Phylogenetic analyses of eight isolates of Phakopsora meibomiae collected in Puerto Rico

Abstract

American soybean rust (AmSR) caused by Phakopsora meibomiae (Arthur) Arthur is limited to certain areas of the Western Hemisphere. It is not known to cause severe losses to economically important crops. Phakopsora meibomiae naturally infects 42 species of legumes of the subfamily Papilionoidea. During 2008, eight isolates of AmSR infecting Lablab purpureus were collected in the central mountainous area of Puerto Rico. Molecular phylogenetic analyses of the internal transcribed spacer (ITS) region, including 5.8S ribosomal DNA (rDNA), were conducted. The topology of the trees generated by parsimony and by Neighbor-Joining methods was similar. Isolates were identified as Phakopsora meibomiae, with 98 and 100% identity. These isolates formed a monophyletic group. Asian Soybean Rust, Phakopsora pachyrhizi, the most closely related species, formed a second clade. Other rust species of the genera Uromyces, Puccinia, Tranzschelia, Hemileia, Ustilago smut, and the edible mushroom Boletus were included in the analyses as outgroups. Phakopsora species grouped in the Pucciniaceae family formed a sister clade to Phakopsoraceae and Uropyxidaceae families.