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.
