miRNA在甜橙果实类胡萝卜素代谢调控中的作用与机制

Fruit color is critical for fruit appearance and commercial value. By using orange fruit color mutants, our research has found that the posttranscriptional mechanism is involved during the red-flesh trait formation in sweet orange , with the miRNA as regulator. We totally identified three fruit specific miRNAs, and predited that they are involved in the regulation of carotenoid and Isoprenoid metabolisms.Based on these results, this project will go further to explore the regulatory mechanism of these miRNAs; including the identification of miRNAs, the characterization of miRNA precursors and their biogenesis, the target gene and interaction mode, and functional characterization on the miRNAs regulatory role on the fruit carotenoid metabolism of sweet orange. Meanwhile, the functionally characterized miRNAs will be overexpressed in rootstock to investigate its regulatory capacity on the fruit quality of scion, the results will be beneficial on the explore of new mode of genetic improvement on fruit quality.

果实色泽品质是决定果实外观商品性的重要感官品质。利用甜橙果实红肉突变体，我们前期发现甜橙果实红肉性状形成过程中存在明显的转录后调控机制，miRNA参与其中调控，共得到3个果实特异性miRNA，其靶基因参与类胡萝卜素和类异戊二烯代谢途径。本项目将进一步研究miRNA对类胡萝卜素代谢的调控机制。内容包括甜橙miRNA的挖掘鉴定，miRNA前体基因MIRNA的鉴定及产生机制，miRNA靶基因及作用机制，以及功能验证miRNA在果实类胡萝卜素代谢中的调控作用。同时利用已鉴定的miRNA在砧木上进行转基因操作，研究其对接穗果实品质性状的影响，探索基于miRNA移动性的果实品质遗传改良模式。

本项目利用甜橙色泽突变体，从果实发育与成熟切入柑橘类胡萝卜素代谢变化的研究。鉴定了3 个果实和花特异性miRNA，并进行了功能分析及互作机制研究。发现miR164和miR477a呈现果实特异表达，miR3954a花特异表达，并构建了超量表达载体进行了功能研究，发现超量表达并没有直接改变类胡萝卜素代谢途径，其中miR164a可能调控柑橘果实的NAC转录因子调控果实成熟，从而影响类胡萝卜素代谢；另一个基因miR3954a超量表达获得了提早开花的性状，通过研究深入明晰了其调控途径。已发表SCI论文4篇，另一篇在审稿过程中。四年来培养博士研究生1名，硕士研究生2名，1名硕士生进入博士阶段学习；项目主持人入选教育部长江学者奖励计划青年学者（2015）及国家万人计划科技创新领军人才（2016）。