Based on previous research, it was found that the transcriptional expression levels of OPT (oligopeptide transporter) protein genes varied largely under the coercion of Fe2+ and Cu2+. In order to further explore the effects of this two metals on OPT genes the present writers analyzed the transcriptional expression levels of OPTs under the coercion of different concentrations of Fe2+ and Cu2+. Using Ganoderma lucidum Rongbao No.1 as the experiment material, the biomass and polysaccharide content were determined when the strain was statically cultured in liquid for 15 d and 30 d under different concentrations (0,50,100, 200 and 400 mg/L) of Fe2+ and Cu2+, then collected samples on 15 d and 30 d respectively, and the transcriptional expression levels of OPTs were analyzed by qRT PCR. The results showed that Fe2+ had a certain promotion on the growth of Rongbao No.1, while Cu2+ inhibited its growth. Both the two metals inhibited the polysaccharides content at early culture stage while promoted it in later culture stage. Expression analysis of the OPTs indicated that, with the exception of three genes (OPT7, OPT8 and OPT9) for which no transcripts were detected, the transcription expression of all other OPTs had differences. At early cultivation stage (15 d), under the coercion of Cu2+ the gene expression level of OPTs was relatively low and had no significant difference; while at the later stage cultivation (30 d) under the coercion of Cu2+ the gene expression levels of OPTs was significantly increased as compared with that of sample at 15 d, and had difference, however, under the coercion of Fe2+ the transcription expression level of the overwhelming majority of OPTs were all at the highest when the Fe2+ concentration at 200 mg/L. Therefore, the biomass and polysaccharides content of G. lucidum were affected at different degrees by different concentrations of Fe2+ and Cu2+, at the same time the transcriptional level of OPTs responded differently, indicating that OPT genes may play important roles during G. lucidum adapting and adsorbing external metal ions. |