scholarly journals Detailed Alignment of Saccharum and Sorghum Chromosomes: Comparative Organization of Closely Related Diploid and Polyploid Genomes

Genetics ◽  
1998 ◽  
Vol 150 (4) ◽  
pp. 1663-1682 ◽  
Author(s):  
R Ming ◽  
S-C Liu ◽  
Y-R Lin ◽  
J da Silva ◽  
W Wilson ◽  
...  

Abstract The complex polyploid genomes of three Saccharum species have been aligned with the compact diploid genome of Sorghum (2n = 2x = 20). A set of 428 DNA probes from different Poaceae (grasses) detected 2460 loci in F1 progeny of the crosses Saccharum officinarum Green German × S. spontaneum IND 81-146, and S. spontaneum PIN 84-1 × S. officinarum Muntok Java. Thirty-one DNA probes detected 226 loci in S. officinarum LA Purple × S. robustum Molokai 5829. Genetic maps of the six Saccharum genotypes, including up to 72 linkage groups, were assembled into “homologous groups” based on parallel arrangements of duplicated loci. About 84% of the loci mapped by 242 common probes were homologous between Saccharum and Sorghum. Only one interchromosomal and two intrachromosomal rearrangements differentiated both S. officinarum and S. spontaneum from Sorghum, but 11 additional cases of chromosome structural polymorphism were found within Saccharum. Diploidization was advanced in S. robustum, incipient in S. officinarum, and absent in S. spontaneum, consistent with biogeographic data suggesting that S. robustum is the ancestor of S. officinarum, but raising new questions about the antiquity of S. spontaneum. The densely mapped Sorghum genome will be a valuable tool in ongoing molecular analysis of the complex Saccharum genome.


2006 ◽  
Vol 3 (3) ◽  
pp. 155-161
Author(s):  
Yi Zhi-Ben ◽  
Sun Yi ◽  
Liang Xiao-Hong ◽  
Zhao Wei-Jun ◽  
Yan Min ◽  
...  

AbstractThe construction of the sorghum (Sorghum bicolor L. Moench) molecular genetic linkage map started in the early 1990s. Molecular genetic maps with a high density of markers covering almost the entire sorghum genome have been completed and integration of a sorghum genetic and physical map is under way. The correlation between genetic linkage groups and relevant chromosomes was established and the locations of the important structures of chromosomes, such as centromeres, long and short arms, nucleolus organizer region (NOR), etc., have been identified on the linkage groups. Molecular cytogenetic mapping of each chromosome has been advanced substantially. With continuing progress in the field, sequencing of the full sorghum genome and study of sorghum functional genomics will be initiated soon.



1999 ◽  
Vol 22 (1) ◽  
pp. 125-132 ◽  
Author(s):  
Claudia T. Guimarães ◽  
Rhonda J. Honeycutt ◽  
Gavin R. Sills ◽  
Bruno W.S. Sobral

Genetic analysis was performed in a population composed of 100 F1 individuals derived from a cross between a cultivated sugarcane (S. officinarum `LA Purple') and its proposed progenitor species (S. robustum `Mol 5829'). Various types (arbitrarily primed-PCR, RFLPs, and AFLPs) of single-dose DNA markers (SDMs) were used to construct genetic linkage maps for both species. The LA Purple map was composed of 341 SDMs, spanning 74 linkage groups and 1,881 cM, while the Mol 5829 map contained 301 SDMs, spanning 65 linkage groups and 1,189 cM. Transmission genetics in these two species showed incomplete polysomy based on the detection of 15% of SDMs linked in repulsion in LA Purple and 13% of these in Mol 5829. Because of this incomplete polysomy, multiple-dose markers could not be mapped for lack of a genetic model for their segregation. Due to inclusion of RFLP anchor probes, conserved in related species, the resulting maps will serve as useful tools for breeding, ecology, evolution, and molecular biology studies within the Andropogoneae.



