The influence of rhizobacteria on the relative expression level of ethylene and abscisic acid biosynthesis genes in potato microplants under osmotic stress

Abstract

Background. Inoculation with rhizobacteria Azospirillum baldaniorum Sp245 and Ochrobactrum cytisi IPA7.2, either individually or in combination, alleviated the effects of osmotic stress on potato microplants (Solanum tuberosum L.). The influence of the bacterial combination of these strains on the relative expression level of genes associated with the anti‑stress response in microclones of the “Nevsky” potato cultivar under osmotic stress in vitro was investigated. Materials and methods. The microplants were cultivated under sterile conditions or inoculated with the strains A. baldaniorum Sp245 and O. cytisi IPA7.2. Osmotic stress was simulated by adding 2.5 % polyethylene glycol (PEG 6000) to the nutrient medium. The relative expression of genes associated with the anti‑stress response was assessed under osmotic stress and bacterial inoculation, either individually or in combination. Results. Under osmotic stress, the gene expression patterns in intact plants and those inoculated with bacteria changed similarly; however, in some cases, inoculation had a more significant effect. This was manifested as: a decreased expression level of ethylene metabolism‑related genes; an increased expression of the StABF2 gene, which encodes an ABA‑dependent protein; a sharp decrease in the expression of the StCYP707A gene, responsible for ABA catabolism. Conclusions. The bacteria contributed to maintaining a homeostatic state of the system, conferring lower sensitivity of inoculated plants to stress compared with sterile plants.