Andropogoneae Evolution and Generic Limits in Sorghum (Poaceae) Using ndhF Sequences

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

“…The low resolution and support for clades in the ITS, trnL-F, and combined trees are consistent with previous studies and may reflect a rapid radiation or slowdown in molecular evolution as these lineages arose (Mason-Gamer et al 1998;Spangler et al 1999). Low rates of nucleotide substitution among members of Andropogoneae have been reported by Mason-Gamer et al (1998) for GBSSI, Spangler et al (1999) for ndhF, Lukens and Doebley (2001) for tb1, and Mathews et al (2002) for PHYB.…”

“…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.…”

“…recommended Arundinella to be included in Andropogoneae. Likewise, phylogenetic trees from all four markers show a similar pattern-internal branches are short and poorly supported, suggesting that the tribe resulted from a rapid radiation or that molecular evolution was relatively slow as these lineages arose (Mason-Gamer et al 1998;Spangler et al 1999). Despite much phylogenetic uncertainty, these studies cast doubt on the monophyly of Maydeae (Watson and Dallwitz 1992) and most of Clayton and Ren- Table 1.…”

“…These features, however, are present in other Panicoideae. A disarticulating rachis internode is a synapomorphy for the tribe (Mathews et al 2002), but delimitation of genera and subtribes is problematic due to a lack of identifiable diagnostic characters (Clayton 1987;Spangler 2000;Mathews et al 2002). Clayton and Renvoize (1986) used morphological characters of the Andropogoneae inflorescence, rachis internode, and spikelet pair to suggest intratribal relationships along axes of increasing complexity.…”

“…DNA sequence data (chloroplast gene NADH dehydrogenase [ndhF]; nuclear genes granule-bound starch synthase [GBSSI or waxy], phytochrome B [PHYB], and teosinte branched 1 [tb1]) have also been used to investigate the phylogeny of Andropogoneae (Mason-Gamer et al 1998;Spangler et al 1999;Spangler 2000;Lukens and Doebley 2001;Giussani et al 2001;Mathews et al 2002). The largest number of genera and species of Andropogoneae in these studies is 23 and 41, respectively.…”