Физиологические эффекты действия на растения фунгицидов триазольной природы

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.

This work compares the presowing treatment of winter wheat seeds with a low-temperature plasma, a constant high-voltage electric field, a plant protection disinfectant, and cold hardening on the resistance of seedlings to freezing and their morphophysiological characteristics at the initial stage of germination. Various treatment combinations were considered, including the effect of the disinfectant jointly with low-temperature plasma treatment. The greatest stimulating effect from the point of view of seedlings’ morphophysiological characteristics was achieved when seeds were cold-hardened. The action of low-temperature plasma is noticeable up to the third day of germination. The treatment with the low-temperature plasma of seeds pretreated and not-pretreated with the disinfectant had a similar effect on the morphophysiological characteristics of seedlings. The plasma treatment and the electric field were combined with each other, i.e., the plasma treatment effects were added to the electric field effects. Resistance to low temperatures was increased with the hardening of seeds treated with the electric field and the disinfectant. Resistance to low temperatures was reduced when treated with the electric field and/or low-temperature plasma after being treated with the disinfectant.

Derivatives of a triazole are used not only as fungicides to prevent infection of plants, but also for treatment. These drugs are actively used against plant diseases caused by basidiomycetes, ascomycetes, and some deuteromycetes. Due to their chemical stability, they have a long-term protective effect, and their solubility in water ensures their movement from the roots to the aerial part of plants. The aim of this work was to study the effect of seed treatment with tebuconazole-containing preparation “Bunker” on the growth of shoots and roots of winter wheat in the light and physiological and biochemical parameters. We used a fungicide of prophylactic and therapeutic action tebuconazole-containing seed treater “Bunker” (August, Russia), the active ingredient of which is tebuconazole (60 g/L). The shoot length and total root length, wet and dry biomass, as well as the content of photosynthetic pigments, reactive oxygen species – hydrogen peroxide (H2O2) and lipid peroxidation products (LPO) reacting with thiobarbituric acid (TBA-RP) in the tissues of shoots and roots were analyzed. The content of chlorophylls a and b and carotenoids in the extract was determined spectrophotometrically at wavelengths of 665, 649, and 440 nm, respectively. The obtained results indicate that the action of the drug is aimed at inhibiting the growth of shoots and reducing the ratio of shoot length to root length, while on the 7-9th day of growth, the effectiveness of its action is higher, and the most significant effect is exerted by an increased dose of the disinfectant (1.5 μL/g). It was found statistically significant stimulation of root growth on the 9th day of cultivation, regardless of the dose of the dressing agent. Despite the significant growth-inhibiting effect, treatment with Bunker was not accompanied by activation of oxidative processes in shoot tissues, with the exception of an increase in the content of H2O2 and TBA-RP at the initial stage of growth (5 days). In root tissues, the content of H2O2 and TBA did not change under the action of the studied preparation. No differences in the content of chlorophylls a and b and carotenoids in the tissues of wheat shoots after treatment with the studied fungicide were found. Based on the data obtained, it can be concluded that seed dressing agents containing tebuconazole as an active ingredient can be used to ensure plant resistance to moisture deficiency and improve mineral nutrition.

Цель работы - оценить перспективы использования фунгицида азоксистробина, являющегося одним из представителей класса стробилуринов, для повышения устойчивости озимой пшеницы к низким температурам. Было изучено влияние азоксистробина на ростовые процессы, жизнеспособность клеток и содержание водорастворимых углеводов у озимой пшеницы (Triticum aestivum L.) сорта Иркутская. Азоксистробин чаще, чем другие синтетические стробилурины, используется в составе многокомпонентных фунгицидных препаратов. Это фунгицид широкого спектра действия, вызывающий ингибирование комплекса III электрон-транспортной цепи митохондрий. Исследования проводились в лабораторных условиях на 3-суточных этиолированных проростках озимой пшеницы. Проростки выращивали в темноте при температуре + 24 °С на растворах азоксистробина, растворенного в 0,36%-м водном растворе диметилсульфоксида; дистиллированной воде и 0,36%-м растворе диметилсульфоксида. Было оценено влияние ряда концентраций азоксистробина (2,5, 5, 10, 20 μM) на рост побегов и корней и жизнеспособность клеток побегов и корней проростков пшеницы. Азоксистробин оказывал концентрационно зависимое ростин-гибирующее действие на побеги и корни. Степень ингибирования варьировалась: для побегов - от 2,8% при концентрации 2,5 μM до 41,7% при концентрации 20 μM, для корней - от 34,6 до 63,1% при этих же концентрациях соответственно. Рост-ингибирующее действие не сопровождалось снижением жизнеспособности клеток побегов и корней, оценка которой проводилась с помощью прижизненного окрашивания флуоресцеин диацетатом. Также оценивали влияние азоксистробина в концентрации 10 μM на содержание сахаров в побегах проростков. При изученной концентрации азоксистробина содержание сахаров было выше на 3,6% по сравнению с проростками, выращенными на растворе диметилсульфоксида. Поскольку ингибирование роста и накопление сахаров являются важными факторами адаптации растений к низким температурам, представляются необходимыми дальнейшие исследования азоксистробина на физиолого-биохимические параметры растений, связанные с развитием низкотемпературной устойчивости.