Jasmonic acid-mediated enhanced regulation of oxidative, glyoxalase defense system and reduced chromium uptake contributes to alleviation of chromium (VI) toxicity in choysum (Brassica parachinensis L.)

The cultivation of leafy vegetables on metal contaminated soil embodies a serious threat to yield and quality. In the present study, the potential role of exogenous jasmonic acid (JA; 0, 5, 10, and 20 mu M) on mitigating chromium toxicity (Cr; 0, 150, and 300 mu M) was investigated in choysum (Brassica parachinensis L.). With exposure to increasing Cr stress levels, a dose-dependent decline in growth, photosynthesis, and physio-biochemical attributes of choysum plants was observed. An increase in Cr levels also resulted in oxidative stress closely associated with higher lipoxygenase activity (LOX), hydrogen peroxide (H2O2) generation, lipid peroxidation (MDA), and methylglyoxal (MG) levels. Exogenous application of JA alleviated the Cr-induced phytotoxic effects on photosynthetic pigments, gas exchange parameters, and restored growth of choysum plants. While exposed to Cr stress, JA supplementation induced plant defense system via enhanced regulation of antioxidant enzymes, ascorbate and glutathione pool, and the glyoxalase system enzymes. The coordinated regulation of antioxidant and glyoxalase systems expressively suppressed the oxidative and carbonyl stress at both Cr stress levels. More importantly, JA restored the mineral nutrient contents, restricted Cr uptake, and accumulation in roots and shoots of choysum plants when compared to the only Cr-stressed plants. Overall, the application of JA2 treatment (10 mu M JA) was more effective and counteracted the detrimental effects of 150 mu M Cr stress by restoring the growth and physio-biochemical attributes to the level of control plants, while partially mitigated the detrimental effects of 300 mu M Cr stress. Hence, JA application might be considered as an effective approach for minimizing Cr uptake and its detrimental effects in choysum plants grown on contaminated soils.

Automated summary

The study investigated the potential role of exogenous jasmonic acid in mitigating chromium toxicity in leafy vegetables grown on metal contaminated soil. The results showed that jasmonic acid helped restore plant growth and physio-biochemical attributes by enhancing the regulation of antioxidant enzymes, ascorbate, glutathione, and glyoxalase system enzymes to suppress oxidative and carbonyl stress.