An effector of a necrotrophic fungal pathogen targets the calcium‐sensing receptor in chloroplasts to inhibit host resistance

• Published in: Molecular plant pathology Vol. 21; no. 5; pp. 686 - 701
• Main Authors: Tang, Liguang, Yang, Guogen, Ma, Ming, Liu, Xiaofan, Li, Bo, Xie, Jiatao, Fu, Yanping, Chen, Tao, Yu, Yang, Chen, Weidong, Jiang, Daohong, Cheng, Jiasen
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.05.2020; John Wiley and Sons Inc
• Subjects: Amino acids; Apoptosis; Ascomycota - pathogenicity; Calcium; Calcium ions; calcium receptors; calcium signaling; Calcium signalling; calcium‐sensing receptor; Chloroplasts; Chloroplasts - metabolism; Disease Resistance; Drug resistance in microorganisms; effector; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fungi; Genetic engineering; Genetically modified plants; Health aspects; Immunity; Infections; Localization; Neurotrophin 1; Original; Pathogenesis; Pathogens; Plant Diseases - genetics; Plant immunity; Plant Immunity - genetics; Plant Immunity - physiology; plant pathogens; Plant resistance; Plants; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - microbiology; Proteins; Receptors; Receptors, Calcium-Sensing - metabolism; Roles; Salicylic acid; Salicylic Acid - metabolism; salicylic acid signalling pathway; Sclerotinia sclerotiorum; Signal transduction; Signaling; SsITL; Transgenic plants; Yeast; Sclerotinia sclerotiorum; calcium-sensing receptor; effector; SsITL; salicylic acid signalling pathway
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/mpp.12922

SsITL, a secretory protein of the necrotrophic phytopathogen Sclerotinia sclerotiorum, was previously reported to suppress host immunity at the early stages of infection. However, the molecular mechanism that SsITL uses to inhibit plant defence against S. sclerotiorum has not yet been elucidated. Here, we report that SsITL interacted with a chloroplast‐localized calcium‐sensing receptor, CAS, in chloroplasts. We found that CAS is a positive regulator of the salicylic acid signalling pathway in plant immunity to S. sclerotiorum and CAS‐mediated resistance against S. sclerotiorum depends on Ca2+ signalling. Furthermore, we showed that SsITL could interfere with the plant salicylic acid (SA) signalling pathway and SsITL‐expressing transgenic plants were more susceptible to S. sclerotiorum. However, truncated SsITLs (SsITL‐NT1 or SsITL‐CT1) that lost the ability to interact with CAS do not affect plant resistance to S. sclerotiorum. Taken together, our findings reveal that SsITL inhibits SA accumulation during the early stage of infection by interacting with CAS and then facilitating the infection by S. sclerotiorum. The secretory protein SsITL inhibits salicylic acid accumulation during the early stage of infection by interacting with CAS (calcium‐sensing receptor) and then facilitating S. sclerotiorum infection.