杨树异源三倍体生长优势的代谢组机制

This project aims to illustrate the metabolomics differences of triploids from different chromosome doubling sources and reveal the metabolomics basis of the triploid poplar with the growth advantages on the aspects of fast growing, growth vigor, etc. due to the comprehensive utilization of ploidy and hybridization. Three triploid populations with the same ploidy but different heterozygosity, from the hybridization of "Zheyin3 #" (P. pseudo-simonii × P. nigra ‘Zheyin3#’) ×"beijingensis" (P.× beijingensis) of the same parents (different sources of 2n female gamete) and the terminal buds of diploid populations were taken as the project materials, to study the metabolomics based on a liquid chromatography-tandem mass spectrometry (LC-MS/MS) platform. The statistical analysis methods and models including the principal component analysis (PCA), random forest (RF) and self-organizing maps (SOM) were used to dig the large-scale metabolome data obtained. Focusing on the correlation of the poplar carbohydrate metabolites, hormone metabolites, nucleic acid metabolites and flavonoid metabolites with the ploidy differences, heterozygosity differences and phenotypic variation, we try to construct a metabolic pathway between the photosynthetic carbon assimilation and the growth and development of poplars, to lay the foundation for clarifying the metabolomics mechanism of triploid poplar with high growth vigor.

为了阐释不同染色体加倍途径来源的三倍体间的代谢组差异，揭示杨树杂种三倍体由于综合利用倍性效应和杂合效应，在速生生长、生长活力等方面的生长优势所形成的代谢组基础。本项目拟以同亲本'哲引3号杨'（P. pseudo-simonii × P. nigra ‘Zheyin3#’）× '北京杨'（P.× beijingensis）杂交来源的同倍性而杂合性不同的3个三倍体群体（不同2n雌配子来源），以及二倍体群体的顶芽为研究材料，开展基于液相色谱串联质谱（LC-MS/MS）平台的代谢组学研究。利用主成分分析、随机森林以及自组织映射等统计分析方法和模型对获得的大尺度代谢组数据进行深入挖掘，重点研究杨树碳水化合物代谢、激素代谢、核酸代谢和类黄酮代谢物与倍性差异、杂合性差异及表型变异的相关关系，构建光合碳同化等与顶芽生长发育相关代谢通路，为阐明杨树三倍体高生优势形成的代谢组机制奠定基础。

异源多倍体具有生长速度快等优势。三倍体由于具有更高的杂合性，相比于二倍体杂种F1具有突出的生长优势，已成为林木遗传改良的重要方法之一。然而，迄今为止，导致多倍体生长优势的主要代谢成分尚不清楚。本研究运用液相色谱-质谱（LC-MS）测试平台，以同亲本来源的二倍体及不同配子类型（即减数第一次分裂核复原（FDR）、减数第二次分裂核复原（SDR）和获得减数分裂后核复原（PMR））的3个三倍体群体为研究对象，重点比较分析顶芽代谢物差异及变化规律。主要鉴定出氨基酸、次级代谢物和碳水化合物等235种代谢产物。通过与KEGG数据库对代谢物功能进行注释，共计注释到181种已知代谢物。其中的10种化合物，即果糖1，6—二磷酸和木酮糖的含量，在所有异源三倍体中均高于二倍体子代。主成份分析表明，丰富的代谢物分成了与倍性组成相对应的不同簇。三倍体的杂合性对碳水化合物和次生代谢产物含量的影响大于对脂质含量的影响。不同生长率的亚组之间的比较显示，黄酮类化合物中的次生代谢物和碳水化合物与基因表达和高生长呈正相关。研究结果为多倍体杨树生长优势因子方面的探讨，提供了重要的代谢因子。