Movement of paraquat in resistant and susceptible biotypes of Erigeron philadelphicus and E. canadensis

Paraquat (1,1'-dimethyl-4,4'-bipyridinium) resistant biotypes of Erigeron philadelphicus and E. canadensis , from fields where paraquat had been used for weed control, showed more than 100 times higher resistance than the susceptible biotype of both plants. Excised leaves of the susceptible biotypes wilted when supplied with more than 5 μ M paraquatat at the cut ends, but those from the resistant biotypes did not wilt even at 500 μ M. Autoradiographs indicated that (¹⁴CH₃)-paraquat taken up through the cut ends was rapidly distributed through the vascular system in leaves of the susceptible biotype, but was barely translocated in leaves of the resistant biotype. The amount of paraquat taken up during 48 h in the resistant biotype was 0.5% of that in the susceptible biotype in light. This difference in paraquat movement may be correlated with paraquat resistance in Erigeron.     

二氯喹啉酸诱导稗草EcDnaJ基因表达

DnaJ作为分子伴侣在植物抗逆中起重要作用. 但目前在二氯喹啉酸逆境下,其在抗药性稗草中表达特点却鲜有报道. 本研究采用RACE技术从抗二氯喹啉酸稗草中克隆了1个DnaJ基因, 命名为EcDnaJ1 (GenBank登录号：JX518598), 其cDNA全长为2 154 bp, 开放阅读框为1 350 bp,编码449 个氨基酸, 理论分子量为48.4 kD, 等电点为9.5. 该蛋白质氮端含有1个保守的J结构域, 中部含有4个模式为CxxCxGxG的锌指结构. Real-time PCR分别测定EcDnaJ1在二氯喹啉酸抗性和敏感的稗草生物型苗期叶、根及成株期根、茎、叶和种子中的表达, 在感、抗生物型的相对表达量分别是0.8～20.9和7.4～30.2, 其中在抗性稗草苗期叶片中相对表达量最高为30.2, 而在敏感稗草种子中最低为0.8, 抗性稗草是敏感稗草的1.4～9.2 倍. 受二氯喹啉酸诱导后, 其在感、抗稗草的相对表达量分别为35.8～72.5和84.9～261.9, 在抗性稗草苗期叶片中相对表达量最高为261.9, 而在敏感稗草的种子中相对表达量最低为35.8, 抗性稗草是敏感稗草的2.4～3.6 倍. 诱导前后, 无论是在苗期根和叶中还是成株期的根、茎、叶和种子中, EcDnaJ1表达量均是抗性稗草高于敏感稗草. 抗、感稗草生物型的EcDnaJ1在mRNA水平差异表达暗示,它可能参与了稗草对二氯喹啉酸的抗药性.     

Delayed Fluorescence and Ultraweak Light Emission from Isolated Chloroplasts (Comparison of Emission Spectra and Concentration Dependence)

The ultraweak light emission of isolated chloroplasts (Hidegand Inaba (1991) Photochem. Photobiol. 52: 137) was investigatedin comparison to delayed light emission. We compared the concentrationdependence and the spectral distribution of the light emittedfrom isolated chloroplasts stored in the dark for 10 s, 2 min(delayed light emission), 4 and 10 h (ultraweak light emission),respectively. In samples with low chlorophyll concentration, spectra of allemission phenomena were maximal at 685–695 nm, but spectraof ultraweak light, especially that of long term (10 h) emission,were broader in the 700–800 nm region than spectra ofdelayed light, indicating emission from a bigger variety ofchlorophyll molecules. The intensity of delayed light and short term (4 h) ultraweaklight exhibited a simple, saturating exponential dependenceon chlorophyll concentration, while long term (10 h) ultraweaklight emission was best described as a saturating exponentialcontaining a quadratic function of the concentration. This differencesuggests that long term ultraweak light emission is broughtabout by reactions distinct from the earlier described mechanismof electron transport related dark photoemission. (Received November 15, 1991; Accepted May 18, 1992)     

Ultraweak photoemission from dark-adapted leaves and isolated chloroplasts

Dark-adapted isolated spinach chloroplasts and leaves, unlike sub-chloroplast fractions, are capable of emitting ultraweak light spontaneously (50-125 counts/s per cm2). The emission of leaves is due to two processes with activation energies of 97 and 25 kJ/mol while in isolated chloroplasts, it is the result of a single process (98 kJ/mol), as indicated by the Arrhenius plots of the intensity. Emission spectra demonstrate that the terminal step of these reactions is the excitation of chlorophyll in both samples. We suggest that the additional component in the ultraweak light emission of leaves may be related to mitochondria.     

