Identification And Characterization Of Maize MicroRNAs Involved In The Very Early Stage Of Seed Germination

microRNA (miRNAs) is a newly identified class of20~24nt non-protein-coding andendogenous small RNA. Plant miRNAs play key roles in a wide range of biological processes,including meristem cell identity, organ polarity, and developmental timing as well as inresponse or tolerance to biotic and abiotic stress. Extensive studies of miRNAs have beenperformed in model plants such as rice, Arabidopsis thaliana and other plants. However, thenumber of miRNAs discovered in maize (Zea mays L.) is relatively low and little is knownabout miRNAs involved in the very early stage during seed germination. Combined withbioinformatic method, the types, abundance, and targets of known and novel miRNAs inmaize were analyzed by small RNA deep sequencing technology, which was based onIllumina/Solexa principium. Identification of novel miRNAs resulted in significantenrichment of the repertoire of maize miRNAs and provided insights into miRNA regulationof genes expressed in imbibed seed. The main results were as follows:1. In this study, a small RNA library from maize seed24hours after imbibition was sequencedby the Solexa technology. Further analysis confirmed the authenticity of115known miRNAsbelonging to24miRNA families and their abundance ranged from2to409637reads.2. The discovery of167novel miRNAs in maize. Both the known and the novel miRNAswere confirmed. We also found10miRNAs that had not been reported in maize, but had beenreported in other plant species. All novel sequences had not been earlier described in otherplant species.3. Putative targets for106novel miRNAs were successfully predicted. Our resultsindicated that miRNA-mediated gene expression regulation is present in maize imbibed seed.4.Finally, the part of conserved and novel miRNA were confirmated with the tail RT-PCRmethod, proved the reliability of the predicted results.