Elucidating melatonin-mediated distinct mechanistic of specific gene expression of coriander (Coriandrum sativum L.) under chromium stress.

The current investigation demonstrates that the application of MEL (0, 1, and 2 μmol L⁻¹) mitigates the effects of Cr stress 0 (no Cr), 50 and 100 mg kg⁻¹ on coriander (Coriandrum sativum L.) plants. Results from the present study showed that the increasing levels of Cr concentration in the soil induced a significant decrease in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid contents, net photosynthesis, transpiration rate and stomatal conductance by 36%, 24%, 17%, 64%, 27%, 23%, 19%, 29%, 36%, 18%, 73%, 83%, and 43% respectively. Results findings also showed that the increasing Cr stress in the soil significantly (p< 0.05) decreases calcium, magnesium, iron, and phosphorus contents by 69%, 51%, 89%, and 109% respectively in the roots and decreased by 164%, 97%, 66%, and 124% respectively in the shoots. However, Cr toxicity boosted the production of reactive oxygen species (ROS) by increasing the contents of oxidative stress indicators. Although activities of various antioxidative enzymes and their specific gene expression and also the nonenzymatic antioxidants initially increased up to a Cr level of 50 μM but decreased gradually with the further increase in the Cr level of 100 μM in the medium, compared to those plants which were grown in the control treatment. Results also revealed that the soluble sugar, reducing sugar, and nonreducing sugar were decreased in plants grown under elevating Cr levels but increased the Cr accumulation in the roots and shoots of C. sativum. Although results also illustrated that the application of MEL also decreased Cr toxicity in C. sativum by increasing antioxidant capacity and their gene expression and thus improved the plant growth, photosynthetic pigments, and decrease oxidative stress in the roots and shoots of C. sativum. [ABSTRACT FROM AUTHOR]