Main content area

Accumulation of hydrogen peroxide and functioning of defense system in overwatered barley seedlings

Shalygo, N. V., Domanskaya, I. N., Radyuk, M. S., Shcherbakov, R. A., Dremuk, I. A.
Russian journal of plant physiology 2012 v.59 no.6 pp. 748-756
Hordeum vulgare, antioxidant activity, antioxidants, ascorbate peroxidase, barley, glutathione, glutathione-disulfide reductase, hydrogen peroxide, leaves, metabolism, oxygen, proteins, seedling growth, seedlings, superoxide dismutase
The effects of overwatering (flooding) on the oxidative potential, the level of low-molecular-weight antioxidants, the content of stress proteins, and activities of antioxidant enzymes in green barley (Hordeum vulgare L.) seedlings were studied. Overwatering retarded barley seedling growth and induced hydrogen peroxide accumulation, a decrease in the total ascorbate content and an increase in the content of reduced glutathione (GSH), but it did not affect the content of oxidized glutathione (GSSG). After the cessation of stress factor action (post-stress period), the content of hydrogen peroxide declined to the initial level, the content of ascorbate reduced still stronger, whereas the content of GSH continued to rise. Under flooding conditions, activities of glutathione reductase (GR) and superoxide dismutase (SOD) increased. After the cessation of stress factor action, activities of these enzymes decreased but remained at rather high levels as compared with control. Activity of catalase (CAT) reduced during stress, whereas activity of ascorbate peroxidase (APX) was not essentially changed. In the post-stress period, CAT activity remained to be low; in contrast, APX activity increased. Barley seedling flooding induced the synthesis of stress proteins, HSP70 and dehydrins (DH). In the post-stress period, the content of stress proteins decreased; however, the content of DH in experimental leaves remained rather high. The results obtained indicate that barley defense system manifested a complex response to overwatering, which may be related to the oxygen shortage under stress conditions and sharp metabolism activation at re-aeration in the post-stress period.