The precise spatial and temporal expression of regulatory genes that control tissue patterning and cell fate is important for plant development. Mis-expression of certain key regulatory genes causes developmental abnormalities in plants. There is increasing evidence that small RNA molecules are important participants in the control of gene expression, providing sequence specificity for targeted regulation of key developmental factors at the post-transcriptional level. Several plant miRNAs have been shown to function in plant development. The lack of miRNA processing protein(s) can cause severe developmental phenotypes. It has been revealed that miR396 is involved in leaf development by controlling the levels of its Growth-Regulating Factor (GRF).However, its function in flower development is unclear.
Prof. YU Diqiu and his team of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to reveal the function of miR396 in flower development. Arabidopsis ecotype Col-0 was used for all real-time qRT-PCR experiments. The pOCA30 binary plasmid was used for an expression vector. Their study demonstrated that the products of all 7 GRF targets can interact with GRF-INTERACTING FACTORs (GIFs) that may function as co-transcription factors. Over-expression of miR396 caused reduced expressions of GRF genes, which disrupted the formation of the GRF/GIF complex, leading to pistil anomalies. Those results indicated that miR396-directed regulation is critical for pistil development.
miRNAs played a key role in regulating plant development, which could be inferred from the developmental defects in dcl1, hyl1, se, and ago1 mutants, and from analyses of plants over-expressing various miRNAs (e.g., miR160, miR164, miR166, and miR319, etc.). YU Diqiu’s study demonstrated that over-expression of miR396 resulted in morphological defects in floral organs. Their results revealed the function of miR396 in reducing the formation of the GRF/GIF complex, which regulated pistil development.