Identification of miRNAs and Their Target Genes Associated with Sweet Corn Seed Vigor by Combined Small RNA and Degradome Sequencing

High seed vigor is significant for agriculture. Low seed vigor of sweet corn hindered the popularization of sweet corn (Zea mays L. saccharata Sturt). To better understand the involvement and regulatory mechanism of miRNAs with seed vigor, small RNA libraries from seeds non-artificially aged and artificially aged for 2 days were generated by small RNA sequencing. A total of 27 differentially expressed miRNAs were discovered, of which 10 were further confirmed by real-time quantitative polymerase chain reaction. Furthermore, targets of miRNAs were identified by degradome sequencing. A total of 1142 targets that were potentially cleaved by 131 miRNAs were identified. Gene ontology (GO) annotations of target transcripts indicated that 26 target genes cleaved by 9 differentially expressed miRNAs might play roles in the regulation of seed vigor, such as peroxidase superfamily protein targeted by PC-5p-213179_17 playing a role in the oxidation–reduction process and response to oxidative stress. These findings provide valuable information to understand the involvement of miRNAs with seed vigor

Molecular Identification and Analysis of Cd-Responsive MicroRNAs in Rice

Cadmium (Cd) is a non-essential heavy metal with high toxicity to plants. MicroRNAs (miRNAs) are a class of small non-coding RNAs that play important roles in plant abiotic stress responses. To investigate whether miRNAs function in Cd stress response, miRNA expression profiles in rice (Oryza sativa) under Cd stress were monitored using microarray assays. A total of 12 Cd-responsive novel miRNAs predicted previously were identified, of which 4 were further validated experimentally. A total of 44 target genes were predicted for the Cd-responsive miRNAs, many of which appeared to regulate gene networks mediating environmental stresses. Several target genes were validated to show a reciprocal regulation by miRNAs. A transgenic approach was also used to determine the role of miRNAs in rice response to Cd stress. Overexpression of miR192 retarded seed germination and seedling growth under Cd stress. These results implied the role of novel miRNAs in the involvement of Cd tolerance of rice