Putrescine Mediates Aluminum Tolerance in Red Kidney Bean by Modulating Aluminum‐Induced Oxidative Stress

Abstract

ABSTRACTPolyamines are important molecules modulating numerous environment stresses in plants. In the present study, the role of putrescine (Put) in the Al tolerance of red kidney bean (Phaseolus vulgaris) was investigated. In roots of red kidney bean, Al stress led to a marked increase of both free Put content and Put‐biosynthetic enzymes activities, and arginine decarboxylase pathway played a predominant role in Al‐induced increase in Put accumulation. Treatment of seedlings with Put reduced Al‐induced lipid peroxidation and reactive oxygen species (ROS) generation, thus alleviating Al‐induced inhibition of root elongation and Al accumulation in root apices. On the other hand, treatment with Put biosynthesis inhibitors reduced Al‐induced Put accumulation and enhanced Al toxicity of red kidney bean. Furthermore, Put treatment inhibited Al‐induced NADPH oxidase activity in roots, while Put biosynthesis inhibitors enhanced NADPH oxidase activity under Al stress. In addition, application of NADPH oxidase inhibitor reduced Al‐induced ROS generation, suggesting that ROS generation under Al stress is mediated, at least in part, by NADPH oxidase. Taken together, these results indicate that Put plays an important role in Al tolerance of red kidney bean by inhibiting NADPH oxidase activity, thus reducing Al‐induced oxidative stress.