miRNAs and their target genes regulate the antioxidant system of Zanthoxylum bungeanum under drought stress.

Plants can accumulate a large amount of reactive oxygen species under adverse conditions such as drought and high temperature, which seriously affect the normal growth and development of plants. The antioxidant system can scavenge the reactive oxygen species produced under drought conditions and so mitigate oxidative damage. However, the regulation patterns of many miRNAs under drought stress are still unclear. The content of antioxidant enzymes and the expression patterns of miRNAs and their target genes related to antioxidant systems were studied under drought stress in Zanthoxylum bungeanum. The results indicate that under drought stress, POD, CAT, APX, proline, MDA and related genes all show positive responses to drought, while SOD and its genes showed a negative response. It is indicated that in the antioxidant process of Z. bungeanum, POD, CAT, and APX play a major role, and SOD plays a supporting role. In addition, GUS histochemical and RT-qPCR experimental results show that the expression levels of miRNAs and their target genes are basically negatively correlated, indicating that miRNAs can inhibit the expression of related genes and are also important regulators in the antioxidant system of Z. bungeanum. According to the expression patterns of antioxidant enzymes, miRNA and its target genes under drought stress, combined with previous research results, a model of plant antioxidant mechanism was constructed to provide a reference for further understanding of plant antioxidant mechanism.