Systematics/Phytogeography / Taxonomie/ Section
Su, Huei-Jiun , Hu, Jer-Ming .
Phylogenetic relationships of Balanophoraceae and Santalales based on floral B homeotic genes.
Balanophoraceae are obligate root parasites, which comprise 17 genera with 44 species in the tropics and subtropics. Plants of Balanophoraceae are composed of underground tuberous structures that attach to the host, and only emerge above ground during reproduction. Unlike typical flowers of the core eudicots that have differentiated sepals and petals, the flowers of Balanophoraceae are highly reduced and the remnant floral organs are sometimes difficult to interpret the ontological origins. Due to the extreme reduction of morphological features in Balanophoraceae, the phylogeny of Balanophoraceae has been controversial. Although recent molecular data shows Balanophoraceae might be close to Santalales, the exact position of Balanophoraceae remains in question. Previous studies also showed these parasitic plants have accelerated DNA substitution rates, which have caused problems in phylogenetic reconstruction. To clarify the affinities of Balanophoraceae and other Santalales members, we compared phylogenetic trees resulted from analyses of nuclear 18S rDNA and the floral B-class homeotic genes. A total of 23 B-class gene homologues were identified for Balanophoraceae and Santalales species. The results of various phylogenetic analyses confirm the basal position of Balanophoraceae in the Santalales. In addition, the substitution rates of B-class genes do not have drastic changes among Balanophoraceae, Santalales and other eudicots, compared with 18S rDNA. These results suggest that floral homeotic genes could be potential tools for reconstructing difficult phylogenies such as holoparasites.
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1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Rm1227, Life Science Building, 1 Roosevelt Road, Sect.4, Taipei, 106, Taiwan
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM