Effect Of Several Elicitors On Bioactive Compounds Accumulation Of Dendrobium Candidum PLBs

Dendrobium candidum,a perennial herb and traditional medicinal plant,which owns higher medicinal value.Owing to the shortage of wild resource and unstable yield and quality of artificial cultivation,the raw materials for the production of D.candidum products were deficient.Thus,the present study used the method of plant tissue culture to produce protocorm-like bodies(PLBs)for providing a new material during industrial production of D.candidum.For enhancing bioactive compound accumulation,the present study investigated the effect of concentration and treatment time of four kinds of elicitors[chitosan,pullulan,salicylic acid(SA),and methyl jasmonate(MeJA)]on bioactive compound accumulation.In addition,the antioxidant activity of D.candidum was evaluated by determination of DPPH radical scavenging activity,reducing power assay and Fe2+-chelating activity.30 mg·L-1 chitosan,200 mg·L-1 pullulan,75 μM SA,and 75μM MeJA were optimal for accumulation of polysaccharides,alkaloids,phenolics,and flavonoids of PLBs during suspension culture.The comparison among the elicitors and their combination showed that MeJA was the optimal elicitor,the favorable MeJA concentration was 75μM.During bioreactor culture,the effect of MeJA treatment time on biomass and bioactive compounds accumulation was studied.The bioactive compound accumulation was promoted when the medium was supplemented with 75μM MeJA after 30 d of bioreactor culture,bioactive compound contents reached the maximum levels,i.e.,386.7 mg·g-1 of polysaccharides,269.5 μg·g-1 of alkaloids,5.1 mg·g-1 of flavonoids,and 4.3 mg·g-1 of phenolics.The present study compared the antioxidant activities among the different materials(bioreactor-cultured PLBs and cultivated plants).The DPPH radical scavenging activity and reducing power were different among PLBs and plants,i.e.,PLBs treated with MeJA>cultivated plants>PLBs without MeJA treatment.The Fe2+-chelating activity of PLBs treated with MeJA>PLBs without MeJA treatment>cultivated plants.The present study found that the bioactive compounds accumulation in bioreactor-cultured PLBs treated with MeJA was higher than cultivated plants,thus its antioxidant activity was improved.The method,which mass production of PLBs in bioreactors and improving bioactive compound accumulation by using elicitors,can promote development of commercial production of D.candidum products.