The effect of trichodiene synthase inhibition in Fusarium graminearum volatiles

JUAN R. GIROTTI; ISMAEL MALBRÁN; CECILIA A. MOURELOS; GLADYS A. LORI; M. PATRICIA JUÁREZ

Ciudad Autónoma de Buenos Aires

Congreso; Reunión Conjunta de Sociedades de BioCiencias; 2017

Fusarium graminearum is the main fungal pathogen associated with 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 several volatile 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. TCH non-producing mutants were obtained using a split marker recombination approach; TRI5 was replaced with a marker gene (hph, which confers resistance to hygromicin B). Seventeen transformants were obtained, 76% of them were -TRI5 mutants confimed by PCR, qRT-PCR, aggressiveness tests (F = 23.28) and inability to produce DON. Volatiles were analyzed by head space-solid phase microextraction (HS-SPME) coupled to capillary gas cromatography-mass spectrometry (CGC-MS). This technique is useful for early detection of F. graminearum before FHB development. In -TRI5 mutants no sesquiterpene volatile compounds were detected. Wheat cultivars were inoculated with TRI synthase inhibitors in field assays, one of the -TRI5 mutants was used as control. Of the chemicals tested, apocynin and eugenol produced a significant inhibition of TRI amounts 2 days post inoculation (dpi). However, TRI production was recovered 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.