IBONE   05434
INSTITUTO DE BOTANICA DEL NORDESTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
VARIATION AND INHERITANCE FOR APOMICTIC COMPONENT IN DIPLOID PASPALUM RUFUM
Autor/es:
DELGADO L; SARTOR ME; GALDEANO F; ZULIANI J; ESPINOZA F; ORTIZ JPA
Lugar:
Bahia Blanca
Reunión:
Workshop; IV Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis en gramíneas forrajeras; 2014
Institución organizadora:
Universidad Nacional del Sur/CERZOS-CONICET
Resumen:
The diploid cytotype of Paspalum rufum (Poaceae) reproduces sexually and is self-sterile however recurrent autopolyploidization through 2n + n fertilization and the ability for apomixis reproduction have been documented in the species. The objectives of this work were to analyze the variation in the functionality of apomixis components in diploid genotypes and explore the inheritance of apospory in a F1 segregant populations derived from individuals with contrasting reproductive behaviors. Works were initiated selecting five individuals from three natural diploid populations (R2, R5 and R6). The reproductive mode of each plant was determined by flow cytometric seed screen (FCSS) analysis and clearing of ovaries at anthesis. Previous works determined that all genotypes formed seeds by sexuality in open pollination conditions. However, in con-specific and inter-specific inter-ploidy crosses and self-pollination induction, several genotypes evidenced variations in the reproductive pathways. While all plants from populations R2 and R6 formed seeds exclusively by sexuality, three genotypes from the R5 developed seeds from both meiotic and aposporous embryo sacs, and one of them (R5#49) was able to complete the apomictic pathway (apospory + parthenogenesis + pseudogamy). Interestingly, embryological observations revealed the presence of both meiotic and aposporous embryo sacs in all genotypes analyzed, suggesting that apospory could be uncoupled from parthenogenesis. Individuals with contrasting reproductive behavior were crossed and the resultant F1 population was analyzed by cytoembryological observations. Genetic analysis of the mode of reproduction of hybrids showed a 15:1 ratio between aposporous vs non-aposporous (meiotic) plants. Furthermore, percentage of apospory showed a transgressive segregation and five types of phenotypes (according to the % of aposporous sacs) could be identified. The results presented here demonstrate the existence of variation in the functionality of apomixis components in natural diploid genotypes of P. rufum. Moreover, the inheritance analysis suggested the presence of at least two (duplicated) additive genes affecting apospory expression. The individuals with contrasting reproductive behaviors identified are valuable material for additional studies of apomixis components at the diploid level. Moreover, analysis of their expression patterns, quantification of specific transcript levels and the understanding of their regulation mechanisms could help to design new strategies for recreating apomixis in a diploid genome environment. In addition, the different proportion of apospory observed in the F1 hybrids opens the possibility for studying the mechanisms controlling the expressivity of the trait in a diploid genetic background.