Preliminary Molecular Identification of Fusarium Infecting Tobacco in Henan

In order to identify the variety of Fusarium causing tobacco diseases in field, the typical infected tobacco plants were sampled from main tobacco growing areas in Henan, pure strains were isolated by tissue separation and identified by morphological method, pathogenicity test, and rDNA-ITS sequences analysis. The results of morphological observation showed that on PDA medium, all of the 22 isolated strains produced dense, gossypine hyphae with yellow, red or purple pigments; macroconidium was oval or sickle in shape, colorless, and multi-cell; microconidium was ovoid to oval in shape, colorless, single-cell or double-cell. BLAST analysis indicated that in GenBank sequence database, the homology of rDNA-ITS sequence was >95.77% between strains No.1-No.11 and Fusarium oxysporum (F. oxysporum, GenBank Accession No. KC429789.1), which was >88.01% between strains No.12-No.18 and Fusarium solani (F. solani, GenBank Accession No. JQ910159.1), >89.72% between strains No.19-No.21 and Fusarium verticillioides (F. verticillioides, GenBank Accession No. HQ176444.1), and >90.74% between strain No.22 and Fusarium proliferatum (F. proliferatum, GenBank Accession No. JX045841.1). Inoculation tests showed that all the mentioned Fusarium could infect living tobacco seedlings and generate typical symptoms. Consequently, the Fusarium infecting tobacco in Henan was identified as F. oxysporum, F. solani, F. verticillioides and F. proliferatum. F. proliferatum infection in Henan tobacco has not been reported before.