RT Journal Article SR Electronic T1 Three LysM effectors of Zymoseptoria tritici collectively disarm chitin-triggered plant immunity JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.06.24.169789 DO 10.1101/2020.06.24.169789 A1 Hui Tian A1 Craig I. MacKenzie A1 Luis Rodriguez-Moreno A1 Grardy C.M. van den Berg A1 Hongxin Chen A1 Jason J. Rudd A1 Jeroen R. Mesters A1 Bart P.H.J. Thomma YR 2020 UL http://biorxiv.org/content/early/2020/06/25/2020.06.24.169789.abstract AB Chitin is a major structural component of fungal cell walls and acts as a microbe-associated molecular pattern (MAMP) that, upon recognition by a plant host, triggers the activation of immune responses. In order to avoid the activation of these responses, the Septoria tritici blotch (STB) pathogen of wheat, Zymoseptoria tritici, secretes LysM effector proteins. Previously, the LysM effectors Mg1LysM and Mg3LysM were shown to protect fungal hyphae against host chitinases. Furthermore, Mg3LysM, but not Mg1LysM, was shown to suppress chitin-induced reactive oxygen species (ROS) production. Whereas initially a third LysM effector gene was disregarded as a presumed pseudogene, we now provide functional data to show that also this gene encodes a LysM effector, named Mgx1LysM, that is functional during wheat colonization. While Mg3LysM confers a major contribution to Z. tritici virulence, Mgx1LysM and Mg1LysM contribute to Z. tritici virulence with smaller effects. All three LysM effectors display partial functional redundancy. We furthermore demonstrate that Mgx1LysM binds chitin, suppresses the chitin-induced ROS burst and is able to protect fungal hyphae against chitinase hydrolysis. Finally, we demonstrate that Mgx1LysM is able to undergo chitin-induced polymerisation. Collectively, our data show that Zymoseptoria tritici utilizes three LysM effectors to disarm chitin-triggered wheat immunity.Competing Interest StatementThe authors have declared no competing interest.