Epsilon Archive for Student Projects

Abstract

In Arabidopsis, endosperm development is very important for viable seed development.
Especially, endosperm cellularization is a crucial event for embryo survival and if it fails, can
lead to embryo arrest, as observed in seeds derived from interploidy and interspecies
hybridization. In case of interploidy crosses, increased ploidy level creates genome dosage
imbalance in endosperm and in case of different species, a similar dosage imbalance basis is
suspected, but remains to be broadly established. In this study, we investigated the viability of
hybrid seeds between two outbreeding species, Arabidopsis lyrata and A. arenosa, in relation
with the development of their endosperm. A. lyrata × A. arenosa (Female × Male) hybrid seeds
were shrivelled, dark brown and inviable, with delayed endosperm cellularization. In contrast,
A. arenosa × A. lyrata produced tiny inviable seeds with precocious endosperm cellularization.
We also investigated if similar mechanisms could exist between different populations of the
same species A. lyrata. In case of intraspecies crosses, A. lyrata Austrian population, when
used as seed plant, produced tiny seeds and when used as pollen donor, produced shrivelled
dark brown aborted seeds. However, no differences in endosperm cellularization were
identified. According to our results, we propose that the hybridization barrier observed between
A. lyrata and A. arenosa and between A. lyrata populations is a consequence of different levels
of parental conflict experienced by the mating partners. Finally, the genetic analysis of A.
arenosa and A. lyrata hybridization barrier suggests that cross direction-dependent multiple
loci are responsible for the non-reciprocal hybrid seed defects we observed.