Xia Kuaifei, Pan Xiaoqin, Chen Huaping, Xu Xinlan, Zhang Mingyong
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, Guangdong, China.
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, Guangdong, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
J Plant Physiol. 2023 Jan;280:153905. doi: 10.1016/j.jplph.2022.153905. Epub 2022 Dec 22.
Rice microRNA168a (osa-miR168a) plays important roles in mediating flowering time, grain yield and vigor, seeding growth, and immunity by targeting the RNA-induced silencing complex component Argonaute 1 (AGO1). However, the functions of miR168a exerted by targeting other genes require further clarification before it could be used in rice molecular breeding. In this study, we identified a new target gene of osa-miR168a-5p (miR168a-5p) in rice called OsOFP3 (ovate family protein 3) and investigated the roles of miR168a-5p in response to brassinosteroids (BRs), salt stress, and nitrogen allocation. Up- and downregulated miR168a-5p expression respectively decreased and increased the expression of the BR-negative regulator OsOPF3. The results of RNA ligase-mediated rapid amplification of cDNA ends (5'RLM-RACE) revealed cleavage sites in OsOPF3 and OsNPF2.4 mRNAs. The phenotype of miR168a-5p transgenic rice was BR-associated and included the lamina bending response to BR, short seeds, and low 1000-grain weight. MicroRNA 168a-5p also regulated the expression of the nitrate transporter, OsNPF2.4, which affected nitrogen allocation, and regulated OsAGO1a expression in response to salt stress. Taken together, rice miR168a-5p regulates BR-associated pathways, nitrogen transport, and stress by targeting OsOFP3, OsNPF2.4, and OsAGO1a, respectively, resulting in a series of important agronomic traits for rice breeding.
水稻微小RNA168a（osa-miR168a）通过靶向RNA诱导沉默复合体组分AGO1（Argonaute 1），在介导开花时间、籽粒产量与活力、种子生长及免疫方面发挥重要作用。然而，在将其应用于水稻分子育种之前，通过靶向其他基因发挥作用的miR168a的功能仍需进一步阐明。在本研究中，我们在水稻中鉴定出osa-miR168a-5p（miR168a-5p）的一个新靶基因OsOFP3（卵形家族蛋白3），并研究了miR168a-5p在响应油菜素内酯（BRs）、盐胁迫及氮分配方面的作用。上调和下调miR168a-5p表达分别降低和增加了BR负调控因子OsOPF3的表达。RNA连接酶介导的cDNA末端快速扩增（5'RLM-RACE）结果揭示了OsOPF3和OsNPF2.4 mRNA上的切割位点。miR168a-5p转基因水稻的表型与BR相关，包括对BR的叶片弯曲反应、种子短小及千粒重低。微小RNA 168a-5p还调控了硝酸盐转运蛋白OsNPF2.4的表达，其影响氮分配，并在响应盐胁迫时调控OsAGO1a的表达。综上所述，水稻miR168a-5p分别通过靶向OsOFP3、OsNPF2.4和OsAGO1a来调控与BR相关的途径、氮转运及胁迫，从而产生一系列对水稻育种重要的农艺性状。
