MOLECULAR EVOLUTION OF THE LEGUMINOSAE - PHYLOGENY OF THE 3 SUBFAMILIES BASED ON RBCL-SEQUENCES

The rbcL gene of 49 species (37 genera, 24 tribes of the Leguminosae a nd two species of the Polygalaceae) was amplified by polymerase chain reaction (PCR) and sequenced directly. rbcL sequences were evaluated w ith character state (Maximum Parsimony) and distance methods (Neighbou r-Joining). The traditional classification of Leguminosae, especially in case of the basal groups, was assumed to be based on apparently anc estral or derived features. Analyses of molecular data show that such seemingly 'old' taxa, i.e. Cercideae, Gleditsia, Gymnocladus and Cerat onia, form distinct evolutionary lines, but not necessarily basal grou ps of the Leguminosae. Using Polygalaceae as an outgroup, the analysis of rbcL sequences showed that the tribes Detarieae/Amherstieae and Ce rcideae appear to have diverged earlier than the remaining tribes of C aesalpinioideae and might deserve a subfamily rank. The next groups to separate were the sister groups of Caesalpinieae/Cassieae and Papilio noideae. The closely interconnected Caesalpinieae/Cassieae complex for ms the base of the Mimosoideae. Papilionoideae and Mimosoideae are mon ophyletic. Caesalpinioideae is paraphyletic to the other subfamilies, and the classical division of Leguminosae into three subfamilies is no t supported. Within Papilionoideae, molecular data indicate that the t ribe Sophoreae (and even the genus Sophora) is a heterogeneous collect ion of species that needs a comprehensive revision. Copyright (C) 1996 Elsevier Science Ltd