利用动态关联分析解析玉米籽粒油脂代谢的遗传和分子机制

Maize oil contains rich polyunsaturated fatty acids and high energy, thus it is significant to improve the oil content of maize kernel. Previously, we reported RNA sequencing of developing maize kernels from 368 inbred lines producing 28679 gene expression data and indentified several loci significantly associated with kernel oil concentration. Gene co-expression dynamics study is a novel bio-computational approach to identify new candidate genes for genetic and functional studies of complex traits and explore the regulation of gene transcription in metabolic pathway in yeast and human. In the present research, we will use 26 previously reported maize kernel oil susceptibility genes as the lead to probe transcriptome gene expression data for functionally associated genes by liquid association. Consequently, the function of candidate genes will be investigated by association analysis, expression profiling, transcriptional activation analysis and transgenic technology. In addition, the phylogenetic analysis of candidate genes will be performed. Finally, the functional sites of candidate genes will be validated to be able to be used for marker-assisted selection of maize. All these studies will provide useful information for understanding the genetic and molecular mechanisms of lipid metabolism in maize kernels, and provide a theoretical basis for selective breeding of high oil maize.

玉米油不仅富含不饱和脂肪酸，而且具有较高的能量，提高玉米籽粒油份含量意义重大。玉米籽粒油份是受多基因控制的数量性状，前期我们对368份材料授粉后15天的籽粒进行RNA测序分析，获得了28679个基因的表达数据，鉴定了一批与油份代谢相关的基因。在这个基础上，我们将创新性的利用基因对共表达模式的动态关联分析这一在酵母和人类中发展出来的新方法，全基因组范围内挖掘更多的与含油量相关的基因及其共表达模式网络，探索代谢途径中基因转录调控关系，深入解析籽粒油脂代谢的分子机制。并通过候选基因关联分析、表达分析、转录激活活性分析以及转基因技术验证候选基因的功能；利用群体遗传学鉴定候选基因的选择进化机制，并评估其育种价值。最终解析玉米籽粒油脂代谢的遗传和分子机制，为高油玉米的选择育种提供基因资源和理论依据。

游离脂肪酸在植物的生长发育中有着重要的作用，不仅作为底物合成膜脂参与植物自身的生长发育，也是植物能量存储的主要形式，并且部分脂肪酸还会作为第二信使底物参与植物抵抗逆境胁迫的调控通路。因此，研究与脂肪酸调控相关基因在玉米籽粒品质以及非生物胁迫响应中的生物学功能对于解析植物脂质代谢通路有着重要意义。采用全基因组动态关联分析（Liquid association, LA）对玉米中含油量关联基因进行动态关联分析并筛选出玉米籽粒中负调控三酰甘油生成的关键基因ZmNAC77；通过对ZmNAC77进行候选基因关联分析、表达分析等研究，初步探讨了该基因在三酰甘油累积以及非生物逆境胁迫响应中的生物学功能。创建ZmNAC77玉米基因编辑材料，验证了该基因负调控玉米籽粒的油份品质，而该基因的过表达株系可显著增强玉米耐盐以及耐旱性。利用酵母双杂筛选了ZmNAC77的互作蛋白，初步解析了ZmNAC77的分子机制。该研究有助于进一步阐述玉米脂质代谢途径的调控机制，为高品质抗逆玉米种质资源的创新提供了理论依据。