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.
The function of the patatin‐like phospholipase A NOT LIKE DAD (NLD) in the sperm cells of maize pollen is necessary for successful fertilization, whereas its disruption promotes the development of haploid embryos, which represent an important plant breeding tool.
Fine mapping restricted a major QTL (quantitative trait locus) responsible for haploid induction in maize to an interval containing a single gene coding for NLD.
A 4‐bp insertion in NLD leading to a predicted truncated protein is responsible for haploid induction.
Expression of NLD is restricted to sperm cells.
Wild‐type NLD is anchored to the plasma membrane, whereas the truncated protein present in inducer lines loses its membrane attachment.
Mutation of NLD orthologs may allow to establish doubled haploid breeding techniques in crop species lacking such tools.
- Received January 26, 2017.
- Revision received February 8, 2017.
- Accepted February 9, 2017.
- © 2017 The Authors
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