Abstract
EXPORTIN1 proteins control
the nucleo-cytoplasmic shuttling of proteins in eukaryotes but their function
has not been genetically assessed in plants. We show that single mutants of the
two EXPORTIN1 genes in Arabidopsis
thaliana have no phenotypes, but that double mutants are
gametophytic-defective. Pollen
grains carrying both mutant alleles are poorly competitive whereas embryo sacs
were arrested at different stages. Depending on the genotype of the maternal sporophyte,
fertilization of the egg cell could occur but zygotes never developed. Our
findings show that EXPORTIN1 function is required to complete female
gametogenesis and in the transition from maternal to embryonic development.
Figure legend > a3/+; b1/b1 (A-D, upper panel) a3/a3;
b1/+ (E-G, I-J, lower panel). Open mature siliques, arrowheads
indicate aborted or undeveloped ovules. (B,F) Decolorized aniline blue (DAB)-stained pistils 3 days after pollination. Genotypes
are given for the female gametophyte. (C,D,G,I,J) DIC images of whole-mounted cleared a3/a3; b1/
b1 ovules. Percentages
represent the occurrence of the depicted phenotype. Arrowheads show endosperm
nuclei in G and I, or the zygote in J. (H) Single ovule PCR to detect the paternal XPO1A allele, three days after pollination of a3/a3; b1/+ pistils with wt pollen. Bars equal 20 um except in A, E: 500 um and in B, F: 100 um.
Attached is the full version of the paper published in Genetics. | Phenotype of xpo1 female gametophytes in sesqimutants.  2 genotypically identical embryo sacs have different phenotypes depending on the mother. |