Identification, comparison, and functional analysis of salivary phenol‐oxidizing enzymes in B emisia tabaci B and T rialeurodes vaporariorum

The differences in the ability of the invading whitefly, B emisia tabaci ( G ennadius) (commonly known as biotype B and hereafter as B) and T rialeurodes vaporariorum ( W estwood) (both H emiptera: A leyrodidae) to utilize salivary phenol‐oxidizing enzymes – polyphenol oxidase ( PPO ) and peroxidase ( POD ) to detoxify plant defensive phenolic compounds were explored. Polyphenol oxidase and POD were found in the saliva of both B and T . vaporariorum . For tomato colonies, the PPO and POD activities in the watery saliva of B were 2.27‐ and 1.34‐fold higher than those of T . vaporariorum . The PPO activities against specific phenolic compounds commonly found in plants were compared. The activities of those from B were significantly greater than those from T . vaporariorum . We also measured PPO activity in both species after they had fed on plants that were undamaged or had been previously damaged with either a plant pathogen [ P hytophthora infestans ( M ont.) de B ary ( P eronosporales)] infection, mechanical damage, B infestation, or exogenous salicylic acid. For B, PPO activities in watery saliva increased 229, 184, 152, and 139% in response to the four treatments, whereas those of T . vaporariorum only increased 133, 119, 113, and 103%, respectively. Biotype B infestation significantly increased the total phenolic content of tomato leaves. Meanwhile, feeding on tomato infestation with B had no significant effect on the survival rate of B, but decreased the survival rate of T . vaporariorum significantly. These results suggest that B has stronger ability utilizing PPO to detoxify high concentrations of phenolics than T . vaporariorum , and this contributes to a significant advantage for B to hold high fitness on plants with induced resistance. Possible roles of salivary PPO in the competition between B and T . vaporariorum are discussed.