PtHMGR 的过表达增强了杨树的耐旱性和耐盐性。
Overexpression of PtHMGR enhances drought and salt tolerance of poplar.
机构信息
Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China.
Jiangsu Provincial Key Construction Laboratory of Special Biomass Resource Utilization, Nanjing Xiaozhuang University, Nanjing, China.
出版信息
Ann Bot. 2020 Apr 25;125(5):785-803. doi: 10.1093/aob/mcz158.
BACKGROUND AND AIMS
Soil salinization and aridification are swiftly engulfing the limited land resources on which humans depend, restricting agricultural production. Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is important in the biosynthesis of terpenoids, which are involved in plant growth, development and responses to environmental stresses. This study aimed to provide guidance for producing salt- and drought-resistant poplar.
METHODS
A protein expression system was used to obtain PtHMGR protein, and high-performance liquid chromatography was used to detect the activity of PtHMGR protein in vitro. In addition, a simplified version of the leaf infection method was used for transformation of 'Nanlin895' poplar (Populus×euramericana). qRT-PCR was used to identify expression levels of genes.
KEY RESULTS
PtHMGR catalysed a reaction involving HMG-CoA and NADPH to form mevalonate. Overexpression of PtHMGR in Populus × euramericana 'Nanlin895' improved drought and salinity tolerance. In the presence of NaCl and PEG6000, the rates of rooting and survival of PtHMGR-overexpressing poplars were higher than those of wild-type poplars. The transgenic lines also exhibited higher proline content and peroxidase and superoxide dismutase activities, and a lower malondialdehyde level under osmotic stress. In addition, the expression of genes related to reactive oxygen species (ROS) scavenging and formation was altered by osmotic stress. Moreover, the effect of osmotic stress on transcript levels of stress-related genes differed between the transgenic and wild-type poplars.
CONCLUSION
PtHMGR catalysed a reaction involving HMG-CoA and NADPH to form mevalonate in vitro. Overexpression of PtHMGR promoted root development, increased the expression of ROS scavenging-related genes, decreased the expression of ROS formation-related genes, and increased the activity of antioxidant enzymes in transgenic poplars, enhancing their tolerance of osmotic stress. In addition, overexpression of PtHMGR increased expression of the stress-related genes KIN1, COR15 and AAO3 and decreased that of ABI, MYB, MYC2 and RD22, enhancing the stress resistance of poplar.
背景与目的
土壤盐渍化和干旱化迅速吞噬着人类赖以生存的有限土地资源，限制了农业生产。羟甲基戊二酰辅酶 A 还原酶（HMGR）在萜类化合物的生物合成中起着重要作用，而萜类化合物参与植物的生长、发育以及对环境胁迫的响应。本研究旨在为培育耐盐耐旱杨树提供指导。
方法
采用蛋白表达系统获得 PtHMGR 蛋白，并用高效液相色谱法检测 PtHMGR 蛋白在体外的活性。此外，采用简化的叶片侵染法转化‘南林 895’杨树（Populus×euramericana）。用 qRT-PCR 鉴定基因的表达水平。
主要结果
PtHMGR 催化 HMG-CoA 和 NADPH 反应生成甲羟戊酸。在‘南林 895’杨树中过表达 PtHMGR 可提高其耐旱耐盐性。在 NaCl 和 PEG6000 存在的情况下，PtHMGR 过表达杨树的生根率和成活率均高于野生型杨树。在渗透胁迫下，转基因株系的脯氨酸含量、过氧化物酶和超氧化物歧化酶活性较高，丙二醛含量较低。此外，渗透胁迫还改变了与活性氧（ROS）清除和生成相关的基因的表达。而且，渗透胁迫对转基因和野生型杨树中应激相关基因的转录水平的影响不同。
结论
PtHMGR 在体外催化 HMG-CoA 和 NADPH 反应生成甲羟戊酸。过表达 PtHMGR 促进了根系的发育，增加了 ROS 清除相关基因的表达，降低了 ROS 生成相关基因的表达，提高了转基因杨树中抗氧化酶的活性，增强了其对渗透胁迫的耐受性。此外，过表达 PtHMGR 增加了应激相关基因 KIN1、COR15 和 AAO3 的表达，降低了 ABI、MYB、MYC2 和 RD22 的表达，增强了杨树的抗逆性。
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