SummaryChilling stress has seriously limited the global production and geographical distribution of rice. However, the molecular mechanisms associated with plant responses to chilling stress are less known. In this study, we revealed a member of β‐ketoacyl‐ACP synthase I family (KASI), OsKASI‐2 which confers chilling tolerance in rice. OsKASI‐2 encodes a chloroplast‐localized KASI enzyme mainly expressed in the leaves and anthers of rice and strongly induced by chilling stress. Disruption of OsKASI‐2 led to decreased KAS enzymatic activity and the levels of unsaturated fatty acids, which impairs degree of unsaturation of membrane lipids, thus increased sensitivity to chilling stress in rice. However, the overexpression of OsKASI‐2 significantly improved the chilling tolerance ability in rice. In addition, OsKASI‐2 may regulate ROS metabolism in response to chilling stress. Natural variation of OsKASI‐2 might result in difference in chilling tolerance between indica and japonica accessions, and Hap1 of OsKASI‐2 confers chilling tolerance in rice. Taken together, we suggest OsKASI‐2 is critical for regulating degree of unsaturation of membrane lipids and ROS accumulation for maintenance of membrane structural homeostasis under chilling stress, and provide a potential target gene for improving chilling tolerance of rice.

中文翻译：

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OsKASI-2 是调节水稻膜脂不饱和水平和耐冷性所必需的

摘要 低温胁迫严重限制了水稻的全球生产和地理分布。然而，与植物响应冷胁迫相关的分子机制却鲜为人知。在这项研究中，我们发现了 β-酮酰基-ACP 合酶 I 家族 (KASI) 的成员 OsKASI-2，它赋予水稻耐冷性。OsKASI-2编码叶绿体定位的 KASI 酶，主要在水稻的叶子和花药中表达，并受到冷胁迫的强烈诱导。扰乱OsKASI-2导致KAS酶活性和不饱和脂肪酸水平下降，从而损害膜脂的不饱和度，从而增加水稻对冷胁迫的敏感性。然而，过度表达OsKASI-2显着提高水稻的耐冷能力。此外，OsKASI-2可能会调节 ROS 代谢以应对冷应激。自然变异OsKASI-2可能会导致之间的耐冷性差异籼稻和粳稻种质和 Hap1OsKASI-2赋予水稻耐冷性。综合起来，我们建议OsKASI-2对调节膜脂不饱和度和ROS积累以维持低温胁迫下膜结构稳态至关重要，为提高水稻的耐冷性提供潜在的靶基因。