菜心芥子油苷合成相关基因BraAOP2长距离调控结球甘蓝/菜心嫁接体花期的机理研究

Cabbage (Brassica oleracea L. var. capitata) is one of the most important vegetables belonging to Brassica genus in Cruciferae. Nornally, cabbage reproduces one time in a year, which seviously restricts the breeding process. We found that cabbage flowering can be accelerated through grafting onto the early bolting flower chinese cabbage (Brassica. campestris L. ssp. chinensis var. utilis Tsen. et .Lee) rootstock. However, the regulatory mechanism of early bolting in cabbage heterografts is largerly unknown. Glucosinolates are an important group of secondary metabolites characteristic of the Brassicales order. It is reported that there is cross-talk between the networks controlling flowering and glucosinolate profiles, as glucosinolate biosynthetic genes within the GS-AOP locus have been associated with the control of onset of flowering. BraAOP2 gene from flowering chinese cabbage stocks was expressed in cabbage scions. In addition, alerted glucosinolate profile were detected in cabbage scions, suggesting that the flowering signal regulated by BraAOP2 in rootstocks was transported to cabbbage scions through graft-transmissible action, but little is known about the transport processes. In this projest, we are going to verify the transporting way of flowering signal from rootstocks to cabbage scions, which is maybe regulated by the graft-transmissible action of BraAOP2 mRNA , protein or glucosinolates. The aim of our project is to reveal the mechanism of accelerated flowering in cabbage heterograft with flowering chinese cabbage rootstock, enrich our understanding of glucosinolate transports and also supply theoretical basis for cabbage breeding about the regulation of flowering time.

结球甘蓝是我国普遍栽培的蔬菜，育种周期长是制约其品种选育进程的因素，因此花期调控在甘蓝育种中至关重要。本项目组发现甘蓝与易抽薹的菜心嫁接后可提早抽薹，但是关于甘蓝/菜心嫁接体中花期提前的调控机制尚不清楚。芥子油苷是十字花科蔬菜重要的次生代谢产物，最新研究发现拟南芥AOP2基因催化的芥子油苷代谢可调控其开花进程。甘蓝与菜心嫁接后可在甘蓝中检测到菜心BraAOP2基因的表达及相应芥子油苷组分的改变，表明菜心BraAOP2调控的开花信号可能通过嫁接向甘蓝转运并调控其开花，但具体的转运方式尚不清楚。本项目拟在此基础上应用生物化学和分子生物学技术分别从mRNA转运、蛋白转运和终产物芥子油苷转运三方面探究菜心BraAOP2基因调控的开花信号在嫁接体中的传递方式，解析菜心BraAOP2基因调控甘蓝/菜心嫁接体开花的分子机制，为通过农艺技术和代谢工程手段调控甘蓝花期奠定理论基础。

结球甘蓝绿体春化型植物，其春化特征导致其一年只能繁殖一代，制约其品种选育进程的因素，因此花期调控在甘蓝育种中至关重要。本项目组前期发现甘蓝与易抽薹的菜心嫁接后可提早抽薹，但是关于甘蓝/菜心嫁接体中花期提前的调控机制尚不清楚。芥子油苷是十字花科蔬菜重要的次生代谢产物，最新研究发现拟南芥AOP2基因催化的芥子油苷代谢可调控其开花进程。甘蓝/菜心嫁接体与甘蓝/甘蓝嫁接体中甘蓝接穗开花起始阶段蛋白质组学分析证实芥子油苷途径参与甘蓝/菜心嫁接体的花期调控。研究结果显示，甘蓝与菜心嫁接后甘蓝接穗中AOP2调控的芥子油苷组分发生变化，BraAOP2的转基因实验也表明BraAOP2可以调控十字花科蔬菜的开花进程，但这一过程并不完全依赖于芥子油苷途径。此外，通过RT-PCR、WB方法，结合转录组学、蛋白组学的手段在甘蓝接穗中检测到菜心BraAOP2基因的mRNA和蛋白，说明BraAOP2基因调控的开花信号通过mRNA和蛋白传递到甘蓝接穗中。我们的研究揭示BraAOP2通过长距离转运调控植物开花进程的具体作用形式，加深了对芥子油苷调控植物花期作用机制的认识，同时为通过农艺技术和代谢工程手段调控甘蓝及其它十字花科蔬菜中芥子油苷的组分进而调控其抽薹开花时间奠定理论基础，在十字花科育种中具有重要的理论意义和现实价值。