Plant pathogenic fungi Colletotrichum and Magnaporthe share a common G₁ phase monitoring strategy for proper appressorium development

Abstract

Summary To breach the plant cuticle, many plant pathogenic fungi differentiate specialized infection structures (appressoria). In Colletotrichum orbiculare (cucumber anthracnose fungus), this differentiation requires unique proper G1/S phase progression, regulated by two‐component GTPase activating protein CoBub2/CoBfa1 and GTPase CoTem1. Since their homologues regulate mitotic exit, cytokinesis, or septum formation from yeasts to mammals, we asked whether the BUB2 function in G1/S progression is specific to plant pathogenic fungi. Colletotrichum higginsianum and Magnaporthe oryzae were genetically analyzed to investigate conservation of BUB2 roles in cell cycle regulation, septum formation, and virulence. Expression profile of cobub2Δ was analyzed using a custom microarray. In bub2 mutants of both fungi, S phase initiation was earlier, and septum formation coordinated with a septation initiation network protein and contractile actin ring was impaired. Earlier G1/S transition in cobub2Δ results in especially high expression of DNA replication genes and differing regulation of virulence‐associated genes that encode proteins such as carbohydrate‐active enzymes and small secreted proteins. The virulence of chbub2Δ and mobub2Δ was significantly reduced. Our evidence shows that BUB2 regulation of G1/S transition and septum formation supports its specific requirement for appressorium development in plant pathogenic fungi.

Functional analysis of CfSnf1 in the development and pathogenicity of anthracnose fungus Colletotrichum fructicola on tea-oil tree

“…Asexual conidia play critical roles in the disease cycle and infection of Colletotrichum [29, 30]. The Δ CfSnf1 mutant produced dramatically decreased conidiation, which is consistent with the studies in M. oryzae [28, 35].…”

“…Like most fungal pathogens, asexual conidia are important for the disease cycle and infection in Colletotrichum [29, 30]. To examine the role of CfSnf1 in conidiation, WT, Δ CfSnf1 mutant, and Δ CfSnf1 / CfSNF1 were cultured in liquid shaking PDB for 4 days.…”

Fatty Acid Synthase Beta Dehydratase in the Lipid Biosynthesis Pathway Is Required for Conidiogenesis, Pigmentation and Appressorium Formation in Magnaporthe oryzae S6

“…The neighboring clade to FAS1 M. oryzae S6 has the Colletotrichum sp. (green) [ 54 , 55 ], which differentiates specialized appressoria to breach the plant’s cuticle [ 55 ]. This plant pathogen shares common G1 phase that controls and coordinates appressorium development [ 55 ].…”

“…(green) [ 54 , 55 ], which differentiates specialized appressoria to breach the plant’s cuticle [ 55 ]. This plant pathogen shares common G1 phase that controls and coordinates appressorium development [ 55 ]. The other neighboring two clades to M. oryzae S6 FAS1 consist of four different genus’, which are Sporothrix, Ophiostoma, Hypoxylon and Grosmannia (yellow), that have no reports of similarities with Magnaporthe except in protein sequence [ 56 ].…”

Cytoplasmic retention and degradation of a mitotic inducer enable plant infection by a pathogenic fungus

“…The various steps required for the formation of appressorium in these phytopathogenic fungi are linked to the different cell cycle phases. There is a G1/S control to induce the formation of appressorium, first described in C. orbiculare (Fukada and Kubo, 2015), but also operating in M. oryzae (Fukada et al, 2019); and there is a S-phase checkpoint required for appressorium differentiation in M. oryzae (Osés-Ruiz et al, 2017; Osés-Ruiz and Talbot, 2017).…”