小麦小分子RNA TaMIR1129介导植株抵御低氮逆境功能研究

Function analysis of TaMIR1129,a small molecule RNA member in wheat,in mediating plant tolerance to nitrogen deprivation

本研究针对迄今有关小麦小分子RNA（miRNA）家族成员介导植株氮素吸收和利用机理尚少见报道的现状,对TaMIR1129的表达特征和介导植株抵御低氮逆境功能进行了研究。结果表明,TaMIR1129呈低氮胁迫诱导表达,表现为随氮浓度降低（0.02~6mmol/L）和处理时间延长（0~48h）表达水平不断增高特征。此外,低氮诱导的高表达水平在恢复供氮后表达下调。表明该miRNA对介质中氮素应答呈典型的时间及浓度依赖特征。TaMIR1129作用2个靶基因,包括Molybdenum cofactor sulfurase（TaMCS）和Major facilitator family transporter（TaMFFT）,上述基因应答低氮特征与TaMIR1129相反。遗传转化结果表明,超表达TaMIR1129具有显著增强植株抵御低氮逆境的能力。表现为与野生型对照相比,转基因系Sen 1和Sen 2低氮处理后植株形态增大,干质量增加,氮累积量增多。表明TaMIR1129与作用靶基因构建miRNA/target模块在介导植株抵御低氮逆境中发挥重要作用。

In this study,according to the currently limited investigation on the mechanisms of wheat small molecules（miRNAs）that mediate N acquisition and utilization,we reported the expression patterns of TaMIR1129 and its role in mediating plant tolerance to N deprivation.TaMIR1129 was shown to be induced by N deficiency,showing an elevated expression pattern with the reduction of N concentration（varying from 0.02 to 6mmol/L N）and the extended treatment（0to 48h）.In addition,the elevated expression of TaMIR1129 under N deficiency was dropped down as the N level was recovered to normal N.These results indicated that TaMIR1129 possesses a temporal and concentration-dependent expression manner.TaMIR1129 targets two genes including Molybdenum cofactorsulfurase（TaMCS）and Major facilitator family transporter（TaMFFT）,whose expression patterns under N deprivation were shown to be inverse to TaMIR1129.Transgene analysis revealed that overexpression of TaMIR1129 in tobacco conferred plants improved tolerance to the N-starvation stress.The transgenic lines（Sen 1and Sen 2）exhibited larger phenotypic feature,more biomass,and more N acuumulation after N deprivation treatment than wild type.These results indicated that TaMIR1129 and its target genes can establish miRNA/target modules that play an important role in mediating plant resistance to the N-starvation stress.