Comparison of growth stimulation of HeLa cells,HL-60 cells,and mouse fibroblasts by coenzyme Q10

Summary The addition of coenzyme Q₁₀ to culture media stimulates the serum-free growth of HeLa, HL-60 cells, and mouse fibroblasts (Balb/3T3). With HeLa cells, the stimulation by coenzyme Q₁₀ is additive to the stimulation by ferricyanide, an impermeable electron acceptor for the transplasma membrane electron transport. This combined response to coenzyme Q₁₀ and ferricyanide is enhanced with insulin. -Tocopherylquinone can also stimulate the growth of HeLa cells, but vitamin K₁ is inactive. Specificity of quinone effects is indicated. Serum-free growth of Balb/3T3 and SV 40 transformed BaIb/3T3 (SV/T2) cells is also stimulated by coenzyme Qio with stimulation similar to HeLa cells. However, Balb/3T3 cells are not stimulated by ferricyanide, which does not increase the response to coenzyme Q₁₀. The transformed cells (SV/T2) respond better to ferricyanide alone, but the effects of coenzyme Qio and ferricyanide are not additive. Serum-free growth of HL-60 cells is stimulated dramatically by coenzyme Q₁₀. The extent of growth stimulation on HL-60 cells is almost six-fold that of HeLa or Balb/3T3 cells. The stimulation of NADH-ferricyanide reductase (a transmembrane redox enzyme) by coenzyme Q₁₀ with HL-60 cells is similar to their growth pattern in response to coenzyme Q₁₀. Unlike HL-60, HeLa and Balb/3T3 cells show little stimulation of ferricyanide reduction by coenzyme Q₁₀. The stimulatory effect on both ferricyanide reduction and cell growth by the short side-chain coenzyme Q₂ is much less than that of the long side-chain coenzyme Q₁₀. Ferricyanide reduction by HeLa cells is inhibited by coenzyme Q analogs such as 2,3-dimethoxy-5-chloro-6-naphthyl-mercapto-coenzyme Q and 2-methoxy-3-ethoxyl-5-methyl-6-hexadecyl-mercapto-coenzyme Q. However, these inhibitions are reversed by coenzyme Q₁₀. The growth inhibition of HL-60 cells by other coenzyme Q analogs, such as capsiacin can also be reversed by coenzyme Q₁₀. These data indicate that plasma membrane-based NADH oxidation or modification of the membrane quinone redox balance may be a basis for the growth stimulation.     

Over-expression of COQ10 in Saccharomyces cerevisiae inhibits mitochondrial respiration

COQ10 deletion in Saccharomyces cerevisiae elicits a defect in mitochondrial respiration correctable by addition of coenzyme Q₂. Rescue of respiration by Q₂ is a characteristic of mutants blocked in coenzyme Q₆ synthesis. Unlike Q₆ deficient mutants, mitochondria of the coq10 null mutant have wild-type concentrations of Q₆. The physiological significance of earlier observations that purified Coq10p contains bound Q₆ was examined in the present study by testing the in vivo effect of over-expression of Coq10p on respiration. Mitochondria with elevated levels of Coq10p display reduced respiration in the bc1 span of the electron transport chain, which can be restored with exogenous Q₂. This suggests that in vivo binding of Q₆ by excess Coq10p reduces the pool of this redox carrier available for its normal function in providing electrons to the bc1 complex. This is confirmed by observing that extra Coq8p relieves the inhibitory effect of excess Coq10p. Coq8p is a putative kinase, and a high-copy suppressor of the coq10 null mutant. As shown here, when over-produced in coq mutants, Coq8p counteracts turnover of Coq3p and Coq4p subunits of the Q-biosynthetic complex. This can account for the observed rescue by COQ8 of the respiratory defect in strains over-producing Coq10p.     

A durohydroquinone oxidation site in the mitochondrial transport chain

Although duroquinone had little effect upon NADH oxidation in neutral lipid depleted mitochondria, durohydroquinone was oxidized by ETP at a rate sensitive to antimycin A. Fractionation of mitochondria into purified enzyme systems showed durohydroquinone: cytochromec reductase to be concentrated in NADH: cytochromec reductase, absent in succinate:cytochromec reductase, and decreased in reduced coenzyme Q:cytochromec reductase. Durohydroquinone oxidation could be restored by recombining reduced coenzyme Q:cytochromec reductase with NADH:coenzyme Q reductase. Pentane extraction had no effect upon either durohydroquinone or reduced coenzyme Q₁₀ oxidation, indicating lack of a quinone requirement between cytochromesb andc. Both chloroquine diphosphate and acetone (96%) treatment irreversibly inhibited NADH but not succinate oxidation. Neither reagents had any effect upon durohydroquinone oxidation but both inhibited reduced coenzyme Q₁₀ oxidation 50%, indicating a site of action between Q₁₀ and duroquinone sites. Loss of chloroquine sensitive reduced coenzyme Q₁₀ oxidation after acetone extraction suggests two sites for Q₁₀ before cytochromeb.     

