Isolation and analysis of differentially expressed genes during asexual sporulation in liquid static culture of Ganoderma lucidum by suppression subtractive hybridization.

Ganoderma lucidum differentiates in liquid static culture by forming aerial mycelia and asexual spores, and this differentiation process is accompanied by higher production of anti-tumor compounds ganoderic acids. To gain an insight into the molecular events during asexual sporulation of G. lucidum, comparative transcriptome analysis using suppression subtractive hybridization (SSH) technique was performed to identify preferentially expressed genes in liquid static culture vs. in traditional shaking culture. After macroarray analysis of 1920 cDNAs from SSH library, 147 unigenes which exhibited high expression in static culture were identified. Among these sequences, putative translations of 88 unigenes possessed much similarity to known proteins involved in cell organization, signal transduction, cell metabolism, protein biosynthesis and transcription regulation; 13 had significant similarity to hypothetical proteins; the remaining 46 showed little or no similarity to GenBank sequences. RT-qPCR analysis confirmed increases in transcripts of selected genes under liquid static culture condition. The results of this study present the useful application of EST analysis on G. lucidum and provide preliminary indication of gene expression putatively involved in asexual sporulation process.