Poster: Late and Moved Abstracts

Abs # 1012: Systemin overexpression enhances indirect defence mechanisms in tomato

Presenter:	Corrado, Giandomenico , giacorra@unina.it
Authors	Corrado, Giandomenico  (A)   Guerrieri, Emilio  (B)   Digilio, M. Cristina  (C)   Rao, Rosa  (A)
Affiliations:	(A): Dipartimento di Scienze del Suolo, della Pianta e dell'Ambiente, University of Naples "Federico II" (B): Istituto per la Protezione delle Piante (CNR) (C): Dipartimento di Entomologia e Zoologia Agraria, University of Naples "Federico II"

Plants responds to a wide variety of pest insects with an array of reactions whose overall effect is the activation or enhancement of direct and indirect defence mechanisms. Direct defence mechanisms often require metabolic reconfigurations producing noxious, poisonous, anti-nutritive and anti-digestive compounds for plant-feeding insects, while indirect defences typically involves the production of Volatile Organic Compounds (VOC), which are exploited by natural enemies of pest insects (i.e.: predators and parasitoids) to localise their victims. In Solanaceae, several studies have indicated that a 18 aa peptide, called systemin, is a crucial systemic signal for the induction of metabolic pathways that increase the direct resistance against plant-chewing pests and that the transgenic expression of prosystemin (the 200 aa systemin precursor) activates genes involved in the plant response to wounding and herbivore attack. Here we report that the overexpression of the systemin precursor in tomato increases indirect defence mechanisms (i.e.: transgenic plants are more attractive for parasitoids than control plants) and it enhances the expression of genes involved in early steps of VOCs production. The evidence of the systemin-dependant enhancement of indirect defence mechanisms, which will be extended with the chemical analysis of the VOC blend, suggests that following pest attack, a single plant signal leads to the activation of coordinated responses, supporting the ecological model that the elicitation of multiple yet associated defensive pathways is likely to be advantageous and may be necessary if plants need to defend themselves adaptively from diverse insect species.