ChSte7 Is Required for Vegetative Growth and Various Plant Infection Processes inColletotrichum higginsianum

Abstract

Colletotrichum higginsianum is an important hemibiotrophic phytopathogen that causes crucifer anthracnose in various regions of the world. In many plant-pathogenic fungi, the Ste11-Ste7-Fus3/Kss1 kinase pathway is essential to pathogenicity and various plant infection processes. To date, the role of ChSte7 in C. higginsianum encoding a MEK orthologue of Ste7 in Saccharomyces cerevisiae has not been elucidated. In this report, we investigated the function of ChSte7 in the pathogen. The ChSte7 is predicted to encode a 522-amino-acid protein with a S_TKc conserved domain that shares 44% identity with Ste7 in S. cerevisiae. ChSte7 disruption mutants showed white colonies with irregularly shaped edges and extremely decreased growth rates and biomass productions. The ChSte7 disruption mutants did not form appressoria and showed defects in pathogenicity on leaves of Arabidopsis thaliana. When inoculated onto wounded leaf tissues, the ChSte7 disruption mutants grew only on the surface of host tissues but failed to cause lesions beyond the wound site. In contrast, both the wild-type and complementation strains showed normal morphology, produced appressoria, and caused necrosis on leaves of Arabidopsis. Analysis with qRT-PCR suggested that ChSte7 was highly expressed during the late stages of infection. Taken together, our results demonstrate that ChSte7 is involved in regulation of vegetative growth, appressorial formation of C. higginsianum, and postinvasive growth in host tissues.

ChCDC25 Regulates Infection-Related Morphogenesis and Pathogenicity of the Crucifer Anthracnose Fungus Colletotrichum higginsianum

“…In previous studies, the cAMP and MAPK signaling pathways were reported to regulate appressorial formation and pathogenicity in C. higginsianum (Wei et al, 2016;Yuan et al, 2016;Gu et al, 2017;Zhu et al, 2017). In this work, deletion of ChCDC25 caused obvious defects in conidial germination and appressorial formation.…”

The Mitogen-Activated Protein Kinase CgMK1 Governs Appressorium Formation, Melanin Synthesis, and Plant Infection of Colletotrichum gloeosporioides

“…Further investigations should therefore focus on elucidating the relationship between the CgMK1 gene of C. gloeosporioides and host defense. Previously, upstream components of the Fus3/Kss1 MAPK cascade have been identified and proved to be critical to appressorium formation and pathogenicity of Colletotrichum , such as CoMEKK1 of C. orbiculare ( Sakaguchi et al, 2010 ) and ChSte7 in C. higginsianum ( Yuan et al, 2016 ). Systematic studies of the Fus3/Kss1 signaling cascades in C. gloeosporioides are not well-characterized.…”

The cAMP-PKA Signaling Pathway Regulates Pathogenicity, Hyphal Growth, Appressorial Formation, Conidiation, and Stress Tolerance in Colletotrichum higginsianum

“…Pathogenicity assays of C. higginsianum on Arabidopsis were performed as previously described (Yuan et al, 2016 ). The conidia harvested from 5-days-old PDA agar cultures at 25°C were washed with sterile distilled water twice.…”