Clg2p interacts with Clf and ClUrase to regulate appressorium formation, pathogenicity and conidial morphology in Curvularia lunata

Abstract

Ras is a small GTPase that regulates numerous processes in the cellular development and morphogenesis of many organisms. In this study, we identified and functionally characterized the Clg2p gene of Curvularia lunata, which is homologous with the Ras protein. The Clg2p deletion mutant (ΔClg2p) had altered appressorium formation and conidial morphology and produced fewer, smaller lesions compared with the wild-type strain. When a dominant Clg2p allele was introduced into the mutant, all of these defective phenotypes were completely restored. To further understand the regulation of Clg2p in appressorium formation and conidial morphology, and its role in pathogenicity, seven Clg2p-interacting proteins were screened using a yeast two-hybrid assay. Two of these proteins, Clf, a homologue of Mst11, which corresponds to MAP kinase kinase kinase in Magnaporthe oryzae, and urate oxidase (designated ClUrase) were functionally characterized. Clg2p specifically interacted with Clf through its RA domain to regulate appressorium formation and pathogenicity, whereas the Clg2p-ClUrase interaction regulated conidial morphology without affecting fungal pathogenicity. This report is the first to elucidate the regulatory mechanism of the key Ras protein Clg2p in C. lunata.

Involvement of a Polyketide Synthetase ClPKS18 in the Regulation of Vegetative Growth, Melanin and Toxin Synthesis, and Virulence in Curvularia lunata

“…Curvularia lunata is an important fungal pathogen that causes Curvularia leaf spot (CLS), which is one of the most widely distributed maize leaf diseases worldwide ( Gao et al, 2015a ; Liu et al, 2016 ). To uncover the pathogenicity mechanisms of CLS, most researches have focused on identifying virulence factors, such as melanin ( Gao et al, 2012 , 2015b ), and toxin ( Gao et al, 2014a ; Liu et al, 2009 ).…”

ClNOX1/ClNOXR‐mediated MAPK and cAMP‐PKA signalling pathways and ROS metabolism are involved in Curvularia lunata sexual reproduction and host infection

“…A previous study demonstrated that Clg2P was involved in C. lunata conidial morphology and appressoria-related pathogenicity (Liu et al, 2016). The ClK1 disruption mutants of C. lunata produced fewer conidia and had lower infection rate on maize leaves (Gao et al, 2013).…”

“…A previous study demonstrated that Clg2P was involved in C . lunata conidial morphology and appressoria‐related pathogenicity (Liu et al ., 2016). The ClK1 disruption mutants of C .…”

The key iron assimilation genesClFTR1,ClNPS6were crucial for virulence ofCurvularia lunatavia initiating its appressorium formation and virulence factors

“…It was found that Clg2p interacted with both Clf and ClUrase to regulate appressorium formation, conidial morphology and pathogenicity in C . lunata (Liu et al ., 2016).…”