ABSTRACT
In this study, ultrastructures of anther wall and sporogenous tissue of Leucojum aestivum were investigated during different developmental stages. Cytomictic channels were seen between pollen mother cells during prophase I. Polar distribution was described in the organelle content of pollen mother cells and microspores in early phases of microsporogenesis and also in pollen mitosis. Active secretion was observed in tapetal cells. Previous reports about developmental stages of male gametophyte were compared with the results of this study.
Subject(s)
Liliaceae/growth & development , Liliaceae/ultrastructure , Plant Cells/ultrastructure , Spores/ultrastructure , AnimalsABSTRACT
Garden asparagus, Asparagus officinalis, is reproductively isolated from a related ornamental species with potential breeding value, Asparagus densiflorus cv. Sprengeri, by pre- and post-zygotic barriers. The latter barrier operates at the endosperm level five days after pollination in A. officinalis x A. densiflorus crosses. To try to circumvent this barrier, in vitro embryo rescue using ovule and ovary cultures was tested. Controlled interspecific crosses were made and 2,032 ovules and 826 ovaries were cultured three days after pollination under various culture media and incubation conditions. Ovaries cultured for 60 days became red (similar to mature fruits), but seed formation was incomplete. Transfer of ovules to other media was necessary to promote embryo development. The interspecific embryos increased their length from 35 microns at the initiation of culture to 1,900 microns after 120 days of culture, but seedlings were not obtained. Histological studies revealed differentiation of protoderm only. The possible causes of the failure of the embryos to complete differentiation and morphogenesis are discussed.(AU)
Subject(s)
RESEARCH SUPPORT, NON-U.S. GOVT , Adenine/analogs & derivatives , Cells, Cultured/metabolism , Chimera/growth & development , Germination/physiology , Liliaceae/growth & development , Seeds/growth & development , 2,4-Dichlorophenoxyacetic Acid/pharmacology , Adenine/pharmacology , Cell Culture Techniques , Cell Differentiation/drug effects , Cell Differentiation/physiology , Cells, Cultured/cytology , Cells, Cultured/drug effects , Chimera/physiology , Culture Media , Germination/drug effects , Gibberellins/pharmacology , Liliaceae/drug effects , Liliaceae/metabolism , Naphthaleneacetic Acids/pharmacology , Plant Growth Regulators/pharmacology , Plants/cytology , Plants/growth & development , Plants/metabolism , Seeds/drug effects , Seeds/metabolism , Vitamins/pharmacologyABSTRACT
Garden asparagus, Asparagus officinalis, is reproductively isolated from a related ornamental species with potential breeding value, Asparagus densiflorus cv. Sprengeri, by pre- and post-zygotic barriers. The latter barrier operates at the endosperm level five days after pollination in A. officinalis x A. densiflorus crosses. To try to circumvent this barrier, in vitro embryo rescue using ovule and ovary cultures was tested. Controlled interspecific crosses were made and 2,032 ovules and 826 ovaries were cultured three days after pollination under various culture media and incubation conditions. Ovaries cultured for 60 days became red (similar to mature fruits), but seed formation was incomplete. Transfer of ovules to other media was necessary to promote embryo development. The interspecific embryos increased their length from 35 microns at the initiation of culture to 1,900 microns after 120 days of culture, but seedlings were not obtained. Histological studies revealed differentiation of protoderm only. The possible causes of the failure of the embryos to complete differentiation and morphogenesis are discussed.