Characterization of Fusarium species associated with tobacco diseases in northwestern Argentina

MERCADO CÁRDENAS, G.; CURTI, R.; HARRIES, E.; RODRIGUERO, M.; BERRUEZO, L.; STENGLEIN, S.; GALVAN, M.

EUROPEAN JOURNAL OF PLANT PATHOLOGY

SPRINGER

Año: 2018

0929-1873

Tobacco (Nicotiana tabacum L.) production is centred in the northwestern region of Argentina (NWA), where 23 the incidence of root rot and stem diseases has increased considerably in recent years. This study aimed to 24 analyse the genetic, morphological and pathogenic diversity of the Fusarium oxysporum and F. solani 25 complexes (hereafter FOSC-FSSC), causing Fusarium wilt and root rot. One hundred tobacco fields were 26 surveyed at six locations during two consecutive seasons, and 130 isolates were recovered from symptomatic 27 tobacco plants. The isolates were characterized by morphological traits, molecular characteristics (EF1-α 28 sequence) and pathogenicity tests. All of the isolates were identified as members of the FOSC or FSSC, 29 exhibiting considerable intra-group variation. Three morphotypes were differentiated based on morphological 30 characters in both complexes. The phylogenetic tree generated from the EF1-α sequences confirmed the isolates´ 31 identification. The pathogenicity of the isolates towards tobacco seedlings was assessed in a greenhouse. 32 Considerable variability in pathogenicity was observed among the isolates. Differences in the levels of 33 pathogenicity were recorded. In the FOSC and FSSC, 81 % and 60 % of the isolates were pathogenic, 34 respectively. In this study, members of FOSC and FSSC exhibited considerable variability in morphological 35 characteristics and virulence, and a portion of them were non-pathogenic for tobacco. To the best of our 36 knowledge, this study is the first to provide information on the variability of the pathogens associated with 37 tobacco wilt and root rot in NWA. This work contributes to the development of sustainable management 38 strategies in tobacco production.