Changes in genomic methylation patterns during the formation of triploid asexual dandelion lineages

Authors

  • KOEN JF VERHOEVEN,

    1. Netherlands Institute of Ecology (NIOO-KNAW), Department of Terrestrial Ecology, Boterhoeksestraat 48, 6666 GA, Heteren, The Netherlands
    2. Laboratory of Nematology, Wageningen University and Research Centre, PO Box 8123, 6700 ES Wageningen, The Netherlands
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  • PETER J VAN DIJK,

    1. KeyGene NV, PO Box 216, 6700 AE Wageningen, The Netherlands
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  • ARJEN BIERE

    1. Netherlands Institute of Ecology (NIOO-KNAW), Department of Terrestrial Ecology, Boterhoeksestraat 48, 6666 GA, Heteren, The Netherlands
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Koen Verhoeven, Fax: +31 26 4723227; E-mail: k.verhoeven@nioo.knaw.nl

Abstract

DNA methylation is an epigenetic mechanism that has the potential to affect plant phenotypes and that is responsive to environmental and genomic stresses such as hybridization and polyploidization. We explored de novo methylation variation that arises during the formation of triploid asexual dandelions from diploid sexual mother plants using methylation-sensitive amplified fragment length polymorphism (MS-AFLP) analysis. In dandelions, triploid apomictic asexuals are produced from diploid sexual mothers that are fertilized by polyploid pollen donors. We asked whether the ploidy level change that accompanies the formation of new asexual lineages triggers methylation changes that contribute to heritable epigenetic variation within novel asexual lineages. Comparison of MS-AFLP and AFLP fragment inheritance in a diploid × triploid cross revealed de novo methylation variation between triploid F1 individuals. Genetically identical offspring of asexual F1 plants showed modest levels of methylation variation, comparable to background levels as observed among sibs in a long-established asexual lineage. Thus, the cross between ploidy levels triggered de novo methylation variation between asexual lineages, whereas it did not seem to contribute directly to variation within new asexual lineages. The observed background level of methylation variation suggests that considerable autonomous methylation variation could build up within asexual lineages under natural conditions.

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