Genome Evolution in the Genus Sorghum (Poaceae)

Abstract

The DNA sequence phylogeny splits Sorghum into two lineages, one comprising the 2n = 10 species with large genomes and their polyploid relatives, and the other with the 2n = 20, 40 species with relatively small genomes. An apparent phylogenetic reduction in genome size has occurred in the 2n = 10 lineage. Genome size evolution in the genus Sorghum apparently did not involve a 'one way ticket to genomic obesity' as has been proposed for the grasses.

Comprehensive Molecular Cytogenetic Analysis of Sorghum Genome Architecture: Distribution of Euchromatin, Heterochromatin, Genes and Recombination in Comparison to Rice

“…The sorghum genome has been estimated to be 2-fold larger than the genome of rice (Price et al 2005). However, rice and sorghum chromosomes are largely colinear indicating that sorghum genome expansion relative to rice is not due to a large-scale genome duplication event (Peng et al 1999;Wilson et al 1999;Klein et al 2003) even though there is strong evidence for segmental and possibly a whole-genome duplication in the common progenitor of rice and sorghum (Paterson et al 2003;Yu et al 2005).…”

“…The C4 grasses are particularly well adapted to regions of lower latitude that have higher average temperatures and are prone to drought (Edwards et al 2004). Among the C4 grasses, sorghum has a relatively small genome containing 818 Mbp of DNA distributed among 10 chromosomes (Price et al 2005). The importance of sorghum as a subsistence cereal crop in the semiarid tropics (Doggett 1988;National Research Council 1996), potential importance in biofuel production (Gnansounou et al 2005), adaptation to drought (Doggett 1988;National Research Council 1996), diverse germplasm (i.e., Menz et al 2004), and close relationship to maize (Kellogg 2001;Swigonova et al 2004) make this species a valuable target for grass genome research.…”

“…For example, rice has an 370-to 490-Mbp genome distributed among 12 chromosomes and wheat has an 16,900-Mbp genome distributed among three sets of 7 chromosomes (http:/ /www.rbgkew.org.uk/cval/ homepage.html). Moreover, even within the genus Sorghum (Poaceae), chromosome numbers (2n ¼ 10, 20, 30, 40) and genome size vary considerably (8.1-fold) (Price et al 2005). Variation in genome size among the grasses is due primarily to differences in polyploidy, segmental duplications, and accumulation of repetitive sequences (Saghai Maroof et al 1996;Tikhonov et al 1999;Gaut 2002;Levy and Feldman 2002;Vandepoele et al 2003).…”

Chromosome differentiation and genome organization in carnivorous plant family Droseraceae

“…molecular tree (Rivadavia et al 2003) and many cytological papers with Drosera chromosome size, evolutional trend of the large increase of chromosome size and genome size emerges in the several Northern Hemisphere species possessed M-type chromosomes (Hoshi and Kondo 1998a;Hoshi and Kondo 1998b;Hoshi et al 2008Hoshi et al , 2010. Evolutionally chromosome-size increase is rather common event in angiosperm, although the evolutional size decrease with DNA amount is rarely seen in some plants families such as Malvaceae (Wendel et al 2002), Brassicaceae and Poaceae (Price et al 2005). The mechanisms of the DNA loss are, however, not clearly understood because the number of examples are still low.…”

Utilization of wild relatives for maize (Zea mays L.) improvement

“…Wild crop relatives have been playing enormously important roles both in the depiction of plant genomes and the genetic improvement of their cultivated (Brar, 2005;Hajjar and Hodgkin, 2007;Pickering et al, 2006;Canci and Toker, 2009;Miller and Seiler, 2003). They have contributed immensely to resolving several fundamental questions, particularly those related to the origin, evolution, phylogenetic relationship, cytological status and inheritance of genes of an array of crop plants; provided several desirable donor genes for the genetic improvement of their domesticated counterparts; and facilitated the innovation of many novel concepts and technologies while working on them directly or while using their resources (Bai et al, 1995;Clifford, 1995;Kamala et al, 2002;Nevo et al, 2002 ;Nevo, 2004;Raskina et al, 2002Raskina et al, , 2004Sharma et al, 2005;Price et al, 2005Price et al, , 2006Dillon et al, 2005Dillon et al, , 2007Peleg et al, 2005Peleg et al, , 2007Petersen et., 2006;Salina et al, 2006;Matsuoka and Takumi, 2007;Bennetzen et al, 2007;Gill et al, 2007;Feldman and Kislev, 2007;Oliver et al, 2008;Loskutov, 2008;Gavrilova et al, 2008;Kuhlman et al, 2008;Xu et al, 2009;Wang et al, 2009;Ashraf et al, 2009;Nevo and Chen, 2010;Chittaranjan, 2011). For example, a wild rice (Oryza officinalis) has recently been used to change the time of flowering of the rice cultivar Koshihikari (Oryza sativa) to avoid the hottest part...…”