The Glycosylphosphatidylinositol Anchor Biosynthesis Genes GPI12, GAA1, and GPI8 Are Essential for Cell-Wall Integrity and Pathogenicity of the Maize Anthracnose Fungus Colletotrichum graminicola

Abstract

Glycosylphosphatidylinositol (GPI) anchoring of proteins is one of the most common posttranslational modifications of proteins in eukaryotic cells and is important for associating proteins with the cell surface. In fungi, GPI-anchored proteins play essential roles in cross-linking of β-glucan cell-wall polymers and cell-wall rigidity. GPI-anchor synthesis is successively performed at the cytoplasmic and the luminal face of the ER membrane and involves approximately 25 proteins. While mutagenesis of auxiliary genes of this pathway suggested roles of GPI-anchored proteins in hyphal growth and virulence, essential genes of this pathway have not been characterized. Taking advantage of RNA interference (RNAi) we analyzed the function of the three essential genes GPI12, GAA1 and GPI8, encoding a cytoplasmic N-acetylglucosaminylphosphatidylinositol deacetylase, a metallo-peptide-synthetase and a cystein protease, the latter two representing catalytic components of the GPI transamidase complex. RNAi strains showed drastic cell-wall defects, resulting in exploding infection cells on the plant surface and severe distortion of in planta-differentiated infection hyphae, including formation of intrahyphal hyphae. Reduction of transcript abundance of the genes analyzed resulted in nonpathogenicity. We show here for the first time that the GPI synthesis genes GPI12, GAA1, and GPI8 are indispensable for vegetative development and pathogenicity of the causal agent of maize anthracnose, Colletotrichum graminicola.

Disruption of calcineurin catalytic subunit (cnaA) in Epichloë festucae induces symbiotic defects and intrahyphal hyphae formation

“…The formation of intrahyphal hyphae is widespread in fungi, occurring in response to hyphal and/or cellular damage (Bowman et al, 2006;Calonge, 1968;Takeshita et al, 2006). Such structures have been observed previously in CWI MAP kinase, membrane-associated protein and component of striatininteracting phosphatase and kinase complex mutants of E. festucae; chitin synthase mutants of A. nidulans, Fusarium graminearum and Colletotrichum graminicola; and glycosylphosphatidylinositol synthesis gene mutants of N. crassa and C. graminicola (Becker et al, 2015;Bowman et al, 2006;Green et al, 2016Green et al, , 2017Horiuchi et al, 1999;Kim et al, 2009;Oliveira-Garcia and Deising, 2016;Werner et al, 2007). In A. fumigatus, intrahyphal hyphae formation was promoted by treatment with caspofungin, which inhibits b-1,3-glucan synthase (Walker et al, 2015).…”

“…crassa and C . graminicola (Becker et al ., ; Bowman et al ., ; Green et al ., ; Horiuchi et al ., ; Kim et al ., ; Oliveira‐Garcia and Deising, ; Werner et al ., ). In A .…”

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

“…Iron limitation had a significant effect on the transcription of genes required at specific stages of morphogenesis, and, this held true for genes involved in cell wall biogenesis in conidiation and fungal infection structures (Oliveira‐Garcia and Deising, 2016). The expression of the RBT5 in C .…”

GPI7‐mediated glycosylphosphatidylinositol anchoring regulates appressorial penetration and immune evasion during infection of Magnaporthe oryzae

“…In plant pathogenic fungi, several studies have addressed roles of GPI anchoring during infection (Rittenour and Harris, 2013;Oliveira-Garcia and Deising, 2016b). In F. graminearum, the Δgpi7 mutants were reduced in radial growth rates, formed aberrantly shaped macroconidia, and were significantly reduced in virulence due to a defect of in planta proliferation (Rittenour and Harris, 2013).…”