Evolutionary History of the Grasses

Dated historical biogeography of the temperate Loliinae (Poaceae, Pooideae) grasses in the northern and southern hemispheres

“…Following Gaut (2002), the inferred dates were derived from the plastid gene ndhV of nine Poaceae representatives [Anomochloa (Anomochloeae), Leersia (Oryzeae); Avena (Aveneae); Poa (Poeae); Hordeum (Triticeae); Setaria and Pennisetum (Paniceae); Sorghum and Zea (Andropogoneae) plus Joinvillea (Joinvilleaceae; outgroup)], and a phylogeny of the family concordant with that presented by Clark et al (1995) and the Grass Phylogeny Working Group (GPWG, 2001). We used as calibration lower and upper bounds previously reported on the age of the family based on pollen (Linder, 1987;Jacobs et al, 1999;Kellogg, 2002Kellogg, , 2001) and phytoliths (Prasad et al, 2005) fossil records that varied between 55-80 My and that were imposed as minimum and maximum constraints to the crown node of the Poaceae, respectively. Divergence times and additional parameters (based on the F84 + G model and 100,000 MCMC iterations, with rttm and rttmsd set at 6.0, rtrate and rtratesd set at 0.02, brownmean and brownsd set at 0.16, and big time set at 100, see below) were calculated using the programs Baseml (PAML package, Yang, 1997), Estbranches (Thorne et al, 1998) and Multidivtime (Kishino et al, 2001).…”

Molecular Diversity, Structure and Domestication of Grasses

“…Three major grass crops -maize, wheat, and rice -share a common ancestor within the last 55-70 million years (Kellogg, 2001). Despite the differentiation that has occurred over this time period, chromosomal synteny between each of these genomes remains (Ahn et al, 1993).…”

Rice (Oryza) hemoglobins

“…Sequencing of the O. glaberrima and O. rufipogon genomes will be completed soon and most likely a number of rice genomes (including that of O. barthii , which is postulated as the ancestor of O. glaberrima 59, 151, 152 ) will be sequenced within the near future. This will provide new Hb sequences for phylogenetic analysis and the understanding of the evolution of rice Hbs, including the identification of ancestral rice Hbs and the evaluation of the effect of rice domestication and breeding during the evolution of rice Hbs.…”