High-throughput sequencing reveals microRNAs and their targets in response to drought stress in wheat (Triticum aestivum L.)

Abstract

Drought is a major factor that influences the productivity of crops including wheat. However, drought tolerance is a complex trait involving many genes and cellular pathways. To help understand the complex regulatory mechanisms governing drought tolerance in wheat, we performed small RNA sequencing analysis in a highly drought-tolerant wheat variety (Triticum aestivum L. cv. XF 20). Experimental plants were cultivated in the presence of PEG6000 to induce drought stress, while control plants were grown in the absence of PEG6000. Sequencing results confirmed the expression of 199 previously reported miRNAs. We also identified 32 novel miRNAs in this species. The expression of 37 miRNAs was significantly affected by PEG6000-induced drought stress (27 upregulated, 10 downregulated), including 5 novel miRNAs. Degradome sequencing showed that 222 target gene mRNAs were cleaved by these miRNAs. The target genes identified by psRNATarget and degradome were all enriched in gene ontology categories. There were significant differences in the number of target genes regulated by differentially expressed miRNAs, especially in signal transducer, response to stress and antioxidant pathways. MiRNA targets that are known to be related to drought and/or stress response in plants included 6-phosphogluconate dehydrogenase, epoxide hydrolase, sucrose synthase and phytochrome and flowering time regulatory protein. Our results shed light on the molecular mechanisms of drought tolerance in wheat, and identify drought-responsive miRNAs and their targets in a drought-resistant variety. These results could be exploited to improve wheat and related plants, which is expected to be vital as agriculture addresses the consequences of climate change.