TheMagnaporthe griseaclass VII chitin synthase is required for normal appressorial development and function

Abstract

The plant pathogenic fungus Magnaporthe grisea is able to enter its host via appressorium-mediated penetration. Earlier investigations have shown that these infection structures are rich in the cell wall polysaccharide chitin. Previously, we have described how the transcription of a class VII chitin synthase-encoding gene CHS7 is completely dependent on the putative transcription factor Con7p during the germination of conidia, and how con7(-) mutants are unable to form appressoria under any conditions tested. Because of the pleiotropic effects of the con7(-) mutation, we examined the consequences of the targeted deletion of CHS7. The chs7(-) mutants generated were unable to form appressoria on artificial surfaces, except following the application of the exogenous inducers 1,16-hexadecanediol and cyclic adenosine monophosphate. The appressoria formed had a reduced chitin content and were often found to be smaller and misshapen compared with the wild-type. chs7(-) mutants were significantly reduced in their ability to enter rice plants, but growth in planta was not affected. Reverse transcriptase-polymerase chain reaction analysis demonstrated that CHS7 transcription was strongly induced on germination of spores, and a green fluorescent protein-tagged Chs7p protein was found to be produced abundantly during infection-related morphogenesis. Together, these data suggest that the class VII chitin synthase Chs7p of M. grisea is required for normal appressorium formation and function.

MAP kinase signalling pathway components and targets conserved between the distantly related plant pathogenic fungi Mycosphaerella graminicola and Magnaporthe grisea

“…grisea. Microscopy, including 4,6-diamidino-2-phenylindole (DAPI) staining and GFP visualisation, was conducted as described previously (Odenbach et al, 2009). All oligonucleotides used in this study are listed in Table 1 and were obtained from Eurofins-MWG-Operon (Ebersberg, Germany).…”

Disruption of the chitin synthase gene CHS1 from Fusarium asiaticum results in an altered structure of cell walls and reduced virulence

“…Chitin synthases in fungi were previously classified into six categories (Roncero, 2002;Ruiz-Herrera et al, 2002) and a seventh class has recently been identified (Choquer et al, 2004;Mandel et al, 2006;Martín-Udíroz et al, 2008;Kim et al, 2009;Odenbach et al, 2009). A class I chitin synthase gene (CHS1) from F. asiaticum has been shown to play a role during mycelium development (Li et al, 2003).…”

The Myosin Motor Domain of Fungal Chitin Synthase V Is Dispensable for Vesicle Motility but Required for Virulence of the Maize PathogenUstilago maydis

“…This b-1,4-linked polymer of N-acetylglucosamine is synthesized by chitin synthases (CHSs), which are thought to be delivered in secretory vesicles to the growth region (Sietsma et al, 1996;Bartnicki-Garcia, 2006). Studies in numerous fungi have shown that the deletion of CHSs results in a weakening of the cell wall and causes abnormal growth of the fungal hyphae (Fujiwara et al, 1997;Horiuchi et al, 1999;Werner et al, 2007), as well as appressoria (Werner et al, 2007;Odenbach et al, 2009). Consequently, CHSs perform crucial roles in plant infection (e.g., Madrid et al, 2003;Garcera-Teruel et al, 2004;Martin-Udiroz et al, 2004Soulie et al, 2006;Weber et al, 2006;Werner et al, 2007).…”