Análisis filogenetico de la subtribu Otachyriinae (Poaceae, Panicoideae, Paspaleae)

ACOSTA, JUAN; SCATAGLINI, M. AMALIA; REINHEIMER, RENATA; ZULOAGA, FERNANDO OMAR

La Plata

Jornada; XXXIV Jornadas Argentinas de Botánica; 2013

Sociedad Argentina de Botánica

The subtribe Otachyriinae was established, within tribe Paniceae, by Butzin in 1970, originally including 18 genera. Recent phylogenetic studies, based on molecular data, indicated that Otachyriinae belongs to tribe Paspaleae and is represented by the genera Anthaenantia, Hymenachne, Dallwatsonia, Otachyrium, species of Panicum sect. Laxa, Plagiantha, and Steinchisma. These taxa show a peculiar diversity in photosynthetic types, including C4 species, C3-C4 intermediates and C3 species. The internal evolutionary relationships among members of Otachyriinae have not been explored in detailed yet. With the aim of providing new evidence to understand phylogenetic relationships of taxa included in Otachyriinae, 21 new sequences of the ndhF gene from 34 species were generated and analyzed using Bayesian Inference and Maximum Parsimony. The evolution of the photosynthetic pathway were studied employing maximum parsimony (MP), Markov chain Monte Carlo (MCMC), and Maximum likelihood (ML) methods. Our results confirm that subtribe Otachyriinae is monophyletic. Within the subtribe, Anthaenanthia is a C4 monophyletic genus and the sister group of the remaining species included in this treatment. Hymenachne and Panicum sect. Laxa, in its traditional concept, are polyphyletic genera; Dallwatsonia, P. auritum, and P. hemitomon are treated within Hymenachne while three species of Panicum sect. Laxa considered as a new genus in the subtribe. The genus Otachyrium recover as paraphyletic, while all species of Steinchisma are recovered as a monophyletic group with high support. Finally, our data suggest that C4 and C3-C4 photosynthesis evolved just once each during the speciation of the subtribe from a C3 ancestor.