1, 2, 4-triazole derivatives, including tebuconazole, have been reported to show positive physiological effects in cereals apart from fungicidal activity and to increase plants’ tolerance against temperature stress. This study investigates the mechanisms of increasing frost resistance of etiolated winter wheat (Triticum aestivum L., “Irkutskaya” variety) seedlings by tebuconazole-based seed dresser “Bunker” (1.5 μL g⁻¹ of seeds) and tebuconazole (30 μg g⁻¹ of seeds). To identify ABA-dependent and ABA-independent pathways of frost resistance, we used fluridone (FLD, 5 mg L⁻¹), an inhibitor of endogenous abscisic acid (ABA) synthesis. FLD effectively inhibited the accumulation of carotenoids in the shoots and prevented the formation of carotenoids caused by the “Bunker” and tebuconazole. In non-hardened seedlings, FLD stimulated coleoptile and first leaf growth, but did not suppress the growth inhibitory effects of “Bunker” and tebuconazole. In shoots of hardened seedlings, FLD reduced the retarding effect of tebuconazole. Regardless of seedling age, temperature, and the protectant treatment, FLD had no effect on the sugar content in the shoots. FLD did not essentially influence frost resistance induced by “Bunker” and tebuconazole in cold-hardened seedlings. Fluridone increased H₂O₂ content and guaiacol peroxidase activity under control conditions (both with tebuconazole and without tebuconazole) and during cold hardening (in seedlings from seeds treated with tebuconazole). ABA levels in cold-hardened seedlings treated with FLD alone, tebuconazole alone, or a combination of the two were two to three times lower than in untreated hardened seedlings. Changes in indole-3-acetic and salicylic acids in response to FLD and tebuconazole treatment indicate complex interactions with signaling cellular systems. Our results suggest that tebuconazole activates ABA-independent pathways more strongly than ABA-dependent pathways in enhancing frost resistance. The potential mechanisms of tebuconazole action in plant cells are discussed.

Synthetic auxins are used in agriculture as herbicides worldwide, which leads to localized pollution and their potential entry into food crops during early developmental stages. Triticum aestivum L. is a major agricultural crop, and for this reason, understanding the mechanisms by which herbicides affect photosynthetic and lipid metabolic processes in wheat is crucial for assessing yield reduction risks. This study aimed to evaluate the toxic effects of three synthetic auxins, 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and clopyralid (CLD) on growth parameters, membrane permeability, lipid peroxidation (LPO) product content, fatty acid (FA) profiles, and photosynthetic pigment levels in both etiolated and green spring wheat seedlings. FA content was assessed using gas chromatography-mass spectrometry. The results revealed that NAA and 2,4-D exerted the most pronounced inhibitory effects on seedling growth, whereas 2,4-D and CLD increased membrane permeability. In etiolated seedlings exposed to synthetic auxins, there was an elevation in FA content noted. Conversely, in green seedlings, exposure to all tested synthetic auxins led to a reduction in FA content, particularly affecting polyunsaturated fatty acids (PUFAs), as well as declines in chlorophyll and carotenoid levels. CLD reduced odd-chain fatty acid content (OCFAs) and very long-chain fatty acid content (VLCFAs) to undetectable levels. The increase in LPO products under the action of 2,4-D and CLD indicates oxidative stress as a possible cause of the decrease in PUFA content in green seedlings. These findings suggest that synthetic auxins have detrimental impacts on the photosynthetic apparatus of wheat, which in turn may have negative consequences for its productivity.

The work is devoted to studying the influence of the physiological state of inflorescences on the frequency of formation of androclinic structures in the culture of isolated anthers of winter wheat (Triticum aestivum L.) variety Irkutskaya. Changes in respiratory activity, the content of nonstructural carbohydrates and H₂O₂ levels were studied in the tissues of flowers in the process of low-temperature pretreatment of isolated shoots. Differences in the physiological and biochemical parameters of flowers were revealed depending on the position in the inflorescence and the duration of temperature pretreatment. It has been shown that long-term isolation of winter wheat shoots leads to carbohydrate starvation, but it is accompanied by a decrease in respiratory activity and a decrease in the level of ROS in the tissues of the inflorescences only under the influence of low positive temperatures. The role of alternative cyanide-resistant oxidase and ROS as possible components of the physiological system for reprogramming the development of microspores from the gametophytic to the sporophytic path has been proposed.

Changes in the fatty acid composition and content of lipid peroxidation products were studied in the tissues of winter wheat flowers (Triticum aestivum L.) variety Irkutskaya in the process of low-temperature pretreatment of isolated shoots. Compliance of the specified changes is shown as most and least effective for induced androgenesis in vitro periods of exposure. The distribution of fatty acids in the inflorescences of winter wheat was studied and differences in the content of these components were revealed depending on temperature and flowers location in different parts of the inflorescence. An increase in the content of α-linolenic acid in flower tissues was found during low-temperature treatment, which may indicate the possibility of hardening of isolated spikes in the absence of light. It has been established that the duration of cold exposure, the degree of development of flowers, and their metabolic activity determine the intensity of lipid peroxidation processes in the tissues of the spikes. It was found that the most favorable period of pretreatment of isolated shoots for androgenesis in vitro was accompanied by changes in the middle part of the spikes, characteristic of low-temperature hardening: an increase in the content unsaturated and reduced content of saturated fatty acids as well as lipid peroxidation (LPO) products.

The work is devoted to studying the influence of the physiological state of inflorescences on the frequency of androclinic structures formation in the culture of isolated anthers of winter wheat (Triticum aestivum L.) variety Irkutskaya. Changes in the content of indole-3-acetic acid (IAA), abscisic acid (ABA), as well as jasmonic acid (JA) and salicylic acid (SA) in flower tissues during low-temperature pretreatment (4°C in the dark for 7 and 14 days) of isolated shoots were studied using chromatographic mass spectrometry method. An increased content of JA and SA was detected in flowers from the lower part of the spike already under control conditions. A simultaneous increase in the content of IAA, ABA and JA in the middle part of the inflorescence was shown after 7 days of low-temperature exposure. Based on the obtained data, it was suggested that ABA and JA signaling systems were involved in the process of switching genes responsible for the reprogramming of microspores. It is likely that IAA was the key factor in stabilizing the ABA content, what prevented critical damage to anther tissues. An increase in the SA content throughout the entire period of low-temperature exposure indicates its role in reducing the efficiency of androgenesis in vitro after 14 days of exposure due to its negative effect on the biosynthesis of IAA and JA. In the first and second parts of the our cycle works, an increase in the content of unsaturated fatty acids and changes in respiration activity were revealed in the process of low-temperature pretreatment of donor spikes of winter wheat. To summarize all data we can approve that the changes occurred in the flowers of winter wheat during the period of low-temperature pretreatment could only partly be attributed to the acclimation and resistance phases of low-temperature hardening. Isolation of shoots led to a decrease in the level of water-soluble carbohydrates and a rapid onset of the exhaustion phase, what was probably the reason for the decrease in the efficiency of androgenesis with an increase in the period of low-temperature treatment.