In vitro plants of Vitis vinifera respond to infection with the fungus Phaeoacremonium parasiticum by synthesizing the phytoalexin nerolidol

Abstract

This study investigated terpene biosynthesis in basal and apical tissues of in vitro-grown plants of Vitis vinifera cv. Chardonnay infected or not (control) with Phaeoacremonium parasiticum. This pathogen is one of the prevalent agents involved in the grapevine “hoja de malvon” disease. The main terpene identified by gas chromatography electron impact mass spectrometry (GC-EIMS) was nerolidol, which was found in apical and basal tissues at a concentration of ca. 0.12 μg mg FW−1. Consistent with this, an increment in terpene synthase (TPS) activity, assessed as tritiated farnesyl pyrophosphate ([1−3H]-FPP) transformed into hexane-soluble radioactive products in infected plants, was observed. TPS activity increased in correlation with the fungal concentration. Nerolidol inhibited in vitro mycelium growth and reduced fungal growth, in a concentration dependent manner. According to our results, the response of grapevine tissues to Pm. parasiticum is systemic, as it can be visualized by an augment of transcript abundance of VvPNLinNer1. It is also characterized by an increase of de novo synthesis of TPS responsible for the biosynthesis of phytoalexin nerolidol. This is the first report in assessing in vitro grapevines response to woody fungus by modulating the route of terpene synthesis so increasing the phytoalexin nerolidol.