Plant & Animal Genome IX Conference

Workshop: Apomixis
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GENETIC DISSECTION OF DIPLOSPOROUS AUTONOMOUS APOMIXIS IN TARAXACUM

¹ Netherlands Institute of Ecology (NIOO-CTO), PO Box 40, 6666 ZG, Heteren, The Netherlands

² Laboratory of Genetics, Wageningen University, Dreijenlaan 2, 6703 HA, Wageningen, The Netherlands

In apomictic Taraxacum, reduction during meiosis I is replaced by nuclear restitution (Taraxacum type of diplospory); embryo and endosperm development are autonomous. We dissected apomixis in intraspecific crosses between sexual diploids (2x=16) and apomictic triploids(3x=24). Progenies were analyzed using flow cytometry, co-dominant DNA markers and cyto-embryological techniques. Recovery of recombinants in which diplospory, embryo parthenogenesis and endosperm autonomy were uncoupled indicates that apomixis is controlled by several independent genes. The genetics of diplospory was studied in detail. Segregation studies and linkage analysis reveal that diplospory is controlled by a single dominant gene located on one of the satellite chromosomes. Diplospory-linked markers were absent in diploid hybrid progeny, suggesting that they were not transmitted via haploid pollen grains. Further analysis revealed that non-transmission was not caused by preferential chromosome pairing (univalent inheritance), but because of recessive lethality of the diplospory chromosomal region.