Systematics/Phytogeography / Taxonomie/ Section
Chhetri, Hari , Columbus, J. Travis .
Phylogenetics of Zoysieae (Poaceae, Chloridoideae) based on ITS and trnL-F sequences, a preliminary report.
Tribe Zoysieae (sensu Peterson et al. 2007; Columbus et al. 2007) comprises Calamovilfa (4 spp.), Crypsis (8), Spartina (16), Sporobolus (160) and Zoysia (10). The tribe has the distribution from tropical to warm temperate regions and most species are halophytes. Inflorescence type varies from primary branches only (Spartina) to rebranched panicles (all other genera). Morphological characters for recognizing Sporobolus are a ciliate ligule, inflorescence an open or contracted panicle, one-flowered spikelet, and one-nerved lemma. However, these characters are also more or less shared by all other genera in the clade, thus making boundaries among genera obscure. Preliminary studies of leaf blade Kranz anatomy show that two variants of C4 photosynthesis, NAD-ME and PCK, are predicted for Zoysieae. Previous studies have shown that Calamovilfa, Crypsis and Spartina are nested within Sporobolus. A preliminary analysis based on ITS and trnL-F sequences from 28 taxa does not provide support for the monophyly of the genus Sporobolus. Parsimony bootstrap analysis of ITS, trnL-F and the combined phylogeny (ITS + trnL-F) yielded the similar support values. In this phylogeny, the North American genus, Calamovilfa, forms a monophyletic group that is sister to all other genera in the clade. Likewise, the five species of Spartina sampled here form a monophyletic clade nested within Sporobolus. Crypis is sister to the clade formed by Calamovilfa, Spartina and Sporobolus and sister to all of these is Zoysia. Comprehensive sampling of taxa, particularly from the five Sporobolus sections of Baaijens and Veldkamp (1991), will be required to produce a robust phylogeny. Diversification of inflorescence form, photosynthetic pathway, and micromorphological characters will be investigated in order to map character evolution onto the molecular phylogeny.
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1 - Rancho Santa Ana Botanic Garden, Botany, 1500 N College Ave., Claremont, California, 91711, USA
2 - Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California, 91711, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 11:15 AM