Small RNA sequencing reveals the role of pearl millet miRNAs and their targets in salinity stress responses

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important crop in arid and semi-arid areas of India and Africa. It is well known for its tolerance to abiotic stresses, but it lags behind other cereals in terms of research and development. MicroRNAs (miRNAs) are a versatile group of small regulatory RNAs of 20-22 bases that play important roles in plant growth, development, and stress responses. However, the regulatory mechanisms underlying miRNA-mediated responses to salinity stress in pearl millet are still unclear. In this study, we performed small RNA sequencing to identify conserved and novel miRNAs from the salinity tolerant pearl millet genotype. In total, 130 million sequence reads were generated, and 81 conserved and 14 novel miRNAs were identified as salinity stress responsive microRNAs. We also performed target prediction for these miRNAs, and a total of 448 pearl millet mRNAs were identified as the targets. Among these target mRNAs, 122 (similar to 25%) encode transcription factors. A pathway analysis showed that differentially expressed miRNAs and their target genes can regulate the auxin response pathway. Quantitative real-time PCR analysis of miRNAs and their targets showed consistent expression patterns. These results suggest that miRNAs play a role in salinity stress tolerance in pearl millet. (C) 2020 SAAB. Published by Elsevier B.V. All rights reserved.