Cold acclimation (CA) is a well‐known strategy employed by plants to enhance freezing tolerance (FT) in winter. Global warming could disturb CA and increase the potential for winter freeze‐injury. Thus, developing robust FT through complete CA is essential. To explore the molecular mechanisms of CA in woody perennials, we compared field and artificial CAs. Transcriptomic data showed that photosynthesis/photoprotection and fatty acid metabolism pathways were specifically enriched in field CA; carbohydrate metabolism, secondary metabolism and circadian rhythm pathways were commonly enriched in both field and artificial CAs. When compared with plants in vegetative growth in the chamber, we found that the light signals with warm air temperatures in the fall might induce the accumulation of leaf abscisic acid (ABA) and jasmonic acid (JA) concentrations, and activate Ca²⁺, ABA and JA signaling transductions in plants. With the gradual cooling occurrence in winter, more accumulation of anthocyanin, chlorophyll degradation, closure/degradation of photosystem II reaction centers, and substantial accumulation of glucose and fructose contributed to obtaining robust FT during field CA. Moreover, we observed that in Rhododendron ‘Elsie Lee’, ABA and JA decreased in winter, which may be due to the strong requirement of zeaxanthin for rapid thermal dissipation and unsaturated fatty acids for membrane fluidity. Taken together, our results indicate that artificial CA has limitations to understand the field CA and field light signals (like short photoperiod, light intensity and/or light quality) before the low temperature in fall might be essential for complete CA.

中文翻译：

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影响耐冻性的因素：越冬常绿植物田间和人工冷驯化之间的比较转录组学研究。

冷驯化（CA）是植物在冬季提高耐寒性（FT）的一种众所周知的策略。全球变暖可能会扰乱CA，并增加冬季冻害的可能性。因此，通过完整的CA开发强大的FT是必不可少的。为了探索木本多年生植物中CA的分子机制，我们比较了田间和人工CA。转录组数据表明，光合作用/光保护和脂肪酸代谢途径在田间CA中特别丰富。在田间和人工CA中，碳水化合物代谢，次级代谢和昼夜节律途径通常都丰富。当与室内营养生长的植物进行比较时，我们发现秋季秋天带有温暖空气温度的光信号可能会诱导叶片脱落酸（ABA）和茉莉酸（JA）浓度的积累，植物中2 ⁺，ABA和JA信号转导。随着冬季逐渐降温，花青素的积累，叶绿素降解，光系统II反应中心的关闭/降解以及葡萄糖和果糖的大量积累有助于在田间CA获得稳定的FT。此外，我们观察到杜鹃花'Elsie Lee'冬季的ABA和JA减少，这可能是由于玉米黄质对快速散热的强烈需求以及不饱和脂肪酸对膜流动性的强烈需求。两者合计，我们的结果表明，在秋天的低温可能对于完整CA必不可少之前，人工CA在理解野外CA和野外光信号（如短光周期，光强度和/或光质量）方面有局限性。