水稻miR396在赤霉素信号传导中的作用

The GRFs(Growth Regulating Factor) are the targets of miR396. The mechanism of why most GRFs respond to Gibberellins is still unknown. We had acquired a transgenic lines over-expressing miR396, which presented as dwarf. We discovered that the positive response of GRFs to GAs was caused by negative response of miR396 to GAs. Furthermore, we revealed that the miR396/GRFs are in the down-stream of DELLA protein and in the up-stream of cell-cycle-related genes. However, the precise location between miR396 and cell-cycle-related genes is still unknown. Here, we want to fully elucidate the precise location of miR396 in the Gibberellins signal cascade, that is (1) Whether miR396 is the direct target of DELLA? (2) What is/are the direct target of GRFs? (3) Over-express the miR396-resistant-version of GRF, which is mutated by codon degeneracy. We will reveal the specific role of a specific GRF gene through transgenic lines and get the useful materials in breeding. Thus, the roles of miR396 in GA signalling cascade will be fully revealed by this study.

水稻miR396的靶基因为GRF家族，业已知道多数GRF的表达受赤霉素的诱导，但不知其响应赤霉素的分子机制。我们先前已获得了水稻miR396过表达的矮化植株。我们发现，miR396负响应赤霉素的方式是GRF正响应赤霉素的原因。miR396/GRF处在DELLA蛋白的下游和细胞周期基因的上游，但不知miR396在DELLA蛋白和细胞周期基因间的精确位置。本研究欲在已有的研究基础上，探索miR396在GA信号传导中的精确位置，试图阐明（1）miR396是否是DELLA蛋白的靶基因；（2）什么是GRF的靶基因；（3）利用密码子的兼并性突变个别GRF基因，过量表达抗miR396的突变版GRF成员,根据转化植株的表型推测特定GRF成员的功能，并获得有育种价值的突变体材料。通过本研究，对miR396参与GA信号途径的机制作出细致地阐述。

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