Methyl jasmonate as modulator of Cd toxicity in Capsicum frutescens var. fasciculatum seedlings

• 50 mg L−1 Cd significantly decreased root growth and chlorophyll b concentration.
• Low levels of MeJA significantly reduced leaf MDA production induced by Cd.
• Low levels of MeJA restored the root growth and leaf chlorophyll b concentration.
• Low levels of MeJA significantly enhanced the activities of SOD and CAT in leaf.

Methyl jasmonate (MeJA) elicits protective effects as form of plant response to abiotic stress. However, related studies on plant response to metal stress are insufficient. This study aimed to examine the effects of MeJA on growth and physiological responses of Capsicum frutescens seedlings exposed to cadmium (Cd) stress. The study was performed in an artificial climate chamber. Results showed that 50 mg L−1 Cd significantly impaired the growth of the seedlings by increasing leaf MDA content and decreasing chlorophyll b. These effects were significantly mitigated by MeJA at low concentrations (0.1 µmol L−1). The dry weights of different plant parts, chlorophyll content, and leaf catalase and ascorbate peroxidase activities were increased by a low MeJA concentration (0.1 µmol L−1) but were decreased by a high MeJA concentration (1000 µmol L−1). Significant increases in endogenous jasmonic acid were observed at 48 h after the samples were treated with Cd and 0.1 µmol L−1 MeJA. These results suggested that low exogenous MeJA concentrations exhibited protective effects on the growth and physiology of C. frutescens seedlings under Cd stress.