剪接因子OsSRL1调控水稻铁转运的分子机理

The strictly regulated of Fe transport in plants is the basic for healthy of plants and human. People mainly focus on the functional analysis of transcription factors on regulating Fe transport in plants, less was carried out on the role of mRNA splicing on Fe transport. Nowadays, the significant role of alternative splicing (AS) on plants development and stress responses become more and more clear. When we do transcriptomic analysis, we found that much more AS events were induced under Fe-deficient conditions, the splicing factors were also under changes in expression levels and AS, indicating that splicing factors may play roles in regulating Fe transport and Fe-deficiency responses through AS . We performed Fe concentration analysis on several SR splicing factors mutant and found the mutation of OsSRL1 resulted in significantly more Fe translocating from roots to shoots compared with the wild type rice under Fe-deficient conditions, whereas several Fe transport related genes were changed in expression and/or AS, suggesting that OsSRL1 was necessary for normal Fe transport under Fe-deficient conditions. To figure out the mechanisms involved, we will figure out the functional transcript version of OsSRL1, perform phenotypic analysis and expression of Fe-marker gene on genetic materials with changes in OsSRL1 expression levels; moreover, we will screen the RNAs and proteins that interacted with OsSRL1, and functional analysis of these candidate genes, finally, make it clear the molecular mechanisms involved for OsSRL1 regulating Fe transport in rice. The study will enhance our knowledge on Fe transport and regulation in plants, and provide knowledge for breeding high quality crops in the future.

植物铁素转运的严格调控是保证植物与人类健康的基础。目前人们对其调控机理的研究主要集中在转录水平，而对转录后调控认识很少。近年来mRNA剪接调控在植物发育与逆境响应中的重要性日趋体现，我们分析水稻转录组时发现，缺铁强烈诱导可变剪接的发生，而剪接因子的表达与剪接也受铁调控，表明剪接因子可能通过调控下游mRNA的剪接实现对缺铁的响应。突变体表型筛选发现，剪接因子OsSRL1突变体在缺铁条件下铁向地上部转运显著加强，缺铁耐性提高，且多个铁转运及代谢相关基因出现差异表达与剪接，表明该基因参与调控铁转运。为阐明其分子机理，我们将通过转基因互补明确功能型OsSRL1转录本；分析该转录本的差异表达遗传材料中铁转运及相关基因表达确认其功能；通过对与其结合的RNA与蛋白的功能分析，从分子水平解析OsSRL1调控水稻铁转运的作用机制，该研究将极大加深人们对植物铁转运调控的认识，为培育高品质作物提供理论依据。

植物必需元素转运的严格调控是保证植物与人类健康的基础。目前人们对其调控机理的研究主要集中在转录水平，而对转录后调控认识很少。本项目主要以剪接因子OsSRL1为研究对象，通过分析发现OsSRL1具有6条转录本，OsSRL1.1是其主效转录本定位于细胞核，主要表达于根的维管束、根茎结合部和叶片。敲除OsSRL1导致老叶磷含量显著升高，且磷的再分配受阻。通过转录组分析（RNA-seq）结合RNA免疫沉淀（RIP）筛选到OsSRL1 调控的下游候选铁和磷转运相关基因及与调控水稻响应逆境和信号转导等多种生物学过程。研究明确了OsSRL1可通过调控下游营养转运相关的mRNA的剪接实现对铁磷等营养元素的吸收及转运的调控。该项目的研究成果为SR家族蛋白参与养分调控提供了分子水平的直接证据，也为通过分子育种培育养分高效及籽粒品质提高提供新的基因资源。本项目共发表SCI论文6篇，申请并授权发明专利一项，项目主持人获2019年中国植物生理与分子生物学会卫志明青年创新奖，培养研究生5名。