Deciphering phenylalanine-derived salicylic acid biosynthesis in plants
Yukang Wang, Shuyan Song, Wenxuan Zhang, Qianwen Deng, Yanlei Feng, Tao Mei, Mengna Kang, Qi Zhang, Lijia Yang, Xinyu Wang, Changan Zhu, Xiaowen Wang, Wanxin Zhu, Yixiao Zhu, Pengfei Cao, Jia Chen, Jinheng Pan, Shan Feng, Xianyan Chen, Huaxin Dai, Shiyong Song, Jinghua Yang, Tianlun Zhao, Fangbin Cao, Tao Zeng, Xing‐Xing Shen, Robert L. Last, Jianping Hu, Jingquan Yu, Pengxiang Fan, Ronghui Pan
Abstract
Salicylic acid (SA) is a ubiquitous plant hormone with a long history in human civilization1,2. Because of the central role of SA in orchestrating plant pathogen defence, understanding SA biosynthesis is fundamental to plant immunity research and crop improvement. Isochorismate-derived SA biosynthesis has been well defined in Arabidopsis. However, increasing evidence suggests a crucial function for phenylalanine-derived SA biosynthesis in many other plant species1. Here we reveal the phenylalanine-derived SA biosynthetic pathway in rice by identifying three dedicated enzymes — peroxisomal benzoyl-CoA:benzyl alcohol benzoyltransferase (BEBT), the endoplasmic reticulum-associated cytochrome P450 enzyme benzylbenzoate hydroxylase (BBH), and cytosolic benzylsalicylate esterase (BSE) that sequentially convert benzoyl-CoA to benzylbenzoate, benzylsalicylate and SA. The pathogen-induced gene expression pattern and SA biosynthetic functions of this triple-enzyme module are conserved in diverse plants. This work fills a major knowledge gap in the biosynthesis of a key plant defence hormone, establishing a foundation for new strategies to create disease-resistant crops. Diverse plant species synthesize salicylic acid from phenylalanine through a pathway that includes a conserved triple-enzyme module that converts benzoyl-CoA to salicylic acid.