Isolation and characterization of a novel Ganoderma lucidum gene that differentially expressed between shaking culture and liquid static culture

Suppression subtractive hybridization (SSH) was preformed to investigate the differences of gene expression between the shaking culture mode and the liquid static culture mode which favors ganoderic acids production in Ganoderma lucidum. One novel gene preferentially expressed in liquid static culture was identified and analyzed. Its full length cDNA sequence and the 5′-flanking region were then obtained by rapid amplification of cDNA ends (RACE) and self-formed adaptor PCR (SEFA-PCR), respectively. Nucleotide sequence of the gene is not homologous to any of the known Ganoderma genes. The sequence analysis revealed that the open reading frame of this gene encodes a protein of 371 amino acids that has high homology with the mitogen-activated protein kinase (MAPK) of other five species-Postia (97%), Coprinopsis (91%), Neurospora (86%), Aspergillus (83%), and Saccharomyces (80%)-so that it can be defined as a G. lucidum MAPK gene (GenBank accession number: JF781125). Computer assisted analysis revealed that this new G. lucidum MAPK gene contains thirteen exons and twelve introns. The quantitative real-time RT-PCR (qRT-PCR) analysis showed that this new gene had a much higher expression level in liquid static culture than in traditional shaking culture. Results of this research established a good foundation for further study on the functions of the G. lucidum MAPK at the molecular level.