Studies on reduced and oxidized coenzyme Q (ubiquinones). II. The determination of oxidation-reduction levels of coenzyme Q in mitochondria,microsomes and plasma by high-performance liquid chromatography

Reduced and oxidized coenzyme Q₁₀ (Q₁₀H₂ and Q₁₀) in guinea-pig liver mitochondria were rapidly extracted and determined by high-performance liquid chromatography (HPLC). The percentages of Q₁₀H₂ as compared to the total (sum of Q₁₀ and Q₁₀H₂) were increased by the addition of respiratory substrates such as succinate, malate and β-hydroxybutyrate (State 4). The levels of Q₁₀H₂ in State 4 were increased more extensively with electron-transport inhibitors such as KCN, NaN₃ and antimycin A. These results indicate that the method for determining Q₁₀H₂ and Q₁₀ by HPLC is quite useful for investigation of the physiological function of coenzyme Q in mitochondria and other organelles. The reduced and oxidized coenzyme Q levels of rat liver mitochondria, which contain both coenzyme Q₉ and coenzyme Q₁₀, were measured simultaneously. The results suggest that coenzymes Q₉ and Q₁₀ play a similar role as an electron carriers. The liver microsomes of guinea-pig contained approx. 133 nmol total coenzyme Q₁₀ per g protein. The Q₁₀H₂ levels of microsomes were increased from 46.5 to 67.5 and 64.8% with NADH and NADPH, respectively. The plasma levels of total coenzyme Q were 0.92 μg/ml for man, 0.35 μg/ml for guinea-pig and 0.27 μg/ml for rat. The reduced coenzyme Q were also present in those plasma samples. The levels of reduced coenzyme Q were 51.1, 48.9 and 65.3%, respectively.     

The site of inhibition of mitochondrial electron transfer by coenzyme Q analogues.

The effects of 33 quinone derivatives on mitochondrial electron transfer in yeast were examined. Twenty-two of the compounds were also tested for their effects on the growth of yeast cells. Four strong inhibitors of electron transfer were identified: 5-n-undecyl-6-hydroxy-4, 7-dioxobenzothiazole, 7-ω-cyclohexyloctyl-6-hydroxy-5,8-quinolinequinone, 7-n-hexadecyl-mercapto-6-hydroxy-5, 8-quinolinequinone, and 3-n-dodecylmercapto-2-hydroxy-1, 4-naphthoquinone. They inhibit the growth of yeast with ethanol as an energy source, but not when glucose is the energy source. The NADH oxidase activity of isolated mitochondria is 50% inhibited by these quinone derivatives at about 10^?8m, or 0.5 μmol/g mitochondrial protein; 1000-fold higher concentrations do not affect electron transfer from NADH or succinate to coenzyme Q₂. The effects of the inhibitors on cytochrome spectra indicate that they block electron transfer between cytochromes b and c₁. A possible antagonism between these compounds and coenzyme Q at a site between cytochromes b and C₁ is discussed in terms of Mitchell's “protonmotive Q cycle” hypothesis (Mitchell, P. (1976) J. Theor. Biol. 62, 327–367). 6-β-naphthylmercapto-5-chloro-2,3-dimethoxy-1,4-benzoquinone inhibits electron transfer between succinate and coenzyme Q₂ or phenazine methosulfate, suggesting a site in the succinate-coenzyme Q reductase complex with a different quinone specificity from that of the site in the cytochrome bc₁ complex. Seven of the quinone derivatives inhibit growth on both glucose and ethanol media, indicating that their effect is not the result of inhibition of respiration.     

