Eurasian S. Grandis (poaceae) Molecular Systematics Study

The Stipeae, belonging to the subfamily Pooideae, family Poaceae, mainly distributed in thealpine steppe, desert steppe and grassland areas of temperate, subtropical and tropical regions,includes400-500species and24genera. In China, there are67species and10genera in Stipeae,which developed into the constructive species and dominant species of all kinds of grasslands inwestern China. In this study, we used8chloroplast DNA fragments and one nuclear genefragment to analysis the phylogeny of Eurasian Stipeae. In addition, we retrieved3chloroplastfragments and1nuclear fragment from Genbank to assess the monophyly of the Eurasia Stipoidsand the phylogenetic relationships of Stipoids worldwide. The main contents are as follows:1. Phylogeny of Eurasian StipeaeUsing eight chloroplast fragments (trnL-F, trnH-psbA, rpl16, rbcL, ndhH-rps15,rps19-psbA, rpl22-rps19, rps15-ndhF) and one nuclear DNA sequences (ITS) to infer thephylogeny of Eurasian Stipoids. The ingroup taxa include46species from10genera ofEurasian Stipeae, and Avena sativa L., Trisetum bifidum (Thunb.) Ohwi, Melica scabrosaTrin., Diarrhena manshurica Maxim., Phaenosperma globosa Munro ex Benth. andDeyeuxia tibetica Bor were choosed as outgroups. The results showed that:a. Sinochasea Keng, Duthiea Hack. and Stephanachne Keng form a stable clade, which isdistinguished from the other Stipoids. The remaining Stipoids form a100%supportedclade. Our results support to remove these three genera from Stipeae.b. Achnatherum coreanum (Honda) Ohwi and Piptatherum kuoi S. M. Phillips&Z. L. Wuare supported to be a stable clade. These two species with the moist habitat are mainlydistributed at the forest edge or under the forest, but the other Stipeae with the drierhabitat mainly in the open area. In addition, these two species have some distinctivemorphological characters: glumes with transverse veinlets; lemma with5veins; embryowith a cleft similar to the ‘bambusoid embryo’; leaves with the vascular near the lowerepidermis. Our results support to treat these two species as a new genus.c. The monophyly of Stipa s.s. is strong supported with100%bootstrap value. Stipa s.s. issplited into two clades that correlated with their habitats.d. Piptatherum P. Beauv. is a monophyletic group.e. Psammochloa villosa (Trin.) Bor is sister group to Achnatherum sibiricum (L.) Keng exTzvelev. Achnatherum saposhnikovii (Roshev.) Nevski is sister group to Achnatherum.Psammochloa villosa and Achnatherum saposhnikovii are supported to incorporate intoAchnetherum. A. saposhnikovii is treated as a separate section of Achnatherum.f. Both of Achnatherum and Ptilagrostis are polyphyly. Achnatherum splendens is sister group to Stipa s.s.; other Achnatherum is splited into two parts, and sister to the twodifferent groups of Ptilagrostis respectively; Piptatherum is sister to one of theAchnatherum+Ptilagrostis clade, and Trikeraia is sister to anotherAchnatherum+Ptilagrostis clade; Orthoraphium is sister toTerikeraia+Achnatherum+Ptilagrostis clade.2. Phylogeny of worldwide StipeaeCombining the sequenced data and download data from Genbank in the Stipeae, wechose three chloroplast fragments (trnL-F, trnH-psbA, rpl16) and one nuclear sequence (ITS)to study the phylogeny of worldwide Stipeae. The all generic represents in Stipeae (22genera)were included except Macrochloa Kunth and Anemanthele Veldkamp. Avena L., TrisetumPers., Melica L., Diarrhena Beauv., Phaenosperma Munro ex Benth. et Hook. f. andDeyeuxia Clarion are used as the out groups. The phylogentic analyses indicate that:a. The removal of Sinochasea, Stephanchne and Duthiea from Stipeae are supported, andthese taxa consist to a new tribe-Duthieeaea.b. Worldwide Stipeae, excluding the taxa of new tribe Duthieeaea, is a monotypic groupwith100%bootstrap support.c. Eurasian Stipeae is not monophyly, and scattered into all of the caldes in the BI tree.d. The core Stipeae form three main clades: the first clade includes America, Australia, andEurasian Stipeae (Amelichloa Arriaga and Barkworth, Nassella Desv., Jarava Ruiz andclade contains Eurasian Stipa s.s., Piptatherum and Piptochaetium, Aciachne,Ortachne, Hesperostipa from North America with low level of support (70%bootstrap);the third clade comprises Ptilagrostis, Achnatherum, Trikeraia and Orthoraphium fromEurasian.e. The group of Achnatherum, Ptilagrostis, Piptatherum, Nassella and Jarava is not anatural monophyly.f. The group of Austrostipa, Hesperostipa, Stipa s.s., Piptochaetium and Trikeraia aremonophyletic.