embryo sac

Megaspore- and megagametophytogenesis in tobacco mutant with reduced cells number in embryo sacs were studied. It is established, that the mutation causes a disturbance of one pair of homologous chromosomes conjugation in meiosis. Consequently alongside with the haploid (24-chromosomal) spores aneuploid (23-chromosomal) spores forms which are developed into abnormal embryo sacs. At cenocyte stage of megagametophytes development falling out of 1-2 mitoses and/or their abnormal course were observed, as well as abnormalities in embryo sacs polarization.

The embryo sacs structure in the two mutant lines of Nicotiana tabacum L. was investigated. The various disturbances in the megagametopyte structure were detected. In the М-3 line the gametophyte mutation suppresses the nucleus mitotic activity and cell walls initiation in embryo sacs. These disturbances lead to the formation of low-nuclear coenocytic or cellular gametophytes. In М-2 line the cellular gametophytes with increased number of cells and nucleus was dominated. The reason of this phenomenon is an increase of mitosis number during a gametophytogenesis.

The research of extreme low (10°С) and high (37°С) temperatures influence under in vitro conditions on phenotypic display of three mutations in Nicotiana tabacum L. with of a certain morphological type domination was conducted. The BG-141.4 line is character- ized by low-cellular embryo sacs formation, in the SG-27/4 line the trait of the increased number of nucleus and cells in embryo sacs exhibits, the line М-3 differs by high frequency of cenocyte low- cellular embryo sacs.

Laburnum anagyroides Medik. (Leguminosae) is a promising ornamental woody plant, which is native to the Mediterranean. It is characterized by the following indicators of seed reproduction during introduction in the Lower Volga region: potential seed productivity is 5.24 ± 0.08 ovules on 1 ovary, real seed productivity is 1.53 ± 0.05 seeds per 1 fruit, the reproduction efficiency coefficient is 29.2%. Seeds quickly pass into a state of deep physical rest and cannot independently leave this state in spring.