Polar Localizing Class V Myosin Chitin Synthases Are Essential during Early Plant Infection in the Plant Pathogenic FungusUstilago maydis

Abstract

Fungal chitin synthases (CHSs) form fibers of the cell wall and are crucial for substrate invasion and pathogenicity. Filamentous fungi contain up to 10 CHSs, which might reflect redundant functions or the complex biology of these fungi. Here, we investigate the complete repertoire of eight CHSs in the dimorphic plant pathogen Ustilago maydis. We demonstrate that all CHSs are expressed in yeast cells and hyphae. Green fluorescent protein (GFP) fusions to all CHSs localize to septa, whereas Chs5-GFP, Chs6-GFP, Chs7-yellow fluorescent protein (YFP), and Myosin chitin synthase1 (Mcs1)-YFP were found at growth regions of yeast-like cells and hyphae, indicating that they participate in tip growth. However, only the class IV CHS genes chs7 and chs5 are crucial for shaping yeast cells and hyphae ex planta. Although most CHS mutants were attenuated in plant pathogenicity, Dchs6, Dchs7, and Dmcs1 mutants were drastically reduced in virulence. Dmcs1 showed no morphological defects in hyphae, but Mcs1 became essential during invasion of the plant epidermis. Dmcs1 hyphae entered the plant but immediately lost growth polarity and formed large aggregates of spherical cells. Our data show that the polar class IV CHSs are essential for morphogenesis ex planta, whereas the class V myosin-CHS is essential during plant infection.

Investigating chitin deacetylation and chitosan hydrolysis during vegetative growth in Magnaporthe oryzae

“…, 2015; Sanchez‐Leon et al . , 2011; Takeshita, Yamashita, Ohta, & Horiuchi, 2006; Weber, Assmann, Thines, & Steinberg, 2006). We hypothesized that Cda4:mCherry may therefore colocalize with a chitin synthase, which would provide a valuable insight into possible coordinated transport of these proteins and the mechanism of chitin deacetylation.…”

Hyphal and cytoskeleton polarization in Tuber melanosporum: A genomic and cellular analysis

“…Myosin CHSs may play a role in a secretion pathway that is essential for the virulence of fungal pathogens. In U. maydis and Fusarium oxysporum, myosin CHSs are critically involved in (and required for) polarized growth during plant infection ( Weber et al, 2006 andMartín-Urdíroz et al, 2008). In U. maydis, it has been suggested that the Myosin Motor Domain (MMD) of ChsV supports exocytosis but not the long-range delivery of transport vesicles ( Treitschke et al, 2010).…”

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“…and Septoria sp. cultured in increased concentrations of fungicides are lower than the growth rate of the wild type [10]- [12].…”