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| MicroRNAs (miRNAs), which are about 21 nucleotide RNAs, are ubiquitous regulators of gene expression in eukaryotic organisms. Some miRNAs act as an important endogenous regulator in plant organ formation and development. miR164 is a conservative miRNA family that exists in a variety of different plants. Studies showed that miR164 regulates lateral root formation and leaf shape. However, there is no any report about miR164 involved in flower initiation and fruit development. We analyze the genomic DNA in tomato (Solanum lycopersicum) and find only one ortholog, designated as Sl-miR164. The target gene (NAM) of Sl-miR164 was predicted and cloned. Quantitative RT-PCR shows miR164 expresses highly in stem and fruit, whereas Nam expresses highly in all tissues, including root, stem, leaf, flower and fruit. Overexpression of miR164 results in delayed petal withering and falling off, and overexpression of NAM gene results in abnomal flower with thick sepal, no petal and stamen. The transgenic plants，overexpressing miR164 and NAM gene result in parthenocarpic fruit. Moreover, Sl-miR164 and Sl-NAM overexpression altered the transcript levels of a number of MADS box transcription factor genes, which involved in flower development and morphology. Our data demonstrate that tomato Sl-miR164 play important role in flower morphogenesis and fruit development. |
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| Keywords:Molecular biology; Sl-miR164; NAM; flower morphogenesis; MADS box |
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