The surface of plants forms a defense barrier that directly inhibits the first point of contact of microorganisms with the host. To understand this defense mechanism in Moniliophthora perniciosa interaction with Theobroma cacao cv Catongo, the aim of this study was to compare the changes in protein expression in basidiospores of the fungus M. perniciosa in response the leaf water washes (LWW) of two contrasting cocoa varieties for resistance to witches' broom disease. A total of 8.1 × 108 basidiospores were used for each treatment containing washed leaf material. Germinated basidiospores in the absence of LWW were used as control. The proteomic analysis was performed by the 2D-PAGE technique combined with mass spectrometry (MS). Protein extraction was based on the SDS-dense method followed by sonication for cell disruption and phenol extraction. Sixty-four proteins had accumulation of variation when compared to the control (no LWW). Proteins were identified associated with energy (ATP synthase) and protein (BiP) metabolism, whose accumulation was reduced by basidiospores germinated in leaf wash from Catongo cocoa. The reduction in ATP synthase of the basidiospores germinated the Catongo LWW suggests a shift from aerobic to fermentative metabolism of the fungus in response to components of the LWW. Furthermore, proteins involved in virulence were identified along with fungal resistance to polyketide cyclase, glycoside hydrolase, multidrug transporter protein (SFM) and proteins related to oxidative stress and fermentation, such as catalase A and alcohol dehydrogenase (ADH). The data showed an effect of cocoa phylloplane substances on the germination of fungal basidiospores through differences in protein expression patterns in the presence of LWW of the CCN51 and Catongo genotypes. These results may reveal mechanisms of resistance, host susceptibility and pathogen virulence.
Keywords: CCN51; Catongo; Proteome; Witches’ broom.
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