Phylogenetic analyses of Aurantioideae (Rutaceae) based on non-coding plastid DNA sequences and phytochemical features

Sequences of the plastid DNA atpB/rbcL intergenic spacer and rps16 intron f rom 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 speci es segregated as Bergera, e.g., Murraya koenigii and M. siamensis) and Merr illia are transferred to Citreae s.l. This conclusion is also well supporte d by phytochemistry, demonstrating accumulation of carbazoles in Bergera an d Clausena, and of 8-prenylated coumarins and polyoxygenated flavonoids in Murraya s.s. and Merrillia. Formation of both carbazoles, as well as 8-pren ylated coumarins, and polyoxygenated flavonoids in Micromelum suggests rela tionships between Clauseneae s.s. and Citreae s.l. The monophyly of several larger genera in both tribes is supported by relatively high bootstrap per centages and specific chemical profiles for e.g., Clausena, Micromelum, Gly cosmis and Atalantia. In contrast, molecular, chemical, and other data show that none of the subtribes recognized within Aurantioideae reflect phyloge netic 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 outgro up genera, Zanthoxylum (Rutoideae) and Toddalia (Toddalioideae) are much cl oser to each other than to Ruta (Rutoideae).