Dataset Information

The first comprehensive genetic linkage map of a marsupial: the tammar wallaby (Macropus eugenii).

ABSTRACT: The production of a marsupial genetic linkage map is perhaps one of the most important objectives in marsupial research. This study used a total of 353 informative meioses and 64 genetic markers to construct a framework genetic linkage map for the tammar wallaby (Macropus eugenii). Nearly all markers (93.8%) formed a significant linkage (LOD > 3.0) with at least one other marker, indicating that the majority of the genome had been mapped. In fact, when compared with chiasmata data, >70% (828 cM) of the genome has been covered. Nine linkage groups were identified, with all but one (LG7; X-linked) allocated to the autosomes. These groups ranged in size from 15.7 to 176.5 cM and have an average distance of 16.2 cM between adjacent markers. Of the autosomal linkage groups (LGs), LG2 and LG3 were assigned to chromosome 1 and LG4 localized to chromosome 3 on the basis of physical localization of genes. Significant sex-specific distortions toward reduced female recombination rates were revealed in 22% of comparisons. When comparing the X chromosome data to closely related species it is apparent that they are conserved in both synteny and gene order.

SUBMITTER: Zenger KR

PROVIDER: S-EPMC1462270 | biostudies-other | 2002 Sep

REPOSITORIES: biostudies-other

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The first comprehensive genetic linkage map of a marsupial: the tammar wallaby (Macropus eugenii).

Zenger Kyall R KR McKenzie Louise M LM Cooper Desmond W DW

Genetics 20020901 1

The production of a marsupial genetic linkage map is perhaps one of the most important objectives in marsupial research. This study used a total of 353 informative meioses and 64 genetic markers to construct a framework genetic linkage map for the tammar wallaby (Macropus eugenii). Nearly all markers (93.8%) formed a significant linkage (LOD > 3.0) with at least one other marker, indicating that the majority of the genome had been mapped. In fact, when compared with chiasmata data, >70% (828 cM) ...[more]

PMID: 12242243

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Project description:BackgroundJapanese gentians (Gentiana triflora and Gentiana scabra) are amongst the most popular floricultural plants in Japan. However, genomic resources for Japanese gentians have not yet been developed, mainly because of the heterozygous genome structure conserved by outcrossing, the long juvenile period, and limited knowledge about the inheritance of important traits. In this study, we developed a genetic linkage map to improve breeding programs of Japanese gentians.ResultsEnriched simple sequence repeat (SSR) libraries from a G. triflora double haploid line yielded almost 20,000 clones using 454 pyrosequencing technology, 6.7% of which could be used to design SSR markers. To increase the number of molecular markers, we identified three putative long terminal repeat (LTR) sequences using the recently developed inter-primer binding site (iPBS) method. We also developed retrotransposon microsatellite amplified polymorphism (REMAP) markers combining retrotransposon and inter-simple sequence repeat (ISSR) markers. In addition to SSR and REMAP markers, modified amplified fragment length polymorphism (AFLP) and random amplification polymorphic DNA (RAPD) markers were developed. Using 93 BC1 progeny from G. scabra backcrossed with a G. triflora double haploid line, 19 linkage groups were constructed with a total of 263 markers (97 SSR, 97 AFLP, 39 RAPD, and 30 REMAP markers). One phenotypic trait (stem color) and 10 functional markers related to genes controlling flower color, flowering time and cold tolerance were assigned to the linkage map, confirming its utility.ConclusionsThis is the first reported genetic linkage map for Japanese gentians and for any species belonging to the family Gentianaceae. As demonstrated by mapping of functional markers and the stem color trait, our results will help to explain the genetic basis of agronomic important traits, and will be useful for marker-assisted selection in gentian breeding programs. Our map will also be an important resource for further genetic analyses such as mapping of quantitative trait loci and map-based cloning of genes in this species.

Project description:Interspecies hybrids between distinct species of the genus Xiphophorus are often used in varied research investigations to identify genomic regions associated with the inheritance of complex traits. There are 24 described Xiphophorus species and a greater number of pedigreed strains; thus, the number of potential interspecies hybrid cross combinations is quite large. Previously, select Xiphophorus experimental crosses have been shown to exhibit differing characteristics between parental species and among the hybrid fishes derived from crossing them, such as widely differing susceptibilities to chemical or physical agents. For instance, genomic regions harboring tumor suppressor and oncogenes have been identified via linkage association of these loci with a small set of established genetic markers. The power of this experimental strategy is related to the number of genetic markers available in the Xiphophorus interspecies cross of interest. Thus, we have undertaken the task of expanding the suite of easily scored markers by characterization of Xiphophorus microsatellite sequences. Using a cross between Xiphophorus maculatus and X. andersi, we report a linkage map predominantly composed of microsatellite markers. All 24 acrocentric chromosome sets of Xiphophorus are represented in the assembled linkage map with an average intergenomic distance of 7.5 cM. Since both male and female F1 hybrids were used to produce backcross progeny, these recombination rates were compared between "male" and "female" maps. Although several genomic regions exhibit differences in map length, male- and female-derived maps are similar. Thus Xiphophorus, in contrast to zebrafish, Danio rerio, and several other vertebrate species, does not show sex-specific differences in recombination. The microsatellite markers we report can be easily adapted to any Xiphophorus interspecies and some intraspecies crosses, and thus provide a means to directly compare results derived from independent experiments.

Dataset Information

The first comprehensive genetic linkage map of a marsupial: the tammar wallaby (Macropus eugenii).

Publications

The first comprehensive genetic linkage map of a marsupial: the tammar wallaby (Macropus eugenii).

Similar Datasets

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