Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding
<p>Abstract</p> <p>Background</p> <p>White clover (<it>Trifolium repens</it>) is a ubiquitous weed of the temperate world that through use of improved cultivars has also become the most important legume of grazed pastures world-wide. It has long been suspect...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2012-04-01
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| Series: | BMC Plant Biology |
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| Online Access: | http://www.biomedcentral.com/1471-2229/12/55 |
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| author | Williams Warren M Ellison Nicholas W Ansari Helal A Verry Isabelle M Hussain S |
| author_facet | Williams Warren M Ellison Nicholas W Ansari Helal A Verry Isabelle M Hussain S |
| author_sort | Williams Warren M |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>White clover (<it>Trifolium repens</it>) is a ubiquitous weed of the temperate world that through use of improved cultivars has also become the most important legume of grazed pastures world-wide. It has long been suspected to be allotetraploid, but the diploid ancestral species have remained elusive. Putative diploid ancestors were indicated by DNA sequence phylogeny to be <it>T. pallescens</it> and <it>T. occidentale</it>. Here, we use further DNA evidence as well as a combination of molecular cytogenetics (FISH and GISH) and experimental hybridization to test the hypothesis that white clover originated as a hybrid between <it>T. pallescens</it> and <it>T. occidentale</it>.</p> <p>Results</p> <p><it>T. pallescens</it> plants were identified with chloroplast <it>trnL</it> intron DNA sequences identical to those of white clover. Similarly, <it>T. occidentale</it> plants with nuclear ITS sequences identical to white clover were also identified. Reciprocal GISH experiments, alternately using labeled genomic DNA probes from each of the putative ancestral species on the same white clover cells, showed that half of the chromosomes hybridized with each probe. F<sub>1</sub> hybrids were generated by embryo rescue and these showed strong interspecific chromosome pairing and produced a significant frequency of unreduced gametes, indicating the likely mode of polyploidization. The F<sub>1</sub> hybrids are inter-fertile with white clover and function as synthetic white clovers, a valuable new resource for the re-incorporation of ancestral genomes into modern white clover for future plant breeding.</p> <p>Conclusions</p> <p>Evidence from DNA sequence analyses, molecular cytogenetics, interspecific hybridization and breeding experiments supports the hypothesis that a diploid alpine species (<it>T. pallescens</it>) hybridized with a diploid coastal species (<it>T. occidentale</it>) to generate tetraploid <it>T. repens</it>. The coming together of these two narrowly adapted species (one alpine and the other maritime), along with allotetraploidy, has led to a transgressive hybrid with a broad adaptive range.</p> |
| first_indexed | 2024-04-13T06:33:43Z |
| format | Article |
| id | doaj.art-6f8520d6ef06479bb4258f27bb7a6442 |
| institution | Directory Open Access Journal |
| issn | 1471-2229 |
| language | English |
| last_indexed | 2024-04-13T06:33:43Z |
| publishDate | 2012-04-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Plant Biology |
| spelling | doaj.art-6f8520d6ef06479bb4258f27bb7a64422022-12-22T02:58:00ZengBMCBMC Plant Biology1471-22292012-04-011215510.1186/1471-2229-12-55Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breedingWilliams Warren MEllison Nicholas WAnsari Helal AVerry Isabelle MHussain S<p>Abstract</p> <p>Background</p> <p>White clover (<it>Trifolium repens</it>) is a ubiquitous weed of the temperate world that through use of improved cultivars has also become the most important legume of grazed pastures world-wide. It has long been suspected to be allotetraploid, but the diploid ancestral species have remained elusive. Putative diploid ancestors were indicated by DNA sequence phylogeny to be <it>T. pallescens</it> and <it>T. occidentale</it>. Here, we use further DNA evidence as well as a combination of molecular cytogenetics (FISH and GISH) and experimental hybridization to test the hypothesis that white clover originated as a hybrid between <it>T. pallescens</it> and <it>T. occidentale</it>.</p> <p>Results</p> <p><it>T. pallescens</it> plants were identified with chloroplast <it>trnL</it> intron DNA sequences identical to those of white clover. Similarly, <it>T. occidentale</it> plants with nuclear ITS sequences identical to white clover were also identified. Reciprocal GISH experiments, alternately using labeled genomic DNA probes from each of the putative ancestral species on the same white clover cells, showed that half of the chromosomes hybridized with each probe. F<sub>1</sub> hybrids were generated by embryo rescue and these showed strong interspecific chromosome pairing and produced a significant frequency of unreduced gametes, indicating the likely mode of polyploidization. The F<sub>1</sub> hybrids are inter-fertile with white clover and function as synthetic white clovers, a valuable new resource for the re-incorporation of ancestral genomes into modern white clover for future plant breeding.</p> <p>Conclusions</p> <p>Evidence from DNA sequence analyses, molecular cytogenetics, interspecific hybridization and breeding experiments supports the hypothesis that a diploid alpine species (<it>T. pallescens</it>) hybridized with a diploid coastal species (<it>T. occidentale</it>) to generate tetraploid <it>T. repens</it>. The coming together of these two narrowly adapted species (one alpine and the other maritime), along with allotetraploidy, has led to a transgressive hybrid with a broad adaptive range.</p>http://www.biomedcentral.com/1471-2229/12/55<it>Trifolium repens</it>White cloverAllopolyploidInterspecific hybridization |
| spellingShingle | Williams Warren M Ellison Nicholas W Ansari Helal A Verry Isabelle M Hussain S Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding BMC Plant Biology <it>Trifolium repens</it> White clover Allopolyploid Interspecific hybridization |
| title | Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding |
| title_full | Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding |
| title_fullStr | Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding |
| title_full_unstemmed | Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding |
| title_short | Experimental evidence for the ancestry of allotetraploid <it>Trifolium repens</it> and creation of synthetic forms with value for plant breeding |
| title_sort | experimental evidence for the ancestry of allotetraploid it trifolium repens it and creation of synthetic forms with value for plant breeding |
| topic | <it>Trifolium repens</it> White clover Allopolyploid Interspecific hybridization |
| url | http://www.biomedcentral.com/1471-2229/12/55 |
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