The effect of heavy metals and thidiazuron on winter wheat (Triticum aestivum L.) seedlings

Abstract We studied the influence of a synthetic cytokinin-like growth regulator thidiazuron (TDZ) and ions of heavy metals (HMs) -Pb , and Ni 2+ on the growth, generation of superoxide anion, concentration of total peroxides, lipid peroxidation, and catalase activity in the leaves of 7-day-old winter wheat plants (Triticum aestivum L. cv. 'Mironovskaya 808'). It was found that 1 mM solution of HMs inhibited the growth of roots in the following sequence: Zn . HMs inhibited the growth of aboveground parts of young wheat plants, too. HMs stimulated superoxide production by a factor of 1.3-4.9. The content of total peroxides in wheat leaves increased in the presence of HMs in the growth medium. Our analyses showed that malonic dialdehyde (MDA) content in leaves increased with increasing Cu 2+ or Ni 2+ concentra tions in the medium and hardly changed with increasing Pb 2+ or Zn 2+ concentrations. HMs enhanced catalase activity in wheat plants 1.1-2.8-fold at all concentrations studied. All these regularities are indications of HMs-induced oxidative stress in wheat plants. In most treatments, TDZ alleviated the HMs-induced oxidative stress and promoted an increase in Wilkinson tolerance index (WTI). This suggests that the wheat seedlings treated with TDZ were more HMs-resistant than the untreated ones

Role of salicylic acid in acclimation to low temperature

Low temperature is one of the most important limiting factors for plant growth throughout the world. Exposure to low temperature may cause various phenotypic and physiological symptoms, and may result in oxidative stress, leading to loss of membrane integrity and to the impairment of photosynthesis and general metabolic processes. Salicylic acid (SA),phenolic compound produced by a wide range of plant species, a may participate in many physiological and metabolic reactions in plants. It has been shown that exogenous SA may provide protection against low temperature injury in various plant species, while various stress factors may also modify the synthesis and metabolism of SA. In the present review, recent results on the effects of SA and related compounds in processes leading to acclimation to low temperatures will be discussed

Sydnone Imines: A Novel Class of Plant Growth Regulators

An increase in the yield of the main cereal crops in the context of global climate changes requires additional impacts on plants. Natural and synthetic plant growth regulators (PGRs) are used to increase plant productivity and reduce the injury level caused by abiotic stressors. There is a growing need for novel highly effective plant growth stimulants to exhibit their effects at low doses and to not pose an environmental threat or injury to the crop quality. The derivatives of sydnone imine (SI), a mesoionic heterocycle possessing a 1,2,3-oxadiazole core, have been used as medicines until now but have not been used for agricultural applications. Some SI derivatives have recently been found to exhibit PGR properties. Herein, we report on the study of the PGR potential of nine SI derivatives bearing variable substituents at N(3), C(4), and N6 positions of the heterocycle designed to disclose the “molecular structure-PGR activity” relationship in this family. The SI derivatives were used in a wide concentration range (10−9–10−4 mol/L) for a pre-sowing treatment of winter wheat (Triticum aestivum L., two cultivars) and maize (Zea mays L., two hybrids) seeds in germinating experiments. All compounds were found to affect the growth of the axial organs of germinants, with the growth-stimulating or -inhibitory effect as well as its rate being considerably different for wheat and maize and, in many cases, also for roots and shoots. In addition, a pronounced concentration dependence of the effect was disclosed for many cases. The features of the molecular structure of SIs affecting their growth-regulating properties were elucidated. Compounds 4, 6, 7, and 8, which had exhibited a growth-promoting effect in germinating experiments, were used at appropriate concentrations for pot experiments on the same crops. For all compounds, the experiments showed a stimulating effect on the growth of roots (up to 80%), shoots (up to 112%), leaf area (up to 113%), fresh weights of roots (up to 83%), and aerial parts of the plants (up to 87%) or only on some of these parameters. The obtained results show a healthy outlook for the use of SI derivatives as promoting agents for improving the growth of cereal crop plants

Control of cucumber (Cucumis sativus L.) tolerance to chilling stress – evaluating the role of ascorbic acid and glutathione

