Study of Antioxidants in Leaves of Xerophytes of Georgia
Abstract
Climate warming may appear fatal for many plant species. Thanks to evolutionary formed mechanisms of resistance xerophytes possess high ability of adaptation to elevated temperature and water deficiency. That is why the knowledge of biology of drought resistant species seems very important for possible recovering of deserted regions in future. Antioxidant system is regarded to play an essential role in plant resistance against water deficiency. On the base of analysis of antioxidant system, stress-adaptation strategies of xerophytes, growing at two arid habitats of Georgia – v. Udabno (Iori plateau) and Kotsakhura gorge (Kvernaqi hill), has been investigated. It was established that several mechanisms of antioxidant system are involved in stress-resistance of studied xerophytes. In some cases these mechanisms were similar in species of the same habitat and may be linked with environmental conditions; while in some cases the specific peculiarities of plants were revealed. In particular, ascorbate-tocopherol system was activated inmost experimental species. Protective mechanism of phenolic substances accumulation was active in all species as well. Udabno plants were distinguished by the accumulation of osmoprotective soluble carbohydrates; while accumulation of another osmoprotectant-proline was common in both habitat plants.
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Introduction
Recent scientific investigations offer a strong evidence of climate global change to undesirable direction. Moreover, last seven years are regarded as the hottest during the whole history of climate observation (WMO provisional report, 2021). Climate warming may appear fatal for many plant species. Presumably the geographic range and borders of a great number of species will change (Garamvolgyi and Hufnagel, 2013; Allen et al., 2015). Thanks to evolutionary formed nonspecific biological mechanisms of resistance xerophytes possess high ability of adaptation to elevated temperature, water deficiency, intensive irradiation, etc.; especially the antioxidant system plays an essential role (Laxa et al., 2019). That is why the knowledge of biology of drought resistant species seems very important for future forecasting and possible recovering of deserted regions.
The investigation of stress-adaptation strategies of xerophytes, growing at two arid habitats of Georgia – v. Udabno (Iori plateau) and Kotsakhura gorge (Kvernaqi hill), on the base of analysis of antioxidant system, was the purpose of the presented study. Demonstrated data may be regarded as the part of long-term investigations, which aim to explore the drought resistance mechanisms of plant species occupying dry habitats of Georgia (Badridze et al., 2021; Badridze et al., 2022). Content of ascorbic acid, tocopherol, carotenoids, anthocyanins, soluble phenols, proline, total proteins, soluble carbohydrates and activity of catalase and peroxidase were studied in leaves of experimental plants.
Conclusion
Analyzing the experimental results it may be concluded that several mechanisms of the antioxidant system are involved in stress-resistance of studied xerophytes. In some cases these mechanisms were similar in species of the same habitat and may be linked with environmental conditions; while in some cases the specific peculiarities of plants were revealed. In particular: 1. ascorbate-tocopherol system was activated in all experimental species (except Berberis). 2. Protective mechanism of phenolic substances accumulation was active in all species as well (except Peganum). 3. Udabno plants were distinguished by the accumulation of soluble carbohydrates; while accumulation of another osmoprotectant-proline was common in both habitat plants (except Pyrus)
