钙对芍药花茎机械强度的调控及其分子机制研究

Gigantic flower but insufficient mechanical strength of inflorescence stem in herbaceous peony (Paeonia lactiflora Pall.) could often cause stem bending and so affect its quality of cut flower. While pre-harvest calcium applications can enhance its mechanical strength of inflorescence stem and improve the quality of inflorescence stem. Until now, the effects of spraying calcium on the P. lactiflora inflorescence stem microstructure, chemical composition and related gene expression have been investigated, but it is not clear yet that many unknown metabolic pathways and the molecular network may be involving in. Based on the pre-harvest treatment with positive and negative calcium regulation in cut P. lactiflora, scanning electron microscopy, transmission electron microscopy and X-ray diffraction technology will be used to clarify the effect of calcium regulation on microstructure change of inflorescence stem and its relationship to mechanical strength. Meanwhile, transcriptome, proteomics and metabonomics technology with Solexa, iTRAQ, LC-MS and NMR will be systematically used to explore the mechanism of mechanical strength of P. lactiflora inflorescence stem responses to calcium regulation in transcription, protein and metabolism levels, to excavate the key genes, proteins and metabolites in calcium regulation on the mechanical strength of inflorescence stem, and further to build its molecular network. Eventually, these results would systematically elucidate the molecular mechanism of calcium controlling the mechanical strength of P. lactiflora inflorescence stem from multiple levels of structure, transcriptional regulation, protein regulation and metabolic regulation, which would provide theoretical basis for improving the quality of P. lactiflora inflorescence stem from the molecular level.

芍药花朵硕大而花茎机械强度不足容易引起茎秆弯曲，影响切花品质。采前喷施外源钙可提高花茎机械强度，改善花茎品质。申请者前期探索了喷钙对芍药茎秆结构、化学组分及相关基因表达的影响，但对于喷钙可能涉及的许多未知代谢途径与分子网络尚不清楚。本项目拟通过对芍药切花采前进行正、反向钙调控处理，运用扫描电镜、透射电镜及X射线衍射技术弄清钙调控对芍药花茎微观结构变化的影响及其与机械强度的关系；同时，采用以Solexa、iTRAQ、LC-MS和NMR为主的转录组学、蛋白组学和代谢组学技术系统地探究芍药花茎机械强度在转录水平、蛋白水平和代谢水平对钙调控的响应机制，发掘钙调控花茎机械强度的关键基因、关键蛋白与代谢物，进一步构建钙调控花茎机械强度的分子网络。最终，从结构水平、转录水平、蛋白水平以及代谢水平调控等多个层面详尽地阐明钙对芍药花茎机械强度调控的分子机制，为从分子水平上改良芍药茎秆机械强度提供理论依据。

芍药花朵硕大而花茎机械强度不足容易引起茎秆弯曲，严重影响切花品质。前期研究表明，采前喷施外源钙可提高花茎机械强度，改善花茎品质。项目组在对芍药切花采前进行正、反向钙调控处理基础之上，运用扫描电镜、透射电镜及X射线衍射技术对花茎进行观察，发现钙能够通过调控花茎木质部次生细胞壁加厚及其细胞层数、增加木质素沉积来增强花茎机械强度，而并未改变花茎细胞壁的晶体结构，从而弄清了钙调控对芍药花茎微观结构变化的影响及其与机械强度的关系。同时，采用转录组学、蛋白组学和代谢组学技术系统地探究芍药花茎机械强度在转录水平、蛋白水平和代谢水平对钙调控的响应，共鉴定到128,926个unigene、5,045个蛋白和10,919个代谢物，通过组学联合分析发现，钙能够通过调控光合作用、钙信号传导、碳水化合物代谢、能量代谢、苯丙烷生物合成等通路来影响花茎机械强度，并筛选出多个钙调控芍药花茎机械强度的关键基因与蛋白，通过系统的分子生物学研究明确了COMT基因在花茎机械强度调控中的重要作用，进而构建了钙对芍药花茎机械强度调控的分子网络。这一结果阐明了钙对芍药花茎机械强度调控的分子机制，为从分子水平上改良芍药茎秆机械强度提供理论依据。