A Phylogeny ofSetaria(Poaceae, Panicoideae, Paniceae) and Related Genera Based on the Chloroplast GenendhF

Abstract

The genus Setaria is the largest genus in the so-called bristle clade, a monophyletic group of panicoid grasses distinguished by the presence of sterile branches, or bristles, in their inflorescences. The clade includes both foxtail millet and pearl millet, the latter an important cereal crop in dry parts of the world. Other members of the clade are weeds that are widespread agricultural pests. Previous molecular phylogenetic studies have suggested that Setaria might not be monophyletic but did not have a large enough sample of species to test this rigorously. In addition, taxonomic studies have suggested a close relationship between Setaria and Paspalidium, with some authors combining them into a single genus, but molecular studies included too few Paspalidium accessions for a meaningful conclusion. Accordingly, we have produced 77 new sequences of the chloroplast gene ndhF for 52 species not in previous analyses. These were added to available sequences for 35 species in 10 genera of the bristle clade and four outgroup taxa. We find that Setaria species fall into several moderately to strongly supported clades that correlate with geography but not with the existing subgeneric classification. Relationships among these clades and among other genera within the bristle clade are unclear. Constraint experiments using the approximately unbiased test reject the monophyly of Pennisetum, Setaria, and Setaria plus Paspalidium, as well as several other groupings, although the test may be overly sensitive and prone to Type I error. The more conservative Shimodaira-Hasegawa test fails to reject monophyly of any of the tested clades.

Comparative analysis of genetic diversity of 8 millet genera revealed by ISSR markers

“…Thus, our findings do not support the results of the phylogenetic studies performed by Doust et al (2007) or Kellogg et al (2009), which indicated that the Setaria genus is a collection of unrelated groups. Although Setaria accessions formed a distinct branch in the present study, no clear geographic structure within the genus was found, contrary to the findings of Li et al (2012), in which a clear geographic structure was revealed by using ISSR markers.…”

Reference genome sequence of the model plant Setaria

“…Setaria, a member of the grass subfamily Panicoideae, tribe Paniceae is closely related to other Paniceae, including switchgrass, proso millet and pearl millet [16][17][18][19] (Fig. 1).…”

VIII. Subfamily Panicoideae Link (1827)

“…Kellogg et al (2009) suggest that this genus is related to the Australian species of Setaria formerly classified in Paspalidium.…”

“…Although one representative Pseudoraphis was included by Kellogg et al (2009) in Cenchrinae, its position remains unresolved. It is supported as sister to Chamaeraphis by Morrone et al (2012), but the position of the clade within the subtribe is not clear. )…”

“…Both form clumps connected by long rhizomes. Members of the two are sisters in molecular phylogenies (Doust et al 2007;Kellogg et al 2009;Morrone et al 2012), and the two genera could be merged. Leaf blades hard, sometimes with a sharp point; ligule a fringe of hairs.…”