[The influence of 24-epibrassidinole on the hormone status of wheat plants under sodium chloride].

We studied the influence of the preconditioning of wheat germ (Triticum aestivum L.) with 0.4 microM 24-epibrassidinole (EB) on the growth and hormone status of plants under the influence of 2% NaCl. The preconditioning with EB promoted the lowering of the extent of the damaging influence of pickling on the growth of germs. The important contribution to the realization of the protective action of EB in the preconditioning of plants is probably that of its ability to lower the level of stress-induced abscisic acid accumulation and the decrease in the content of indole-acetic acid. At the same time, the cytokinin concentration in plants preconditioned with EB under pickling was practically the same as in plants without stress. This fact combined with data about the ability of EB to induce the increase in cytokinin content in wheat, obtained before, allowed us to assume that the protective action of EB on plants is connected, first of all, with the prevention of the increase in level of hormones of cytokinin nature under pickling.

[Mechanisms of protective action of wheat germ agglutinin on cell growth in wheat seedling roots under salinity]. / Mekhanizmy zashchitnogo vliianiia aggliutinina zarodysha pshenitsy na rost kletok kornei prorostkov pshenitsy pri zasolenii.

Effects of 20 nM wheat germ agglutinin (WGA) on relative growth rate, mitotic index (MI) and the cell area in the root extension zone were investigated in seedling of Triticum aestivum L. under the influence of 2% NaCl. It was elucidated that pretreatment of wheat seedling with WGA prevented a salinity induced inhibition of root cell growth, and accelerated the restoration of cell growth after stress removal. The protective WGA effect on root cell growth may be due, presumably, to reorganization of phytohormone balance caused by WGA treatment, which could lead to accumulation of LAA and decrease in the ABA level.

[NOR (nucleolar organizer region) activity in wheat species with different ploidy levels treated with phytohormones]. / Aktivnost' IaOR u pshenits raznogo urovnia ploidnosti pri vozdeistvii fitogormonov.

The effects of the phytohormones 6-benzylaminopurine (BAP) and 24-epibrassinolide (EB) on the nucleolar sizes in the interphase nuclei of root meristem were studied using the silver-staining procedure in wheat species with different ploidy levels (a polyploid series). In addition, the effects of the phytohormones on the cell mitotic activity in the roots of 5-day-old seedlings were studied. The higher the wheat species ploidy level, the higher its sensitivities to BAP and EB were. In diploid wheat, the maximum increase in the nucleolar organizing region (NOR) activity was observed after treatment with considerably higher phytohormone concentrations compared to tetra- and hexaploid wheat species. The phytohormone treatment increased both the sizes and the number of nucleoli in meristematic cells of seedling roots in all wheat species studied. It was assumed that the differences between the responses of wheat species with three different ploidy levels to different concentrations of phytohormones were related to their effects on the methylation/demethylation of cytosine residues in the rDNA promoter region.

[Pattern of formation of nuclear chromosomal apparatus after remote hybridization in wheat and buckwheat: effect of low temperature]. / Osobennosti formirovaniia khromosomnogo apparata iadra pri otdalennoi gibridizatsii pshenitsy i grechikhi: deistvie ponizhennoi temperatury.

We studied the pattern of embryo formation in wheat and buckwheat interspecific hybrids. Formation of non-reduced gametes in the embryo sac was induced by low temperature (4-7 degrees C). Changed thermal conditions during meiosis proved to favor formation of hybrid embryos. Vital embryos have been obtained. Karyotypic analysis on the metaphase plates from the root meristem demonstrated different genotypes. Heterogeneous embryos caring both maternal and paternal chromosomes as well as the embryos caring solely maternal or paternal chromosomes have been revealed. Spermatozoa penetrate the embryo sac as a cell, which increases aminopeptidase activity. Sometimes low temperature induces formation of somatic embryos from nucellus cells in the plants.