Zhu Bao, Zhang Yanjun, Gao Rong, Wu Zhihua, Zhang Wei, Zhang Chao, Zhang Penghong, Ye Can, Yao Linbo, Jin Ying, Mao Hui, Tou Peiyao, Huang Peng, Zhao Jiangzhe, Zhao Qiao, Liu Chang-Jun, Zhang Kewei
Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, China.
China-Mozambique "Belt and Road" Joint Laboratory on Smart Agriculture, Zhejiang Normal University, Jinhua, China.
Nature. 2025 Jul 23. doi: 10.1038/s41586-025-09175-9.
Salicylic acid (SA) is a pivotal phytohormone for plant responses to biotic and abiotic stresses. Plants have evolved two pathways to produce SA: the isochorismate synthase and phenylalanine ammonia lyase (PAL) pathways. Whereas the isochorismate synthase pathway has been fully identified, the PAL pathway remains incomplete. Here we report the full characterization of the PAL pathway for SA biosynthesis via functional analysis of rice (Oryza sativa) SA-DEFICIENT GENE 1 (OSD1) to OSD4. The cinnamoyl-coenzyme A (CoA) ligase OSD1 catalyses the conversion of trans-cinnamic acid to cinnamoyl-CoA, which is subsequently transformed to benzoyl-CoA via the β-oxidative pathway in peroxisomes. The resulting benzoyl-CoA is further converted to benzyl benzoate by the peroxisomal benzoyltransferase OSD2. Benzyl benzoate is subsequently hydroxylated to benzyl salicylate by the endoplasmic reticulum membrane-resident cytochrome P450 OSD3, which is ultimately hydrolysed to salicylic acid by the cytoplasmic carboxylesterase OSD4. Evolutionary analyses reveal that the PAL pathway was first assembled before the divergence of gymnosperms and has been conserved in most seed plants. Activation of the PAL pathway in rice significantly enhances salicylic acid levels and plant immunity. Completion of the PAL pathway provides critical insights into the primary salicylic acid biosynthetic pathway across plant species and offers a precise target for modulating crop immunity.
水杨酸（SA）是植物应对生物和非生物胁迫的关键植物激素。植物进化出两条产生SA的途径：异分支酸合酶途径和苯丙氨酸解氨酶（PAL）途径。虽然异分支酸合酶途径已被完全确定，但PAL途径仍不完整。在这里，我们通过对水稻（Oryza sativa）SA缺陷基因1（OSD1）至OSD4的功能分析，报告了SA生物合成PAL途径的完整特征。肉桂酰辅酶A（CoA）连接酶OSD1催化反式肉桂酸转化为肉桂酰CoA，随后通过过氧化物酶体中的β-氧化途径将其转化为苯甲酰CoA。生成的苯甲酰CoA通过过氧化物酶体苯甲酰转移酶OSD2进一步转化为苯甲酸苄酯。苯甲酸苄酯随后被内质网膜驻留细胞色素P450 OSD3羟基化为水杨酸苄酯，最终被细胞质羧酸酯酶OSD4水解为水杨酸。进化分析表明，PAL途径在裸子植物分化之前首次组装，并在大多数种子植物中保守。水稻中PAL途径的激活显著提高了水杨酸水平和植物免疫力。PAL途径的完成提供了对跨植物物种的主要水杨酸生物合成途径的关键见解，并为调节作物免疫力提供了精确靶点。
