Celis, Marcela , Fuentes-Soriano , Sara .
Pollen diversity and evolution in Tigridieae (Iridaceae) in the context of recent molecular phylogenetic findings.
Tigridieae, a diverse tribe of ca. 15 genera and 170 species, is restricted to the Americas. Although vegetatively uniform, the group exhibits sizeable variation in floral morphology, and differences in tepal orientation, color patterning, type of nectar produced, and structure of the stamens and style branches. In Tigridieae the number of pollen apertures has been used to delimit the two subtribes (Tigridiinae, 2 sulci vs.Cipurinae, 1 sulcus). In this study we expanded the phylogenetic and palinologycal analyses of the South AmericanTigridieae by studying for the first time the genus Cardenanthus and increasing the sampling of Calydorea, Cypella, Herbertia and South American Tigridia; making it the largest sampling of the tribe to date. The phylogenetic utility of pollen number of sulci and other palynological characters (e. g. pollen size, aperture size, pattern of pollen ornamentation, and lumina and muri size) was carefully evaluated within the tribe. Pollen evolution was studied in light of new molecular phylogenies based on the nuclear ribosomal internal transcribed spacer (nrITS) and five plastid DNA regions -- the non-coding trnL-trnF, the trnL intron, the non-coding trnH-psbA intergenic spacer, the matK gene, and the trnK3 gene. Molecular phylogenetic and statistical analyses of the new palynological data suggested that differences in number of sulci, lumina size, muri size, and patterns of ornamentation are taxonomically and phylogenetically informative and can be used to distinguish some taxa and clades in Tigridieae. The number of pollen apertures (i.e. two sulci) did not support the recognition of subtribeTigridiinae as traditionally circumscribed, however bi-sulcate pollen supported the expansion of Tigridia to include seven other genera (Ainea,Cardiostigma, Cobana, Colima, Fosteria, Rigidella, Sessilanthera). Pollen number of apertures and ornamentation supported the recognition of the polyphyletic Cypella lineages. Our preliminaryresults indicate that pollen morphology is potentially useful for understanding phylogenetic relationships within the tribe Tigrideae and should be further investigated.
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1 - Universidad Nacional de Colombia, Apartado 7495, Bogotá, Colombia
2 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166, USA
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM