One of the important functions of long non-coding RNA (lncRNA) is to be competing endogenous RNAs (ceRNAs). As miR398 is reported to respond to different stressors, it is necessary to explore its relationship with lncRNA in the cold resistance mechanism of winter wheat. Tae-miR398-precursor sequence was isolated from the winter wheat (Triticum aestivum). RLM-RACE verified that tae-miR398 cleaved its target CSD1. Quantitative detection at 5°C, –10°C and –25°C showed that the expression of tae-miR398 decreased in response to low temperatures, whereas CSD1 showed an opposite expression pattern. LncR9A, lncR117 and lncR616 were predicted and verified to interact with miR398. tae-miR398 and three lncRNAs were transferred into Arabidopsis thaliana respectively. The lncR9A were transferred into Brachypodium distachyom. Transgenic plants were cultivated at –8°C and assessed for the expression of malondialdehyde, chlorophyll, superoxide dismutase and miR398-lncRNA-target mRNA. The results demonstrate that tae-miR398 regulates low temperature tolerance by downregulating its target, CSD1. lncRNA regulates the expression of CSD1 indirectly by competitively binding miR398, which, in turn, affects the resistance of Dn1 to cold. miR398-regulation triggers a regulatory loop that is critical to cold stress tolerance in wheat. Our findings offer an improved strategy to crop plants with enhanced stress tolerance.

Background: Heilongjiang Province has a long and cold winter season (the minimum temperature can reach -30 ℃), and few winter wheat varieties can safely overwinter. Dongnongdongmai1 (Dn1) is the first winter wheat variety that can safely overwinter in Heilongjiang Province. This variety fills the gap for winter wheat cultivation in the frigid region of China and greatly increases the land utilization rate. To understand the molecular mechanism of the cold response, we conducted RNA-sequencing analysis of Dn1 under cold stress. Results: Approximately 120,000 genes were detected in Dn1 under cold stress. The numbers of differentially expressed genes (DEGs) in the six comparison groups (0 ℃ vs. 5 ℃, -5 ℃ vs. 5 ℃, -10 ℃ vs. 5 ℃, -15 ℃ vs. 5 ℃, -20 ℃ vs. 5 ℃ and -25 ℃ vs. 5 ℃) were 11,313, 8313, 15,636, 13,671, 14,294 and 13,979, respectively. Gene Ontology functional annotation suggested that the DEGs under cold stress mainly had “binding”, “protein kinase” and “catalytic” activities and were involved in “oxidation–reduction”, “protein phosphorylation” and “carbohydrate metabolic” processes. Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the DEGs performed important functions in cold signal transduction and carbohydrate metabolism. In addition, major transcription factors (AP2/ERF, bZIP, NAC, WRKY, bHLH and MYB) participating in the Dn1 cold stress response were activated by low temperature. Conclusion: This is the first study to explore the Dn1 transcriptome under cold stress. Our study comprehensively analysed the key genes involved in cold signal transduction and carbohydrate metabolism in Dn1 under cold stress. The results obtained by transcriptome analysis could help to further explore the cold resistance mechanism of Dn1 and provide basis for breeding of cold-resistant crops.