Phylogeny of Magnoliaceae based on ten chloroplast DNA regions

Abstract

Phylogenetic analyses of ten chloroplast DNA regions, ndhF, rbcL, matK, ORF350, trnL intron, trnL-trnF, trnH-psbA, rbcL-atpB, trnK 5' intron, and trnK 3' intron (8,719 bp in aligned sequences) from 48 selected taxa were carried out to address phylogenetic questions in the family Magnoliaceae. The major clades in the molecular tree are considerably different from the currently suggested classification system and from the traditionally recognized subgroups in the family. Eleven major clades were recognized with strong support in the subfamily Magnolioideae: (1) MICHELIA clade: Michelia, Elmerrillia, sect. Maingola, sect. Alcimandra, and sect. Aromadendron, (2) YULANIA clade: subgen. Yulania, (3) GYNOPODIUM clade: Pachylarnax, sect. Manglietiastrum, and sect. Gynopodium, (4) KMERIA clade: Kmeria, (5) THEORHODON clade: sect. Theorhodon sensu stricto (excluding sect. Splendentes, which was recently separated from sect. Theorhodon) and sect. Magnolia, (6) GWILLIMIA clade: sect. Gwillimia, sect. Lirianthe, and sect. Blumiana, (7) TALAUMA clade: sect. Talauma and sect. Splendentes, (8) MANGLIETIA clade: Manglietia, (9) RYTIDOSPERMUM clade: sect. Rytidospermum sensu stricto (excluding Magnolia fraseri, M. macrophylla, and M. dealbata) and sect. Oyama, (10) FRASERI clade: M. fraseri, and (11) MACROPHYLLA clade: M. macrophylla and M. dealbata. The recognition of eleven major clades in the subfamily Magnolioideae in this study is in good agreement with previous molecular studies based on less sampling or fewer DNA regions. All of these eleven clades were highly supported with bootstrap values exceeding 80% in both maximum parsimony and maximum likelihood analyses and with posterior probabilities exceeding 0.98 in a Bayesian analysis. However, detailed relationships among the major clades were weakly supported. The molecular data suggest that the taxonomic circumscription of infrafamilial delimitations and compositions should be reconsidered.