Genetics ◽  
1992 ◽  
Vol 132 (4) ◽  
pp. 1119-1130 ◽  
Author(s):  
R Whitkus ◽  
J Doebley ◽  
M Lee

Abstract Linkage relationships were determined among 85 maize low copy number nuclear DNA probes and seven isozyme loci in an F2 population derived from a cross of Sorghum bicolor ssp. bicolor x S. bicolor ssp. arundinaceum. Thirteen linkage groups were defined, three more than the 10 chromosomes of sorghum. Use of maize DNA probes to produce the sorghum linkage map allowed us to make several inferences concerning processes involved in the evolutionary divergence of the maize and sorghum genomes. The results show that many linkage groups are conserved between these two genomes and that the amount of recombination in these conserved linkage groups is roughly equivalent in maize and sorghum. Estimates of the proportions of duplicated loci suggest that a larger proportion of the loci are duplicated in the maize genome than in the sorghum genome. This result concurs with a prior estimate that the nuclear DNA content of maize is three to four times greater than that of sorghum. The pattern of conserved linkages between maize and sorghum is such that most sorghum linkage groups are composed of loci that map to two maize chromosomes. This pattern is consistent with the hypothesized ancient polyploid origin of maize and sorghum. There are nine cases in which locus order within shared linkage groups is inverted in sorghum relative to maize. These may have arisen from either inversions or intrachromosomal translocations. We found no evidence for large interchromosomal translocations. Overall, the data suggest that the primary processes involved in divergence of the maize and sorghum genomes were duplications (either by polyploidy or segmental duplication) and inversions or intrachromosomal translocations.



Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 184-203 ◽  
Author(s):  
C L Brubaker ◽  
A H Paterson ◽  
J F Wendel

Allotetraploid cotton species (Gossypium) belong to a 1-2 million year old lineage that reunited diploid genomes that diverged from each other 5-10 million years ago. To characterize genome evolution in the diploids and allotetraploids, comparative RFLP mapping was used to construct genetic maps for the allotetraploids (AD genome; n = 26) and diploids (A and D genomes; n = 13). Comparisons among the 13 suites of homoeologous linkage groups permitted comparisons of synteny and gene order. Two reciprocal translocations were confirmed involving four allotetraploid At genome chromosomes, as was a translocation between the two extant A genome diploids. Nineteen locus order differences were detected among the two diploid and two allotetraploid genomes. Conservation of colinear linkage groups among the four genomes indicates that allopolyploidy in Gossypium was not accompanied by extensive chromosomal rearrangement. Many inversions include duplicated loci, suggesting that the processes that gave rise to inversions are not fully conservative. Allotetraploid At and Dt genomes and the A and D diploid genomes are recombinationally equivalent despite a nearly two-fold difference in physical size. Polyploidization in Gossypium is associated with enhanced recombination, as genetic lengths for allotetraploid genomes are over 50% greater than those of their diploid counterparts.Key words: restriction fragment length polymorphism (RFLP), Gossypium, evolution, polyploidy.



Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 282-295 ◽  
Author(s):  
Elizabeth S Jones ◽  
Natalia L Mahoney ◽  
Michael D Hayward ◽  
Ian P Armstead ◽  
J Gilbert Jones ◽  
...  

A molecular-marker linkage map has been constructed for perennial ryegrass (Lolium perenne L.) using a one-way pseudo-testcross population based on the mating of a multiple heterozygous individual with a doubled haploid genotype. RFLP, AFLP, isoenzyme, and EST data from four collaborating laboratories within the International Lolium Genome Initiative were combined to produce an integrated genetic map containing 240 loci covering 811 cM on seven linkage groups. The map contained 124 codominant markers, of which 109 were heterologous anchor RFLP probes from wheat, barley, oat, and rice, allowing comparative relationships between perennial ryegrass and other Poaceae species to be inferred. The genetic maps of perennial ryegrass and the Triticeae cereals are highly conserved in terms of synteny and colinearity. This observation was supported by the general agreement of the syntenic relationships between perennial ryegrass, oat, and rice and those between the Triticeae and these species. A lower level of synteny and colinearity was observed between perennial ryegrass and oat compared with the Triticeae, despite the closer taxonomic affinity between these species. It is proposed that the linkage groups of perennial ryegrass be numbered in accordance with these syntenic relationships, to correspond to the homoeologous groups of the Triticeae cereals.Key words: Lolium perenne, genetic linkage map, RFLP, AFLP, conserved synteny.



