miR827调控的磷平衡在玉米抗甘蔗花叶病毒中的作用机制研究

Maize dwarf mosaic disease caused by Sugarcane mosaic virus (SCMV) has a world-wide distribution and poses a serious threat to maize yield and quality in China. microRNAs (miRNAs) play essential regulatory roles in plant development and environmental stress responses. It is important to identify host miRNAs in response to virus infection and illuminate the roles they play in the interaction between virus and host. Our previous results of high-throughput sequencing and verified experiments showed that SCMV infection significantly down-regulated the expression of miR827 and induced the expression of its putative target gene, PHOSPHATE TRANSPORTER 5 (PHT5). The roles of miR827 in regulation of phosphate (Pi) homeostasis has been reported, however, the involvement of miR827 in the interaction between SCMV and maize is unknown. Based on previous researches, we will investigate the effects of SCMV infection on the accumulation of Pi, miR827 and its putative targets in SCMV resistant and susceptible maize inbred lines, respectively. The target genes of miR827 will be confirmed and cloned. Brome mosaic virus vector and maize protoplast will be used to explore the roles of silencing and over-expression of miR827 and its target genes in the accumulation of Pi and SCMV infection, respectively. In addition, the effects of phosphate (Pi) on the resistance of maize to SCMV will be explored on the condition of Pi deficiency or toxicity. These efforts should help to reveal the roles and molecular mechanism of Pi homeostasis regulated by miR827 in the resistance of maize to SCMV, contribute to control viral diseases by agronomic measures and provide new resistant materials by the approach of small RNA regulation.

甘蔗花叶病毒（SCMV）侵染引起的玉米矮花叶病是世界性病害，严重影响我国玉米的产量和品质。miRNA在植物生长发育和响应环境胁迫中发挥重要调控作用。鉴定响应病毒侵染的寄主miRNA并解析其在病毒与寄主互作中的功能意义重大。前期，通过高通量测序和验证实验表明，SCMV侵染下调miR827并诱导其潜在靶基因磷酸盐转运蛋白5的表达。miR827主要调控磷平衡，但如何参与SCMV和玉米互作尚不清楚。本项目拟在此基础上，确定SCMV侵染不同抗病材料对磷元素、miR827及其潜在靶基因积累的影响；明确并克隆miR827的靶基因；通过沉默和过表达研究miR827及其靶基因在SCMV致病和磷积累中的作用；研究磷缺乏或过剩对玉米抗SCMV的影响。预期研究结果将揭示miR827调控的磷平衡在玉米抗SCMV中的作用和分子机制，为利用农艺措施防治SCMV和采用小RNA调控创制持久抗病的玉米提供新材料和理论依据。

甘蔗花叶病毒（SCMV）侵染引起的玉米矮花叶病是世界性病害，严重影响我国玉米的产量和品质。miRNA在植物生长发育和响应环境胁迫中发挥重要调控作用。鉴定响应病毒侵染的寄主miRNA并解析其在病毒与寄主互作中的功能意义重大。通过项目研究，我们确定了SCMV侵染不同抗感玉米材料对miR827及其靶标积累的影响，克隆了miR827的靶基因PHT5;2和PHT5;4，通过玉米原生质体共表达明确了miR827对PHT5;2和PHT5;4的靶向作用，获得了STTM技术沉默和人工miRNA过表达miR827的玉米种质资源，正在开展BMV载体沉默和玉米原生质体瞬时表达miR827靶标基因PHT5;2和PHT5;4对SCMV致病和复制影响的研究。研究结果为采用小RNA调控创制持久抗病的玉米提供新材料和理论依据。.玉米褪绿斑驳病毒（MCMV）是我国玉米上重要的检疫性有害生物，与SCMV复合侵染引起玉米致死性坏死病（MLND），一旦发病，玉米植株早枯死亡。MLND在我国云贵地区发生，且有蔓延趋势，严重威胁我国玉米产业的安全。前期我们鉴定了SCMV和MCMV复合侵染病毒小RNA的特征。在此基础上，我们开展了SCMV和MCMV复合侵染对玉米miRNA表达影响的研究，确定了响应病毒侵染的miRNA及其靶基因，预测了新的miRNA及其靶基因。这些结果有利于我们从miRNA角度解析SCMV和MCMV复合侵染引起MLND的机制，为创建持久抗病的玉米提供新的靶点和视野。.鉴于MCMV和SCMV对我国玉米产业的威胁，我们建立了快速检测MCMV和同时检测SCMV和MCMV的重组酶聚合酶扩增（RPA）技术，实现了MLND的诊断和病原物的检测。研究结果表明，建立的RPA方法在38℃条件下恒温反应30 min即可完成扩增检测，特异性好，灵敏度高，为田间和基层实验室快速诊断MLND和同时检测SCMV和MCMV提供了一种新方法。