杨树异源三倍体营养生长优势的分子基础

The biological mechanism of the vegetative growth advantage of allotriploid poplarhas attracted much attention.However, it develops slowly for the limit of research materials. In this project, using three allotriploid poplar populations with different heterozygosities and one diploid poplar population derived from the same parents as materials(P. pseudo-simonii × P. nigra ‘Zheyin3#’ as female parentand P.× beijingensisas male parent),the molecular basis of the vegetative growth advantage in allotriploid poplar will be studied based on transcriptomics and proteomics analysis technics according to previous studies. The differentially expressed genes and differential proteins related to chlorophyll content, leaf area and photosynthetic rate in triploid population will be focused.The patterns of differentially expressed genes in triploid population derived from different types of 2n female gameteswith different levels of heterozygosityandtriploids with significantly different photosynthetic rate will be discussedonthetranscription and translation level, and thenthe related gene regulatory networkin triploids will be analyzed. The above studies will clarify the genetic regulatory mechanism of vegetative growth and reveal the molecular basis of the vegetative growth advantage in allotriploid poplar.Moreover, it will deepen the basic theory of tree polyploidy breeding and provides a basis for the formulation of triploid breeding strategies in poplar.

杨树异源三倍体营养生长优势形成的生物学机制一直倍受关注，但受研究材料创制困难的限制，研究进展缓慢。项目以不同倍性以及同倍性而杂合性不同的3个'哲引3号杨'×'北京杨'杂种三倍体群体，以及同亲本组合二倍体群体为材料，在前期研究的基础上，采用转录组学和蛋白组学分析技术，开展杨树异源三倍体营养生长优势形成的分子基础研究，重点解析三倍体群体叶片的叶绿素含量、叶面积、光合速率相关的差异基因和差异蛋白；探讨杂和性不同的不同2n配子类型来源的三倍体群体间，以及光合速率显著差异三倍体间在转录和翻译水平的基因差异表达变化；解析三倍体相关差异基因调控网络；阐明杨树三倍体营养生长遗传调控机制，揭示杨树异源三倍体营养生长优势形成的分子基础，深化林木多倍体育种基础理论，为制定杨树异源三倍体育种策略提供依据。

杨树异源三倍体营养生长优势形成的生物学机制一直倍受关注。以‘哲引3号杨’ב北京杨’同亲本杂交组合不同2n配子类型来源的单叶高光合速率或单叶低光合速率的杨树杂种三倍体群体，以及同亲本组合的二倍体群体为对象，采用RNA-seq、iTRAQ MS/MS以及Label-free定量技术等方法，开展了杨树异源三倍体不同叶序叶片基因表达变化，以及杨树异源三倍体营养生长优势关键基因及其调控机制等研究，发现青杨异源三倍体叶片与营养生长性状直接相关miRNA表达随叶片发育并不表现剂量效应，而营养生长性状相关差异基因表达表现出剂量效应，其中高光合速生型和低光合速生型三倍体与二倍体相比，参与光合作用、碳固定、蔗糖和淀粉合成与分解、激素合成与信号转导等相关通路上的重要差异基因显著高表达；而三倍体低光合速生型与高光合速生型植株相比，与细胞分裂素、玉米素、赤霉素合成和信号转导相关的差异基因上调表达，加之叶片数量多，使低光合类型同高光合速生型三倍体一样，与二倍体相比均表现出营养生长优势等。因此提出了杨树三倍体叶片发育与营养生长相关miRNA表达无剂量效应，导致miRNA对其靶基因的负调控作用相对较弱的青杨异源三倍体营养生长优势遗传调控模型。进而基于三倍体转录组数据，利用自顶向下图形高斯模型（GGM）算法解析出GRF5及其下游基因的调控网络，具有重要方法学意义；过表达其中GRF5-1可抑制细胞分裂素氧化酶CKX1基因的转录，促进细胞分裂素含量升高，证明GRF5-1剂量增加是三倍体叶片变大、光合效率提高的原因之一。而生长缓慢的杨树四倍体、六倍体叶片营养生长相关差异miRNA与基因表达变化模式与三倍体恰好相反的研究结果，与青杨异源三倍体营养生长优势遗传调控模型相互形成佐证。有关研究结果对于深化林木多倍体育种基础理论、指导林木三倍体育种策略制定以及关键基因筛选等具有重要的理论和实际指导意义。