Effect of azospirillum lectins on the activity of proteolytic enzymes and their inhibitors in wheat seedling roots

The lectins of associative nitrogen-fixing strains Azospirillum brasilense Sp7 and Sp245 were shown to exert a multidirectional effect on the activity of acidic (pH 3.5), neutral (pH 6.8), and alkaline (pH 7.8) proteinases. The lectin of the epiphytic A. brasilense Sp7 decreased proteolytic activity at all pH values, whereas the lectin of the endophytic A. brasilense Sp245 activated neutral and alkaline proteinases, while not affecting the alkaline ones. Experiments with protease inhibitors made it possible to conclude that the lectins of the studied A. brasilense strains alter the ratio between the activities of different protease types in germinating seeds. The activity of trypsin inhibitors in wheat seedling roots was found to increase in the presence of the lectins. Our results indicate a broader spectrum of effects of azospirilla lectins on the host plant organism.