Chitosan versus yeast extract driven elicitation for enhanced production of fragrant compound 2-hydroxy-4-methoxybenzaldehyde (2H4MB) in root tuber derived callus of Decalepis salicifolia (Bedd. ex Hook.f.) Venter

Decalepis salicifolia (Bedd. ex Hook.f.) Venter is a new source of the commercially important flavor compound 2-hydroxy-4-methoxybenzaldehyde (2H4MB), a structural isomer of vanillin, with high pharmacological value and used as a flavoring agent at industrial level for making soft drink and bakery products. The natural availability of this high-valued plant is not able to meet the ever-increasing demands due to limited studies. Considering the importance of suspension culture over excised root culture, present communication provides a protocol for the suspension culture of root tuber derived callus of D. salicifolia for the first time. Maximum frequency (84.8%) callus induction was obtained on Murashige and Skoog (MS) medium augmented with (1.0 µM) thidiazuron (TDZ) + (1.0 µM) α-naphthalene acetic acid (NAA). Two important biotic elicitors, chitosan (CH) and yeast extract (YE) at different concentrations (50, 100, 200 and 300 µM) were used as elicitor to investigate the effects on biomass content, 2H4MB content, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity in cell suspension culture with different contact periods i.e. 24, 48 72 and 96 h. The results showed the supremacy of CH over YE and maximum biomass was 9.7 DW g/l at optimum contact period of 72 h when suspension culture was treated with 200 µM CH. Maximum content of 2H4MB was14.8 µg/g at 200 µM CH and it was found to be 1.4-fold increase in relation to the control (10.8 µg/g). The maximum TPC and TFC were 4.8 mg/g and 4.0 mg/g respectively at 200 µM CH and 72 h of the contact period. The DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity (RSA) had also been evaluated and most of the suspension culture showed the correlation with TPC and TFC. The maximum RSA (63.8%) and hydroxyl radical scavenging activity (HRSA) (55.2%) were revealed the ability of plant as a potent antioxidant agent. Thus, a new protocol has been developed for the elicitors-induced enhancement of metabolites and antioxidant activity in suspension culture of D. salicifolia .