Liang G, He H, Li Y, Wang F, Yu D

The precise control of gene regulation, and hence, correct spatio-temporal tissue patterning, is crucial for plant development. Plant microRNAs can constrain the expression of their target genes at post-transcriptional levels. Recently, miR396 has been characterized to regulated leaf development by mediating cleavage of its GRF targets. miR396 is also preferentially ...

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expressed in flowers. However, its function in flower development is unclear. In addition to narrow leaves, pistils with a single carpel were also observed in miR396 over-expression plants. The dramatically reduced expression levels of miR396 targets (GRF1, 2, 3, 4, 7, 8, and 9) caused pistil abnormalities, because the miR396-resistant version of GRF was able to rescue miR396-over-expressing plants. Both GRFs and GIFs are highly expressed in developing pistils, and their expression patterns are negatively correlated with that of miR396. GRF interacted with GIF to form the GRF/GIF complex in plant cell nucleus, and both GRFs and GIFs showed transactivation abilities. miR396 suppressed the expression of GRFs, resulting in reduction of GRF/GIF complex. gif single mutant displayed normal pistils whereas gif triple mutant, gif1/gif2/gif3, produced abnormal pistils, which was a phenocopy of 35S:MIR396a/grf5 plants. GRF and GIF function as co-transcription factors and both are required for pistil development. Our analyses reveal an important role for miR396 in controlling carpel number and pistil development via regulation of the GRF/GIF complex.

Date: Nov. 27, 2013

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