Table_9_Multi-Approach Analysis Reveals Pathways of Cold Tolerance Divergence in Camellia japonica.XLSX

Understanding the molecular mechanism of the cold response is critical to improve horticultural plant cold tolerance. Here, we documented the physiological, transcriptome, proteome, and hormonal dynamics to cold stress in temperate genotype (Tg) and subtropical genotype (Sg) populations of Camellia japonica. Tg C. japonica suffered minimal osmotic and oxidative damage compared to Sg C. japonica under the same cold treatment. Transcriptional and translational differences increased under the cold treatment, indicating that Tg C. japonica was affected by the environment and displayed both conserved and divergent mechanisms. About 60% of the genes responding to cold had similar dynamics in the two populations, but 1,896 transcripts and 455 proteins differentially accumulated in response to the cold between Tg and Sg C. japonica. Co-expression analysis showed that the ribosomal protein and genes related to photosynthesis were upregulated in Tg C. japonica, and tryptophan, phenylpropanoid, and flavonoid metabolism were regulated differently between the two populations under cold stress. The divergence of these genes reflected a difference in cold responsiveness. In addition, the decrease in the abscisic acid (ABA)/gibberellic acid (GA) ratio regulated by biosynthetic signal transduction pathway enhanced cold resistance in Tg C. japonica, suggesting that hormones may regulate the difference in cold responsiveness. These results provide a new understanding of the molecular mechanism of cold stress and will improve cold tolerance in horticultural plants.

解析植物冷应答的分子机制，对于提升园艺植物的耐寒性至关重要。本研究以山茶（Camellia japonica）的温带基因型（Tg, temperate genotype）和亚热带基因型（Sg, subtropical genotype）群体为材料，系统测定了其在冷胁迫下的生理、转录组、蛋白质组及激素动态变化特征。在相同冷处理条件下，温带基因型山茶相较于亚热带基因型山茶，仅遭受极轻微的渗透胁迫与氧化损伤。冷胁迫下，转录与翻译层面的差异逐渐增大，表明温带基因型山茶受到环境影响，同时具备保守与差异化的冷应答机制。约60%的冷响应基因在两个群体中具有相似的表达动态，但温带与亚热带基因型山茶间，共有1896个转录本与455个蛋白质在冷胁迫响应过程中存在差异积累。共表达分析结果显示，温带基因型山茶中核糖体蛋白及光合相关基因呈上调表达；而冷胁迫下，两个群体在色氨酸、苯丙烷类及黄酮类代谢通路的调控模式存在显著差异。这些基因的表达差异，反映出两者冷应答能力的不同。此外，通过生物合成信号转导通路调控的脱落酸（abscisic acid, ABA）/赤霉素（gibberellic acid, GA）比值下降，提升了温带基因型山茶的耐寒性，这表明激素或可调控不同群体间的冷应答差异。本研究结果为解析冷胁迫的分子机制提供了新视角，同时有助于提升园艺植物的耐寒性。