Abstract
Peach (Prunus persica L.) is one of the most important worldwide fresh fruits. Since fruit growth largely depends on adequate water supply, drought stress is considered as the most important abiotic stress limiting fleshy fruit production and quality in peach. Plant responses to drought stress are regulated both at transcriptional and post-transcriptional level. As post-transcriptional gene regulators, miRNAs (miRNAs) are small (19–25 nucleotides in length), endogenous, non-coding RNAs. Recent studies indicate that miRNAs are involved in plant responses to drought. Therefore, Illumina deep sequencing technology was used for genome-wide identification of miRNAs and their expression profile in response to drought in peach. In this study, four sRNA libraries were constructed from leaf control (LC), leaf stress (LS), root control (RC) and root stress (RS) samples. We identified a total of 531, 471, 535 and 487 known mature miRNAs in LC, LS, RC and RS libraries, respectively. The expression level of 262 (104 up-regulated, 158 down-regulated) of the 453 miRNAs changed significantly in leaf tissue, whereas 368 (221 up-regulated, 147 down-regulated) of the 465 miRNAs had expression levels that changed significantly in root tissue upon drought stress. Additionally, a total of 197, 221, 238 and 265 novel miRNA precursor candidates were identified from LC, LS, RC and RS libraries, respectively. Target transcripts (137 for LC, 133 for LS, 148 for RC and 153 for RS) generated significant Gene Ontology (GO) terms related to DNA binding and catalytic activites. Genome-wide miRNA expression analysis of peach by deep sequencing approach helped to expand our understanding of miRNA function in response to drought stress in peach and Rosaceae. A set of differentially expressed miRNAs could pave the way for developing new strategies to alleviate the adverse effects of drought stress on plant growth and development.
Highlights
Peach (Prunus persica L.) is considered to be one of the most widely grown and economically important stone fruit species in the Rosaceae, comprising more than 3,000 species in approximately 110 genera distributed worldwide [1]
In addition to its ecological and high economic importance, peach is emerging as a model tree species for both comparative genomic studies, evolutionary studies and plant development research owing to its small genome size of 300 Mb and the relatively short reproductive time [2,3]
Four small RNA libraries were constructed by the use of total RNAs isolated from control leaf (LC), drought-stressed leaf (LS), control root (RC), and drought-stressed root (RS) tissues
Summary
Peach (Prunus persica L.) is considered to be one of the most widely grown and economically important stone fruit species in the Rosaceae, comprising more than 3,000 species in approximately 110 genera distributed worldwide [1]. In 2010, it was estaminated that world annual production of peaches and nectarines exceeded 19 million metric tons according to FAO statistics (FAOSTAT, http://faostat.fao.org). In addition to its ecological and high economic importance, peach is emerging as a model tree species for both comparative genomic studies, evolutionary studies and plant development research owing to its small genome size of 300 Mb (just about twice comparing with Arabidopsis thaliana) and the relatively short reproductive time [2,3]. The genus Prunus, which includes peach, nectarine, apricot, weet and sour cherry, have stone fruits with fleshy mesocarp, but the growth and development of these fruits, especially large-fruited species like peach, are seriously affected by drought. Drought stress is one of the major abiotic stresses limiting fruit production and quality during the 4–6 week period before harvesting [5,6]
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