Plant & Animal Genomes XV Conference Plant & Animal Genomes XV ConferenceJanuary 13-17, 2007
Town & Country Convention Center
San Diego, CA
Giandomenico Corrado1 , Emilio Guerrieri2 , Marianna Pasquariello1 , Maria Cristina Digilio3 , Pasquale Cascone1 , Rosa Rao1
Plants produce several defensive compounds in response to pests. Some of these chemicals have a direct effect on pest metabolism (direct defence), while others, including the so called Volatile Organic Compounds (VOC), indirectly increase plant resistance. VOCs represent specific cues for predators and parassitoids, the natural enemies of the pests, to locate the infested plant.
The study of induced responses against insects and the identification of the genes controlling their expression is of great interest to understand ecological relationships and develop new strategies of pest control.
We investigated if the plant hormone systemin can increase the indirect defence mechanisms via transcriptional activation of genes involved in the production of volatile compounds. We report that the overexpression of the systemin precursor is associated with an enhanced attractiveness of the aphid parasitoid Aphidius ervi. The GC-MS analysis of the volatiles collected from transgenic and control plants revealed that systemin is involved in the production and/or release of biologically active VOC.
Moreover Real time PCR experiments indicated that prosystemin over-expression associates with an increased level of expression of two members of the Lox genes family, hydroperoxide lyases, important for the production of a vast class of VOC, and germacrene C synthase, a key gene involved in production of terpenoid volatile compounds in tomato.
Our data indicated that systemin is an important element of the whole defensive response in tomato, and we conclude that in this plant a single gene leads to the systemic activation of coordinated and associated responses against pests.