The effect of chitosan and β-cyclodextrin on glucosinolate biosynthesis in Brassica rapa ssp. pekinensis (Chinese cabbage) shoot culture

Chitosan is a polycationic polysaccharide derived from chitin, and beta-cyclodextrin is a type of macrocyclic oligosaccharide linked by alpha-1,4 glycosidic bonds. These compounds are recognized as effective elicitors in the biosynthesis of secondary metabolites in plants. These elicitors were studied to assess the growth of shoots and the synthesis of glucosinolates (GSLs) from elicited shoots in Chinese cabbage under controlled in vitro conditions for the first time. Chitosan at 150 mg L-1 supplemented in the optimized shoot induction recovered maximum quantities of total GSLs (7.344 mu mol g-1 DW) at the end of 5th week of culture duration, followed by beta-cyclo-dextrin (15 mg L-1) with the synthesis of GSLs (6.379 mu mol g-1 DW) at the end of 4th week of culture. The application of chitosan completely deteriorated the growth of shoots, whereas beta-cyclodextrin did not affect and even increased the growth of shoots (4.66 g DW). Upon elicitation, the individual got GSLs contents exhibited various fold changes (1.78-to-23.5-fold). Real-time PCR analysis of essential GSLs biosynthesis genes like MAM1, ST5b, AOP2, FMOGS-OX1, CYP83B1, CYP81F2, ST5a, and CYP81F4 revealed substantial higher expression upon elicitation. This present study would provide a steady production of GSLs in Chinese cabbage shoots with the influence of carbohydrate-based elicitors for pharmaceutical or food companies in the future.