Abstract
Drought stress is a major obstacle to agricultural production. Tibetan wild barley with rich genetic diversity is useful for drought-tolerant improvement of cereals. MicroRNAs (miRNAs) play critical roles in controlling gene expression in response to various environment perturbations in plants. However, the genome-wide expression profiles of miRNAs and their targets in response to drought stress are largely unknown in wild barley. In this study, a polyethylene glycol (PEG) induced drought stress hydroponic experiment was performed, and the expression profiles of miRNAs from the roots of two contrasting Tibetan wild barley genotypes XZ5 (drought-tolerant) and XZ54 (drought-sensitive), and one cultivated barley Tadmor (drought-tolerant) generated by high-throughput sequencing were compared. There were 69 conserved miRNAs and 1574 novel miRNAs in the dataset of three genotypes under control and drought conditions. Among them, seven conserved miRNAs and 36 novel miRNAs showed significantly genotype-specific expression patterns in response to drought stress. And 12 miRNAs were further regarded as drought tolerant associated miRNAs in XZ5, which mostly participate in gene expression, metabolism, signaling and transportation, suggesting that they and their target genes play important roles in plant drought tolerance. This is the first comparation study on the miRNA transcriptome in the roots of two Tibetan wild barley genotypes differing in drought tolerance and one drought tolerant cultivar in response to PEG treatment. Further results revealed the candidate drought tolerant miRNAs and target genes in the miRNA regulation mechanism in wild barley under drought stress. Our findings provide valuable understandings for the functional characterization of miRNAs in drought tolerance.
Highlights
Drought, one of the most widespread natural disasters in the world, seriously affects agricultural production [1]
It was observed that only few reads were matched with the reported miRNAs in databases, while others were still unknown, which indicates the complexity of miRNAs in barley
MicroRNAs have been recognized as negative regulator of their target genes, so we mainly focus on drought responsive miRNAs that were down-regulated in XZ5, of miRNAs in three barley genotypes were significantly altered after 24 h drought stress induced by
Summary
One of the most widespread natural disasters in the world, seriously affects agricultural production [1]. In recent years, prolonged drought has caused severe damage to crops in various agricultural areas worldwide [2]. Breeding for drought tolerant crop cultivars is one of the most effective approaches to reduce the impact of dehydration on plant growth and achieve greater economic gains. Plants gradually developed robust mechanisms (morphological, physiological, biochemical and molecular) to adapt to drought stress [3]. There are different drought response patterns in crop varieties, and any two varieties with similar drought tolerance may exhibit different gene expression and metabolism pathways. It is important to identify drought tolerant genetic resources and to understand the specific mechanism, to prevent reduced crop production
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