INVESTIGADORES
DELGADO Luciana
congresos y reuniones científicas
Título:
VARIATION AND INHERITANCE FOR APOMICTIC COMPONENT IN DIPLOID PASPALUM RUFUM
Autor/es:
DELGADO LUCIANA; SARTOR, MARÍA E.; GALDEANO, FLORENCIA; ZULIANI, JULIÁN; ESPINOZA, FRANCISCO; ORTIZ, JUAN PABLO AMELIO
Lugar:
Bahía Blanca
Reunión:
Seminario; IV Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis en gramíneas forrajeras; 2014
Institución organizadora:
CERZOS, CONICET-UNS
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.