Abstract
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 (~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.
Highlights
Salinity is a severe abiotic stress, globally it reduces agricultural productivity (Su and Hock, 2016)
We performed small RNA sequencing of pearl millet under salinity stress and identified 81 conserved and 14 novel miRNAs that were differentially regulated by the salinity stress
These miRNAs are predicted to have a total of 448 target genes, and 25% of them are annotated as transcription factor genes
Summary
Salinity is a severe abiotic stress, globally it reduces agricultural productivity (Su and Hock, 2016). Worldwide 20% of cultivated and 33% of irrigated agricultural lands are affected by salinity. The salinized areas are increasing at a rate of 10% annually (Machado and Serralheiro, 2017). It has been predicted that more than 50% of the arable land would be salinized by the year 2050. (Shrivastava and Kumar, 2015). Yield losses due to salinity have high economic impacts on agriculture. The estimated economic impact of soil salinity on irrigated are around 27 billion US$ per year (Qadir et al, 2014). Soil salinity causes yield losses of 55%, 28%, and 15% in corn, wheat and cotton, respectively (Zo€rb et al, 2019)
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