AUTHOR=Wei Wei , Xiong Ying , Zhu Wenjun , Wang Nancong , Yang Guogen , Peng Fang 

TITLE=Colletotrichum higginsianum Mitogen-Activated Protein Kinase ChMK1: Role in Growth, Cell Wall Integrity, Colony Melanization, and Pathogenicity

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01212

DOI=10.3389/fmicb.2016.01212

ISSN=1664-302X

ABSTRACT=<p><italic>Colletotrichum higginsianum</italic> is an economically important pathogen that causes anthracnose disease in a wide range of cruciferous crops. To facilitate the efficient control of anthracnose disease, it will be important to understand the mechanism by which the cruciferous crops and <italic>C. higginsianum</italic> interact. A key step in understanding this interaction is characterizing the mitogen-activated protein kinases (MAPK) signaling pathway of <italic>C. higginsianum</italic>. MAPK plays important roles in diverse physiological processes of multiple pathogens. In this study, a Fus3/Kss1-related MAPK gene, <italic>ChMK1</italic>, from <italic>C. higginsianum</italic> was analyzed. The results showed that the Fus3/Kss1-related MAPK ChMK1 plays a significant role in cell wall integrity. Targeted deletion of <italic>ChMK1</italic> resulted in a hypersensitivity to cell wall inhibitors, reduced conidiation and albinistic colonies. Further, the deletion mutant was also unable to form melanized appressorium, a specialized infection structure that is necessary for successful infection. Therefore, the deletion mutant loses pathogenicity on <italic>A. thaliana</italic> leaves, demonstrating that <italic>ChMK1</italic> plays an essential role in the early infection step. In addition, the <italic>ChMK1</italic> deletion mutant showed an attenuated growth rate that is different from that of its homolog in <italic>Colletotrichum lagenarium</italic>, indicating the diverse roles that Fus3/Kss1-related MAPKs plays in phytopathogenic fungi. Furthermore, the expression level of three melanin synthesis associated genes were clearly decreased in the albinistic <italic>ChMK1</italic> mutant compared to that of the wild type strain, suggesting that ChMK1 is also required for colony melanization in <italic>C. higginsianum</italic>.</p>