Some biochemical responses of common bean (Phaseolus vulgaris L.) to two spotted spider mite (Tetranychus urticae Koch)

Induced resistance was studied in two resistance and susceptible (Naz and Akhtar, respectively) common bean cultivars against two spotted spider mite, Tetranuychus urticae Koch (Acari; Tetranychidae(. In this study the amounts of total phenols, malondialdehyde, antioxidant activity, and the activity of plant defensive enzymes [guaiacol peroxidase (GPX), and ascorbate peroxidase (APX)] were measured for uninfected (control) and infected (1, 3 and 5 days after infestation) plants. The amounts of total phenols and antioxidant activity were higher in cultivar Naz (max: 0.8 and 53.67 respectively) compared to Akhtar, but the amount of malondialdehyde was low in Naz. Also, cultivar Naz exhibited greater enzymatic activity (GPX: 37.29 and APX: 21.87), than cultivar Akhtar. These results suggested that the plant defensive enzymes such as GPX, and APX were involved in common bean resistance to T. urticae. Thus, increased activity of GPX and APX along with accumulation of total phenols increased plant resistance to T. urticae.