Toxigenic profile of Fusarium equiseti isolated from Argentinean soybean and pathogenicity on soybean seedlings

BARROS, G.; ALANIZ ZANON, M. S.; HAIDUKOWSKI, M.; PASCALE, M.; SCANDIANI, M.M.; CHULZE, S.

Mendoza

Conferencia; ISM 2011 Conference; 2011

Universidad Nacional de Río Cuarto

Fusarium equiseti represent the most abundant specie in the Fusarium complex isolated in Argentina from flowers, soybean pods and seeds. The aims of the present study were: (1) to assess the production of major type A and type B trichothecenes (diacetoxyscirpenol, neosolaniol, T-2 toxin and HT-2 toxin, nivalenol, deoxynivalenol) and zearalenone by 40 F. equiseti isolates on rice culture; (2) to evaluate the aggressiveness of two F. equiseti isolates in causing root rot of soybean seedlings under controlled conditions. Mycotoxins were determined by HPLC with fluorescence detection after derivatisation with 1-anthronylnitrile for type A trichothecenes (i.e. diacetoxyscirpenol, neosolaniol, T-2 toxin and HT-2 toxin), by HPLC with UV detection for type B trichothecenes (i.e. nivalenol and deoxynivalenol) and by TLC for zearalenone. Twenty-two out of 40 F. equiseti isolates produced diacetoxyscirpenol, nivalenol and ZEA alone or in combination, while none of the strains were able to produce deoxynivalenol, neosolaniol, T-2 toxin and HT-2 toxin. In relation to pathogenicity test, the inoculation of seedlings was performed using the method described by Xue et al. (2007). The results show that both F. equiseti strains tested were unable to develop root rot symptoms on soybean seedlings. The variable retention in toxigenicity and the low aggressiveness displayed by F. equiseti isolates suggests that this specie have a saprophytic lifestyle in the soybean agroecosystem in Argentina.