State of antioxidant and osmoprotective systems in etiolated winter wheat seedlings of different cultivars due to their drought tolerance

Abstract

Climatic changes bring the problem of drought tolerance of winter cereals to the fore at the earliest stages of development, immediately after autumn sowing. The reaction of antioxidant and osmoprotective systems of etiolated seedlings of winter wheat (Triticum aestivum L.) under osmotic stress was investigated. Seeds of seven cultivars were germinated for 4 days in Petri dishes on filter paper moistened with distilled water (control) or nonpenetrating osmotic agent PEG 6000 at a concentration of 12% (osmotic pressure 0.17 MPa) at 24°C. After that, the mass of shoots and roots of seedlings of experimental and control treatments were determined. Biochemical parameters were also determined in the shoots of 4-day-old seedlings. The highest ability to maintain shoot growth under osmotic stress was in the 'Tobak'; it was medium in the 'Antonivka', 'Lira Odeska, and 'Darynka Kyivska', and low in the 'Bogdana', 'Doskonala', and 'Avgustina'. In the least resistant 'Doskonala' and 'Avgustina', the content of lipid peroxidation product malondialdehyde was significantly increased in the shoots under osmotic stress. In the non-resistant cultivars and, also, in the medium-resistant 'Darynka Kyivska', an increase in hydrogen peroxide content was noted under osmotic stress. High-and medium-resistant cultivars were characterised by an increase in superoxide dismutase (SOD) activity in response to osmotic stress. Also, high-and medium-resistant cultivars showed a high catalase (CAT) activity. Osmotic stress caused an increase in guaiacol peroxidase activity in all cultivars, regardless of their drought tolerance. The proline content increased to some extent in all cultivars in response to stress exposure; however, no relationship was found between the amount of proline and drought resistance. The content of sugars under osmotic stress increased only in high and medium drought-resistant cultivars. Drought-resistant cultivars were also characterised by a high base content of flavonoid compounds absorbing UV-B and their retention under osmotic stress. Under osmotic stress, the strongest correlation (p ≤ 0.05) was found between the resistance to osmotic stress and the SOD activity (r = 0.93) as well as the sugar content (r = 0.85). In addition, a significant correlation was found between the drought tolerance and the flavonoid content and the CAT activity in seedlings. The complex of these indicators can be used to assess the drought tolerance of various genotypes of etiolated winter wheat seedlings.

Growth responses of wheat seedlings of different varieties to heat-stress and their relation to the antioxidant system state and osmolytes accumulation

“…Proline content in the seedling shoots was evaluated using ninhydrin reagent (Bates et al, 1973). Total sugar content was assayed using anthrone reagent by the Morris-Roe method with modifications (Kolupaev et al, 2022).…”

“…One of the key antioxidant defense enzymes is considered to be SOD, which converts SAR into hydrogen peroxide (Kolupaev et al, 2020b). We did not directly determine its activity, but the low level of SAR generation in the most heat-resistant Antonivka variety indicates the contribution of this enzyme to antioxidant protection of wheat seedlings under heat stress (Fig.…”

“…When discussing the possible involvement of proline in the response of wheat seedlings to hyperthermia, attention should also be drawn to the negative correlation between its content and catalase activity under stress, which was found to be significant at P ≤ 0.05. There is evidence in the literature of reciprocal relationships between proline content and gene expression and activity of antioxidant enzymes (Kolupaev et al, 2020b). Probably, in genotypes characterized by high activity of antioxidant enzymes, the contribution of proline to the protective mechanisms is less significant.…”

“…Quite naturally, the important role of these components of the antioxidant system should not be overestimated, since the antioxidant system itself is very multicomponent, and its components are in a complex functional interaction with each other (Kolupaev et al, 2020b). For a more comprehensive characterization of antioxidant protection of wheat seedlings of different varieties under hyperthermia, it is necessary to further study the contribution of other components of the antioxidant system, in particular ascorbate-glutathione cycle, whose role has been shown in other experimental models (Lou et al, 2018).…”

“…However, disruption of the pro/antioxidant balance and redox regulation processes is considered one of the key causes of cell damage and death (Kumar & Rai, 2014;Gautam et al, 2017). In this regard, the activation of the antioxidant system is considered as an important protective reaction of plants to high temperatures (Kolupaev et al, 2020b).…”