Due to its subtropical origins, rice (Oryza sativa) is sensitive to low-temperature stress. In this study, we identify LOC_Os04g24110, annotated to encode the UDP-glycosyltransferase enzyme UGT90A1, as a gene associated with the low-temperature seedling survivability (LTSS) quantitative trait locus qLTSS4-1. Differences between haplotypes in the control region of OsUGT90A1 correlate with chilling tolerance phenotypes, and reflect differential expression between tolerant and sensitive accessions rather than differences in protein sequences. Expression of OsUGT90A1 is initially enhanced by low temperature, and its overexpression helps to maintain membrane integrity during cold stress and promotes leaf growth during stress recovery, which are correlated with reduced levels of reactive oxygen species due to increased activities of antioxidant enzymes. In addition, overexpression of OsUGT90A1 in Arabidopsis improves freezing survival and tolerance to salt stress, again correlated with enhanced activities of antioxidant enzymes. Overexpression of OsUGT90A1 in rice decreases root lengths in 3-week-old seedlings while gene-knockout increases the length, indicating that its differential expression may affect phytohormone activities. We conclude that higher OsUGT90A1 expression in chilling-tolerant accessions helps to maintain cell membrane integrity as an abiotic stress-tolerance mechanism that prepares plants for the resumption of growth and development during subsequent stress recovery.

中文翻译：

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糖基转移酶OsUGT90A1有助于在水稻低温胁迫期间保护质膜。

由于其亚热带起源，水稻（Oryza sativa）对低温胁迫敏感。在这项研究中，我们将LOC_Os04g24110（注释为编码UDP-糖基转移酶UGT90A1）确定为与低温幼苗生存能力（LTSS）数量性状基因座qLTSS4-1相关的基因。OsUGT90A1对照区域中单倍型之间的差异与耐寒性表型相关，反映了耐性和敏感种质之间的差异表达，而不是蛋白质序列差异。OsUGT90A1的表达最初是通过低温增强的，其过表达有助于在寒冷胁迫下维持膜的完整性，并在胁迫恢复过程中促进叶片的生长，这与由于抗氧化剂酶活性增加而导致的活性氧水平降低有关。此外，在拟南芥中过表达OsUGT90A1可提高冷冻存活率和对盐胁迫的耐受性，这又与抗氧化酶活性的增强有关。水稻中OsUGT90A1的过表达减少了3周龄幼苗的根长，而基因敲除则增加了根长，表明其差异表达可能影响植物激素的活性。我们得出的结论是，耐低温种质中较高的OsUGT90A1表达有助于维持细胞膜的完整性，这是一种非生物胁迫耐受机制，可为植物在随后的胁迫恢复中恢复生长和发育做好准备。水稻中OsUGT90A1的过表达减少了3周龄幼苗的根长，而基因敲除则增加了根长，表明其差异表达可能影响植物激素的活性。我们得出的结论是，耐低温种质中较高的OsUGT90A1表达有助于维持细胞膜的完整性，这是一种非生物胁迫耐受机制，可为植物在随后的胁迫恢复中恢复生长和发育做好准备。水稻中OsUGT90A1的过表达减少了3周龄幼苗的根长，而基因敲除则增加了根长，表明其差异表达可能影响植物激素的活性。我们得出的结论是，耐低温种质中较高的OsUGT90A1表达有助于维持细胞膜的完整性，这是一种非生物胁迫耐受机制，可为植物在随后的胁迫恢复中恢复生长和发育做好准备。