State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China.
BMC Plant Biol. 2021 Jan 6;21(1):10. doi: 10.1186/s12870-020-02746-0.
Low temperature is a major abiotic stress that seriously limits mangrove productivity and distribution. Kandelia obovata is the most cold-resistance specie in mangrove plants, but little is known about the molecular mechanism underlying its resistance to cold. Osmotin is a key protein associated with abiotic and biotic stress response in plants but no information about this gene in K. obovata was reported.
In this study, a cDNA sequence encoding osmotin, KoOsmotin (GenBank accession no. KP267758), was cloned from mangrove plant K. obovata. The KoOsmotin protein was composed of 221 amino acids and showed a calculated molecular mass of 24.11 kDa with pI 4.92. The KoOsmotin contained sixteen cysteine residues and an N-terminal signal peptide, which were common signatures to most osmotins and pathogenesis-related 5 proteins. The three-dimensional (3D) model of KoOsmotin, contained one α-helix and eleven β-strands, was formed by three characteristic domains. Database comparisons of the KoOsmotin showed the closest identity (55.75%) with the osmotin 34 from Theobroma cacao. The phylogenetic tree also revealed that the KoOsmotin was clustered in the branch of osmotin/OLP (osmotin-like protien). The KoOsmotin protein was proved to be localized to both the plasma membrane and cytoplasm by the subcellular localization analysis. Gene expression showed that the KoOsmotin was induced primarily and highly in the leaves of K. obovata, but less abundantly in stems and roots. The overexpressing of KoOsmotin conferred cold tolerance in Escherichia coli cells.
As we known, this is the first study to explore the osmotin of K. obovata. Our study provided valuable clues for further exploring the function of KoOsmotin response to stress.
低温是一种主要的非生物胁迫，严重限制了红树林的生产力和分布。白骨壤是红树林植物中最耐寒的物种，但对其耐寒性的分子机制知之甚少。渗透素是一种与植物的非生物和生物胁迫反应相关的关键蛋白，但在白骨壤中没有关于该基因的信息。
在这项研究中，从红树林植物白骨壤中克隆了一个编码渗透素的 cDNA 序列，命名为 KoOsmotin（GenBank 登录号 KP267758）。KoOsmotin 蛋白由 221 个氨基酸组成，计算分子量为 24.11 kDa，等电点为 4.92。KoOsmotin 包含 16 个半胱氨酸残基和一个 N 端信号肽，这是大多数渗透素和病程相关蛋白 5 的共同特征。KoOsmotin 的三维（3D）模型由三个特征结构域组成，包含一个α-螺旋和十一个β-折叠。数据库比较表明，KoOsmotin 与可可中的渗透素 34 具有最接近的同一性（55.75%）。系统进化树也表明，KoOsmotin 聚类在渗透素/OLP（渗透素样蛋白）分支中。亚细胞定位分析表明，KoOsmotin 蛋白定位于质膜和细胞质。基因表达表明，KoOsmotin 主要且高度诱导白骨壤叶片表达，但在茎和根中表达较少。过表达 KoOsmotin 可赋予大肠杆菌细胞耐寒性。
据我们所知，这是首次研究白骨壤的渗透素。我们的研究为进一步探讨 KoOsmotin 对胁迫的反应功能提供了有价值的线索。