Additive effects and potential inhibitory mechanism of some common aromatic pollutants on in vitro mitochondrial respiration

The in vitro toxicity of multiple hydrophobic compounds was the focus of this study. A mitochondrial respiratory assay, sensitive to perturbations caused by hydrophobic chemicals, was utilized to measure the effects of individual aromatic hydrocarbon pollutants and their mixtures on mitochondrial respiratory function. Benzene, naphthalene, acenaphthene, and 1-chloronaphthalene, common industrial solvents shown to interact additively in vivo, were evaluated using this in vitro assay system. Mitochondrial respiration was inhibited 50% (EC₅₀) by 525 ppm (6.7 mM) benzene, 15 ppm (117 μM) naphthalene, 3.9 ppm (25.5 μM) acenaphthene, or 3.8 ppm (23.4 μM) 1-chloronaphthalene. NADH:O₂ oxidoreductase (NADH → O₂), NADH: ubiquinone oxidoreductase, and ubiquinol:O₂ oxidoreductase activities were inhibited by all four compounds, whereas succinate:O₂ oxidoreductase, cytochrome c oxidase, and duroquinol: O₂ oxidoreductase activities were not inhibited. Inhibition of mitochondrial respiration occurred at the level of ubiquinone (coenzyme Q₁₀) for all four aromatic hydrocarbons. The ultraviolet absorbance spectrum of isolated Q₁₀ was also altered by naphthalene, acenaphthene, or 1-chloronaphthalene, suggesting a specific interaction between that component of the respiratory chain and these aromatic hydrocarbons. Inhibition by a mixture of 2, 3, or 4 of the compounds tested was additive, reflecting a summation effect of each compound present in the mixture. This additive nature is consistent with previously reported effects of these compounds in vivo and with compounds having similar modes of action. The similar mode of action in vitro is a specific interaction with coenzyme Q₁₀, not a generalized membrane perturbation as speculated to occur in vivo, and is the likely mechanism for the observed additive toxicity.     

Proliferation of cultured glioma cells mediated by coenzyme Q<Subscript>10</Subscript> under conditions of serum deprivation

The effect of coenzyme Q₁₀ on glioma-cell proliferation under serum-deprived conditions has been studied. Our results have shown that the addition of coenzyme Q₁₀ into a serum-free culture medium enhances cell viability, stimulates cell growth, restores mitochondrial potential, and increases the quantity of energized mitochondria. It is found that coenzyme Q₁₀-induced glioma-cell proliferation in conditions of serum deficiency is a result of an intracellular reduced glutathione concentration with subsequent activation of protein kinase C, ERK1/2, and phosphoinositol-3-kinase.     

Large seasonal changes in Q10 of soil respiration in a beech forest

We analyzed one year of continuous soil respiration measurements to assess variations in the temperature sensitivity of soil respiration at a Danish beech forest. A single temperature function derived from all measurements across the year (Q₁₀ = 4.2) was adequate for estimating the total annual soil respiration and its seasonal evolution. However, Q₁₀'s derived from weekly datasets ranged between three in summer (at a mean soil temperature of 14 °C) and 23 in winter (at 2 °C), indicating that the annual temperature function underestimated the synoptic variations in soil respiration during winter. These results highlight that empirical models should be parameterized at a time resolution similar to that required by the output of the model. If the objective of the model is to simulate the total annual soil respiration rate, annual parameterization suffices. If however, soil respiration needs to be simulated over time periods from days to weeks, as is the case when soil respiration is compared to total ecosystem respiration during synoptic weather patterns, more short‐term parameterization is required. Despite the higher wintertime Q₁₀'s, the absolute response of soil respiration to temperature was smaller in winter than in summer. This is mainly because in absolute numbers, the temperature sensitivity of soil respiration depends not only on Q₁₀, but also on the rate of soil respiration, which is highly reduced in winter. Nonetheless, the Q₁₀ of soil respiration in winter was larger than can be explained by the decreasing respiration rate only. Because the seasonal changes in Q₁₀ were negatively correlated with temperature and positively correlated with soil moisture, they could also be related to changing temperature and/or soil moisture conditions.     

