L-DOPA Inhibited Early Root Growth in Rice Involves Biochemical Alterations in Macromolecules and Associated Hydrolytic Enzymes

The present study was conducted to explore the effect of L-DOPA (1-1000μM) on biochemical alterations during the early root growth under hydroponic conditions in the roots of O. sativa (rice). Seedling growth measured in terms of root length and shoot length exhibited a significant decline with increasing L-DOPA concentrations. It was observed that L-DOPA-exposure significantly enhanced the contents of water-soluble proteins and carbohydrates in roots of rice after 120h in a dose-response manner. Proteins and carbohydrates content increased by 7.7- and 2.3-folds, respectively at 1000 μM -exposure. On the other hand, the activities of hydrolyzing enzymes - proteases and amylases reduced apparently. At 1000 μM, activities of proteases, α-amylases, and β−amylases decreased by 1.91- , 1.90-, and 1.85- times, respectively. In addition, L-DOPA exposure significantly enhanced the activities of enzymes - peroxidases, polyphenol oxidases by 1.76- and 1.91- times, respectively, over control at 1000μM L-DOPA. An upregulation in the activities of these enzymes indicate their response to L-DOPA induced toxicity in rice seedlings and provide protection. The study concludes that L-DOPA-induced toxicity in hydroponically grown seedlings of rice involves the biochemical alterations in terms of macromolecules and the activities of associated hydrolytic enzymes to fight against the L-DOPA induced stress.