Abstract
BackgroundBoth drought and heat stress are serious global problems, leading to agricultural production loss. MicroRNAs (miRNAs) play important roles in plant species responding to individual drought and heat stress. However, the miRNAs and mRNAs in association with combined drought and heat in crops like tomato remains unclear.ResultsWe studied the crosstalk of miRNAs and their target genes in tomato plants grown under simultaneous drought and heat stress that frequently happen in field conditions. In total, 335 known miRNAs representing 55 miRNA families and 430 potential novel miRNAs were identified in Solanum lycopersicum L. using small RNA deep sequencing. Through expression analysis, miRNAs in association with drought, heat and the combination of these were investigated. In total, 61, 74 and 37 miRNAs were differentially regulated for combination (of both stresses) vs control, combination vs drought and combination vs heat, respectively. Target genes with different expression levels were found using degradome sequencing, which were mainly involved in transcription factor activity, sequence-specific DNA binding, transcription, regulation of transcription, nucleus, DNA binding etc. The quantitative real-time polymerase chain reaction (qRT-PCR) results confirmed the accuracy of sequencing.ConclusionsOur study serves as valuable knowledge on how crop adapted to combined drought and heat stress by regulating miRNAs and mRNAs, which provide information for crop improvement to deal with future climate changes.
Highlights
Both drought and heat stress are serious global problems, leading to agricultural production loss
There were 11,490,162, 10,175,417, 12,103,236 and 13, 096,254 raw reads identified in tomatoes at control, drought, heat and their combination, respectively (Table 1)
We found that combined stress provoked specific miRNAs response with 74 and 37 showing up/down regulation in comparison with drought and heat
Summary
Both drought and heat stress are serious global problems, leading to agricultural production loss. MicroRNAs (miRNAs) play important roles in plant species responding to individual drought and heat stress. The miRNAs and mRNAs in association with combined drought and heat in crops like tomato remains unclear. Heat stress caused by temperatures above optimum could induce complex response in plant [2]. The miRNAs-mRNAs relationship has been widely identified by dengradome sequencing in various crops, such as tomato [6] and orchard grass [7]. Active response of miRNAs and mRNAs in plants has been widely associated to individual abiotic stress, including drought condition [7, 8] and high temperature [6]. It was found that 111 miRNAs were predominantly expressed in wheat after dehydration
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