Biocontrol Engineering Research Center of Plant Disease & Pest, Biocontrol Engineering Research Center of Crop Disease & Pest, Yunnan University, Kunming, China; School of Life Science, Yunnan University, Kunming, China.
Yunnan Institute of Materia Medica, Yunnan Baiyao Group Company Limited, Kunming, China.
Phytochemistry. 2022 Oct;202:113306. doi: 10.1016/j.phytochem.2022.113306. Epub 2022 Jul 4.
Nicotiana tabacum (tobacco) is one of the most important industrial crops and its productivity is vulnerable to drought, particularly in Yunnan province, China due to the long water-deficit spring. Here, we aimed at identifying caffeic acid O-methyltransferase (COMT) in melatonin biosynthesis to provide genetic resources against drought tolerance of tobacco. The integration of the genome-wide identification, phylogenetic relationships, and conserved domain/motif analysis revealed that NtCOMT1 could be the probable functional COMT homolog for melatonin production. In vitro enzyme activity test approved that NtCOMT1 enabled the conversion of N-acetylserotonin into melatonin, occurring both in the cytoplasm and nucleus by subcellular localization analysis. The K and V values for NtCOMT1 at the optimum temperature (30 °C) were 266.0 μM and 2.155 nmol/min/mg protein. NtCOMT1 was significantly induced by drought stress; whereby if this gene functioned on promoting drought resistance was further conducted. Overexpression of NtCOMT1 resulted in decreased wilting in transgenic tobacco plants subjected to dehydration treatment. The combinatorial effects of NtCOMT1 in increasing melatonin content, inducing antioxidant system, and elevating the expression of drought-related genes could deliver the drought tolerance in tobacco. The characterization of NtCOMT1 may represent a solution to cope with the increasing drought stress in tobacco production in Yunnan province.
烟草（Nicotiana tabacum）是最重要的工业作物之一，其生产力容易受到干旱的影响，特别是在中国云南地区，由于春季长期缺水。在这里，我们旨在确定褪黑素生物合成中的咖啡酸-O-甲基转移酶（COMT），以提供烟草抗旱的遗传资源。通过全基因组鉴定、系统发育关系和保守结构域/基序分析的整合，揭示了 NtCOMT1 可能是产生褪黑素的功能性 COMT 同源物。体外酶活性测试证实，NtCOMT1 能够将 N-乙酰血清素转化为褪黑素，通过亚细胞定位分析，这种转化既发生在细胞质中，也发生在细胞核中。NtCOMT1 在最适温度（30°C）下的 K 和 V 值分别为 266.0 μM 和 2.155 nmol/min/mg 蛋白。干旱胁迫显著诱导 NtCOMT1 的表达；如果该基因在促进抗旱性方面起作用，则进一步进行研究。过表达 NtCOMT1 导致转基因烟草植物在脱水处理时萎蔫减少。NtCOMT1 增加褪黑素含量、诱导抗氧化系统和提高与干旱相关基因的表达的组合效应可以赋予烟草耐旱性。NtCOMT1 的特性可能为应对云南省烟草生产中日益增加的干旱压力提供了一种解决方案。
