Abstract
Cadmium (cd) toxicity has become a major threat to the crop productivity and vegetables appeared to be on major risk. In present study, the potential of methyl jasmonate (MeJA, 0.015 µM) and gamma-aminobutyric acid (GABA 15 µM) was explored to alleviate the cd toxicity (12 µM) in tomato and brinjal seedlings. Cd declined fresh dry mass by 21% and 18% in tomato seedlings and 27% and 25% in brinjal seedlings. Cd significantly damage pigments contents (Chl a, Chl b and Car), PS II photochemistry (Chl a fluorescence kinetics) and photosynthetic gas exchange parameters in both seedlings. Furthermore, Cd exacerbated oxidative biomarkers and antioxidant enzymes CAT, SOD, POD and GST in both the seedlings. Phytohormones MeJA and GABA application to seedlings led to significant declined Cd uptake, oxidative biomarkers, antioxidative enzymes activity and up-regulation in leaves gas exchange parameters, photosynthetic performance and seedlings growth parameters. Additionally, biosynthetic inhibitors diethyldithiocarbamic acid (DIECA) of MeJA and 3-Mercaptopropionic acid (MPA) of GABA further raised Cd uptake, thereby excessive increase in oxidative biomarkers worsened Cd toxicity on photosynthesis, hence growth was greatly reduced. Thus, the study concludes that as compared to brinjal seedlings, tomato showed greater tolerance to Cd toxicity, and GABA plays a crucial role in mitigating the Cd toxicity, however, GABA and MeJA together more efficiently alleviated the toxicity.