In vitro cultures of Vitis vinifera cv. Chardonnay synthesize the phytoalexin nerolidol upon infection by Phaeoacremonium parasiticum

ESCORIAZA G; GIL M; SANSBERRO P; GARCÍA LAMPASONA S; GATICA M; BOTTINI R; PICCOLI P

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Año: 2011

0021-8561

This study investigated terpene synthase activity (TPS) and production of terpenes with antifungal properties in in vitro plants, callus and cell suspension cultures of Vitis vinifera cv. Chardonnay infected with Phaecremonium parasiticum. The highest TPS activity, assessed as tritiated farnesyl pyrophosphate ([1-3H]-FPP) transformed into hexane-soluble radioactive products, was observed in basal leaves increasing in correlation with the fungal concentration and preceded the fungal growth suggesting systemic response. TPS activity was 10-fold higher in inoculated callus than in in vitro plants. When tested in inoculated cell suspension cultures TPS activity showed maximal 8 h post [1-3H]-FPP application and then declined. The main compound found in in vitro inoculated plants by gas chromatography-electron impact mass spectrometry (GC-EIMS) was cis-nerolidol, which was found in apical and basal leaves at a concentration of 0.12 µg mg FW-1. Grape callus inoculated with Pm. parasiticum produced increased amounts of the phytoalexins cis-nerolidol and α-pinene while squalene decreased, as fungal amount rose. Finding of α-pinene suggests that both terpene biosynthetic pathways, the cytosolic and the plastidial, operated in callus. Neither TPS activity nor nerolidol were identified in fungal cultures, which suggest that nerolidol is synthesized by grapevines in response to the fungal attack. In inoculated cell suspension cultures the most abundant terpene was trans-nerolidol, with an estimated amount of 0.18 µg mg-1. Nerolidol showed in vitro fungistatic activity towards Pm. parasiticum. This is the first report that grapevine tissues synthesize the phytoalexins nerolidol in response to infection with fungi