Induction of volatile organic compounds of Lycopersicon esculentum Mill. and its resistance to Botrytis cinerea Pers. by burdock oligosaccharide

In the present study, we investigated the induction of volatile organic compounds (VOCs) of Lycopersicon esculentum Mill. and its resistance to Botrytis cinerea Pers. by burdock oligosaccharide. The disease severity of L. esculentum was evaluated 48 h after treatment with 0.6% burdock oligosaccharide, followed by inoculation with a spore suspension of B. cinerea. The formation of O-2(+), the activity of lipoxygenases (LOX), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), and the quantity and quality of changes in VOCs were determined a period of time after treatment with 0.6% burdock oligosaccharide. The results demonstrated that the disease index in treated plants was decreased by 42.5% compared with control 96 h after inoculation. The production of O-2(+) reached a maximum 6 h after treatment (1.36-fold compared with control). There was an increase in LOX, POD, CAT and SOD activity in response to burdock oligosaccharide treatment and the enzymes showed different trends in the time-course of induction. At 120 h after treatment, (E)-2-hexenal was increased by 92% compared with control, whereas methyl salicylate showed a gradual increase with induction period. Previous results had demonstrated that chitosan elicitor enhanced the production VOCs of L. esculentum and decreased plant susceptibility towards B. cinerea. Together, these findings suggest that increasing the production of VOCs in response to burrdock oligosaccharide may be an important mechanism for L. esculentumin its defense against pathogens. In addition, burrdock oligosaccharide may act as a potent elicitor of resistance to disease in L. esculentum.