Exogenously applied putrescine ameliorates zinc toxicity in oilseed rape (Brassica napus L.) by modulating the antioxidant system

Objective: The external application of putrescine (Put) may overcome the adverse impact of different abiotic stresses. The current study assessed the effect of Put on the growth and antioxidative responses of oilseed rape (Brassica napus L.) seedlings under excess levels of zinc (Zn).Methods: The experiment was carried out as a completely randomized design with four treatments and four replications in a Hoagland nutrient solution containing supplemental concentrations of ۲۰ μM ZnCl۲ (Zn treatment), ۰.۲ mM Put (Put treatment), ۲۰ μM ZnCl۲ + ۰.۲ mM Put (Put + Zn), and a control treatment without extra Zn and Put.Results: The excess Zn led to the reduction of plant growth and pigment content. The content of total phenols, flavonoids, and flavonols was not significantly changed except that of the flavonols in the roots which was enhanced under Zn toxicity. Likewise, phenylalanine ammonia-lyase (PAL) and antioxidant enzyme activity and also the content of hydrogen peroxide (H۲O۲) and malondialdehyde (MDA) was increased upon exposure to excess Zn. In contrast, Put improved the growth and pigment content of oilseed rape under Zn stress. Put also enhanced the flavonoids and flavonols content and induced the activity of PAL and polyphenol oxidase under Zn toxicity. However, H۲O۲, MDA, superoxide dismutase, and peroxidase in oilseed rape exposed to Put declined under Zn excess.Conclusion: In conclusion, Put alleviated the negative impact of Zn toxicity partially due to the minimized endogenous levels of Zn in the root, the reduction of the H۲O۲ and MDA content, and modulation of the antioxidant system.

کلیدواژه ها:

Antioxidative response ، Brassica napus ، Phenolic Compounds ، Plant Growth ، Put ، Zinc stress