Molecular Phylogeny of Nicotiana (Solanaceae) Based on the Nucleotide Sequence of the matK Gene

Abstract

Intrageneric relationships in the genus Nicotiana were investigated by comparison of DNA sequences of the matK gene of the chloroplast genome. A total of 40 taxa were examined in this study, representing 39 of the approximately 70 wild species of this genus. We obtained the full sequences of the 1530 bp matK ORFs; no variations in length due to insertions or deletions were found. The phylogenetic trees obtained from maximum parsimony (MP) and neighbour‐joining (NJ) methods were fundamentally consistent. The genus Nicotiana formed a clade in these trees. The traditional classification of this genus was mostly in agreement with the molecular phylogeny. However, all three subgenera and some sections did not form a monophyletic group. Character‐state mappings were used to infer a centre of origin, biogeographic history, and transition of chromosome number. The results support the previous hypothesis that this genus originated in South America and subsequently spread to other continents. The suggestion that the ancestral basic chromosome number is x = 12 and that polyploidy and aneuploidy have occurred independently several times during the evolution of Nicotiana species is also discussed.

Ribosomal DNA evolution and gene conversion in Nicotiana rustica

“…Evidence from plastid DNA sequence data indicates that an ancestor of N. paniculata is the maternal genome donor (Aoki and Ito, 2000). Gill (1991) suggested in the nucleocytoplasmic interaction hypothesis that the paternal genome of newly formed allopolyploids was most likely to reorganise to accommodate an alien cytoplasmic background.…”

“…Phylogenetic studies of the chloroplast sequence suggest that the ancestor of N. paniculata and/or N. knightiana (section Paniculatae) may be the maternal genome donor of N. rustica (Aoki and Ito, 2000;Chase et al, 2003). The closest relative of N. undulata (section Undulatae) is N. glutinosa although Goodspeed (1954) placed N. glutinosa in section Tomentosae.…”

Dispersals of Hyoscyameae and Mandragoreae (Solanaceae) from the New World to Eurasia in the early Miocene and their biogeographic diversification within Eurasia

“…Lycium L. (Solanaceae) has been suggested to be dispersed in a single event by birds from the New World to Eurasia followed by spreading into southern Africa (Fukuda et al, 2001;Levin and Miller, 2005). Long-distance dispersal has been also advocated as an explanation for the wide distribution of Nicotiana L. (Solanaceae) in the Americas, Australia and Africa (Aoki and Ito, 2000;Clarkson et al, 2004;Mummenhoff and Franzke, 2007).…”

Genomic relationships among Nicotiana species with different ploidy levels revealed by 5S rDNA spacer sequences and FISH/GISH

“…Several recent studies have examined the molecular phylogenetics among Nicotiana species including putative amphidiploid/tetraploid species. These phylogenies have been based on plastid genes (Aoki and Ito, 2000;Clarkson et al, 2004) and internal transcribed spacer (ITS) sequences of 45S rDNA (Chase et al, 2003). However, relationships at the genome level are quite limited (Chase et al, 2003).…”