Biologichni Studii / Studia Biologica

Background. The antioxidant system (AOS), which includes both high-molecular and low-molecular antioxidants, plays an important role in protecting plants from oxidative stress. Previous studies have shown that exposure to high temperature and insolation caused an increase in the activity and thermal stability of antioxidant enzymes, which can be considered a mechanism of adaptation of the protein-synthesizing system to the effects of high temperatures. The enzymatic antioxidant system does not provide 100 % protection to plant cells under stress. Antioxidant metabolites play an important role in plant adaptation to hyperthermia and other abiotic stress factors that lead to the generation of excessive amounts of ROS. The protective role of low-molecular-weight antioxidants in the development of stress tolerance to abnormally high temperatures and insolation, as well as changes in the activity of polyphenol oxidase (PPO) and phenolic content in bryophytes, has not been sufficiently studied. Therefore, the aim of the work was to study seasonal changes in the quantitative content of phenolic compounds (PhC), anthocyanin and carotenoid pigment complexes in mosses in post-anthropogenic areas, as well as changes in PPO activity as indicators of abiotic stress.
Materials and Methods. The objects of research were: the dominant moss species Ptychostomum imbricatulum (Müll. Hal.) Holyoak & N. Pedersen in the experimental areas of the sulfur mining dump of the Novoyavoriv State Mining and Chemical Enterprise “Sirka” (Lviv region), as well as the new species for the flora of Ukraine Campylopus introflexus (Hedw.) Brid., which was first discovered on the technogenic substrates the “Nadiya” mine dump in the Chervonohrad mining and industrial district, and later on former peat quarries in the vicinity of Lopatyn and Olesko in Lviv region. The research was conducted in the summer and autumn of 2023. The intensity of lighting in the experimental areas was measured with a GM1030C luxmeter (Benetech, China).
The determination of the total content of PhC in the gametophyte of mosses was carried out spectrophotometrically using the Folin-Denis reagent. Polyphenol oxidase activity was determined spectrophotometrically by the rate of oxidation of paraphenylenediamine. The quantitative content of carotenoids was determined using the method of D. Arnon. The content of anthocyanins was determined using a hydrochloric acid. The determination of flavonoids was carried out according to the method of A. Pekal. The results were statistically analyzed, determining the mean value, median, standard deviation (SD), and the first and the third quartiles for each characteristic in all the variants of the experiment.
Results and Discussion. The highest PhC content in C. introflexus plants from the studied areas was observed in July, August, and November, which is apparently due to the accumulation of these compounds under stressful conditions. The highest PPO activity in the gametophyte of the C. introflexus moss was observed in the summer in the northern section of the top of the “Nadiya” mine dump; in November, a higher PhC content and decreased PPO activity were detected. In summer, at high temperatures, light intensity, and pronounced moisture deficiency, an increase in the content of phenols, anthocyanins, carotenoids, and flavonoids was observed in samples of P. imbricatulum moss from the base to the top of the sulfur mining dump. In the autumn period, in response to decreasing temperature and light intensity, less intensive biosynthesis of antioxidant metabolites occurred on all research transects, although the trend of increasing of their content from the base to the top persisted.
Conclusion. The survival strategy of bryophytes under the intense influence of abiotic stress factors in the studied post-anthropogenic territories consists in increasing of the pool of low-molecular metabolites and an enhanced activity of polyphenol oxidase, which contributes to their stress resistance. Based on the research results, it can be assumed that the existence of P. imbricatulum and C. introflexus in post-technogenic territories initiates adaptogenesis and leads to the formation of mechanisms of moss resistance to the action of stress factors, which are based on nonspecific protective reactions that ensure the adaptation of the plant organism to changing environmental conditions.