Biochemical and molecular characterization of enhanced growth of Panax ginseng C. A. Meyer treated with atmospheric pressure plasma

Abstract

We confirmed that micro dielectric barrier discharge plasma improved the growth and immunity of Panax ginseng C. A. Meyer seedlings. The growth rate of the ginseng seedlings was compared by height and weight monitoring. The length and weight of the aerial part of the 3 min. Plasma treated ginseng increased by 25% and 54%, respectively, compared to the untreated ginseng. The difference between the initial root weight before planting in the soil and the root weight 5 weeks after planting in the soil increased by 28% and 22% for the 3 and 10 min. Plasma treated ginseng, respectively. Chlorophyll and total phenolic contents were increased 62% and 56%, respectively in the aerial part of the plasma-treated ginseng seedlings compared to the untreated controls. Radical scavenging activity was also increased by 18% in the 3 min plasma treated ginseng seedlings. The plasma treatment increased the expression level of chlorophyll metabolism-related and auxin response factor genes in ginseng and might be the result of ginseng growth development by enhancing plant growth hormone. Increasing disease resistance through induced systemic resistance can ultimately improve crop productivity by strengthening the immune system. We demonstrated this by comparing the transcription patterns of genes involved in the pathogenic defense mechanisms of ginseng. The expression of the pathogen-associated PgPR2, PgPR5, PgPR10 and PgCAT genes improved significantly and rapidly in the plasma treated ginseng seedlings. In particular, mRNA expression levels of the PgPR2 and PgPR5 genes were significantly increased 5- and 3-fold, respectively, in the 10 min plasma treated seedlings. An increased expression level of abscisic acid signaling related genes (PgABF and PgPYL) means an increased resistance to stress, which in turn, could affect the enhanced antioxidant activity. Our results suggest that plasma can enhance the growth and increase the immunity of ginseng seedlings especially by improving its resistance to pathogens. Effective control of diseases using plasma technology could be one of the biggest factors that increase the yield of perennial medicinal plants such as ginseng.