Practice question

Gynogenesis derives haploid plants from female gametic lineage, typically through in vitro culture of unpollinated ovules, ovaries, or isolated embryo sacs under defined media conditions. Under specific culture conditions, cells of embryo sac such as egg cell, synergids, antipodals, or nucellar tissue undergo sporophytic development without fertilization, forming haploid embryo with maternal genome and maternal cytoplasm. Unlike androgenesis that samples male gametes, gynogenesis recovers maternal genotype useful when male gametophyte is recalcitrant or expresses self-incompatibility leading to albinism. Sugar beet, onion, cucumber, and melon routinely use ovule culture to generate haploids because anther culture produces predominantly albino or low-response plants in these species. Procedure involves surface sterilization of flower buds, aseptic excision of ovules before anthesis, placement on inductive media enriched with sucrose and growth regulators, and sequential regeneration steps before chromosome doubling to create maternal doubled haploids capturing maternal combinations. In some species, unfertilized ovule culture also generates diploid plants through somatic tissue of integuments, requiring marker analysis to distinguish true gynogenic haploids from somatic clones; careful flow cytometry and microsatellite genotyping ensure true haploid origin and maternal inheritance before chromosome doubling and field evaluation.