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Devos N Raspé O Oh SH Tyteca D Jacquemart AL 《Molecular phylogenetics and evolution》2006,38(3):767-778
Sequence data from a portion of the external transcribed spacer (ETS) and from the internal transcribed spacers (ITS1 and ITS2) of 18S-26S nuclear ribosomal DNA were used together with chloroplast DNA PCR-RFLP data to unravel patterns of allotetraploid speciation within the Western European Dactylorhiza polyploid complex. A maximum likelihood tree based on combined ETS and ITS sequences suggests that the Western European Dactylorhiza allotetraploids have evolved by hybridization between four main diploid lineages. Cloned sequences and the topology of the ITS plus ETS tree indicate that the allotetraploid species D. elata, D. brennensis, and D. sphagnicola have originated from the autotetraploid D. maculata together with the diploid D. incarnata, while D. majalis, D. traunsteineri, and D. angustata seem to have evolved by hybridization between the D. fuchsii s.str and D. incarnata lineages. Finally, the diploid D. saccifera lineage seems to have been involved together with the D. incarnata lineage in the formation of the allotetraploid D. praetermissa. The observed congruence between the chloroplast tree and the ITS/ETS tree suggests a directional evolution of the nrDNA after polyploidization in favor of the maternal genome. Considered together with morphological, biogeographical, and ecological evidence, the molecular analysis leads us to recognize four species within the investigated allotetraploid complex, namely D. majalis, D. praetermissa, D. elata, and D. sphagnicola. 相似文献
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Julien Beaulieu Martine Jean François Belzile 《Molecular genetics and genomics : MGG》2009,281(4):421-435
Polyploidy is known to be common in plants and recent work has focused on the rapid changes in genome structure and expression
that occur upon polyploidization. In Arabidopsis, much of this work has been done on a synthetic allotetraploid obtained by crossing a tetraploid Arabidopsis thaliana (2n = 4x = 20) with A. arenosa (2n = 4x = 32). To explore an alternative route to polyploidy in this model species, we have developed a synthetic allopolyploid by
crossing two diploid species: A. thaliana (2n = 2x = 10) and Arabidopsis lyrata subsp. petraea (2n = 2x = 16). F1 hybrids were easy to obtain and phenotypically more similar to A. lyrata. Spontaneous chromosome doubling events occurred in about 25% of the F1s, thus restoring fertility. The resulting allotetraploids (2n = 26) exhibited many genomic changes typically reported upon polyploidization. Nucleolar dominance was observed as only the
A. lyrata rDNA loci were expressed in the F1 and allotetraploids. Changes in the degree of methylation were observed at almost 25% of the loci examined by MSAP analysis.
Finally, structural genomic alterations did occur as a large deletion covering a significant portion of the upper arm of chromosome
II was detected but no evidence of increased mobility of transposons was obtained. Such allotetraploids derived from two parents
with sequenced (or soon to be sequenced) genomes offer much promise in elucidating the various changes that occur in newly
synthesized polyploids. 相似文献
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M. J. Asins E. A. Carbonell 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1986,72(4):559-568
Summary Interspecific relationship studies between A, S and D genome diploid species, and between AAGG and AABB allotetraploid species of the genus Triticum were conducted using isoenzymatic characters located in dry mature seeds. Data was analyzed by the factorial analysis of correspondences, and dendograms were obtained by two different genetic distances. The discussion of results was based on the limitations of the study, intraspecific variability differences, isoperoxidase frequency differences and chromosomal location of peroxidases in T. aestivum cv. Chinese Spring. The closest relationship was found between dicoccoides and carthlicum. Relationships found between T. turgidum L. and T. timopheevvi Zhuk., both allotetraploid species and boeoticum; this species and speltoides; tauschi and searsii, and the last two species with bicorne, are discussed at the phylogenetic level. 相似文献
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