玉米FEA4互作蛋白和lncRNA3协同调控穗发育的分子机理研究

Maize inflorescence meristem activity determines deeply the ear development and final ear architecture as well as kernel number per ear. Therefore, dissecting the molecular mechanisms of key factors regulating ear inflorescence development would expose to us the genetic and molecular controls of ear development, as well as facilitate to improve ear architecture. The applicant has early shown that a bZIP transcription factor FEA4 controls inflorescence development likely through a novel pathway. Further, two putative interactors and a downstream target, a long non-coding RNA named lncRNA3, have been screened. Based on these results, this study would: 1). characterize the functions and mechanisms of two interactors and lncRNA3 during ear development via knocking out, over-expressing them in combination with omics; 2). dissect the possible genetic interaction and regulation relationships between FEA4, its putative interactors and lncRNA3; 3) build up a molecular network in which FEA4, its interactors and lncRNA3 are invloved based on transcriptome analysis between all single and double mutants. By these studies, we aim to expose the mechanisms by which FEA4 and its related components are coordinated to regulate ear development and ear architecture. These results would supply us with new genetic resources and theoretical basis for optimizing ear architecture and creating new varieties in maize breeding.

玉米雌花序分生组织发育决定果穗发育，进而穗形态建成和单穗粒数。因此，解析调控雌穗发育和穗型关键因子的作用机制不仅有助于我们深入认识果穗发育的遗传和分子调控，也为穗型改良提供理论指导。项目组前期研究已证明一个bZIP转录因子FEA4参与一条途径调控穗发育，并鉴定到2个互作蛋白和1个表达水平受FEA4调控的长链非编码RNA (lncRNA3)。在此基础上，本项目拟: 通过敲除和增强表达及组学等手段鉴定FEA4互作蛋白和lncRNA3在穗发育中的功能及其作用机制；基于遗传互作分析和表达调控分析，鉴定FEA4及2个互作蛋白与lncRNA3的调控关系；基于单、双突变体与野生型的转录组比较分析，构建FEA4及其互作蛋白和lncRNA3调控雌穗发育的分子途径。综合以上研究，以期阐明FEA4、互作蛋白和lncRNA3协同调控雌穗发育及其形态建成的分子机理，为玉米穗型改良和新品种选育提供遗传资源和理论基础。

玉米bZIP转录因子FEA4是调控花序发育与穗形态建成的关键因子，但其发挥作用的分子机制及其下游通路尚不清楚。本项目拟从FEA4互作蛋白及其下游靶基因入手解析其作用机制。虽然项目前期未能鉴定出FEA4可能的下游靶基因lncRNA281的生物学功能，但我们后期的工作详细解析了FEA4由其互作蛋白GRXs介导的生化作用机制。FEA4自身以单体/二聚体共存的形式存在，并对氧化态敏感，且受与其互作的氧化还原酶（MSCA1和其同源蛋白ZmGRX2、ZmGRX5）的调控。被还原的FEA4处于单体状态，而在grx三突变体中，其氧化态（二聚体）明显增加，并大大增强了在基因组上的结合能力和对下游靶基因的转录调控能力。因此，FEA4的功能与其二聚体的形式紧密相关，并受到细胞内氧化还原态的调控。这一发现对我们利用FEA4以改良穗型提供了理论指导。