Chilling temperatures (1-10 ºC) are known to disturb cellular physiology, cause oxidative stress via creating imbalance between generation and metabolism of reactive oxygen species (ROS) leading finally to cell and/or plant death. Owing to known significance of low molecular antioxidants - ascorbic acid (AsA) and glutathione (GSH) in plant stress-tolerance, this work analyzes the role of exogenously applied AsA and GSH in the alleviation of chilling stress (3°C)-impact in cucumber (Cucumis sativus L. cv. Vjaznikowskij 37) plants. Results revealed AsA and GSH concentration dependent metabolism of ROS such as superoxide (O2•‾) and the mitigation of ROS-effects such as lipid peroxidation (LPO) as well as membrane permeability (measured as electrolyte leakage) in C. sativus leaf discs. AsA concentration (750 µM) and GSH (100 µM) exhibited maximum reduction in O2•‾ generation, LPO intensity as well as electrolyte leakage, all of these were increased in cold water (3°C and 25°C)-treated leaf discs. However, AsA, in particular, had a pronounced antioxidative effect, more expressed in case of leaf discs during chilling (3°C); whereas, at temperature 25°C, some AsA concentrations (such as 50 and 100 mM AsA) exhibited a prooxidative effect that requires molecular-genetic studies. Overall, it is inferred that AsA and GSH have high potential for sustainably increasing chilling-resistance in plants

Efektyvumo indeksas kaip Triticum aestivum reakcijos į augimo reguliatorius integralus rodiklis

e-ISSN 2335-8947Siekiant pagerinti augalų sunkiųjų metalų toleranciją, tirtas sintetinių Thidiazurono (TDZ), Cytodefo (CTD) bei Epin-Extra® (24-EB) ir natūralaus Ribav-Extra® (RE) augalų augimo reguliatorių efektyvumas. Tikslui pasiekti buvo parinkti tokie parametrai: ašinis augimas kaip augalų reakcijos į aplinką integralus rodiklis), superoksido pokyčiai (oksidacinio streso rodiklis), malono dialdehido kiekis (oksidacinio pažeidimo laipsnio augaluose rodiklis), katalazės aktyvumas (antioksidacinės apsaugos sistemos aktyvumo rodiklis) ir augimo reguliatorių geba pakeisti sunkiųjų metalų absorbciją bei translokaciją augaluose. Efektyvumo indeksas apskaičiuotas remiantis žieminių kviečių daigų, paveiktų 10 μM arba 1 mM Zn2+, Cu2+ ir Ni2+ ar Pb2+ sunkiaisiais metalais, tyrimo rezultatais. Taip pat buvo sukurta empirinė augalų augimo reguliatorių efektyvumo skalė. Nustatyta, kad tirtų augimo reguliatorių efektyvumas, atsižvelgiant į toleranciją sunkiesiems metalams, didėjo taip: TDZ < CTD < RE < 24-EBIn the current study we investigated the effectiveness of synthetic Thidiazuron (TDZ), Cytodef (CTD), Epin- Extra® (24-EB) and natural Ribav-Extra® (RE) plant growth regulators (PGR) with a view to improving the heavy metal-tolerance in intact plants. To evaluate the effectiveness of PGR we chose the following parameters: the axial growth (as an integral indicator of the plant response to the environment), the superoxide generation (as an indicator of oxidative stress), the malondialdehyde (MDA) content (as an indicator of oxidative damage degree in plants), catalase (CAT) activity (as an indicator of the antioxidant defence systems activity) and the PGR capacity to change absorption and translocation of heavy metals in plants. The efficiency index was estimated on the basis of the results of winter wheat (Triticum aestivum L.) seedlings affected by 10 μM or 1 mM Zn2+, Cu2+ and Ni2+ or Pb2+ heavy metals. An empirical scale of the efficiency of PGR was developed. The study found that the efficiency of the PGR investigated with respect to tolerance of heavy metals increased as follows: TDZ <CTD <RE <24-EBLietuvos agrarinių ir miškų mokslų centro Sodininkystės ir daržininkystės institutasVytauto Didžiojo universitetasŽemės ūkio akademij

Evaluation of zinc accumulation, allocation, and tolerance in Zea mays L. seedlings: implication for zinc phytoextraction

