β-glucosidase PYK 10 gene expression in Arabidopsis thaliana (L.) Heynh. seedlings under clinorotation and X-radiation

Aim. Among plants used in spaceflight experiments, species of family Brassicaceae are considered as the most resistant to radiation exposure. It is supposed that ER-bodies, which are derivative of granular endoplasmic reticulum and selectively accumulate an enzyme β-glucosidase, may be responsible for this resistance. We firstly investigated expression of β-glucosidase PYK10 gene in A. thaliana seedlings under slow horizontal clinorotation and Х-radiation of doses 0.5 Gy, 1 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, 10 Gy, and 12 Gy. Methods. Seedlings were grown on agar nutrient medium. PYK 10 expression was determined using a method of real-time PCR. Results. Significant enhancement of PYK 10 expression and increasing a number of ER-bodies in A. thaliana seedlings under the influence of clinorotation and X-radiation in comparison with control was established. An increase in the number of ER-bodies was due to PYK 10 high expression and β-glucosidase synthesis without a rise of enzyme activity under clinorotation, while β-glucosidase activity increased under X-radiation. Plant responses to X-radiation became adaptive during 10 days after radiation, in which β-glucosidase plays a crucial role. Conclusions. Increased PYK 10 expression in A. thaliana seedlings under clinorotation and X-radiation is a part of the internal program of plant protection against the action of environmental factors. ER-bodies containing β-glucosidase may be one of the main components of the plant protection system from the influence of clinorotation and X-radiation. Keywords: Arabidopsis thaliana (L.) Heynh., ER-bodies, β-glucosidase, gene expression, clinorotation, Х-radiation.