The effect of trichodiene synthase inhibition in Fusarium graminearum volatiles.

GIROTTI JUAN R.; MALBRAN ISMAEL; LORI GLADYS; JUÁREZ M PATRICIA

Buenos Aires

Congreso; II Reunión conjunta de Sociedades de Biociencias.; 2017

Sociedad de Biociencias

Fusarium graminearum is the main fungal pathogen associatedwith Fusarium head blight (FHB). The trichothecene (TCH) deoxynivalenol (DON) is one of the major mycotoxins produced contaminating agricultural products. Trichodiene synthase catalyze the synthesis of trichodiene (TRI) intermediate in the biosynthesis of TCHs,coded by the TRI5 gene. During trichothecene metabolism severalvolatile organic compounds (VOC), including TRI, are produced.Our aims were to obtain a non TCH-producing strain of F. graminearum, and to test the effect of synthetic analogues of plant-derived chemicals on the production of TRI by F. graminearum. TCHnon-producing mutants were obtained using a split marker recombination approach; TRI5 was replaced with a marker gene (hph, whichconfers resistance to hygromicin B). Seventeen transformants wereobtained, 76% of them were -TRI5 mutants confirmed by PCR,qRT-PCR, aggressiveness tests (F = 23.28) and inability to produceDON. Volatiles were analyzed by head space-solid phase microextraction (HS-SPME) coupled to capillary gas cromatography-massspectrometry (CGC-MS). This technique is useful for early detectionof F. graminearum before FHB development. In -TRI5 mutants nosesquiterpene volatile compounds were detected. Wheat cultivarswere inoculated with TRI synthase inhibitors in field assays, oneof the -TRI5 mutants was used as control. Of the chemicals tested, apocynin and eugenol produced a significant inhibition of TRIamounts 2 days post inoculation (dpi). However, TRI production wasrecovered at later stages (> 7dpi) due to continue fungal growth.Further experiments are necessary to determine the appropriate inhibitor concentrations and/or inoculation period to prevent TCH formation throughout the critical period (15 days) of FHB development.These studies are of interest in FHB control.Keywords: Fusarium, Trichodiene, HS-SPME, GC-MS