Effect of exogenous methyl jasmonate on airborne benzene removal by Zamioculcas zamiifolia: The role of cytochrome P450 expression, salicylic acid, IAA, ROS and antioxidant activity

Abstract

The exogenous application of methyl jasmonate (MeJA) has emerged as a promising approach for enhancing plant stress resistance. However, little is known about the effect of exogenous MeJA for promoting airborne benzene removal by plants. Here, we elucidated the effect of various MeJA concentrations on Zamioculcas zamiifolia stress response in relation to antioxidant enzyme activity, indole-3-acetic acid (IAA) contents, reactive oxygen species (ROS) accumulation and the expression levels of cytochrome P450 monooxygenase gene responsible for benzene hydroxylation. Exogenous MeJA at low physiological levels (10, 30 and 50μM) enhanced plant resistance to benzene stress through triggering the activities of antioxidant enzymes, enhancing IAA levels and lowering ROS accumulation. Moreover, MeJA at 10, 30 and 50μM induced the expression levels of P450. Higher expression levels of P450 could indirectly enhance benzene removal ability of the plants. Interestingly, the upregulated P450 trends were consistent with the increasing IAA contents and MeJA concentrations. However, MeJA at high concentrations (100μM) declined gaseous benzene removal due to limited antioxidant activity, low IAA contents and high ROS accumulation as well as closed stomata. Moreover, under 100μM MeJA treatment, high levels of ROS and salicylic acid downregulated the expression levels of P450. Our results provide comprehensive evidence with regard to the exogenous application of MeJA for promoting plant stress resistance and enhancing airborne benzene phytoremediation.