Formation of adaptive reactions in Arabidopsis thaliana wild-type and mutant jin1 plants under action of abscisic acid and salt stress

To elucidate the possible role of the transcription factor (TRF) JIN1/MYC2 in implementation of stress-protective effects of abscisic acid (ABA), the effect of exogenous ABA on the state of stomata and the activity of antioxidant enzymes and proline content under salt stress conditions in Arabidopsis thaliana plants of wild type (Col-0) and jin1 mutants with impaired jasmonate signaling was investigated. Treatment of leaves' epidermis with ABA (10 or 100 mu M) caused the closing of stomata in Col-0 plants but has hardly any influence on stomatal aperture in jin1 mutants. Salt stress (200 mM NaCl exposure for 24 h) caused a reduction of the water content in the plant leaves of both genotypes. Addition of 10 mu M ABA into the growing medium contributed to a maintaining of normal hydration in wild-type but not in 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 enhancing the proline content in wild-type plants at salt stress and had a less significant effect on its amount in jin1 plants. Treatment with ABA under physiologically normal 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. A conclusion about the participation of TRF JIN1/MYC2 in the formation of certain ABA-induced physiological responses of Arabidopsis plants was made.