The effects of exogenous methyl jasmonate on volatile compounds, key enzymes, and sensory quality in tobacco (a model plant)

Abstract

Abstract Flue-cured tobacco belongs to the Solanaceae family, which plays a great role as a model plant in both basic and applied research. In order to investigate the effect of exogenous regulator methyl jasmonate (MeJA) on the aroma quality of tobacco, tobacco leaves were sprayed with different concentrations of MeJA (0 µmol/L, 30 µmol/L, 60 µmol/L, 90 µmol/L and 120 µmol/L) at 48 hours before harvesting. The volatile compounds in the tobacco, sensory evaluation, and changes in key enzyme activities were determined, along with their correlations. The results showed that MeJA could affect the relative content of volatile substances. Under 90 µmol/L MeJA treatment, the relative content of benzyl alcohol, which was phenylpropane aroma substance, increased by 79.48%, compared with the control (0 µmol/L MeJA). After the tobacco leaves were dried and rolled, the sensory quality and aroma of the MeJA treatments scored higher than those of the control. Among them, the improvement in smoking quality was most significant under 90 µmol/L MeJA treatment. Under MeJA treatment, the activities of aroma-related enzymes polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL), and 4-coumarate:CoA ligase (4CL) were enhanced, with 4CL activity showing the most significant change (3.56 times higher than the control). The results of cluster analysis and correlation analysis showed that key enzyme activity, sensory quality, and volatile compounds varied with different concentrations of MeJA treatment, and there was a significant positive correlation between them (P < 0.05), demonstrating a close relationship. In conclusion, exogenous spraying of 90 µmol/L MeJA can improve the aroma quality of tobacco.