Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China; University of the Chinese Academy of Sciences, Beijing, 100039, China.
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; University of the Chinese Academy of Sciences, Beijing, 100039, China; CAS Engineering Laboratory for Vegetation Ecosystem Restoration on Islands and Coastal Zones, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
J Plant Physiol. 2022 Jan;268:153559. doi: 10.1016/j.jplph.2021.153559. Epub 2021 Nov 12.
Canavalia rosea (Sw.) DC is a perennial twining herb distributed in the semi-arid and saline-alkali areas of coastal regions and has evolved halotolerance. In this study, we present the first comprehensive survey of the metallothionein (MT) gene family in C. rosea. MT proteins belong to a family of low-molecular-weight polypeptides with a high content of cysteine residues, which have an affinity to bind with heavy metal ions. MTs also play important roles in stress responses as reactive oxygen species (ROS) scavengers. A total of six CrMTs were identified in the C. rosea genome and classified into four subgroups by phylogenetic analysis. An analysis of the cis-acting elements revealed that a series of hormone-, stress-, and development-related cis-acting elements were present in the promoter regions of CrMTs. The expression of CrMTs also showed habitat- and environmental stress-regulated patterns in C. rosea. CrMT overexpression in yeast enhanced tolerance to heavy metals and ROS, as well as high osmotic and alkalinity stress, which is consistent with their predicted roles as metal-chelating proteins and ROS scavengers. Our results indicate that the CrMT genes might contribute to the detoxification of plants to metals and provide marked tolerance against abiotic stress. The expression patterns of CrMTs in C. rosea also indicate that CrMTs play important roles in this species' response to extreme environments on tropical islands and reefs, probably by improving the thermotolerance of C. rosea plants.
锦鸡儿（Canavalia rosea）是一种分布在沿海半干旱和盐碱地区的多年生攀援草本植物，具有耐盐性。在本研究中，我们首次对锦鸡儿金属硫蛋白（MT）基因家族进行了全面调查。MT 蛋白属于一类富含半胱氨酸残基的低分子量多肽家族，与重金属离子具有亲和力。MT 还在作为活性氧（ROS）清除剂的应激反应中发挥重要作用。在锦鸡儿基因组中鉴定出了 6 个 CrMT，并通过系统发育分析将其分为 4 个亚组。顺式作用元件分析表明，一系列激素、应激和发育相关的顺式作用元件存在于 CrMT 的启动子区域。CrMT 的表达在锦鸡儿中也表现出了对生境和环境胁迫的调节模式。在酵母中过表达 CrMT 增强了对重金属和 ROS 以及高渗透压和碱性胁迫的耐受性，这与它们作为金属螯合蛋白和 ROS 清除剂的预期作用一致。我们的结果表明，CrMT 基因可能有助于植物对金属的解毒，并为非生物胁迫提供显著的耐受性。CrMT 在锦鸡儿中的表达模式也表明，CrMT 在该物种对热带岛屿和珊瑚礁极端环境的响应中发挥着重要作用，可能通过提高锦鸡儿植物的耐热性来实现。
