林业分子育种，分子设计和新品种培育。

Ethylene is one of the most important plant hormones that regulate plant growth and development. It is actively involved in regulation of leaf organ formation, leaf growth, development and senescence. Ethylene has both stimulatory and inhibitory effects on cell division and expansion during shoot bending, flowering and leaf development. For example, a low dose of ethylene stimulates Arabidopsis growth and expansion while higher level inhibits its growth and development in ACC synthase-deletion or ethylene biosynthesis deficient (acs) line. To further elucidate the molecular mechanism underlying leaf organ development and cell cycle, division and expansion, our laboratory plan to utilize the acs mutant as the experimental material and study the ethylene-regulated post-translational modification (PTM) network and 26S proteasome-mediated protein degradation during leaf development using functional and quantitative PTM proteomics approach and to reveal the multiple and dual-and-opposing effects of ethylene on leaf cell division, differentiation and expansion and uncover the PTM network-mediated cell signaling in cell cycle and the key crosstalks between ethylene and cell cycle. We plan to adopt multiple steps to purify and use mass spectrometer to analyze a large quantity of phosphosites and proteasome-targeted proteins. In addition, we intend to study the biological functions of these newly identified phosphosites and proteasome-targeted protein in leaf cell division, differentiation and expansion. The outcomes of this investigation will be applied to molecular breeding, molecular designing and new cultivar generation of agricultural and forestry crops.