Phylogenetics of Andropogoneae (Poaceae: Panicoideae) Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL–F Sequences

Abstract

Phylogenetic relationships among 85 species representing 35 genera in the grass tribe Andropogoneae were estimated from maximum parsimony and Bayesian analyses of nuclear ITS and chloroplast trnL-F DNA sequences. Ten of the 11 subtribes recognized by Clayton and Renvoize (1986) were sampled. Independent analyses of ITS and trnL-F yielded mostly congruent, though not well resolved, topologies. Arundinella is sister to Andropogoneae in the trnL-F phylogeny and is nested within the tribe in the ITS and combined data trees. Tristachya is sister to Andropogoneae ϩ Arundinella in the ITS phylogeny. Four clades are common to the ITS and trnL-F phylogenies and the trees from the combined data set. Clade A consists of Andropogon, Diectomis, Hyparrhenia, Hyperthelia, and Schizachyrium. Within this clade, Andropogon distachyos, Hyparrhenia, and Hyperthelia form clade C. Clade B consists of Bothriochloa, Capillipedium, and Dichanthium, and clade D includes Chrysopogon and Vetiveria. Analysis of the combined data resulted in an unsupported larger clade comprising clades A and B plus Cymbopogon, and a sister clade of Heteropogon, Iseilema, and Themeda. This larger clade is similar to the core Andropogoneae clade previously reported (Spangler et al. 1999;Mathews et al. 2002). Based on our sample, which represents 41% of the tribe's genera, most of Clayton and Renvoize's (1986) subtribes are not monophyletic.

Phylogenomics of Andropogoneae (Panicoideae: Poaceae) of Mainland Southeast Asia

“…A phylogeny including 40 species of Andropogon retrieves results consistent with those presented here (McKain and Kellogg, unpublished data). Andropogon abyssinicus and A. distachyos formed a clade sister to Hyparrhenia with which they share geographic provenance in Africa (Skendzic et al 2007;Nagahama and Norrmann 2012) and an inflorescence with exactly two axes. Andropogon distachyos is rare in Thailand and might have been imported for fodder.…”

“…The Core Andropogoneae-The core Andropogoneae has been widely accepted and retrieved in all phylogenetic studies to date, including analyses of nuclear genes such as PHYB (Mathews et al 2002), GBSSI (Mason-Gamer et al 1998;Mathews et al 2002), single-copy genes (Estep et al 2014;Welker et al 2015Welker et al , 2016, and ITS (Skendzic et al 2007), chloroplast genes such as ndhF (Giussani et al 2001;Mathews et al 2002) and trnL-F (Teerawatananon et al 2011), and combined data. Two clades are clearly found: 1) the group of Cymbopogon, Dichanthium, Heteropogon, and Themeda and 2) the group of Andropogon, Hyparrhenia, and Schizachyrium.…”

“…Considering the Andropogoneae as a whole, two of the largest genera of the core are Andropogon and Schizachyrium, which together form a clade (Giussani et al 2001;Mathews et al 2002;Skendzic et al 2007;Teerawatananon et al 2011;Estep et al 2014). These are major grasses for forage and ecosystems and have been used as representatives for many studies in ecology, taxonomy, and phylogenetics.…”

“…Hubb., and Pseudosorghum A. Camus (Clayton and Renvoize 1986;Buitenhuis and Veldkamp 2001;Neamsuvan et al 2009; Teerawatananon et al 2014). Few phylogenetic and evolutionary studies have included these genera (but see Skendzic et al 2007;Teerawatananon et al 2011;Soreng et al 2015). Consequently, additional data for these particular genera could help illuminate their evolutionary relationships, divergence pattern, and character evolution relative to other Andropogoneae species.…”

“…Depending on the taxon sample and marker used, Andropogon and Schizachyrium have appeared as polyphyletic or paraphyletic. No study has sampled the genera in any depth in any part of their range (Mathews et al 2002;Skendzic et al 2007;Teerawatananon et al 2011).…”