SAUR72在拟南芥叶片衰老调控中的作用机制

The mechanism underlying the role of SAUR72 in Arabidopsis leaf senescence regulation

植物激素在叶片衰老过程中起着重要的调控作用。本课题组在前期利用拟南芥cDNA文库筛选叶片衰老负调节因子SSPP互作组分的过程中,发现一个生长素响应基因家族成员SAUR72可能与SSPP发生互作。本文首先利用酵母双杂交技术对SAUR72和SSPP之间的蛋白互作进行了验证,并进一步发现SAUR72基因的表达受到衰老诱导和SSPP过表达抑制;过表达SAUR72基因不但造成拟南芥成苗叶片早衰,还能促进幼苗下胚轴和主根伸长、根系等部位pH值下降,暗示着这一生长素响应基因是拟南芥叶片衰老的正调节因子,并可能通过抑制特殊磷酸酶活性、间接促进H^+-ATPase的活性上升而发挥作用。上述研究结果的取得,为明确生长素在叶片衰老调控中的功能奠定了基础。

Plant hormones play important regulatory roles in leaf senescence process. In our previous yeast two-hybrid assay（Y2H） to screen for interactors of the negative leaf senescence regulator SSPP against a c DNA library, we found an auxin response protein SAUR72 as a putative candidate. In this paper, the interaction between SAUR72 and SSPP was verified by Y2H. It was further found that the expression of SAUR72 was induced by senescence and inhibited in SSPPox that displayed delayed leaf senescence phenotype. In addition, overexpression of SAUR72 not only led to precocious leaf senescence in Arabidopsis, but also promoted the elongation of hypocotyls and primary roots as well as the decrease of p H in the root system. All results imply that this auxin response gene is a positive regulator of leaf senescence in Arabidopsis. The current study established foundation to elucidate the function of auxin in leaf senescence regulation.