Abstract
In recent years, with the wanton destruction of the ecological environment by humans and the frequent occurrence of extreme bad weather, many places that should have been warm and blooming in spring have instead experienced the phenomenon of the “April blizzard,” which has seriously affected China's crops, especially spring potato production in most areas. Potato cultivars, especially potato seedlings, are sensitive to frost, and low temperature frost has become one of the most important abiotic stresses affecting potato production. Potato cold tolerance is regulated by a complex gene network. Although some low temperature resistant microRNAs have been identified, little is known about the role of miRNAs in response to low temperature stress in potato. Therefore, the objective of this study is to clarify the influence of low temperature stress on the miRNA expression of potato by comparing the expression differences of miRNA in potato which was treated with different low temperatures. For the study, 307 known miRNAs belonging to 73 small RNA families and 211 novel miRNAs were obtained. When the temperature decreased, the number of both known and novel miRNA decreased, and the minimum temperature was −2°C. Most of the miRNAs respond to low temperature, drought, and disease stress; some conserved miRNAs were first found to respond to low temperature stress in potato, such as stu-miR530, stu-miR156d, and stu-miR167b. The Gene Ontology, Kyoto Encyclopedia of Genes, and Genomes pathway enrichment analysis of 442 different expression miRNAs target genes indicated that there existed diversified low temperature responsive pathways, but Abscisic Acid was found likely to play a central coordinating role in response to low temperature stress in many metabolism pathways. Quantitative real-time PCR assays indicated that the related targets were negatively regulated by the tested different expression miRNAs during low temperature stress. The results indicated that miRNAs may play an important coordination role in response to low temperature stress in many metabolic pathways by regulating abscisic acid and gibberellin, which provided insight into the roles of miRNAs during low temperature stress and would be helpful for alleviating low temperature stress and promoting low temperature resistant breeding in potatoes.
Highlights
Potato (Solanum tuberosum L.) is from the Solanaceae family, which has a history of more than 7,000 years of cultivation
The potato was significantly affected by low temperature, and it was further used for exploring profiling of the low temperature responsive miRNAs by Illumina solexa sequencing in this experiment
In order to identify miRNAs involved in the process of low temperature stress response in the potato, the four sRNA libraries were generated from the four samples which were treated by different low temperature treatments
Summary
Potato (Solanum tuberosum L.) is from the Solanaceae family, which has a history of more than 7,000 years of cultivation. Low temperature freezing will damage the potato cell membrane system (Willick et al, 2018), and have a series of effects on the metabolism of malondialdehyde (Lin et al, 2017), ABA (Huang et al, 2017), proline (Phukan et al, 2016), sugar (Bustamante et al, 2016) and other substances, and lead to changes in molecular metabolism and subsequent physiological metabolism. These physiological responses include induction of transient increases in Ca2+ (Calcium ion) levels, alterations in membrane lipid composition, increases to antioxidant capacity, and accumulation of osmoprotectant (Fu et al, 2016). According to the target gene types, miRNAs that respond to low temperature stress are divided into three categories: the target genes that directly respond to external stimuli, those that indirectly respond to stress by regulating protein transcription factors that play a role in stimulation, and those cooperated by multiple miRNAs that can respond to a variety of stresses and target genes encoding hydrolases or oxidoreductases (Yang et al, 2017)
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