Browsing by Author "Goncalo A.G. Pereira"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Characterization of necrosis and ethylene-inducing proteins (NEP) in the basidiomycete Moniliophthora perniciosa, the causal agent of witches’ broom in Theobroma cacao
    (Elsevier, 2007) Odalys Garcia; Joci A.N. Macedo; Ricardo Tiburcio; Gustavo Zaparoli; Johana Rincones; Livia M.C. Bittencourt; Geruza O. Ceitta; Fabienne Micheli; Abelmon Gestiera; Andre a C. Mariano; Marlene A. Schiavinato; Francisco J. Medrano; Lyndel W. Meinhardt; Goncalo A.G. Pereira; Julio C.M. Cascardo
    The hemibiotrophic basidiomycete Moniliophthora perniciosa causes witches’ broom disease of Theobroma cacao. Analysis of the M. perniciosa draft genome led to the identification of three putative genes encoding necrosis and ethylene-inducing proteins (MpNEPs), which are apparently located on the same chromosome. MpNEP1 and 2 have highly similar sequences and are able to induce necrosis and ethylene emission in tobacco and cacao leaves. MpNEP1 is expressed in both biotrophic and saprotrophic mycelia, the protein behaves as an oligomer in solution and is very sensitive to temperature. MpNEP2 is expressed mainly in biotrophic mycelia, is present as a monomer in solution at low concentrations (<40 mM) and is able to recover necrosis activity after boiling. These differences indicate that similar NEPs can have distinct physical characteristics and suggest possible complementary roles during the disease development for both proteins. This is the first report of NEP1-like proteins in a basidiomycete.
  • Thumbnail Image
    Item
    Production of Calcium Oxalate Crystals by the Basidiomycete Moniliophthora perniciosa, the Causal Agent of Witches’ Broom Disease of Cacao
    (2008) Goncalo A.G. Pereira; Bruno V. de Oliveira; Maria Carolina S. do Rio; Daniela P.T. de Tomazella; Jose A. Fracassi da Silva
    Oxalic acid has been shown as a virulence factor for some phytopathogenic fungi, removing calcium from pectin and favoring plant cell wall degradation. Recently, it was published that calcium oxalate accumulates in infected cacao tissues during the progression of Witches’ Broom disease (WBD). In the present work we report that the hemibiotrophic basidiomycete Moniliophthora perniciosa, the causal agent of WBD, produces calciumoxalate crystals. These crystals were initially observed by polarized light microscopy of hyphae growing on a glass slide, apparently being secreted from the cells. The analysis was refined by Scanning electron microscopy and the compositon of the crystals was confirmed by energy-dispersive x-ray spectrometry. The production of oxalate by M. perniciosa was reinforced by the identification of a putative gene coding for oxaloacetate acetylhydrolase, which catalyzes the hydrolysis of oxaloacetate to oxalate and acetate. This gene was shown to be expressed in the biotrophic-like mycelia, which in planta occupy the intercellular middle-lamella space, a region filled with pectin. Taken together, our results suggest that oxalate production by M. perniciosa may play a role in the WBD pathogenesis mechanism