Genetic control of the development of the haploid generation in Oenothera

The haploid generation of higher plants has to be considered in its own individuality. Special experimental designs are needed to investigate the developmental processes of the male and female gametophytes between meiosis and fertilization. Experiments on Oenothera demonstrate the existence of genes, which action can be described as influencing the competition between meiospores or between gametophytes, or as interaction between different individuals, the gametophytic-gametophytic and gametophytic-sporophytic incompatibility. The development of the haploid generation is regulated by genes. Some of these genes are active only in this phase of the life cycle

Pollen ontogenesis in Oenothera: a comparison of genotypically normal anthers with the male-sterile mutant sterilis

A 12-stage “normal table” of anther development in Oenothera, is presented. The stages are characterized by developmental steps in the reproductive cells and the tapetum, including waves of amylogenesis and lipogenesis as well as the production of the sporoderm layers. This is compared to a corresponding table for the male-sterile (mst) mutant sterilis (ster). Differences between the development of fertile and mst anthers appear after the liberation of the microspores from the tetrads. Male sterility results from a malfunction of the tapetum in the production of ektexine sporopollenin precursors, which aggregate in the tapetal cells. The consequence is the absence of ektexine from the microspores. The endexine is then dissolved, presumably by an enzyme. This process leads to naked microspores whose unprotected cytoplasms are attacked by hydrolytic enzymes present in the thecal fluid. At anthesis the anthers contain only undefined remnants of microspores and tapetum.Fil: Noher de Halac, Inés. Universidad Católica de Córdoba. Facultad de Ciencias de la Salud; ArgentinaFil: Cismondi, Inés Adriana. Universidad Católica de Córdoba. Facultad de Ciencias de la Salud; ArgentinaFil: Harte, Cornelia. Institut für Entwicklungsphysiologie, Universität Köln; Alemani