This work investigated the accumulation, allocation, and impact of zinc (Zn; 1.0 μM–10 mM) in maize (Zea mays L.) seedlings under simulated laboratory conditions. Z. mays exhibited no significant change in its habitus (the physical characteristics of plants) up to 10–1000 μM of Zn (vs 5–10 mM Zn). Zn tolerance evaluation, based on the root test, indicated a high tolerance of Z. mays to both low and intermediate (or relatively high) concentrations of Zn, whereas this plant failed to tolerate 10 mM Zn and exhibited a 5-fold decrease in its Zn tolerance. Contingent to Zn treatment levels, Zn hampered the growth of axial organs and brought decreases in the leaf area, water regime, and biomass accumulation. Nevertheless, at elevated levels of Zn (10mM), Zn2+ was stored in the root cytoplasm and inhibited both axial organ growth and water regime. However, accumulation and allocation of Zn in Z. mays roots, studied herein employing X-ray fluorimeter and histochemical methods, were close to Zn accumulator plants. Overall, the study outcomes revealed Zn tolerance of Z. mays, and also implicate its potential role in Zn phytoextraction

Augimo reguliatoriaus Ribav-Extra įtaka sunkiaisiais metalais paveiktų žieminių kviečių daigams

e-ISSN 2335-8947Tirta natūralaus augimo reguliatoriaus Ribav-Extra ir sunkiųjų metalų (SM) jonų – Pb2+, Cu2+, Zn2+, bei Ni2+ – įtaka žieminio kviečio (Triticum aestivum L.) veislės ‘Mironovskaya 808’ fiziologiniams ir biocheminiams rodikliams. Žieminių kviečių sėklos buvo paveiktos Ribav-Extra (10 ppm) ir 7 dienas augo sunkiųjų metalų druskų tirpaluose (10 μM arba 1 mM), po to įvertintas sunkiųjų metalų kaupimasis augaluose, augalų augimas, superoksido anijonų (• O2 − ) gamyba, lipidų peroksidacija, katalazės ir askorbato peroksidazės aktyvumas. Nustatyta, kad 1 mM SM tirpalas augimo terpėje padidino sunkiųjų metalų kaupimąsi žieminiuose kviečiuose ir slopino šaknų bei ūglių augimą. Ir mažos, ir didelės sunkiųjų metalų koncentracijos kviečių daiguose paskatino • O2 − gamybą ir sukėlė oksidacinius pažeidimus. Beveik visų variantų augaluose sunkiųjų metalų toksinis poveikis sustiprėjo esant didesnėms koncentracijoms. Sėklų apdorojimas Ribav-Extra prieš sėją mažino sunkiųjų metalų poveikį žieminių kviečių daigams, slopino jų sukeltą oksidacinį stresą, mažino • O2 − gamybą, lipidų peroksidacijos intensyvumą ir katalazės aktyvumą. Tai rodo, kad sunkiųjų metalų poveikiui buvo atsparesni augimo reguliatoriumi Ribav-Extra apdoroti žieminių kviečių daigai nei neapdorotiWe studied the influence of a natural plant growth regulator Ribav-Extra and ions of heavy metals (HM) Pb2+, Cu2+, Zn2+ and Ni2+ on the physiological and biochemical indices of the winter wheat (Triticum aestivum L. ) cultivar ‘Mironovskaya 808’. The seeds of wheat were treated with Ribav-Extra (10 ppm) and grown for 7 days on heavy metal salt solutions (10 μM or 1 mM). After that we recorded heavy metals accumulation, growth, generation of superoxide anion (• O2 − ), lipid peroxidation (LPO), and catalase (CAT) and ascorbate peroxidase (APOX) activity. It was found that 1 mM of HM in growth media increased heavy metals accumulation in wheat plants and inhibited the growth of roots and shoots. Both low and high concentrations of heavy metals stimulated • O2 − production and oxidative damage in wheat seedlings. In most treatments, the toxic effect of heavy metals enhanced at higher concentration of metals. Pre-sowing treatment of seeds with Ribav-Extra decreased the negative impact of heavy metals by reducing oxidative stress which led to suppressed • O2 − generation, lipid peroxidation intensity and catalase activity. This suggests that the wheat plants, whose seeds had been treated with Ribav-Extra, were more heavy metal-resistant than the untreated onesLietuvos agrarinių ir miškų mokslų centro filialas Sodininkystės ir daržininkystės institutasVytauto Didžiojo universitetasautŽemės ūkio akademij