Molecular phylogeny of the genus Kalanchoe (Crassulaceae) inferred from nucleotide sequences of the ITS-1 and ITS-2 regions

The study presents an analysis of genotypic diversity in the genus Kalancho e (Crassulaceae) on the level of Internal Transcribed Spacer (ITS) sequence s and the attempt to correlate this diversity with previous findings on eco physiological behavior, habitat preference. infrageneric taxonomic position of the species and DNA polymorphism derived from RAPD-PCR data. The Kalanc hoe species are mainly abundant in Madagascar and eastern continental Afric a and perform in situ diverse modes of crassulacean acid metabolism (CAM), an ecophysiologically relevant adaptation of photosynthesis. Total DNA was extracted from 68 kalanchoe species and varieties. The ITS-1 and ITS-2 regi ons of the nuclear RNA genes were amplified by polymerase chain reaction, c loned and sequenced. The alignments of the sequences were evaluated by dist ance (neighbor joining) and character state (maximum parsimony) methods. Th e main topologies of the obtained ITS phylogenetic trees were quite similar irrespective of the mode of evaluation and show: (A) within the Crassulace ae the genus Kalanchoe forms a monophyletic clade: and (B) within the genus the species form three main clusters which coincide well with the previous ly reported three infrageneric sections of the species distinguishable by c lassical taxonomic criteria, the mode of in situ CAM performance, and DNA f ragment pattern obtained by RAPD-PCR analyses. Moreover, the ITS phylogenet ic trees show that all African Kalanchoe species form a distinct group with in the most derived of the three main clusters. This is consistent with the view that the center of phylogenetic radiation of the genus is located in Madagascar from where the species have spread into the continental Africa. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.