Li Xin, Cao Jiahao, Jiang Guiyun, Deng Wenqi, Deng Huimin, Yang Weiyuan, Yu Yixun, Liu Juanxu
College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Hortic Res. 2025 Feb 11;12(5):uhaf040. doi: 10.1093/hr/uhaf040. eCollection 2025 May.
The shikimate pathway is crucial for the production of aromatic amino acids and various secondary plant products, including anthocyanins. Phosphoenolpyruvate (PEP) is an important source for shikimate production. The pre-chorismate part of the shikimate pathway is confined to plastids. There are three sources of PEP in plastids. PEP can be imported into the plastids from cytoplasm via the PEP/phosphate translocator (PPT), and it can also be generated in plastids via enolase (ENO) and pyruvate orthophosphate dikinase (PPDK) catalysis. A large number of anthocyanins are synthesized in the flowers of most ornamental plants in the coloring stage. However, the source of PEP, the precursor of anthocyanin synthesis, is still unknown. Herein, , and genes were identified and their expression patterns and subcellular localization of encoded proteins were analyzed. Silencing of , , and alone and co-silencing of and or and did not exhibit any visible phenotypic change compared with the control, while co-silencing of and resulted in the flower color change from purple to light purple. The content of PEP, shikimate, flavonoids, anthocyanins, and aromatic amino acids were all significantly decreased in and co-silenced plants. Co-silencing of and did not affect the expression level of key genes in anthocyanin synthesis and shikimate pathways. Furthermore, co-silencing of , , and resulted in a phenotype similar to the co-silencing of and . Altogether, our study suggested that PEP used for anthocyanin synthesis is mainly provided by PhENO1 and PhPPT, rather than PhPPDK.
莽草酸途径对于芳香族氨基酸和各种次生植物产物（包括花青素）的产生至关重要。磷酸烯醇式丙酮酸（PEP）是莽草酸产生的重要来源。莽草酸途径的前分支酸部分局限于质体。质体中有三种PEP来源。PEP可通过PEP/磷酸转运体（PPT）从细胞质导入质体，也可通过烯醇酶（ENO）和丙酮酸磷酸双激酶（PPDK）催化在质体中产生。大多数观赏植物在花期时，花朵中会合成大量花青素。然而，花青素合成前体PEP的来源仍不清楚。在此，我们鉴定了 、 和 基因，并分析了它们的表达模式以及编码蛋白的亚细胞定位。单独沉默 、 和 以及同时沉默 和 或 和 与对照相比未表现出任何可见的表型变化，而同时沉默 和 导致花色从紫色变为浅紫色。在同时沉默 和 的植株中，PEP、莽草酸、类黄酮、花青素和芳香族氨基酸的含量均显著降低。同时沉默 和 不影响花青素合成和莽草酸途径中关键基因的表达水平。此外，同时沉默 、 和 导致的表型与同时沉默 和 相似。总之，我们的研究表明，用于花青素合成的PEP主要由PhENO1和PhPPT提供，而非PhPPDK。
