Peroxidase and Polyphenol Oxidase Activity in Moderate Resistant and Susceptible Vicia faba Induced by Aphis craccivora (Hemiptera: Aphididae) Infestation

Two faba bean, Vicia faba L., cultivars, Gazira2 and Misr1, representing cultivars moderately resistant and susceptible to aphids, were analyzed for peroxidase (POD) and polyphenol oxidase (PPO) activities induced by cowpea aphid, Aphis craccivora Koch. infestation. Two tissue types (whole plant [WP] and detached leaf [DL]), two infestation status (infested and uninfested), and three aphid infestation durations (1, 3, and 5 d) were considered in POD and PPO data analysis. Factorial analysis showed that only cultivar factor has a significant effect on both POD and PPO activity, especially on the first day after aphid infestation (P: 0.0003 and 0.001, respectively). Tissue type has no significant effect, indicating either DL or WP can be used for measuring POD and PPO activities. While the unsignificant different of infestation status reflecting a constitutive resistant character in Gazira2. Mann-Whitney U-test showed that POD and PPO activities in Gazira2 were higher significantly when compared with Misr1 with P value 0.0006 and 0.0015 for POD and PPO, respectively. Repeated measures analysis indicates that the POD and PPO activities on Gazira2 were significantly higher when compared with Misr1. Additionally, POD activity changed significantly over the time in 1, 3, and 5 d after aphid infestation. We concluded that higher activity of POD and PPO in cultivar Gazira2 is strongly associated with their resistant characters.