Selective ablation of diploid embryos
Methods of selecting haploid embryos are disclosed. Methods of producing haploid embryos and non-viable diploid embryos on a plant are provided. Methods for selecting haploid embryos produced from haploid inducer maize lines are provided. Methods for producing improved maize haploid inducer lines are disclosed. Maize haploid inducer lines comprising transgenes causing ablated or abnormal diploid embryos are disclosed.
1. A method of selecting for haploid maize embryos comprising:
a) pollinating a first maize plant with the pollen from a maize haploid inducer line to produce embryos wherein said maize haploid inducer line comprises an embryo expressed lethal polynucleotide operably linked to an embryo-preferred promoter, a non-transmission pollen polynucleotide operably linked to a pollen-specific promoter, and an embryo expressed inhibitor polynucleotide that prevents the lethality of said embryo expressed lethal polynucleotide wherein said non-transmission pollen polynucleotide and said embryo expressed inhibitor polynucleotide are linked so that they will segregate together;
b) producing haploid embryos and non-viable diploid embryos; and
c) selecting haploid maize embryos;
further wherein said embryo expressed lethal polynucleotide is barnase and said embryo expressed inhibitor polynucleotide is barstar.
2. A transgenic maize haploid inducer line comprising a first and second expression cassette, wherein said first expression cassette comprises a polynucleotide that is lethal to embryos operably linked to an embryo-preferred promoter and wherein said second cassette comprises a non-transmission pollen polynucleotide operably linked to a pollen-specific promoter and a polynucleotide that inhibits the lethality of said polynucleotide that is lethal to embryos, wherein said polynucleotide that is lethal to embryos is a barnase polynucleotide and said polynucleotide that inhibits the lethality of said polynucleotide that is lethal to embryos is a barstar polynucleotide.
3. The transgenic maize haploid inducer line of claim 2 wherein said polynucleotide that is lethal to embryos is operably linked to a lec1 promoter.
4. A transgenic maize haploid inducer line comprising a first and second expression cassette wherein; said first expression cassette comprises a barnase polynucleotide that is operably linked to a led promoter and is lethal to embryos and wherein; said second cassette comprises a barstar polynucleotide that inhibits the lethality of said polynucleotide that is lethal to embryos and wherein, said second expression cassette also comprises an alpha-amylase polynucleotide operably linked to a PG47 promoter wherein expression of said alpha-amylase polynucleotide operably linked to a PG47 promoter does not allow pollen transmission.