Altered Leaf Structure and Function in Triazine-Resistant Common Groundsel (Senecio vulgaris)

Anatomical and physiological characteristics of leaves of triazinesusceptible and -resistant biotypes of common groundsel (Senecio vulgaris L.) were studied in order to explain the differences in light-saturated photosynthetic rates previously reported. Leaves were of uniform leaf plastochron index from greenhouse-grown plants. Susceptible plants had greater leaf fresh and dry weights and leaf areas, while resistant plants had greater specific leaf mass (mg fresh weight/cm²). Susceptible plants had greater amounts of total chlorophyll per unit leaf weight and a higher chlorophyll a/b ratio. Soluble protein in leaves was higher in susceptible chloroplasts on a weight and area basis, but similar to resistant chloroplasts on a unit chlorophyll basis. Activity of ribulose 1,5-bisphosphate carboxylase was higher in resistant plants on a fresh weight, leaf area, and milligram chlorophyll basis. Stomatal frequency, length, and arrangement were similar between biotypes, as were transpiration and conductance. Resistant leaves had less air space (v/v), more cells in palisade and spongy mesophyll, and a greater volume of palisade tissue than spongy, when compared to susceptible leaves. Differences in leaf structure and function between biotypes are probably due to a complex of developmental adaptations which may be only indirectly related to modified photosystem II in resistant plants. These results indicate that the consistently lower rates of net photosynthesis and yield in resistant plants cannot be explained solely on the basis of these leaf characteristics. Several possible mechanisms to account for reduced productivity are suggested.     

Differential Light Responses of Photosynthesis by Triazine-resistant and Triazine-susceptible Senecio vulgaris Biotypes

Studies were conducted to determine a physiological basis for competitive differences between Senecio vulgaris L. biotypes which are either resistant or susceptible to triazine herbicides. Net carbon fixation of intact leaves of mature plants was higher at all light intensities in the susceptible biotype than in the resistant biotype. Quantum yields measured under identical conditions for each biotype were 20% lower in the resistant than in the susceptible biotype. Oxygen evolution in continuous light measured in stroma-free chloroplasts was also higher at all light intensities in the susceptible biotype than in the resistant biotype. Oxygen evolution in response to flashing light was measured in stroma-free chloroplasts of both biotypes. The steady-state yield per flash of resistant chloroplasts was less than 20% that of susceptible chloroplasts. Susceptible chloroplasts displayed oscillations in oxygen yield per flash typically observed in normal chloroplasts, whereas the pattern of oscillations in resistant chloroplasts was noticeably damped. It is suggested that modification of the herbicide binding site which confers s-triazine resistance may also affect the oxidizing side of photosystem II, making photochemical electron transport much less efficient. This alteration has resulted in a lowered capacity for net carbon fixation and lower quantum yields in whole plants of the resistant type.     

Light emission from tryptophan oxidation by hypobromous acid

The emission of ultraweak light from cells is a phenomenon associated with the oxidation of biomolecules by reactive oxygen species. The indole moiety present in tryptophan, serotonin and melatonin is frequently associated with the emission of light during the oxidation of these metabolites. This study presents results for hypobromous acid (HOBr) oxidation of tryptophan as a putative endogenous source of ultraweak light emission. We found that chemiluminescence elicited by the oxidation of tryptophan by HOBr was significantly higher than by hypochlorous acid (HOCl). This difference was related to secondary oxidation reactions, which were more intense using HOBr. The products identified during oxidation by HOCl, but depleted by using HOBr, were N‐formylkynurenine, kynurenine, 1,2,3,3a,8,8a‐hexahydro‐3a‐hydroxypyrrolo[2,3‐b]‐indole‐2‐carboxylic acid, oxindolylalanine and dioxindolylalanine. The emission of light is dependent on the free α‐amino group of tryptophan, and hence, the indole of serotonin and melatonin, although efficiently oxidized, did not produce chemiluminescence. The emission of light was even greater using taurine monobromamine and dibromamine as the oxidant compared to HOBr. A mechanism based on bromine radical intermediates is suggested for the higher efficiency in light emission. Altogether, the experimental evidence described in the present study indicates that the oxidation of free tryptophan or tryptophan residues in proteins is an important source of ultraweak cellular emission of light. This light emission is increased in the presence of taurine, an amino acid present in large amounts in leukocytes, where this putative source of ultraweak light emission is even more relevant. Copyright © 2012 John Wiley & Sons, Ltd.     

