Isolation of mycoparasitic-related transcripts by SSH during interaction of the mycoparasite Stachybotrys elegans with its host Rhizoctonia solani
Mycoparasitism by antagonistic fungi involves changes in the biochemistry and physiology of both partners. Analysis of genes that are expressed during mycoparasite–host interaction represents a powerful strategy to obtain insight into the molecular events underlying these changes. The aim of this study is to identify genes whose expression is upregulated when the mycoparasite Stachybotrys elegans is in direct confrontation with its host Rhizoctonia solani. Suppression subtractive hybridization (SSH) was used to create a subtracted cDNA library, and differential screening was applied to identify the over-expressed transcripts. We report the analysis of 2,166 clones, among which 47% were upregulated during mycoparasitism. Two hundred and sixty-one clones were sequenced that corresponded to 94 unique genes. Forty-four of these were identified as novel genes, while the remainder showed similarity to a broad diversity of genes with putative functions related to toxin production, pathogenicity, and metabolism. As a result of mycoparasitism, 15 genes belonged to R. solani among which 9 genes were assigned putative functions. Quantitative RT-PCR was used to examine the upregulation of 12 genes during the course of mycoparasitism. Seven genes showed significant upregulation at least at one-time point during interaction of the mycoparasite with its host. This study describes a first step toward knowledge of S. elegans genome. The results present the useful application of EST analysis on S. elegans and provide preliminary indication of gene expression putatively involved in mycoparasitism.
KeywordsMycoparasitism SSH Differential screening Gene expression Mycoparasitism-induced genes ESTs
The Biocontrol NSERC Network and the Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grant provided funding for this study. We thank M. Strömvik for her help in data mining and M. Elias for her technical expertise.
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