Antioxidant response of the invasive alien species Parthenium hysterophorus L. under abiotic stress conditions with special emphasis on boiling-stable antioxidant enzymes.
Invasive alien plants have broad distribution throughout the world, displacing the indigenous vegetation, stunting the growth or development of native plants and diminishing their establishment in agricultural and natural areas. Parthenium hysterophorus is a noxious potential invader of a region whose harmful status can be attributed to its allelopathic effects and prolific seed production. However, there has been little research on the physiological and biochemical mechanisms governing its abiotic stress tolerance. Plants growing under natural conditions were sampled at random in the vicinity of Jalandhar. Samples were subjected to analysis for abiotic stress-induced changes in reactive oxygen species and free radical-scavenging boiling-stable antioxidant enzymes. Indices of oxidative stress such as malondialdehyde (MDA) and the membrane injury index (MII) were also studied. In order to discover a possible reason for the biological invasiveness of P. hysterophorus, in the present investigation we studied enzymatic and non-enzymatic biochemical changes that might explain it. Malondialdehyde and MII, indices of stress, increased with a rise in hydrogen peroxide and superoxide anion content in an organ- and abiotic condition-dependent manner, affirming oxidative stress to the plant. An elevated level of the antioxidant metabolite GSH was observed in June, which played a positive role in minimising the oxidative stress. Antioxidative enzymes such as BsSOD, BsPOD, BsGST, BsMDAR, BsPDI, BsTRx exhibited activities that increased in an organ and abiotic condition-dependent manner. On the basis of the obtained results, we conclude that P. hysterophorus has the potential to cope with abiotic stress by accumulating abiotic stress-related metabolites and proteins.