EST analysis of cDNA libraries from the entomopathogenic fungus Beauveria (Cordyceps) bassiana. I. Evidence for stage-specific gene expression in aerial conidia, in vitro blastospores and submerged conidia

Abstract

The entomopathogenic fungus Beauveria (Cordyceps) bassiana holds much promise as a pest biological control agent. B. bassiana produces at least three in vitro single cell infectious propagules, including aerial conidia, vegetative cells termed blastospores and submerged conidia, that display different morphological, biochemical and virulence properties. Populations of aerial conidia, blastospores and submerged conidia were produced on agar plates, rich liquid broth cultures and under conditions of nutrient limitation in submerged cultures, respectively. cDNA libraries were generated from mRNA isolated from each B. bassiana cell type and ∼2500 5′ end sequences were determined from each library. Sequences derived from aerial conidia clustered into 284 contigs and 963 singlets, with those derived from blastospores and submerged conidia forming 327 contigs with 788 singlets, and 303 contigs and 1079 contigs, respectively. Almost half (40–45 %) of the sequences in each library displayed either no significant similarity (e value >10−4) or similarity to hypothetical proteins found in the NCBI database. The expressed sequence tag dataset also included sequences representing a significant portion of proteins in cellular metabolism, information storage and processing, transport and cell processes, including cell division and posttranslational modifications. Transcripts encoding a diverse array of pathogenicity-related genes, including proteases, lipases, esterases, phosphatases and enzymes producing toxic secondary metabolites, were also identified. Comparative analysis between the libraries identified 2416 unique sequences, of which 20–30 % were unique to each library, and only ∼6 % of the sequences were shared between all three libraries. The unique and divergent representation of the B. bassiana transcriptome in the cDNA libraries from each cell type suggests robust differential gene expression profiles in response to environmental conditions.

Lectin mapping reveals stage-specific display of surface carbohydrates in in vitro and haemolymph-derived cells of the entomopathogenic fungus Beauveria bassiana

“…In vitro blastospores and submerged conidia represent morphologically and biochemically distinct B. bassiana cells, considered to be adaptive responses to the availability of nutrients and nutrient deprivation, respectively (Bidochka et al, 1987;Cho et al, 2006;Thomas et al, 1987). The surface carbohydrate epitopes of submerged conidia were very similar to those of aerial conidia, with the notable exception of the loss of fucose and b-GalNAc residues.…”

Tenebrionid secretions and a fungal benzoquinone oxidoreductase form competing components of an arms race between a host and pathogen

“…A gene fragment displaying homology to benzoquinone reductases was identified in a B. bassiana expressed sequence tagged (EST) library (44,45). The gene fragment was used to query the B. bassiana genome (14), leading to the identification of the full-length genomic sequence of BbbqrA (gene locus ID: XM_008596690).…”

Identification of novel genes associated with conidiation inBeauveria bassianawith suppression subtractive hybridization

“…The cDNA A15 was expressed during conidiation and showed similarity to a hydrophobin. Hydrophobin proteins were highly expressed during the B. bassiana conidiation reported by Cho et al (2006). Hydrophobins are unique small molecular mass fungal proteins.…”

“…cDNA libraries from B. bassiana recently were generated from mRNA isolated from aerial conidia, blastospores and submerged conidia respectively. Approximately 40-45% of sequences in each library show no significant similarity or similarity to hypothetical Accepted for publication 16 September 2007.proteins found in the NCBI database (Cho et al 2006), indicating the scarcity of fungal sporulation gene sequences in the GenBank.…”