1995 ◽  
Vol 66 (2) ◽  
pp. 109-126 ◽  
Author(s):  
Jinrui Shi ◽  
David G. Heckel ◽  
Marian R. Goldsmith

SummaryWe present data for the initial construction of a molecular linkage map for the domesticated silkworm, Bombyx mori, based on 52 progeny from an F2 cross from a pair mating of inbred strains p50 and C108, using restriction fragment length polymorphisms (RFLPs). The map contains 15 characterized single copy sequences, 36 anonymous sequences derived from a follicular cDNA library, and 10 loci corresponding to a low copy number retrotransposon, mag. The 15 linkage groups and 8 ungrouped loci account for 23 of the 28 chromosomes and span a total recombination length of 413 cM; 10 linkage groups were correlated with established classic genetic maps. Scoring data from Southern blots were analysed using two Pascal programs written specifically to analyse linkage data in Lepidoptera, where females are the heterogametic sex and have achiasmatic meiosis (no crossing-over). These first examine evidence for linkage by calculating the maximum lod score under the hypothesis that the two loci are linked over the likelihood under the hypothesis that the two loci assort independently, and then determine multilocus linkage maps for groups of putatively syntenic loci by calculating the maximum likelihood estimate of the recombination fractions and the log likelihood using the EM algorithm for a specified order of loci along the chromosome. In addition, the possibility of spurious linkage was exhaustively tested by searching for genotypes forbidden by the absence of crossing-over in one sex.



Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 137-142 ◽  
Author(s):  
M. D. Gale ◽  
P. J. Sharp ◽  
S. Chao ◽  
C. N. Law

A molecular map of wheat, Triticum aestivum, is being developed. Problems associated with the large genome size, the large number of linkage groups, polyploidy, and limited polymorphism at the DNA level are being overcome. In addition to the breeding applications expected from the map, various uses for restriction fragment length polymorphism markers as tools in cytogenetic manipulation of wheat chromosomes and those from related species are being found. These include identification of aneuploid genotypes, added precision in intervarietal chromosome manipulations, tests of chromosome stability, identification of alien chromosomes, and marker-aided introgression of genes of agronomic importance from related species.Key words: wheat, restriction fragment length polymorphism, genetic maps, aneuploidy, alien chromosomes.



The Analyst ◽  
2009 ◽  
Vol 134 (8) ◽  
pp. 1675 ◽  
Author(s):  
Vinay Gidwani ◽  
Reza Riahi ◽  
Donna D. Zhang ◽  
Pak Kin Wong


1981 ◽  
Vol 37 (1) ◽  
pp. 55-69 ◽  
Author(s):  
G. G. Foster ◽  
M. J. Whitten ◽  
C. Konovalov ◽  
J. T. A. Arnold ◽  
G. Maffi

SUMMARYLinkage data and revised maps for 52 autosomal loci in L. cuprina are presented. Examination of the linkage relationships of biochemically and morphologically similar mutations in L. cuprina, Musca domestica L. and Drosophila melanogaster (Mg) suggests that the major linkage groups have survived largely intact during the evolution of the higher Diptera.



Genome ◽  
1993 ◽  
Vol 36 (4) ◽  
pp. 782-791 ◽  
Author(s):  
Jorge A. G. da Silva ◽  
Mark E. Sorrells ◽  
William L Burnquist ◽  
Steven D. Tanksley

An RFLP linkage map of the wild sugarcane species Saccharum spontaneum L. (2n = 8x = 40–128) was constructed, comprising 216 loci, detected by 116 DNA probes, and distributed over 44 linkage groups. At a density of at least one marker every 25-cM interval, the coverage of the genome was estimated as 86%. For the generation of RFLP markers, probes were surveyed from seven DNA libraries: three sugarcane cDNA, one oat cDNA, one rice cDNA, and one barley cDNA, as well as one sugarcane genomic. Sixty-two maize genomic clones that were previously mapped on maize were used to initiate a comparative map between the sugarcane, sorghum, and maize genomes. Based on the RFLP segregation data, we conclude that this species is an autopolyploid, with an estimated genome size of 2107 cM.Key words: sugarcane, polyploid, RFLP, map, genome.



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