Cold-induced early flowering in tobacco: Insights from JA biosynthesis and signaling

Low temperature, as a prominent abiotic stressor, adversely affects plant growth, development, and crop productivity. The floral transition in angiosperms necessitates precise regulatory control to ensure reproductive success. However, the molecular mechanisms underlying low-temperature-induced early flowering in tobacco remain elusive. In this study, to unravel the regulatory machinery of cold stress tolerance, systematic analyses, including phenotypic characterization, phytohormone profiling, transcriptomic and proteomic assays, as well as integrative multi-omics analysis, were conducted on shoot apical meristems of the cold-sensitive cultivar Yunyan87 and cold-tolerant cultivar Xiangyan7 following cold stress. Phenotypic observations revealed that Yunyan87 exhibited early flowering under low temperature, accompanied by reduced plant height and total leaf count, whereas Xiangyan7 showed no significant phenotypic alterations. Notably, distinct differences in phytohormone profiles were observed between the two cultivars post-treatment, with jasmonic acid (JA) being highly associated with low temperature-induced early flowering. Integrative multi-omics analysis pinpointed two pivotal pathways: α-linolenic acid metabolism and plant phytohormone signal transduction. Further dissection of the JA biosynthesis pathway demonstrated that, compared to Yunyan87, Xiangyan7 displayed upregulated LOX2S expression, downregulated ACX expression, elevated JA levels, and upregulated JAZ expression under cold stress. Additionally, four key candidate genes were identified, namely SAPK1-like, PP2C-51 , SCL9 , and ARR12-like . Based on these findings, we present a working hypothesis that the reduced JA accumulation in Yunyan87 represses JAZ degradation, thereby enhancing JAZ-mediated inhibition of MYC2/3 and TOE1/2. This repression alleviates inhibition of FT , ultimately promoting early flowering. In conclusion, this study indicates that JA biosynthesis and signaling play central roles in regulating cold-induced early flowering in tobacco, providing a theoretical framework for improving tobacco cold tolerance and manipulating flowering time in tobacco cultivation. • Yunyan87 exhibited early flowering under low temperature, whereas Xiangyan7 showed no significant phenotypic alterations. • Jasmonic acid (JA) was found highly associated with low temperature-induced early flowering. • Two pivotal pathways and four key candidate genes were identified to be involved in cold-induced early flowering. • A hypothetical JA-mediated regulatory model for cold-induced early flowering in tobacco was proposed.