Unconventionally secreted effectors of two filamentous pathogens target plant salicylate biosynthesis

• Published in: Nature communications Vol. 5; no. 1; p. 4686
• Main Authors: Liu, Tingli, Song, Tianqiao, Zhang, Xiong, Yuan, Hongbo, Su, Liming, Li, Wanlin, Xu, Jing, Liu, Shiheng, Chen, Linlin, Chen, Tianzi, Zhang, Meixiang, Gu, Lichuan, Zhang, Baolong, Dou, Daolong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.08.2014; Nature Publishing Group; Nature Pub. Group
• Subjects: 13/89; 14/19; 14/35; 14/63; 38/39; 38/77; 42/35; 42/70; 631/326/193/2542; 631/449/2169; 82/80; 82/83; Biosynthesis; Catalytic Domain; Fungal Proteins - metabolism; Fungal Proteins - secretion; Genes; Gossypium - microbiology; Gossypium - physiology; Host-Pathogen Interactions; Humanities and Social Sciences; Hydrolases - genetics; Hydrolases - metabolism; Metabolism; multidisciplinary; Organisms, Genetically Modified; Pathogenesis; Pathogens; Peptides; Phytophthora - genetics; Phytophthora - metabolism; Phytophthora - pathogenicity; Plant diseases; Plant Diseases - microbiology; Protein Transport; Proteins; Salicylates - metabolism; Science; Science (multidisciplinary); Verticillium - genetics; Verticillium - metabolism; Verticillium - pathogenicity; Virulence; Virulence Factors - genetics; Virulence Factors - metabolism; China
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms5686

Plant diseases caused by fungi and oomycetes pose an increasing threat to food security and ecosystem health worldwide. These filamentous pathogens, while taxonomically distinct, modulate host defense responses by secreting effectors, which are typically identified based on the presence of signal peptides. Here we show that Phytophthora sojae and Verticillium dahliae secrete isochorismatases (PsIsc1 and VdIsc1, respectively) that are required for full pathogenesis. PsIsc1 and VdIsc1 can suppress salicylate-mediated innate immunity in planta and hydrolyse isochorismate in vitro . A conserved triad of catalytic residues is essential for both functions. Thus, the two proteins are isochorismatase effectors that disrupt the plant salicylate metabolism pathway by suppressing its precursor. Furthermore, these proteins lack signal peptides, but exhibit characteristics that lead to unconventional secretion. Therefore, this secretion pathway is a novel mechanism for delivering effectors and might play an important role in host–pathogen interactions. Salicylate is a regulator of innate immunity to infection in plants. Here, Liu et al. show that two plant pathogens secrete enzymes that disrupt salicylate biosynthesis and plant immunity, and reveal that these effectors are secreted via an unconventional mechanism.