Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing, 100193, China.
School of Horticulture and Landscape Architecture, Henan Institute of Science and Technology, Xinxiang, 453003, Henan, China.
Plant Cell Rep. 2019 Dec;38(12):1527-1540. doi: 10.1007/s00299-019-02463-5. Epub 2019 Aug 30.
SmPPT, which encodes 4-hydroxybenzoate polyprenyl diphosphate transferase involved in ubiquinone biosynthesis, confers salt tolerance to S. miltiorrhiza through enhancing the activities of POD and CAT to scavenge ROS. Ubiquinone (UQ), also known as coenzyme Q (CoQ), is a key electron transporter in the mitochondrial respiratory system. UQ is composed of a benzene quinone ring and a polyisoprenoid side chain. Attachment of polyisoprenoid side chain to the benzene quinone ring is a rate-limiting step catalyzed by 4-hydroxybenzoate polyprenyl diphosphate transferase (PPT). So far, only a few plant PPT-encoding genes have been functionally analyzed. Through genome-wide analysis and subsequent molecular cloning, a PPT-encoding gene, termed SmPPT, was identified from an economically and academically important medicinal model plant, Salvia miltiorrhiza. SmPPT contained many putative cis-elements associated with abiotic stresses in the promoter region and were responsive to PEG-6000 and methyl jasmonate treatments. The deduced SmPPT protein contains the PT_UbiA conserved domain of polyprenyl diphosphate transferase and an N-terminal mitochondria transit peptide. Transient expression assay of SmPPT-GFP fusion protein showed that SmPPT was mainly localized in the mitochondria. SmPPT could functionally complement coq2 mutation and catalyzed UQ6 production in yeast cells. Overexpression of SmPPT increased UQ production and enhanced salt tolerance in S. miltiorrhiza. Under salinity stress conditions, transgenic plants accumulated less HO and malondialdehyde and exhibited higher peroxidase (POD) and catalase (CAT) activities compared with wild-type plants. It indicates that SmPPT confers salt tolerance to S. miltiorrhiza at least partially through enhancing the activities of POD and CAT to scavenge ROS.
SmPPT 编码 4-羟基苯甲酸多萜二磷酸转移酶，参与泛醌生物合成，通过增强 POD 和 CAT 的活性来清除 ROS，从而赋予丹参耐盐性。泛醌（UQ），也称为辅酶 Q（CoQ），是线粒体呼吸系统中的关键电子转运体。UQ 由苯醌环和聚异戊二烯侧链组成。聚异戊二烯侧链与苯醌环的连接是由 4-羟基苯甲酸多萜二磷酸转移酶（PPT）催化的限速步骤。到目前为止，只有少数植物 PPT 编码基因被进行了功能分析。通过全基因组分析和随后的分子克隆，从经济和学术上重要的药用模式植物丹参中鉴定出一个 PPT 编码基因，命名为 SmPPT。SmPPT 启动子区域含有许多与非生物胁迫相关的假定顺式元件，对 PEG-6000 和茉莉酸甲酯处理有响应。推导的 SmPPT 蛋白含有多萜二磷酸转移酶的 PT_UbiA 保守结构域和一个 N 端线粒体转运肽。SmPPT-GFP 融合蛋白的瞬时表达分析表明，SmPPT 主要定位于线粒体。SmPPT 可以在酵母细胞中功能互补 coq2 突变并催化 UQ6 的产生。SmPPT 的过表达增加了 UQ 的产生并增强了丹参的耐盐性。在盐胁迫条件下，与野生型植物相比，转基因植物积累的 HO 和丙二醛较少，过氧化物酶（POD）和过氧化氢酶（CAT）活性较高。这表明 SmPPT 通过增强 POD 和 CAT 的活性来清除 ROS，至少部分赋予丹参耐盐性。
