LAZY1基因家族调控根系向地性的分子机理研究

根系向地性(Gravitropism)指根尖在感受到重力刺激后，能通过一系列生理生化反应，使得根尖调整方向，朝着被称为重力设定角的方向生长。根系向地性已有几百年研究历史，但其中一些过程，特别是早期从重力信号转导到根冠中柱细胞中PIN蛋白的极性重定位，还很不清楚。申请人在蒺藜苜蓿和拟南芥里同时发现了LAZY1家族的一些成员能通过控制重力刺激后的生长素转运蛋白PIN的极性定位和生长素流方向来调控根系向地性。国外研究组陆续也有类似报道，对其工作机理也有类似发现，但其调控根系向地性的详细分子机理仍然不清楚。在前期基础上，本研究拟详细解析LAZY1家族蛋白在根冠中柱细胞中的动态定位及其对重力刺激的反应，对其与互作蛋白一起通过调控囊泡运输来调控重力刺激下的PIN蛋白极性重定位进行深研。本项目研究成果将深入揭示LAZY1家族成员与互作蛋白一起协同调控根系向地性的详细分子机理。

Root gravitropism is the process that root adjusts its growth direction towards the so-called gravitropic setpoint angle (GSA) through a series of physiological and biochemical processes upon perception of the gravitropic stimulus. Despite that gravitropism has been studied for hundreds of years, many remain unclear, particularly the early events from signal transduction to the relocation of auxin transporter PIN proteins in columella cells. We have previously reported that certain members of the LAZY1 gene family in Medicago truncatula and Arabidopsis control root gravitropism by directing the polarization of PIN proteins within the columella cells and resultantly the auxin flow to the correct site. Recently, there are similar results and mechanical studies reported by other groups. On the basis of previous work and recent progress, here we propose to conduct in-depth research into the molecular function and dynamic localization of the LAZY1 family members that control root gravitropism. We will also perform profound investigations into the transcytosis mechanisms modulated by LAZY1 family members and their partners, which is critical for the polarization of PINs in the columella cells upon gravistimulation. This work will not only unveil the detailed molecular mechanism of root gravitropism centered by LAZY1 gene family, but also significantly advance the current understanding towards the early events of root gravitropism.