PHYLOGENETIC-RELATIONSHIPS OF THE SOYBEAN SUDDEN-DEATH SYNDROME PATHOGEN FUSARIUM-SOLANI F SP PHASEOLI INFERRED FROM RDNA SEQUENCE DATA ANDPCR PRIMERS FOR ITS IDENTIFICATION

Phylogenetic relationships of several species within the Fusarium sola ni-complex were investigated using characters from the nuclear ribosom al DNA, Genetic variation within 24 isolates, including 5 soybean sudd en death syndrome (SDS) strains, was assessed using rDNA sequence data and restriction fragment length polymorphic markers, By these techniq ues, the causal agent of soybean SDS was identified as F. solani f. sp , phaseoli, In separate cladistic analyses, Plectosphaerella cucumerin a and Nectria cinnabarina or F. ventricosum were used for rooting purp oses, Monophyly of the F. solani-complex was strongly supported by boo tstrap and decay analyses, Parsimony analysis indicates that this comp lex is composed of a number of phylogenetically distinct species, incl uding Neocosmospora vasinfecta, F. solani f. sp, phaseoli, and biologi cal species designated as MPI, MPV, and MPVI of N. haematococca. The r esults demonstrate complete congruence between biological and phylogen etic species within the N. haematococca-complex. In addition, DNA sequ ence data were used to design a PCR primer pair which could specifical ly amplify DNA from isolates of the SDS pathogen from infected plants.