Embryogenesis at the crossroads - some perspectives on over a century of plant embryo research

Much of the early research in embryogenesis in flowering plants was restricted to comparative and descriptive studies of embryo and endosperm development in a number of species. This was followed by a period in which experimental studies involving isolation and culture of progressively smaller embryos, induction of embryo-like structures in the somatic cells of plants and deflection of pollen grains of cultured anthers in the embryogenic pathway, predominated. Emphasis in recent years has been on the molecular and genetic analysis of embryogenesis using one or two model systems. The isolation of embryo-defective mutants from Arabidopsis and characterization of the protein products of the mutated genes have provided new information on gene action in the zygote and its immediate division products during progressive development of the embryo.