CONICET | Buscador de Institutos y Recursos Humanos

Background and Aims: The diploid cytotype of P. rufum reproduces by sexuality and is self-sterile. However, recurrent auto-polyploidization through 2n + n fertilization and the ability for apomixis were documented in one genotype of the species. The objectives of this work were to analyze the variation in the functionality of apomixis components in diploid genotypes of P. rufum and identify individuals with contrasting reproductive behaviours. Methods: Samples of five individuals from three natural populations (R2, R5 and R6) were used. Seeds were obtained after open pollination, selfing, conspecific interploidy crosses and interspecific interploidy self-pollination induction. Reproductive behaviour of each plant was determined by using the Flow Cytometric Seed Screen (FCSS) method. Embryo sacs were observed by using the clearing technique. Key Results: In open pollination all genotypes form seeds by sexuality and no evidences of apomeiotic reproduction were detected. However, in conspecific interploidy crosses and interspecific interploidy self-pollination induction, variations in the reproductive pathways were observed. While all plants from population R2 and R6 formed seeds exclusively by sexuality, three genotypes from R5 developed seeds from both meiotic and aposporous embryo sacs, and one of them (R5#49) through the complete apomictic pathway (apospory + parthenogenesis + pseudogamy). Cytoembryological observations revealed the presence of both meiotic and aposporous embryo sacs in all genotypes analyzed suggesting that parthenogenesis could be uncoupled from apospory in some genotypes. Conclusions: Results presented in this work demonstrated the existence of variation in the functionality of apomixis components in natural diploid genotypes of P. rufum and allowed the identification of individuals with contrasting reproductive behaviours.

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