Romanchuk S. Expression of a β-glucosidase gene and ultrastructure of endoplasmic reticulum bodies in root cells of Аrabidopsis thaliana under the influence of clinorotation and ionizing radiation

The dissertation is devoted to investigations of the influence of simulated microgravity (slow clinorotation, 2 rev/min) and ionizing radiation (X-radiation in doses of 0,5 Gy – 12 Gy), to some extent, being equivalent to those in the cabin of manned spacecraft, on the endoplasmic reticulum bodies (ER-bodies), containing β-glucosidase enzyme and being inherent in Brassicaceae species, in root cells of A. thaliana model object, by methods of light, confocal, and transmission electron microscopy, biochemistry and molecular biology, to determine the participation of ER-bodies in plant tolerance to the effects of these factors. A significant increase in the average area of ER-bodies on the section of cell in the root cap and in the root distal elongation zone, and their variability in shape and size, which may indicate an increase in the accumulation of β-glucosidase in them, as well as the profiles of granular endoplasmic reticulum, both under the influence of clinorotation and X-irradiation have been established. The total enzyme activity was almost unchanged under clinorotation compared to the control, but increased significantly after X-irradiation to varying degrees depending on the radiation dose. The rapid activation of PYK10 gene expression in seedlings under clinorotation and in the first hours after X-irradiation was recorded. On the 10th day after irradiation, PYK10 gene expression levels and total β-glucosidase activity decreased as compared with those at 2 h after irradiation. Increasing the expression of PYK10 gene under clinorotation allows us to assign it to the list of stress genes that respond to microgravity, i.e, they are gravisensitive. The obtained data demonstrate the involvement of the granular endoplasmic reticulum and its derivatives ER-bodies in responses to the action of the clinorotation and X-irradiation and tolerance of A. thaliana seedlings, as evidenced by the absence of deviations in the morphology and growth of seedlings under the influence of these factors. The established patterns open up new approaches to the study and knowledge of the mechanisms of plant adaptation at the cellular and molecular levels to spaceflight conditions.