Authors:I. Marcińska, I. Czyczyło-Mysza, E. Skrzypek, M. Warchoł, K. Zieliński and E. Dubas
The aim of this study was to determine the effect of selected factors on rye (Secale cereale L.) haploid embryo production by the wide crossing method. The study was performed on fifteen winter rye genotypes. This is the first time for rye when besides the genotype, on the enlargement of ovaries and haploid embryo production, such factors as: type of auxin analogues 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 4-amino-3,5,6-trichloropyridine-2-carboxylic acid (picloram), and the time between florets emasculation and pollination were investigated. All factors had a significant impact on rye ovary enlargement, however the haploid embryo formation depended only on rye genotype, not on kind of auxin and days between emasculation to pollination. In total, twenty one haploid embryos were formed by six genotypes of fifteen tested. On average, 13.86% (after 2,4-D treatment) to 20.05% (after dicamba treatment) enlarged ovaries per emasculated florets were obtained. Most of the ovaries enlarged when florets were pollinated 4 and 6 days after emasculation. Most of the haploid embryos formed when florets were pollinated 6 days after emasculation. The obtained haploid embryos did not germinate.
The first steps in studies on the female and male gametophytes of wheat involved the light microscope analysis of semi-thin sections of embryo sacs containing egg-cells developing in planta. The information thus obtained on the development of the egg-cell from its initial formation to maturity contributed to the successful isolation of egg-cells. The morphological and ultrastructural details of egg-cells isolated 3, 6, 9, 12, 15 and 18 days after emasculation were examined to determine the function of the female gametophyte and its suitability for micromanipulation. A sufficient number of gametoplasts in the right stage of development are required for the successful microinjection and in vitro fusion of egg-cells and male gametes. No data are yet available on the fusiogenicity of wheat egg-cells in various stages of development. Various in vitro fertilisation and microinjection techniques could be of service in gamete fusion experiments aimed at the creation of interspecific and intergeneric hybrids which do not occur in nature due to sporophytic incompatibility. The results acquired in investigations on immature embryos can be used for the study of embryos developing from egg-cells fertilised in vitro.