小麦Ta-miR154的特征及渗透胁迫响应

植物逆境胁迫响应过程中microRNA（miRNA）发挥着重要调控功能，为探讨小麦Ta-miR154的特征及其对渗透胁迫的响应，以矮抗58和中国春为材料，克隆了 Ta-MIRNA 基因并对其序列特征及时空表达模式进行分析。结果显示，小麦 Ta-MIR154 的3个部分同源基因位于第7同源群染色体组上，分别命名为 Ta-MIR154-7A 、 Ta-MIR154-7B 和 Ta-MIR154-7D ；3个部分同源基因间序列差异较大，但在miRNA前体区域高度保守，其中 Ta-MIR154-7A 由于一个核苷酸的变异导致不能生成 Ta-MIR154 。组织表达分析显示， Ta-MIR154 在成熟籽粒中的表达量最高，其次为节间和根系；籽粒形成过程中， Ta-MIR154 从授粉后20 d开始快速上调表达，授粉后30 d表达量最高。干旱胁迫条件下，两品种的叶片中 Ta-MIR154 在受胁迫诱导后均上调表达，且矮抗58的表达水平高于中国春；而根中 Ta-MIR154 的响应模式不同，在中国春中呈先上调后下调的表达趋势，而在矮抗58中呈先下调后上调的表达趋势。盐胁迫条件下，两品种的叶片中 Ta-MIR154 在受胁迫诱导后呈先上调后下调的表达趋势，且中国春的上调幅度大且持续时间长，而在根系中矮抗58的上调表达幅度要大于中国春。推测 Ta-MIR154 在小麦渗透胁迫响应过程中发挥一定的调控功能。

Characterization of Ta-miR154 and Its Response to Osmotic Stresses in Wheat

MicroRNAs (miRNAs) play important regulatory roles in response to stress in plant.In order to characterize a novel wheat miRNA(Ta-miR154),as well as its response to osmotic stress,the genomic fragments of Ta-MIR154 were cloned and characterized,and the spatio-temporal expression patterns of Ta-MIR154 were also analyzed.The results showed that three homologues of Ta-MIR154 were located in homologous chromosome group 7,designatedas Ta-MIR154-7A, Ta-MIR154-7B and Ta-MIR154-7D ,respectively.The sequences of three homologous genes were different,while their miRNA precursor regions were highly conserved.Additionally, Ta-MIR154 cannot be generated from Ta-MIR154-7A due to a nucleotide mutation.Tissue expression analysis indicated that the expression level of Ta-MIR154 was the highest in maturegrains,followed by that in internodes and roots.During the development of wheat grains,the expression of Ta-MIR154 was rapidly up-regulated at the time point of 20 d after pollination (DAP) and reached the highest level at 30 DAP.Under drought stress, Ta-MIR154 was up-regulated in leaves,and its expression level in Aikang 58 was higher than that of Chinese Spring.The responding pattern of the miRNA in roots was quite different from that in leaves,which was firstly increased and then decreased in Chinese Spring;While an opposite pattern was detected in Aikang 58.Under salt stress, Ta-MIR154 was up-regulated firstly and then down-regulated in leaves,and the increasing range was greater and duration was longer in Chinese Spring than that in Aikang 58.Comparatively,the increasing range of Ta-MIR154 in roots of Aikang 58 was greater than that in Chinese Spring.The results indicated that Ta-MIR154 may play a certain regulatory role in the response of osmotic stresses in wheat.