Mitochondrial DNA diversity in wild and cultivated sorghum

Abstract

Cultivated sorghum (Sorghum bicolor ssp. bicolor) is classified into five main races on the basis of spikelet morphology. Isozyme analyses provided new insight into the genetic diversity of sorghum and revealed marked geographic grouping, while nuclear restriction fragment length polymorphisms showed racial differentiation and intraguinea race differentiation. Wild sorghum is diploid or tetraploid and African sorghum (S. bicolor ssp. arundinaceum) is classified into four races, that are considered to be progenitors of cultivated sorghum. We performed mitochondrial DNA analyses to compare the diversity of wild and cultivated sorghum and to study the genetic origin of guinea margaritiferum. The same overall patterns were obtained with the different phenogram construction techniques. Our results confirmed the specificity of guinea margaritiferum and demonstrated the presence of two genetic entities within this subrace. Another guinea group was also noted, which corresponded to Asian guinea roxburghii. In wild sorghum, the arundinaceum race appeared to be homogenous, while the verticilliflorum race was separated into two groups, one of which was associated with the arundinaceum race. The diversity observed in cultivated forms was found to be encompassed within the wild pool, except for one guinea margaritiferum group. There did not seem to be any particular relationship between wild races and cultivated races.

Genetic structure and relationships within and between cultivated and wild sorghum (Sorghum bicolor (L.) Moench) in Kenya as revealed by microsatellite markers

“…Levels and patterns of diversity within and between cultivated and wild sorghum gene pools have been reported before (e.g Morden et al 1990;Cui et al 1995;Deu et al 1995;Casa et al 2005). These previous studies have shown that (i) there is low to moderate genetic differentiation among cultivated and wild sorghum gene pools, (ii) portions of the wild gene pool most genetically similar to cultivars originated in central-north-east Africa and (iii) genetic diversity is greater in wild-weedy than in cultivated sorghums.…”

Phylogeographic Evidence of Crop Neodiversity in Sorghum

“…PCR and DNA sequencing: Genomic DNA was extracted from fresh leaves harvested from a single 3-week seedling per accession following a cetyltrimethylammonium bromide (CTAB) protocol previously described (Deu et al 1995). SP6 (59-GATTTAGGTGACACTATAG-39) and T7 (59-TAATACGA CTCACTATAGGGC-39) tails were added to the 59 ends of primers to facilitate direct sequencing of the PCR products.…”

“…bicolor), namely bicolor, caudatum, durra, guinea, and kafir, as well as 10 intermediate types. This species has been studied with various types of molecular markers (Ollitrault et al 1989;Aldrich et al 1992;Deu et al 1994Deu et al , 1995Cui et al 1995;De Oliveira et al 1996;Menkir et al 1997;Djè et al 2000;Grenier et al 2000;Casa et al 2005) and has recently undergone detailed sequence diversity analysis using small representative panels of diverse accessions (Hamblin et al 2004(Hamblin et al , 2006, which enabled investigation of linkage disequilibrium (LD) and patterns of selection among several hundred loci. This resulted in a fine understanding of ecogeographic patterns of variation in sorghum, in particular with reference to its geographic spreading out of the area of origin in the northeastern part of sub-Saharan Africa.…”

“…bicolor races for cytoplasmic markers (Deu et al 1995). The differences between the other clusters were based on contrasted frequencies of shared alleles, rather than on diagnostic alleles that discriminated one group from all the others.…”

Genetic variability of sorghum landraces from lower Eastern Kenya based on simple sequence repeats (SSRs) markers

“…Levels and patterns of diversity within and between cultivated and wild sorghum gene pools have been reported (Cui et al, 1995;Deu et al, 1995;Casa et al, 2005). In Kenya, studies were done to establish the extent and direction of introgression between cultivated and wild sorghum relatives (Mutegi et al, 2010).…”