转录因子内InDels调控毛白杨木材形成机制研究

Dissecting the molecular regulation of wood formation is an important issue with great application prospects for the efficient development of plantation and the adaptation to diversified market demands. Wood formation are complex and dynamic processes which controlled by multiple genes and underlying regulation networks, in which transcription factors has been proved to be the key switch of regulating secondary growth. However, which genetic variants affect the regulatory functions of transcription factors still need to be further studied. Insertions and deletions (InDels) are one of the major sources of structural genetic variants which distributed widely across the genome. It has significant phenotypic genetic effects on animal and plant diseases and economic or agricultural traits. Therefore, revealing the regulation of InDels within wood formation related transcription factors would be more likely to illuminate the molecular mechanism of wood formation. In this study, we selected Populus tomentosa, an important tree species in north China, as research material. RNA-seq will be used to identify the transcription factors that were differentially expressed in the secondary vascular tissues of high and low biomass individuals. Genomic and bioinformatics methods were used to identify the InDels within the differentially expressed transcription factors. Combining with the existing tree growth and wood property traits, we will identify the key InDels and analysis the genetic regulation mechanism of them. This study will help us to illustrate the molecular regulation mechanism of wood formation and provide theoretical and practical values on further analyzing the genetic regulation mechanism of wood quality phenotype variation and the genetic improvement of wood quality.

木材形成的分子调控机制研究是高效发展人工林、适应多元化需求的极具应用前景的重要问题。木材形成受复杂多基因网络调控，其中转录因子更是木材次生生长的关键，但哪些遗传变异影响了转录因子的调控功能仍需深入研究。插入缺失（InDels）是广泛存在于生物基因组内的自然遗传变异类型并对动植物疾病、农作物产量等具有显著的遗传效应。因此，揭示InDels在木材形成相关转录因子中的作用将更有可能阐明木材形成的分子调控机制。本研究拟选取毛白杨为研究对象，利用RNA-seq技术鉴定高、低生物量个体次生维管组织中差异表达的转录因子；通过基因组学挖掘转录因子内的InDels变异；结合木材材性指标，通过关联分析手段鉴定具有功能的InDels位点并进行遗传调控解析。研究结果将有助于从InDels角度阐明木材形成的分子调控机制，为进一步剖析林木木材品质表型变异形成的遗传调控机制和木材品质遗传改良奠定理论基础与应用价值。

木材形成是受生物学形成途径上多基因、多位点联合调控的数量性状，其遗传调控机制十分复杂，其中转录因子更是调控木材次生生长的关键。利用林木种质资源群体开展木材形成相关转录因子中InDels变异的发掘与遗传效应解析工作，将会有效推动木材形成的分子调控机制研究。本项目以毛白杨为研究对象，利用RNA-seq技术鉴定出86个在次生维管组织中差异表达的转录因子；结合毛白杨种质资源基因库群体（435株），发现了来自78个转录因子中的838个候选InDels等位变异位点；利用MLM模型，共获得来自于16个差异表达转录因子中的19个InDels位点与8个木材生长及品质性状组成了29个显著关联组合，每一InDels标记可解释的表型变异的11.1%-22.0%。利用epiSNP上位性关联分析模型，发现了来自于39个转录因子中的81个InDels标记位点与126个参与木材形成基因中的163个InDels标记位点对所有10个生长与木材品质性状形成了265个显著的InDel-InDel上位性关联组合，表明了发生在转录因子内的InDels位点很可能通过与木材形成相关基因之间的互作效应影响木材形的调控。研究结果为深入研究转录因子与木材形成基因之间的互作机制提供了信息基础，为分子辅助选育技术提供了重要的理论基础与标记资源。