Moderate level of toxic boron causes differential regulation of microRNAs related to jasmonate and ethylene metabolisms in Arabidopsis thaliana

Abstract

Earlier our colleagues detected that the genes related to jasmonate (JA), ethylene, and cell wall modification were significantlyregulated under boron (B) toxicity in wheat. Determination of regulation mechanisms of these novel genes under B toxicity isvery important in Arabidopsis thaliana as a model plant. As key regulators, the microRNAs (miRNAs) regulate gene expression atthe posttranscriptional level and respond to numerous abiotic stresses in plants. In this study, expression levels of miRNAs such asmiR159, miR172, miR319, and miR394 targeting JA and ethylene-related transcription factors and also miR397 targeting laccase weredetermined in Arabidopsis thaliana under toxic B conditions. Stem-loop quantitative reverse transcription polymerase chain reactionwas used to amplify mature miRNAs for expression analyses. Expression levels of miRNAs targeting transcription factors related toJA and ethylene metabolisms were induced remarkably in moderate B toxicity (condition 1B) but not in severe B toxicity (condition3B). Most remarkable regulations were obtained in miR172 and miR319 in Arabidopsis thaliana. Expression level of miR397 did notremarkably change under B toxicity, indicating a lack of posttranscriptional regulation of laccase related to cell wall modification.Moreover, miRNAs targeting transcription factors related to JA and ethylene metabolisms might be oxidative stress-adaptive responsesof Arabidopsis to B toxicity.