Phenotypic, molecular phylogenetic, and pathogenetic characterization of Fusarium crassistipitatum sp. nov., a novel soybean sudden death syndrome pathogen from Argentina and Brazil

Abstract

A novel soybean sudden death syndrome (SDS) pathogen from Argentina and Brazil is formally described herein as Fusarium crassistipitatum based on detailed phenotypic analyses of macro- and microscopic characters and phylogenetic analyses of multilocus DNA sequence data. Fusarium crassistipitatum can be distinguished from the other soybean SDS and bean (Phaseolus/Vigna) root rot pathogens (BRR) phenotypically by the production of yellowish colonies on PDA; and tall, stout, and mostly unbranched conidiophores with a thick-walled base, which form multiseptate conidia apically. Phylogenetic species recognition based on genealogical concordance of a sixgene dataset strongly supported the reciprocal monophyly of F. crassistipitatum with respect to the other SDS and BRR pathogens. Isolates of F. crassistipitatum were able to induce typical SDS foliar and root rot symptoms on soybean that were indistinguishable from those caused by three other SDS pathogens (i.e., F. virguliforme, F. brasiliense, and F. tucumaniae) on susceptible cultivars A-6445RG and N-4613RG in a pathogenicity experiment.