A molecular linkage map of cultivated oat

Genome ◽  
1995 ◽  
Vol 38 (2) ◽  
pp. 368-380 ◽  
Author(s):  
L. S. O'Donoughue ◽  
M. E. Sorrells ◽  
S. D. Tanksley ◽  
E. Autrique ◽  
A. Van Deynze ◽  
...  

A molecular linkage map of cultivated oat composed of 561 loci has been developed using 71 recombinant inbred lines from a cross between Avena byzantina cv. Kanota and A. sativa cv. Ogle. The loci are mainly restriction fragment length polymorphisms detected by oat cDNA clones from leaf, endosperm, and root tissue, as well as by barley leaf cDNA clones. The loci form 38 linkage groups ranging in size from 0.0 to 122.1 cM (mean, 39 cM) and consist of 2–51 loci each (mean, 14). Twenty-nine loci remain unlinked. The current map size is 1482 cM and the total size, on the basis of the number of unlinked loci, is estimated to be 2932.0 cM. This indicates that this map covers at least 50% of the cultivated oat genome. Comparisons with an A-genome diploid oat map and between linkage groups exhibiting homoeology to each other indicate that several major chromosomal rearrangements exist in cultivated oat. This map provides a tool for marker-assisted selection, quantitative trait loci analyses, and studies of genome organization in oat.Key words: Avena, restriction fragment length polymorphism, linkage map, polyploidy, genome evolution.

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.


Genetics ◽  
1992 ◽  
Vol 132 (4) ◽  
pp. 1003-1015 ◽  
Author(s):  
L D Sibley ◽  
A J LeBlanc ◽  
E R Pfefferkorn ◽  
J C Boothroyd

Abstract We have constructed a genetic linkage map for the parasitic protozoan, Toxoplasma gondii, using randomly selected low copy number DNA markers that define restriction fragment length polymorphisms (RFLPs). The inheritance patterns of 64 RFLP markers and two phenotypic markers were analyzed among 19 recombinant haploid progeny selected from two parallel genetic crosses between PLK and CEP strains. In these first successful interstrain crosses, these RFLP markers segregated into 11 distinct genetic linkage groups that showed close correlation with physical linkage groups previously defined by molecular karyotype. Separate linkage maps, constructed for each of the 11 chromosomes, indicated recombination frequencies range from approximately 100 to 300 kb per centimorgan. Preliminary linkage assignments were made for the loci regulating sinefungin resistance (snf-1) on chromosome IX and adenine arabinoside (ara-1) on chromosome V by linkage to RFLP markers. Despite random segregation of separate chromosomes, the majority of chromosomes failed to demonstrate internal recombination events and in 3/19 recombinant progeny no intramolecular recombination events were detected. The relatively low rate of intrachromosomal recombination predicts that tight linkage for unknown genes can be established with a relatively small set of markers. This genetic linkage map should prove useful in mapping genes that regulate drug resistance and other biological phenotypes in this important opportunistic pathogen.


Genome ◽  
2003 ◽  
Vol 46 (2) ◽  
pp. 304-313 ◽  
Author(s):  
R W Jessup ◽  
B L Burson ◽  
G Burow ◽  
Y -W Wang ◽  
C Chang ◽  
...  

Linkage analyses increasingly complement cytological and traditional plant breeding techniques by providing valuable information regarding genome organization and transmission genetics of complex polyploid species. This study reports a genome map of buffelgrass (Pennisetum ciliare (L.) Link syn. Cenchrus ciliaris L.). Maternal and paternal maps were constructed with restriction fragment length polymorphisms (RFLPs) segregating in 87 F1 progeny from an intraspecific cross between two heterozygous genotypes. A survey of 862 heterologous cDNAs and gDNAs from across the Poaceae, as well as 443 buffelgrass cDNAs, yielded 100 and 360 polymorphic probes, respectively. The maternal map included 322 RFLPs, 47 linkage groups, and 3464 cM, whereas the paternal map contained 245 RFLPs, 42 linkage groups, and 2757 cM. Approximately 70 to 80% of the buffelgrass genome was covered, and the average marker spacing was 10.8 and 11.3 cM on the respective maps. Preferential pairing was indicated between many linkage groups, which supports cytological reports that buffelgrass is a segmental allotetraploid. More preferential pairing (disomy) was found in the maternal than paternal parent across linkage groups (55 vs. 38%) and loci (48 vs. 15%). Comparison of interval lengths in 15 allelic bridges indicated significantly less meiotic recombination in paternal gametes. Allelic interactions were detected in four regions of the maternal map and were absent in the paternal map.Key words: linkage map, segmental allopolyploidy, restriction fragment length polymorphism, Poaceae, chromosome pairing.


Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 765-771 ◽  
Author(s):  
L. S. O'Donoughue ◽  
Z. Wang ◽  
M. Röder ◽  
B. Kneen ◽  
M. Leggett ◽  
...  

A restriction fragment length polymorphism (RFLP) map for the A genome of Avena has been developed using F3 families from the cross A. atlantica × A. hirtula. The main source of markers were an oat cDNA and a barley cDNA library. A total of 194 RFLP markers was used, 192 of which were mapped or assigned to linkage groups. Seven main linkage groups, presumably corresponding to the seven chromosomes of the haploid genome, were identified. The linkage groups varied in size from 30 to 118 cM for a total map length of 614 cM. This map provides a tool for the interpretation of genome organization in Avena and for marker selection in the development of a map of hexaploid oats.Key words: restriction fragment length polymorphism, Avena, mapping.


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.


HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 323-324
Author(s):  
Michael J. Havey

PstI-genomic and cDNA clones revealing mapped restriction fragment-length polymorphisms (RFLP) in cucumber (Cucumis sativus L.) were sequenced in order to ensure that these clones remain available and to determine if any clones showing genetic linkage in cucumber are physically linked in Arabidopsis thaliana. Sequence comparisons using translated searches revealed that 80% of the cucumber cDNA clones showed significant (≤e-20) similarities to Arabidopsis expressed sequence tags (ESTs) or genomic sequences, as opposed to relatively few (32%) of the cucumber genomic clones. Two clones revealing RFLPs linked at 2 cM in cucumber showed significant (≤e-20) similarities to sequences separated by 347,616 basepairs on chromosome 4 of Arabidopsis.


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