Cytotype diversity in the Sorbus complex (Rosaceae) in Britain: sorting out the puzzle
• Background and Aims Large scale ploidy surveys using flow cytometry have become an essential tool to study plant genome dynamics and to get insights into the mechanisms and genetic barriers framing ploidy diversity. Being confirmed as an ideal complement to traditional techniques such as chromosom...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión enviada para evaluación y publicación |
| Fecha de publicación: | 2012 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/345851 |
| Acceso en línea: | http://hdl.handle.net/10261/345851 |
| Access Level: | acceso abierto |
| Palabra clave: | Apomixis cytotype mixture flow cytometry genome size hybridization polyploidy whitebeam |
| Sumario: | • Background and Aims Large scale ploidy surveys using flow cytometry have become an essential tool to study plant genome dynamics and to get insights into the mechanisms and genetic barriers framing ploidy diversity. Being confirmed as an ideal complement to traditional techniques such as chromosome counting, the analysis of cytotype diversity in plant systems such as Sorbus will provide primary investigation into the potential patterns and the evolutionary implications of hybrid speciation. • Methods Ploidy levels were assessed by means of the relative nuclear DNA content using propidium iodide flow cytometry in 474 Sorbus samples collected from 65 populations in Southern Wales and South-West England. Statistical tests were applied to evaluate the utility of this technique to confidently discriminate ploidy in the genus. • Key results Flow cytometric profiles revealed the presence of five cytotypes (2x, 3x, 4x and 5x), confirming in many cases chromosome counts previously reported and demonstrating cytotype heterogeneity within specific Sorbus aggregates. Diploid cytotypes were restricted to the potential parental species and homoploid hybrids. Most of the samples processed were polyploid. The occurrence of the pentaploid cytotype had previously only been reported from a single specimen; it is now confirmed for two pentaploid taxa occurring at different sites. • Conclusions FCM has been proved a useful method to carry out population surveys to study ploidy diversity, revealing some cytoypes which occur at very low frequencies. The noteworthy coexistence of several cytotypes in Sorbus populations has been probably facilitated by the overlapping distribution of many of the species studied, which might explain as well the high incidence of potential hybrid apomictic polyploids. These results will provide a solid baseline for molecular research aiming to better understand the genetic pathways controlling the formation and establishment of polyploid Sorbus. |
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