Influence of change in the proportion of H1 histone variants on microsporogenesis and development of male gametophyte in transgenic plants of tobacco [Nicotiana tabacum L.]

As continuation of investigations in to the mechanism of the role of the H1 histone, which is a crucial protein component chromosomes of all eukaryotes, transgenic tobacco plants with different levels of the H1 histone variants were examined. Tobacco has six sequential variants of the H1 histone: two major ones (H1A and H1B), constituting ca. 90% of all H1, and four minor ones (H1C, H1D, H1E and H1F), occurring in very small quantities. The following groups of plants were examined: K - control group with a full set of histone variants; -AB -with the A and B variants removed; -ABCD - with the A, B, C and D variants removed; and -CD - with the C and D variants removed. The analysis of microsporogenesis in those plants, based on preparations squeezed in acetoorcein, revealed the asynchronous course of meiosis in -AB and -ABCD plants, occurrence of chromosomal aberration, and, consequently, the formation of sterile pollen grains (accordingly: 84,4% and 81,4%). In -CD plants, the percentage of aberration and sterile pollen grains was similar to the control material. Electron microscope observations of microsporogenesis showed ultrastructural changes. In -AB and -ABCD plants, a major portion of the pollen grains were degraded. The smallest number of degraded pollen grains, in comparison with the control, was found in the -CD group.