Phylogeny and biogeography of the rice tribe (Oryzeae): evidence from combined analysis of 20 chloroplast fragments.

Based on sequences of 20 chloroplast fragments, we generated a fully resolved phylogeny of Oryzeae and estimated divergence times of its major lineages as well as explored the historical biogeography of the tribe. Our results (1) confirmed the monophyly of Oryzeae and two-subtribe subdivision; (2) indicated that Maltebrunia, Potamophila and Prosphytochloa were genetically distinct enough to deserve generic status but Maltebrunia and Prosphytochloa were sister groups in the subtribe Oryzinae while Potamophila was a member in the subtribe Zizaniinae; (3) suggested that the previously unresolved phylogeny of the subtribe Zizaniinae was most likely explained by insufficient data due to rapid radiation; (4) provided the first well-corroborated timescale for the origin and divergence of Oryzeae, with the crown node of Oryzeae and the deepest split of Oryza at approximately 24 and 15MYA, respectively; (5) developed a biogeographic history of the tribe and substantiated the important roles of long-distance dispersal in the origin and diversification of the tribe Oryzeae.