Herbivory induces a ROS burst and the release of volatile organic compounds in the fern Pteris vittata L.

The arsenic hyper-accumulating fern, Pteris vittata L., was studied to investigate the behavior of lower plants in response to both mechanical (MW) and herbivore wounding (HW). To this end, the cotton leaf worm Spodoptera littoralis was fed on P. vittata and the volatile organic compound (VOC) emission was detected from the fern's head space by using solid phase micro extraction (SPME) and analyzed by GC-MS. Controls were represented by unwounded and MW ferns. The fluorescent probe Amplex red was used to investigate the oxidative burst due to MW and HW by confocal laser scanning microscopy. Ferns responded to herbivore wounding events by emitting the sesquiterpenes (Z)-beta-farnesene, (E)-beta-farnesene, (Z, E)-alpha-farnesene, (E,E)-alpha-farnesene and (E)-nerolidol. An oxidative burst was found close to wounded areas in both MW and HW ferns, and young ferns reacted with a higher H2O2 production after HW. The reported data suggest that lower plants, such as ancient ferns, show two events commonly occurring and reported in many higher and more evolved plants after herbivore attack: an oxidative burst and the emission of volatile terpenoids.