植物激素BR在调控植物发育过程中起着重要作用，主要调节茎的伸长、开花时间、衰老进程等。BR信号转导过程从细胞膜受体BRI1接受信号开始，经过一系列信号传递，最后调节核内下游基因的表达。在信号传递过程中，蛋白质的磷酸化修饰起着重要作用，但是乙酰化修饰是否起着同样重要的作用，我们所知甚少。在研究初期，我们筛选得到一个跟BR信号通路相关的突变体22-76，突变基因编码一个N端乙酰转移酶HLS1，利用LC-MS/MS我们找到HLS1的底物为Auxin合成过程中的重要酶NIT1。因此我们推测，BR通过影响HLS1乙酰化NIT1的过程从而调控植物生长发育。在本研究中，我们将采用遗传学、分子生物学、生物化学的方法，研究HLS1的蛋白功能以及在BR与Auxin信号相互作用过程中的功能，系统研究HLS1在BR调控植物生长发育中的功能与作用，为深入研究植物激素调节植物生长发育的机制提供重要的理论指导。

Brassinosteroids (BRs) are a class of plant steroid hormones and play important roles in a wide range of developmental and physiological processes such as stem elongation, flowering time, senescence. BR signal was accepted by membrane receptor BRI1 and be transducted to the nuclear to regulate gene expression. Protein phosphorylation plays important roles in signal pathway and we want to know whether acetylation also has effects in signal pathway. Recently, we have screened a novel mutant named 22-76，and the gene encodes an N-acetyltransferase HLS1. Through LC-MS/MS, we identified its substrate is NIT1. Therefore, we hypothesize that BRs may regulate plant development through HLS1 acetylate NIT1. In this research, we will apply genetic, molecular biology, biochemical approaches to explore the function of HLS1 in interaction between BR and Auxin signal pathway to disclosure the mechanism by which how HLS1 involved in BR regulating plant growth and development. Our study will provide significant insight into how phytohormones regulate plant development.