Gynogenesis is an asexual mode of reproduction common to
animals and plants, in which stimuli from the sperm cell trigger
the development of the unfertilized egg cell into a haploid embryo.
Fine mapping restricted a major maize QTL (quantitative trait
locus) responsible for the aptitude of inducer lines to trigger gynogenesis
to a zone containing a single gene NOT LIKE DAD (NLD)
coding for a patatin-like phospholipase A. In all surveyed inducer
lines, NLD carries a 4-bp insertion leading to a predicted truncated
protein. This frameshift mutation is responsible for haploid induction
because complementation with wild-type NLD abolishes the
haploid induction capacity. Activity of the NLD promoter is
restricted to mature pollen and pollen tube. The translational
NLD::citrine fusion protein likely localizes to the sperm cell plasma
membrane. In Arabidopsis roots, the truncated protein is no longer
localized to the plasma membrane, contrary to the wild-type NLD
protein. In conclusion, an intact pollen-specific phospholipase is
required for successful sexual reproduction and its targeted
disruption may allow establishing powerful haploid breeding tools
in numerous crops.