High-Throughput Sequencing Reveals HO Stress-Associated MicroRNAs and a Potential Regulatory Network in Seedlings.

Oxidative stress in plants can be triggered by many environmental stress factors, such as drought and salinity. is a model organism for the study of biofuel plants and crops, such as wheat. Although recent studies have found many oxidative stress response-related proteins, the mechanism of microRNA (miRNA)-mediated oxidative stress response is still unclear. Using next generation high-throughput sequencing technology, the small RNAs were sequenced from the model plant 21 (Bd21) under HO stress and normal growth conditions. In total, 144 known miRNAs and 221 potential new miRNAs were identified. Further analysis of potential new miRNAs suggested that 36 could be clustered into known miRNA families, while the remaining 185 were identified as -specific new miRNAs. Differential analysis of miRNAs from the normal and HO stress libraries identified 31 known and 30 new HO stress responsive miRNAs. The expression patterns of seven representative miRNAs were verified by reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis, which produced results consistent with those of the deep sequencing method. Moreover, we also performed RT-qPCR analysis to verify the expression levels of 13 target genes and the cleavage site of 5 target genes by known or novel miRNAs were validated experimentally by 5' RACE. Additionally, a miRNA-mediated gene regulatory network for HO stress response was constructed. Our study identifies a set of HO-responsive miRNAs and their target genes and reveals the mechanism of oxidative stress response and defense at the post-transcriptional regulatory level.