MicroRNA介导的转录后调控在冬小麦春化过程中的作用机理研究

Vernalization is an essential process for winter wheat to switch from vegetative growth to reproductive growth. This character determines potential wheat planting area, grain yield and quality. Small RNA, especially microRNA (miRNA), is a kind of important regulator controlling plant growth and development. However, less information is known about the regulation mechanism of miRNA during winter wheat vernalization. Our previous study on miRNA profile in winter wheat shoot apical meristems (SAM) showed that miR156 and miR172 displayed the similar expression pattern as that found in other plants, indicating the conserved mechanism in plant kingdom. Moreover, we found 39 known miRNAs and 12 novel miRNAs were induced by vernalization, and 25 known miRNAs and 25 novel miRNAs were repressed by vernalization. These results indicate that miRNA could be one kind of important player which regulate winter wheat switching from vegetative to reproduction growth. The proposed project intends to 1) identify varnalization associated miRNA by investigating miRNA profile and their dynamics expression pattern; 2) Identify target genes of the associated miRNA by degradome analysis; 3) validate the effect of associated miRNAs/target genes on wheat flowering by VIGS (virus induced gene silence); 4) illustrate the potential function of miRNA mediated post-transcriptional regulation underlying winter wheat vernalization. The coming results will deepen our understanding on winter wheat vernalization, and in long term, it may benefit wheat breeding.

春化作用是冬小麦由营养生长转向生殖生长的必须过程。作为一类新的重要的调控因子，miRNA在小麦春化过程中的调控作用尚不明了。我们对冬小麦顶端分生组织中的miRNA进行研究，发现小麦miR156和miR172的表达模式与已有的发现相一致。此外，我们发现39个已知miRNA 和12个新miRNA 是春化诱导型，而25个已知miRNA 和25个新miRNA 是春化抑制型。这表明miRNA在冬小麦春化过程中发挥调控作用。本课题拟通过研究不同春化时期冬小麦miRNA的组成和动态变化，揭示出春化相关miRNAs；通过降解组分析，确定这些miRNA调控的靶基因；进而采用VIGS技术验证春化相关miRNA或其靶基因对小麦开花的影响。阐明miRNA介导的转录后调控在小麦春化过程中的作用机理。本研究对于补充和完善冬小麦的春化机理具有重要意义

春化作用是冬小麦由营养生长转向生殖生长的必须过程。小RNA，尤其是microRNA(miRNA)在植物的生长发育过程中发挥着重要的调控作用。本研究通过构建小RNA文库、降解组文库、高通量测序和生物信息学分析，研究了小麦春化过程中的重要调控miRNA及其调控的靶基因。在三叶期、越冬期、返青期、拔节期四个时期，叶子和顶端分生组织中检测到373个已知miRNA，鉴定出55个新miRNA；在不同发育时期叶片和顶端分生组织中分别鉴定出91和92个显著差异表达的miRNA，其中有些差异表达的miRNA在两个组织中的表达趋势一致，而有些趋势不同甚至呈现出相反趋势；定量PCR验证了代表性差异表达miRNA的表达模式。利用降解组文库技术检测到201个保守靶基因，大多数为保守miRNA的靶基因，且为转录因子；利用RLM-5'RACE技术，28个新的靶基因首次得到验证，均为不保守或新发现的miRNA的靶基因，并构建了miRNA-靶基因调控网络图。利用VIGS基因沉默技术研究4个miRNA对小麦开花的影响尚在进行中。本研究不仅揭示了在小麦春化过程中起主导作用的miRNA及其作用机理，而且对补充和完善冬小麦的春化机理和小麦品种培育也具有重要意义。