SUMMARY. To elucidate the possible role of the transcription factor JIN1/MYC2 in implementation of stress-protective effects of abscisic acid (ABA), the effect of exogenous ABA on the state of stomata, the activity of antioxidant enzymes and the content of proline under salt stress conditions in Arabidopsis thaliana plants of wild type (Col-0) and jin1 mutants with impaired jasmonic sig-naling was investigated. Treatment of leaves’ epidermis with ABA (10 or 100 µM) caused the closing of stomata in Col-0 plants but almost not affected on stomatal aperture in jin1 mutants. Salt stress (200 mM NaCl exposure for 24 hours) caused a reduction in the water content in leaves of plants of both genotypes. Adding 10 µM ABA into growing medium contributed to maintaining normal hydration in wild-type, but not jin1, plants under salt stress. ABA treatment caused an almost twofold increase in proline content in the leaves of plants of both genotypes under normal conditions. Pretreatment with phytohormone contributed to enhan-cing the proline content in wild-type plants at salt stress and had less significant effect on its amount in jin1 plants. ABA under optimal conditions increased the catalase activity in wild-type plants, both genotypes under ABA influence showed increased activity of superoxide dismutase (SOD). Under salt stress conditions higher activity of SOD, catalase and guaiacol peroxidase was observed in ABA-treated wild-type plants, but not in jin1 mutants. The conclusion was made about the participation of transcription factor JIN1/MYC2 in the formation of certain ABA-induced physiological responses of Arabidopsis plants.
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