Abstract: The present invention relates to a mutant plant of the Cucurbitaceae family comprising a modified CENH3 gene, which mutant plant, when crossed to a wild-type plant having 2n chromosomes produces progeny, at least 0.1% of which have n chromosomes. Preferably, the modified CENH3 gene comprises at least one mutation compared to an otherwise identical naturally occurring CENH3 gene, which at least one mutation gives rise to at least one non-conservative amino acid change in the Histone Fold Domain of the encoded modified CENH3 protein or to the occurrence of a premature stop codon in the encoded modified CENH3 protein. The invention further relates to a method for the production of haploid or doubled haploid plants and to the plants thus obtained.

Abstract: The present invention relates to a mutant plant of the Cucurbitaceae family comprising a modified CENP-C gene, which mutant plant when crossed to a wild-type plant having 2n chromosomes produces progeny, at least 0.1% of which have n chromosomes. The modification comprises for example a mutation in the CENP-C gene that leads to the occurrence of a premature stop codon or to a non-conservative amino acid change in the C-terminal region of the encoded protein. The plant is for example a Cucumis sativus plant and the modified CENP-C gene encodes a modified CENP-C protein that comprises at least one not-tolerated amino acid change or a premature stop codon in the C-terminal region, when compared to the CENP-C protein of SEQ ID No:1, in particular a mutation selected from E674K and S650N.

Abstract: The present invention relates to a method for the transformation of plastid genomes of plant species, in particular Asteraceae plant species, comprising the steps of providing a transformation vector carrying a DNA sequence of interest; subjecting a plant material, which comprises plastids, to a transformation treatment in order to allow the plastids to receive the transformation vector; placing the thus treated plant material for a period of time into contact with a culture medium without selection agent; subsequently placing the plant material into contact with a culture medium comprising a selection agent; and refreshing the culture medium comprising a selection agent to allow plant material comprising plastids that have acquired the DNA of interest to grow into transformants.

Abstract: The present invention relates to a method for the transformation of plastid genomes of plant species, in particular Asteraceae plant species, comprising the steps of providing a transformation vector carrying a DNA sequence of interest; subjecting a plant material, which comprises plastids, to a transformation treatment in order to allow the plastids to receive the transformation vector; placing the thus treated plant material for a period of time into contact with a culture medium without selection agent; subsequently placing the plant material into contact with a culture medium comprising a selection agent; and refreshing the culture medium comprising a selection agent to allow plant material comprising plastids that have acquired the DNA of interest to grow into transformants.

Abstract: The present invention relates to a method for the transformation of plastid genomes of plant species, in particular Asteraceae plant species, comprising the steps of providing a transformation vector carrying a DNA sequence of interest; subjecting a plant material, which comprises plastids, to a transformation treatment in order to allow the plastids to receive the transformation vector; placing the thus treated plant material for a period of time into contact with a culture medium without selection agent; subsequently placing the plant material into contact with a culture medium comprising a selection agent; and refreshing the culture medium comprising a selection agent to allow plant material comprising plastids that have acquired the DNA of interest to grow into transformants.

Abstract: The invention relates to a method for producing haploid plant embryos, comprising providing microspores or pollen that comprise cell division inducing molecules; pollinating an embryo sac cell, in particular an egg cell, of the plant of which the haploid embryo is to be made with the microspores or pollen; allowing the microspores or pollen to discharge the cell division inducing molecules in or in the vicinity of the embryo sac cell, in particular the egg cell, to trigger division thereof to obtain a haploid plant embryo. When doubled haploid plant embryos are to be produced doubling of the chromosome number takes place at a certain stage after pollination, in particular during cell division or after obtaining the embryo. The invention further relates to the embryos thus obtained, plants regenerated therefrom and progeny thereof.