Phylogenetic Analyses of Aurantioideae (Rutaceae) Based on Non-Coding Plastid DNA Sequences and Phytochemical Features

Abstract: Sequences of the plastid DNA atp B/ rbc L intergenic spacer and rps16 intron from 23 genera and 47 species of Rutaceae were used to resolve phylogenetic relationships in subfamily Aurantioideae. According to these, the subfamily is monophyletic, but its classical subdivision into tribes Clauseneae and Citreae is only justified if the genus Murraya s.s. (exclusive of the species segregated as Bergera , e.g., Murraya koenigii and M. siamensis ) and Merrillia are transferred to Citreae s.l. This conclusion is also well supported by phytochemistry, demonstrating accumulation of carbazoles in Bergera and Clausena , and of 8-prenylated coumarins and polyoxygenated flavonoids in Murraya s.s. and Merrillia. Formation of both carbazoles, as well as 8-prenylated coumarins, and polyoxygenated flavonoids in Micromelum suggests relationships between Clauseneae s.s. and Citreae s.l. The monophyly of several larger genera in both tribes is supported by relatively high bootstrap percentages and specific chemical profiles for e.g., Clausena, Micromelum, Glycosmis and Atalantia. In contrast, molecular, chemical, and other data show that none of the subtribes recognized within Aurantioideae reflect phylogenetic relationships. Only the clades with Clausena + Bergera, Murraya s.s. + Merrillia, and Citrus + Clymenia + Eremocitrus + Fortunella + Poncirus ("true Citrus fruit trees") are well supported by such data. Among the outgroup genera, Zanthoxylum (Rutoideae) and Toddalia (Toddalioideae) are much closer to each other than to Ruta (Rutoideae).