Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2006
Publication Date: 7/23/2006
Citation: Castlebury, L.A., Mengistu, A. 2006. Phylogenetic distinction of Diaporthe/Phomopsis isolates from soybeans[abstract]. Inoculum 57(4)13.
Technical Abstract: Species of Phomopsis and Diaporthe have traditionally been described on the basis of host. The value of morphological characters in distinguishing species has been limited due to the reduced features of the conidiomata. Additionally, many strains exist as endophytes and plant pathogenic strains may not always fruit. Molecular approaches to species problems in Phomopsis have traditionally focused on sequence analysis of the ITS rDNA, but it has not been particularly informative for answering species level questions across this genus. Using intron regions in the translation elongation factor-1 alpha and actin genes, in combination with the ITS, six closely related, well-supported groups among Diaporthe/Phomopsis isolates from soybeans and other hosts were found. Although three groups correspond to named taxa – P. longicolla, Diaporthe melonis, and the D. phaseolorum complex – due to the absence of morphological distinction and biological information, the application of appropriate names to the unidentified genetically distinct taxa is problematic. Furthermore, the biological significance of these genetically distinct groups is unclear. Additional work on host specificity, pathogenicity, and morphology will be required to solve species questions in this genus.