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Hormonal profile and antioxidant defense system of Brassica rapa plants during drought and recovery period

Understanding the plant response and tolerance to drought presents important research issue. Drought often causes significant agricultural losses during lack of rainfall in hot and dry year periods. To overcome a problems caused by such unpleasant environment plants had developed defense system through hormonal and antioxidant responses. With aim to investigate response of Brassica rapa L. ssp. pekinensis to drought, three week old plants were subjected to 7 days of non watering period. One set of plants was harvested after 7 days of drought conditions, while other set was re-watered and harvested after 24 hours. Both sets of treated plants together with corresponding controls were subjected to biochemical and hormonal analysis. Activities of antioxidant enzymes (catalase, guaiacol peroxidase and ascorbate peroxidase) were altered upon drought and recovery period and were higher in comparison to the control. Levels of reduced GSH as well as the MDA content significantly increased during drought period and remain elevated upon recovery. Drought treatment also affected hormonal status of plants. ABA level was 2.6 times higher in drought stressed plants while plants after recovery period contained physiological levels of ABA so as the controls. Furthermore, both, drought and recovery plants accumulated higher levels of conjugated auxins than corresponding controls with tendency of the decrease upon recovery period. Obtained results suggest the significance of measured parameters in Brassica rapa plant defense and tolerance to drought.

drought; glutathione; MDA; abscisic acid; auxin

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