ARS | Publication request: A PHYLOGENETIC ANALYSIS OF TRIFOLIUM

Submitted to: International Conference on Legume Genomics and Genetics
Publication Type: Abstract
Publication Acceptance Date: December 31, 2002
Publication Date: December 31, 2002
Citation: ELLISON, N.W., LISTON, A., STEINER, J.J., TAYLOR, N.L., WILLIAMS, W.M. A PHYLOGENETIC ANALYSIS OF TRIFOLIUM. International Conference on Legume Genomics and Genetics. 2002. Abstract p. 121.

Technical Abstract: Many species of clover (Trifolium L., Trifolieae, Fabaceae) are economically important forage crops, and have been introduced and become established throughout the world. The genus is recognized by its 3(-9) digitately foliolate leaves, flowers generally in many-flowered capitate to spicate racemes, and fruits that are one to few seeded, often indehiscent and included in the calyx. The native distribution of the ca. 250 accepted species encompasses the temperate and, to a lesser extant, subtropical regions of the Northern and Southern Hemispheres (excluding southeast Asia and Australia). The greatest species diversity is in the Mediterranean basin and in the mediterranean climate regions of western North and South America. We undertook a molecular phylogenetic analysis of Trifolium based on DNA sequences of the nuclear ribosomal DNA internal transcribed spacer (ITS) region and the chloroplast trnL intron. We included ca. 90% of all clover species, and outgroups from multiple genera. Maximum parsimony analysis of the combined ITS and cpDNA sequences resolved a monophyletic Trifolium. Relationships within the genus were well-resolved. Novel findings include: 1) The placement of section Chronosemium, the hop clovers, as sister to the remaining sections; and 2) All New World species form a strong supported monophyletic group. This clade is morphologically diverse, and has not been recognized in any previous taxonomic treatment. Our phylogenetic results will form the basis of a robust classification of the genus. They also contribute to our understanding of character evolution and biogeography, and will serve as a framework for all comparative studies of Trifolium.