Cellular redox poise modulation; the role of coenzyme Q10, gene and metabolic regulation

In this communication, the concept is developed that coenzyme Q₁₀ has a toti-potent role in the regulation of cellular metabolism. The redox function of coenzyme Q₁₀ leads to a number of outcomes with major impacts on sub-cellular metabolism and gene regulation. Coenzyme Q₁₀'s regulatory activities are achieved in part, through the agency of its localization in the various sub-cellular membrane compartments. Its fluctuating redox poise within these membranes reflects the cell's metabolic micro-environments. As an integral part of this process, H₂O₂ is generated as a product of the normal electron transport systems to function as a mitogenic second messenger informing the nuclear and mitochondrial (chloroplast) genomes on a real-time basis of the status of the sub-cellular metabolic micro-environments and the needs of that cell. Coenzyme Q₁₀ plays a major role both in energy conservation, and energy dissipation as a component of the uncoupler protein family. Coenzyme Q₁₀ is both an anti-oxidant and a pro-oxidant and of the two the latter is proposed as its more important cellular function. Coenzyme Q₁₀ has been reported, to be of therapeutic benefit in the treatment of a wide range of age related degenerative systemic diseases and mitochondrial disease. Our over-arching hypotheses on the central role played by coenzyme Q₁₀ in redox poise changes, the generation of H₂O₂, consequent gene regulation and metabolic flux control may account for the wide ranging therapeutic benefits attributed to coenzyme Q₁₀.     

Absence of coenzyme Q10 as an intrinsic component of aldehyde oxidase

Many investigators have purified an aldehyde oxidase from mammalian livers, and described reactions of this enzyme with diverse substrates. Coenzyme Q₁₀ was unambiguously identified and found present in some of these enzyme preparations. It was considered that coenzyme Q₁₀ might participate in the functionality of this enzyme, but the validity of the intrinsic association of coenzyme Q₁₀ was questioned. We have similarly purified aldehyde oxidase from rabbit livers. No coenzyme Q₁₀ could be detected under controlled conditions for detecting the presence of coenzyme Q₁₀. It is concluded that coenzyme Q₁₀ may be a contaminant of some aldehyde oxidase preparations, and that it is not intrinsic for the functionality of this enzyme.     

The Role of the Alternative Oxidase in Stabilizing the in Vivo Reduction State of the Ubiquinone Pool and the Activation State of the Alternative Oxidase

A possible function for the alternative (nonphosphorylating) pathway is to stabilize the reduction state of the ubiquinone pool (Q_r/Q_t), thereby avoiding an increase in free radical production. If the Q_r/Q_t were stabilized by the alternative pathway, then Q_r/Q_t should be less stable when the alternative pathway is blocked. Q_r/Q_t increased when we exposed roots of Poa annua (L.) to increasing concentrations of KCN (an inhibitor of the cytochrome pathway). However, when salicylhydroxamic acid, an inhibitor of the alternative pathway, was added at the same time, Q_r/Q_t increased significantly more. Therefore, we conclude that the alternative pathway stabilizes Q_r/Q_t. Salicylhydroxamic acid increasingly inhibited respiration with increasing concentrations of KCN. In the experiments described here the alternative oxidase protein was invariably in its reduced (high-activity) state. Therefore, changes in the reduction state of the alternative oxidase cannot account for an increase in activity of the alternative pathway upon titration with KCN. The pyruvate concentration in intact roots increased only after the alternative pathway was blocked or the cytochrome pathway was severely inhibited. The significance of the pyruvate concentration and Q_r/Q_t on the activity of the alternative pathway in intact roots is discussed.     

Foliar respiration acclimation to temperature and temperature variable Q10 alter ecosystem carbon balance

The response of respiration to temperature in plants can be considered at both short‐ and long‐term temporal scales. Short‐term temperature responses are not well described by a constant Q₁₀ of respiration, and longer‐term responses often include acclimation. Despite this, many carbon balance models use a static Q₁₀ of respiration to describe the short‐term temperature response and ignore temperature acclimation. We replaced static respiration parameters in the ecosystem model photosynthesis and evapo‐transpiration (PnET) with a temperature‐driven basal respiration algorithm (Rd_acclim) that accounts for temperature acclimation, and a temperature‐variable Q₁₀ algorithm (Q_10var). We ran PnET with the new algorithms individually and in combination for 5 years across a range of sites and vegetation types in order to examine the new algorithms' effects on modeled rates of mass‐ and area‐based foliar dark respiration, above ground net primary production (ANPP), and foliar respiration–photosynthesis ratios. The Rd_acclim algorithm adjusted dark respiration downwards at temperatures above 18°C, and adjusted rates up at temperatures below 5°C. The Q_10var algorithm adjusted dark respiration down at temperatures below 15°C. Using both algorithms simultaneously resulted in decreases in predicted annual foliar respiration that ranged from 31% at a tall‐grass prairie site to 41% at a boreal coniferous site. The use of the Rd_acclim and Q_10var algorithms resulted in increases in predicted ANPP ranging from 18% at the tall‐grass prairie site to 38% at a warm temperate hardwood forest site. The new foliar respiration algorithms resulted in substantial and variable effects on PnETs predicted estimates of C exchange and production in plants and ecosystems. Current models that use static parameters may over‐predict respiration and subsequently under‐predict and/or inappropriately allocate productivity estimates. Incorporating acclimation of basal respiration and temperature‐sensitive Q₁₀ have the potential to enhance the application of ecosystem models across broad spatial scales, or in climate change scenarios, where large temperature ranges may cause static respiration parameters to yield misleading results.     

