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文献
摘要 Chilling stress threatens the yield and distribution pattern of global crops, including the tea plant (Camellia sinensis), one of the most important cash crops around the world. Circular RNA (circRNA) plays roles in regulating plant growth and biotic/abiotic stress responses. Understanding the evolutionary characteristics of circRNA and its feedbacks to chilling stress in the tea plant will help to elucidate the vital roles of circRNAs. In the current report, we systematically identified 2702 high-confidence circRNAs under chilling stress in the tea plant, and interestingly found that the generation of tea plant circRNAs was associated with the length of their flanking introns. Repetitive sequences annotation and DNA methylation analysis revealed that the longer flanking introns of circRNAs present more repetitive sequences and higher methylation levels, which suggested that repeat-elements-mediated DNA methylation might promote the circRNAs biogenesis in the tea plant. We further detected 250 differentially expressed circRNAs under chilling stress, which were functionally enriched in GO terms related to cold/stress responses. Constructing a circRNA-miRNA-mRNA interaction network discovered 139 differentially expressed circRNAs harboring potential miRNA binding sites, which further identified 14 circRNAs that might contribute to tea plant chilling responses. We further characterized a key circRNA, CSS-circFAB1, which was significantly induced under chilling stress. FISH and silencing experiments revealed that CSS-circFAB1 was potentially involved in chilling tolerance of the tea plant. Our study emphasizes the importance of circRNA and its preliminary role against low-temperature stress, providing new insights for tea plant cold tolerance breeding. 冷胁迫威胁着全球作物的产量和分布模式，包括世界上最重要的经济作物之一茶树。环状RNA（circRNA）在调节植物生长和生物/非生物胁迫反应中发挥作用。了解circRNA的进化特征及其对茶树低温胁迫的反馈将有助于阐明circRNA在茶树中的重要作用。在目前的报告中，作者在茶树中系统地鉴定了2702个在低温胁迫下的高置信度circRNA，有趣的是，茶树circRNA的产生与其侧翼内含子的长度有关。重复序列注释和DNA甲基化分析表明，circRNA较长的侧翼内含子呈现出更多的重复序列和更高的甲基化水平，这表明重复元件介导的DNA甲基化可能促进茶树circRNA的生物发生。作者进一步检测到250种在低温胁迫下差异表达的circRNA，它们在与冷/应激反应相关的GO术语中功能丰富。构建circRNA-miRNA-mRNA相互作用网络发现了139个差异表达的circRNAs，它们具有潜在的miRNA结合位点，这进一步鉴定了14个circRNA，它们可能有助于茶树的低温反应。作者进一步鉴定了一种关键circRNA，CSS-circFAB1，它在低温胁迫下显著诱导。FISH和沉默实验表明，CSS-circFAB1可能参与茶树的耐冷性。此研究强调了circRNA的重要性及其对低温胁迫的初步作用，为茶树抗寒育种提供了新的见解。 代表图片
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