Effect of salicylic acid and GR۲۴ foliar application on antioxidants activity in peppermint under Cd toxicity

Cadmium is a potential and widespread toxic environmental pollutant, mainly derived from a rapid industrial process that has inhibitory effects on growth, physiological, and biochemical attributes of various plant species, including medicinal plants such as Peppermint (Mentha piperita L.). Plant signaling molecules, when applied exogenously, help to enhance/activate endogenous biosynthesis of potentially important signaling molecules and antioxidants that boost tolerance against various abiotic stresses, e.g., heavy metal stress. The present study documented the protective role of salicylic acid (SA;۰.۱ mM) and synthetic strigolactone (GR۲۴; ۰ and ۱۰ μM), foliar spray, and combinational treatments in reducing Cd toxicity (۰, ۱۰, ۲۰, and ۴۰ ppm) in Peppermint. Biochemical studies, enzymatic antioxidants like CAT, APX, and non-enzymatic antioxidant such as carotenoids, proline, besides other defense compounds like, MDA and H۲O۲ contents were studied at ۲۴h after treatment at flowering stage The biochemical attributes of Peppermint were significantly affected by Cd toxicity; however, foliar spray of SA and GR۲۴ significantly improved photosynthetic pigments (carotenoids) and antioxidants by suppressing the negative impact of Cd. However, the oxidative damage parameters, i.e., MDA and H۲O۲, decreased astonishingly under the treatment of signaling molecules, thereby protecting membrane integrity under Cd stress. Interestingly the biochemical attributes at peppermint improved under SA and GR۲۴ treatments, thus hampered the toxic effect of Cd. As a result, the cross talk between SA and GR۲۴ can synergistically improve the cd-stressed peppermint and modulate the plant defense system.

Keywords:

Antioxidants , cadmium stress , carotenoid oxidative damage , peppermint ,