Embryo lethality in x-ray induced 1-1 heterozygous mutants.
(a) xri1-1 heterozygotes have reduced seed set, with approximately half the number of seeds per silique relative to wild-type plants. This defect is complemented in plants homozygous for an XRI1 genomic transgene. Homozygous xri1-1 plants are sterile.
(b) Dissected siliques reveal the presence of aborted embryos (arrowed) in heterozygotes, which are not found in wild-type plants or plants complemented with the wild-type XRI1 gene. Scale bar = 1 mm.
(c) Confocal laser scanning microscopy images of DAPI-stained pollen from wild-type (WT) and heterozygous xri1-1+/− plants. WT pollen is tricellular, with two generative nuclei (arrowed) and a vegetative nucleus. Pollen from heterozygous xri1-1 is an approximately equal mix of tricellular and bicellular pollen, which has only one generative nucleus. Scale bar = 10 μm.
(d) Quantification of uni-, bi- and tricellular pollen frequencies in wild-type, xri−/+ heterozygotes and complemented xri−/+ heterozygotes.