Coordinated, coenzyme Q reversible, 2,5-dibromothymoquionine inhibition of electron transport and ATPase in Escherichia coli.

2,6-dibromothymoquinone (DBMIB) and other coenzyme Q analogs partially inhibit electron transport and the membrane-bound Mg⁺⁺ stimulated ATPase of $\text{E. coli}$ membranes. The inhibitions by DBMIB are fully reversed by coenzyme Q₆, and other analogs show partial reversal by coenzyme Q₆. Electron transport reactions inhibited are NADH and lactate oxidase, NADH menadione reductase, lactate phenazinemethosulfate reductase and duroquinol oxidase. The concentrations of DBMIB required are similar for electron transport and ATPase inhibition and inhibitions are all increased by uncouplers. Electron transport and ATPase are not inhibited in a DBMIB insensitive mutant. Soluble ATPase extracted from the membranes does not show DBMIB inhibition under either high or low Mg⁺⁺ conditions. Lipophilic chelators show additional inhibition over DBMIB. It appears that coenzyme Q functions at three sites in $\text{E. coli}$ electron transport where ATPase activity is controlled. Coenzyme Q deficient mutants also show decreased electron transport and ATPase activity which is restored by coenzyme Q.     

Interactions Between Ascorbyl Free Radical and Coenzyme Q at the Plasma Membrane

A role for coenzyme Q in the stabilization of extracellular ascorbate by intact cells has beenrecently recognized. The aim of this work was to study the interactions between reducedubiquinone in the plasma membrane and the ascorbyl free radical, as an approach to understandubiquinone-mediated ascorbate stabilization at the cell surface. K-562 cells stabilized ascorbateand decreased the steady-state levels of the semiascorbyl radical. The ability of cells to reduceascorbyl free radical was inhibited by the quinone analogs capsaicin and chloroquine andstimulated by supplementing cells with coenzyme Q₁₀. Purified plasma membranes also reducedascorbyl free radical in the presence of NADH. Free-radical reduction was notobserved inquinone-depleted plasma membranes, but restored after its reconstitution with coenzyme Q₁₀.Addition of reduced coenzyme Q₁₀ to depleted membranes allowed them toreduce the signalof the ascorbyl free radical without NADH incubation and the addition of an extra amount ofpurified plasma membrane quinone reductase further stimulated this activity. Reduction wasabolished by treatment with the reductase inhibitor p-hydroximercuribenzoate and by blockingsurface glycoconjugates with the lectin wheat germ agglutinin, which supports the participationof transmembrane electron flow. The activity showed saturation kinetics by NADH andcoenzyme Q, but not by the ascorbyl free radical in the range of concentrations used. Our resultssupport that reduction of ascorbyl free radicals at the cell surface involves coenzyme Qreduction by NADH and the membrane-mediated reduction of ascorbyl free radical.     

Induction by glucose of an antimycin-insensitive,azide-sensitive respiration in the yeast Kluyveromyces lactis

Increasing the glucose concentration from 0.1 to 10% in exponentially growing cultures of Kluyveromyces lactis CBS 2359 does not repress the antimycin-sensitive respiration (Q_{O 2} of 80 l O₂·h^-1·mg^-1 dry weight) but raises the antimycin-insensitive respiration from 3 to 12 l O₂·h^-1·mg^-1 dry weight. Antimycin A inhibits the growth of K. lactis on a variety of substrates with the exception of glucose at concentrations equal to or higher than 1% where substantial antimycin-insensitive respiratory rates are induced. It can be concluded that a minimal antimycin-insensitive Q_{O 2} is necessary for cellular growth when the normal respiratory pathway is not functional.The antimycin-insensitive respiration elicited by growth in high glucose concentrations is poorly inhibited by hydroxamate and is inhibited by 50% by 90 m azide or 1mm cyanide. These concentrations are much higher than those necessary to inhibit cytochrome c oxidase which is not involved in the antimycin-insensitive respiration as was demonstrated by spectral measurements. A pigment absorbing at 555 nm is specifically reduced after addition of glucose to antimycin-inhibited cells. The same pigment is reoxidized by further addition of high concentrations of sodium azide indicating its participation in the antimycin-insensitive, azide-sensitive respiration.     

