Segregation of molecular markers supports an allotetraploid structure for Medicago sativa × Medicago papillosa interspecific hybrid

Genome ◽  
1991 ◽  
Vol 34 (4) ◽  
pp. 574-578 ◽  
Author(s):  
T. J. McCoy ◽  
C. S. Echt ◽  
L. C. Mancino

Cytogenetic analysis has indicated there is little genomic affinity between the genomes of Medicago sativa L. and Medicago papillosa Boiss. The objective of this study was to determine whether disomic segregation of alleles at isozyme and restriction fragment length polymorphism (RFLP) loci occurs in F1 hybrids of M. sativa × M. papillosa. We examined segregation of alleles at seven isozyme loci and 13 RFLP loci. Of the 20 loci analyzed, 11 exhibited a disomic pattern of inheritance, indicative of strict species-specific chromosome pairing in the M. sativa × M. papillosa hybrids. The other nine loci generally followed disomic inheritance, with exceptions. The results provide significant evidence in support of the concept that M. sativa × M. papillosa hybrids are basically allotetraploids with limited genomic affinity between the genomes. This report also represents the first documentation of the utility of RFLP markers in genetic analysis of alfalfa, a species with an essentially nonexistent genetic map.Key words: isozymes, genomic affinity, alfalfa, introgression, restriction fragment length polymorphism.

Genome ◽  
2001 ◽  
Vol 44 (3) ◽  
pp. 401-412 ◽  
Author(s):  
X -F. Ma ◽  
K Ross ◽  
J P Gustafson

Using wheat ditelosomic lines and in situ hybridization of biotin-labelled DNA probes, 18 restriction fragment length polymorphism (RFLP) markers were physically located on homoeologous groups 1 and 3 chromosomes of wheat. Most of the markers hybridized to chromosome arms in a physical order concordant with the genetic maps. A majority of the markers studied were clustered in non-C-banded, distal euchromatic areas, indicating the presence of recombination hot spots and cold spots in those regions. However, on 1BS the markers were well dispersed, which could be due to the abundance of heterochromatin throughout the arm. An inversion between Xpsr653 and Xpsr953 was observed on 1AL. One new Xpsr688 locus, approximately 20–26% from the centromere, was found on 1AS and 1BS. The physical location of Xpsr170 on group 3 chromosomes probably represents an alternative to the loci on the genetic map. Finally, Xpsr313 was mapped to two physical loci on 1DL. Five markers were located to bins consistent with the deletion-based physical maps.Key words: wheat, physical mapping, in situ hybridization.


2001 ◽  
Vol 31 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Camile Pizeta Semighini ◽  
Guillaume Delmas ◽  
Steven Park ◽  
Donald Amstrong ◽  
David Perlin ◽  
...  

Genome ◽  
2001 ◽  
Vol 44 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Seliina Päällysaho ◽  
Susanna Huttunen ◽  
Anneli Hoikkala

We have identified six restriction fragment length polymorphism (RFLP) markers based on unique gene sequences on the X chromosome of Drosophila virilis and D. littoralis. The markers were localized by in situ hybridization on larval polytene chromosomes, and the conjugation of the X chromosomes of the two species was studied in salivary glands of interspecific hybrid female larvae. The gene arrangement of D. virilis and D. littoralis appeared to be very different at the proximal end of the X chromosome preventing recombination between RFLP markers located in this area. Simple quantitative trait loci (QTL) analysis showed that five of our marker genes (including nonA and Dmca1A, previously found to affect male courtship song in D. melanogaster) are linked with a gene(s) having a major effect on species differences in the male courtship song between D. virilis and D. littoralis. This shows that the song gene(s) may be located inside a large X-chromosomal inversion in D. littoralis (as previously suggested), but that it may also be located on an area between this inversion and the centromere, close to nonA and Dmca1A. Localization of this gene or gene complex will be continued with the aid of our newly identified RFLP markers by making interspecific crosses between D. virilis group species with more similar X chromosomes.Key words: restriction fragment length polymorphism (RFLP), in situ hybridization, Drosophila virilis.


2005 ◽  
Vol 17 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Kirsty M. Townsend ◽  
Vo Ngan Giang ◽  
Carol Stephens ◽  
Paul T. Scott ◽  
Darren J. Trott

Sixty-nine intestinal spirochetes isolated from pigs and poultry in eastern Australia were selected to evaluate the effectiveness of a species-specific PCR-based restriction fragment length polymorphism (RFLP) analysis of the Brachyspira nox gene. For comparative purposes, all isolates were subjected to species-specific PCRs for the pathogenic species Brachyspira hyodysenteriae and Brachyspira pilosicoli, and selected isolates were examined further by sequence analysis of the nox and 16S ribosomal RNA genes. Modifications to the original nox-RFLP method included direct inoculation of bacterial cells into the amplification mixture and purification of the PCR product, which further optimized the nox-RFLP for use in a veterinary diagnostic laboratory, producing sufficient product for both species identification and future comparisons. Although some novel profiles that prevented definitive identification were observed, the nox-RFLP method successfully classified 45 of 51 (88%) porcine and 15 of 18 (83%) avian isolates into 5 of the 6 recognized species of Brachyspira. This protocol represents a significant improvement over conventional methods currently used in veterinary diagnostic laboratories for rapid specific identification of Brachyspira spp. isolated from both pigs and poultry.


2006 ◽  
Vol 96 (10) ◽  
pp. 1157-1163 ◽  
Author(s):  
Xinshun Qu ◽  
Barbara J. Christ

Spongospora subterranea f. sp. subterranea causes powdery scab in potatoes and is distributed worldwide. Genetic studies of this pathogen have been hampered due, in part, to its obligate parasitism and the lack of molecular markers for this pathogen. In this investigation, a single cystosorus inoculation technique was developed to produce large amounts of S. subterranea f. sp. subterranea plasmodia or zoosporangia in eastern black nightshade (Solanum ptycanthum) roots from which DNA was extracted. Cryopreservation of zoosporangia was used for long-term storage of the isolates. S. subterranea f. sp. subterranea-specific restriction fragment length polymorphism (RFLP) markers were developed from randomly amplified polymorphic DNA (RAPD) fragments. Cystosori of S. subterranea f. sp. subterranea were used for RAPD assays and putative pathogen-specific RAPD fragments were cloned and sequenced. The fragments were screened for specificity by Southern hybridization and subsequent DNA sequence BLAST search. Four polymorphic S. subterranea f. sp. subterranea-specific probes containing repetitive elements, and one containing single copy DNA were identified. These RFLP probes were then used to analyze 24 single cystosorus isolates derived from eight geographic locations in the United States and Canada. Genetic variation was recorded among, but not within, geographic locations. Cluster analysis separated the isolates into two major groups: group I included isolates originating from western North America, with the exception of those from Colorado, and group II included isolates originating from eastern North America and from Colorado. The techniques developed in this study, i.e., production of single cystosorus isolates of S. subterranea f. sp. subterranea and development of RFLP markers for this pathogen, provide methods to further study the genetic structure of S. subterranea f. sp. subterranea.


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