Integrative Transcriptomic and Small RNA Analysis Uncovers Key Genes for Cold Resistance in Rice.

Background/objectives: Cold stress is the main environmental factor that affects the growth and development of rice, leading to a decrease in its yield and quality. However, the molecular mechanism of rice's low-temperature resistance remains incompletely understood.

Methods: In this study, we conducted a joint analysis of miRNA and mRNA expression profiles in the cold-resistant material Yongning red rice and the cold-sensitive material B3 using high-throughput sequencing.

Results: 194 differentially expressed miRNAs (DEMIs) and 14,671 differentially expressed mRNAs (DEMs) were identified. Among them, 19 DEMIs, including miR1437, miR1156, miR166, miR1861, and miR396_2 family members, showed opposite expression during the early or late stages of low-temperature treatment in two varieties, while 13 DEMIs were specifically expressed in Yongning red rice, indicating that these miRNAs are involved in rice's resistance to low temperature. In the transcriptome analysis, 218 DEMs exhibited opposite expressions during the early or late stages of low-temperature treatment in two varieties. GO enrichment analysis indicated that these DEMs were enriched in biological processes such as a defense response to fungi, a defense response to bacteria, a plant-type cell wall modification, single-organism cellular processes, a response to chitin, and the regulation of a plant-type hypersensitive response, as well as in cellular components such as the apoplast, nucleus, vacuole, plasma membrane, and plasmodesma. Twenty-one genes were further selected as potential candidates for low-temperature resistance. The joint analysis of miRNA and mRNA expression profiles showed that 38 miRNAs corresponding to 39 target genes were candidate miRNA-mRNA pairs for low-temperature resistance.

Conclusions: This study provides valuable resources for determining the changes in miRNA and mRNA expression profiles induced by low temperatures and enables the provision of valuable information for further investigating the molecular mechanisms of plant resistance to low temperatures and for the genetic improvement of cold-resistant varieties.