The clcase-associated protein ChCAP is important for regulation of hyphal growth, appressorial development, penetration, pathogenicity, conidiation, intracellular cAMP level and stress tolerance in Colletotrichum higginsianum

Authors: ZHU, WENJUN - Wuhan Institute Of Technology; XU, XIAOWEN - Non ARS Employee; PENG, FANG - Wuhan Institute Of Technology; ZHANG, SHAOPENG - Wuhan Institute Of Technology; XU, RAN - Wuhan Institute Of Technology; Chen, Weidong; WEI, WEI - Non ARS Employee

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2019
Publication Date: 1/27/2019
Citation: Zhu, W., Xu, X., Peng, F., Zhang, S., Xu, R., Chen, W., Wei, W. 2019. The clcase-associated protein ChCAP is important for regulation of hyphal growth, appressorial development, penetration, pathogenicity, conidiation, intracellular cAMP level and stress tolerance in Colletotrichum higginsianum. Plant Science. 283:1-10. https://doi.org/10.1016/j.plantsci.2019.02.012.
DOI: https://doi.org/10.1016/j.plantsci.2019.02.012

Interpretive Summary: The anthracnose pathogen Colletotrichum higginsianum has a wide host range of important crops, especially cruciferous crops, and has served as a model system in studying plant­pathogen interactions. In order to gain full understanding of pathogenic mechanisms of this pathogen, we characterized the Cyclase-Associated Protein (ChCAP) gene. Deletion of the ChCAP gene resulted in significant alternation of a number of fungal traits including spore production, growth rate and host penetration, reduced intracellular cAMP levels and a significant reduction in pathogenicity. The deletion mutants caused much smaller lesions compared to the normal type strain. In summary, this study clearly showed the important roles of ChCAP in biology and development of Colletotrichum higginsianum and advanced our understanding of pathogenic mechanisms.

Technical Abstract: Technical Abstract: Colletotrichum higginsianum causes anthracnose disease in a wide range of important crops, particularly cruciferous crops, and has been used as a model system to study plant-pathogen interactions and pathogenicity of hemibiotrophic plant pathogens. Conidiation, hyphae growth, appressorial development and appressorial penetration are significant steps during the infection process of C. higginsianum. However, the mechanisms of these important steps during infection remain incompletely understood. To further investigate the mechanisms of the plant-C. higginsianum interactions during infection progress, we characterized the Cyclase­Associated Protein (ChCAP) gene. Deletion of the ChCAP gene resulted in reduction in conidiation and hyphal growth rate. The pathogenicity of LiChCAP mutants was significantly reduced with much smaller lesion on infected leaves compared to the wild type strain. Further study demonstrated that appressorial formation rate, turgor pressure and penetration ability decreased in LiChCAP mutants, indicating that attenuated pathogenicity of LiChCAP mutants was due to these defective phenotypes. In addition, the LiChCAP mutants sectored on growth media with abnormal, dark color, vesicle-like colony morphology and hyphae tips. Moreover, the LiChCAP mutants had reduced intracellular cAMP levels. Exogenous cAMP could partially rescue the defects of LiChCAP mutants in appressorial formation and penetration rate, but not in colony morphology, conidial shape and virulence, indicating that ChCAP is a key component in the cAMP signaling pathway and likely plays other roles in biology of C. higginsianum. In summary, our findings support the role of ChCAP in regulating conidiation, intracellular cAMP level, hyphal growth, appressorial formation, penetration ability and pathogenicity of this hemibiotrophic fungus.