Putrescine affects tomato growth and response of antioxidant defense system due to exposure to cinnamic acid

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ABSTRACTThe present study deals with the mitigating effects of putrescine (Put) against cinnamic acid (CA). Cinnamic acid in root and shoot exudates of tomato (Solanum lycopersicum L.) acts as an autotoxin, inhibiting growth and metabolic activities. Put has significant role in plant growth and development, as well as in defense against abiotic and biotic challenges. There are no reports on mitigation of allelopathic effects due to CA by Put. Tomato seedlings exposed to CA decreased root and shoot length, fresh and dry weights, photosynthetic pigments, protein and sugar contents, and nitrate reductase activity. These parameters increased when Put were applied in combination with CA and alone. Lipid peroxidation enhanced in seedlings treated with CA, but decreased in combined CA-Put treatment. Histochemical staining indicated that CA-induced oxidative damage which is evident from the presence of reactive oxygen species (ROS) such as O2– and H2O2 in tomato leaves. Put decreased ROS activity and plays promising role in regulation of antioxidant enzyme activities against production of free radicals and improved seedling growth exposed to CA. Put induced tolerance of tomato seedlings to CA autotoxicity was reflected through enhanced growth of the seedlings. Our findings reveal that Put is efficient to mitigate the allelopathic and adverse effects of CA and buttressed the defense system of tomato and eliminated the autotoxic effects of endogenous CA in tomato.