Core Viewpoint - The recent studies from Zhejiang Normal University, Sichuan University, and Zhejiang University have successfully elucidated the biosynthesis pathways of salicylic acid in plants, particularly focusing on the phenylalanine ammonia-lyase (PAL) pathway, which is crucial for plant defense mechanisms [2][10][18]. Group 1: Research Findings - The study published by the team from Zhejiang Normal University and Brookhaven National Laboratory provides a complete analysis of the PAL biosynthesis pathway of salicylic acid from phenylalanine in rice, confirming its conservation in most seed plants [2][9]. - The activation of the PAL pathway in rice significantly enhances salicylic acid levels and the plant's immune capacity [9][10]. - The research identifies three key enzymes involved in the biosynthesis of salicylic acid, filling a long-standing gap in understanding this critical defense hormone [18]. Group 2: Methodology - The PAL biosynthesis pathway involves several steps: 1. OSD1 catalyzes the conversion of trans-cinnamic acid to cinnamoyl-CoA, which is then transformed into benzoyl-CoA through β-oxidation in peroxisomes [6]. 2. Benzoyl-CoA is converted to benzyl benzoate by the action of OSD2 [6]. 3. Finally, benzyl benzoate is hydroxylated to benzyl salicylate by cytochrome P450 enzyme OSD3, which is then hydrolyzed to salicylic acid by OSD4 [5][6][10]. Group 3: Broader Implications - The completion of the PAL pathway provides critical insights into the primary biosynthesis route of salicylic acid across different plant species, offering a precise target for regulating crop immunity [10]. - The findings from these studies contribute to understanding the differences in disease resistance mechanisms among various plant groups, particularly major food crops [13][18].