Steady-State Kinetics of NADH:coenzyme Q Oxidoreductase Isolated from Bovine Heart Mitochondria

Steady-state kinetics of the bovine heart NADH:coenzyme Q oxidoreductase reaction were analyzed in the presence of various concentrations of NADH and coenzyme Q with one isoprenoid unit (Q₁). Product inhibitions by NAD⁺ and reduced coenzyme Q₁ were also determined. These results show an ordered sequential mechanism in which the order of substrate binding and product release is Q₁–NADH–NAD⁺–Q₁H₂. It has been widely accepted that the NADH binding site is likely to be on the top of a large extramembrane portion protruding to the matrix space while the Q₁ binding site is near the transmembrane moiety. The rigorous controls for substrate binding and product release are indicative of a strong, long range interaction between NADH and Q₁ binding sites.     

高寒矮嵩草草甸冬季CO2释放特征

冬季碳排放在高寒草地年内碳平衡中占有重要位置。为探讨高寒草地冬季碳排放特征及温度敏感性,于2003-2005年在中国科学院海北高寒草甸生态系统研究站,利用密闭箱-气相色谱法连续观测了高寒矮嵩草草甸2个冬季的生态系统、土壤呼吸通量特征。结果表明:1)高寒矮嵩草草甸冬季生态系统呼吸、土壤呼吸均具有明显的日变化和季节变化规律,温度是其主要的控制因子,能够解释44%以上的呼吸速率变异。2)冬季生态系统呼吸与土壤呼吸速率在统计上没有显著差异,土壤呼吸占生态系统呼吸的比例高达85%以上。3)2003-2004年冬季生态系统呼吸、土壤呼吸的Q₁₀值分别为1.53,1.38;2004-2005年冬季生态系统呼吸与土壤呼吸的Q₁₀值为1.86,1.68,2个冬季生态系统呼吸的Q₁₀值均高于土壤呼吸。4)未发现高寒矮嵩草草甸冷冬年份的Q₁₀值高于暖冬年份以及冬季的Q₁₀值高于生长季。     

Temperature effect on maintenance and growth respiration coefficients of young, field-grown hinoki cypress (Chamaecyparis obtusa)

Respiration measurements were made on the entire aboveground parts of young, field-grown hinoki cypress (Chamaecyparis obtusa) trees at monthly intervals over a 5-year period, to examine the effect of temperature on maintenance and growth respiration coefficients. The respiration rate of the trees was grouped on a monthly basis and then partitioned into maintenance and growth components. The maintenance respiration coefficient increased exponentially with air temperature. The maintenance respiration coefficient at a temperature of 0°C and itsQ ₁₀ value were 0.205 mmol CO₂ g⁻¹ d.w. month⁻¹ and 1.81, respectively. The growth respiration coefficient, which was virtually independent of temperature, had a mean value of 38.06±1.95 (SE) mmol CO₂g⁻¹ d.w. The growth rate increased exponentially with increasing temperature up to a peak at around 18°C, and thereafter declined, thereby resulting in the growth respiration rate being increasingly less sensitive to increasing air temperature. The reported decreases in theQ ₁₀ value of total respiration with increasing air temperature is due to the way in which the growth component of respiration responds to temperature.     

Hormonal status of tobacco variety Samsun NN exposed to synthetic coenzyme Q10 (ubiquinone 50) and TMV infection

Hormonal system status has been analyzed in leaf disks of hypersensitive tobacco Nicotiana tabacum L. variety Samsun NN during the development of resistance to tobacco mosaic virus (TMV) induced by synthetic coenzyme Q₁₀ (ubiquinone 50). The absolute and relative content of abscisic acid (ABA), indoleacetic acid (IAA), and cytokinins (CKs) was determined after the exposure of leaves to Q₁₀ solution and the subsequent TMV infection. In plants not treated with Q₁₀, CK content increased about 2.5 times 1 day after TMV infection, while a significant increase in the ABA level and a decrease in the IAA level were observed only after 2 days. In the dynamics, Q₁₀ treatment had a protective antiviral effect, significantly decreased the ABA level, and increased the IAA level in sensitized plants compared to nonsensitized ones.