Induced Systemic Resistance Activates Defense Responses to Interspecific Insect Infestations on Tomato

摘要

Externally applied elicitors can induce systemic resistance against more than one pest in plants. Tomato (Lycopersicon esculentum Mill.) was infested at the seedling stage with the serpentine leafminer, Liriomyzci trifolii (Burgess) (Diptera:Agromyzidae), and the whitefly, Bemisia tabaci (Genn.) (Hemiptera:Aleyrodidae). The impact of Pseudo-momw-Induced Systemic Resistance (ISR) in tomato in interspecific interactions between these two phytophagous herbivores was studied in the laboratory. Inductionof resistance by Pseudomonas, and feeding by leafminer larvae and immature whiteflies, resulted in induction of the defense-specific proteins, chitinases. polyphenol oxidases, peroxidases, bate-1,3-glucanase, phenylalanine ammonia lyase, and the accumulation of phenolic compounds. The degree of defense triggering varied among these sources of elicitation, that is, treatment with P. fluorescens and by insect herbivory. On uninduced control plants, whitefly feeding triggered better responses than did leafminer infestation. In contrast, on Pseudomo-nas-induced plants stimulation and elicitor response impaired the preference and performance of both insects. The Pseudomonas-mduced and whitefly pre-infestation of plants caused a reduction of 56.4% of eggs and 67.7% of feeding punctures by the leafminer per plant than on control plants. Whiteily pre-infestation caused a reduction of 32.5% and 37.6% of eggs and feeding punctures by the leafminer, respectively, and Pseudomonas induction alone resulted in a reduction of 36.6% and 33.5% of eggs and feeding punctures by the leafminer, respectively. Leafminer pre-infestation on Pseudomonas-inducQd plants resulted in a reduction of 63.5% and 49.6% in fecundity and progeny production by whiteflies, respectively, whereas leafminer pre-infestation alone caused a reduction of 31.4% in fecundity and an increase of 1.1% progeny production, and Pseudomonas induction alone resulted in a reduction of 35.5% and 32.6% in fecundity and progeny production by whiteflies, respectively. The study indicated that induction of resistance by ISR using Pseudomonas could be used in insect pest management through enhanced defense metabolism for sustainable agriculture.