Transcript profiling of antioxidant genes during biotic and abiotic stresses in Panax ginseng C. A. Meyer

The regulation of reactive oxygen scavengers against biotic and abiotic conditions were investigated in the seedling of Panax ginseng C. A. Meyer. From the EST library we selected the antioxidant marker genes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione synthase (GS). The abiotic chilling, heat, osmotic, oxidative, and wounding stresses and biotic stresses with fungal pathogens were tested against 3-week-grown seedlings. The expression patterns of the genes were analyzed by means of real-time quantitative RT-PCR. The transcriptome result under abiotic stresses showed differential expression and elevated up-regulation of PgSOD, PgGPX, PgGS, and PgAPX, thus it may prove the generation of ROS in ginseng. Whereas, in biotic stress the up-regulation of transcript level merely based on the incompatible interactions. But PgAPX and PgCAT showed no significant change or slight down-regulation of transcript level during pathogen interaction. Thus it may suggest that in ginseng, plant-pathogen interaction triggers defense-related gene transcription via salicylic acid mediated signaling mechanism, and also possess crosstalk signaling networks between abiotic and biotic stress responses.