Activity-dependent neural tissue oxidation emits intrinsic ultraweak photons

Living organisms have been known to spontaneously emit ultraweak photons in vivo and in vitro. Origin of the photon emission remains unclear, especially in the nervous system. The spontaneous ultraweak photon emission was detected here from cultured rat cerebellar granule neurons using a photomultiplier tube which was highly sensitive to visible light. The photon emission was facilitated by the membrane depolarization of neurons by a high concentration of K+ and was attenuated by application of tetrodotoxin or removal of extracellular Ca2+, indicating the photon emission depending on the neuronal activity and likely on the cellular metabolism. Furthermore, almost all the photon emission was arrested by 2,4-dinitrophenylhydrazine, indicating that the photon emission would be derived from oxidized molecules. Detection of the spontaneous ultraweak photon emission will realize noninvasive and real-time monitoring of the redox state of neural tissue corresponding to the neuronal activity and metabolism.     

Mode of action of paraquat in leaves of paraquat-resistant Conyza canadensis (L.) Cronq

The mode of action of paraquat (1,1-dimethyl-4,4-bipyridinium) and the mechanism of resistance to it were studied in leaves of atrazine/paraquat co-resistant (R) and susceptible (S) biotypes of horseweed (Conyza canadensis) collected from Hungarian vineyards. The application of 0·5 mol m^?3 paraquat by spraying onto the surface of the leaves of intact plants in the light rapidly led to typical symptoms of paraquat action in the initial period in both biotypes, i.e. inhibition of CO₂ fixation, suppression of variable chlorophyll fluorescence (F_v), decrease of oxygen evolution and stimulation of ethane production. The inhibitory effect of paraquat in the S plants was irreversible, whereas it was transient in the R plants and those plants recovered gradually afterwards. The R plants recovered from the inhibitory effect of paraquat only in the light, and an increase in light intensity was found to have a pronounced effect on the recovery of F_v. The mechanism of resistance to paraquat in C. canadensis is discussed.     

Increased Heat Sensitivity of the Photosynthetic Apparatus in Triazine-Resistant Biotypes from Different Plant Species

Leaf fragments from five species of triazine-resistant and -susceptibleplants were exposed for brief periods to temperatures above38?C. In resistant leaves, a greater increase in temperature-inducedfluorescence emission was observed than in susceptible leaves,indicative of greater heat sensitivity of the PS II electrontransfer linked to triazine resistance. The kinetics of fluorescenceinduction under low or strong light excitation revealed twodistinct effects of heat exposure; A DCMU-type inhibition whichwas reversed upon cooling and a decrease in the variable fluorescence,due mainly to an increase in the constant fluorescence (O level)in resistant leaves, which was only partially reversible. Agreater deterioration of electron transfer activity in chloroplastsisolated from resistant plants also was detected, under exposuresto a high pH, temperature of 25–35?C and to ferricyanide.This indicates that there is greater instability of the oxygenevolving system in triazine-resistant plants. (Received July 26, 1984; Accepted January 8, 1985)     

Laser-ultraviolet-A induced ultra weak photon emission in human skin cells: A biophotonic comparison between keratinocytes and fibroblasts

Photons participate in many atomic and molecular interactions and processes. Recent biophysical research has discovered an ultraweak radiation in biological tissues. It is now recognized that plants, animal and human cells emit this very weak biophotonic emission which can be readily measured with a sensitive photomultiplier system. UVA laser induced biophotonic emission of cultured cells was used in this report with the intention to detect biophysical changes between young and adult fibroblasts as well as between fibroblasts and keratinocytes. With suspension densities ranging from 1-8 x 106 cells/ml, it was evident that an increase of the UVA-laser-light induced photon emission intensity could be observed in young as well as adult fibroblastic cells. By the use of this method to determine ultraweak light emission, photons in cell suspensions in low volumes (100 microl) could be detected, in contrast to previous procedures using quantities up to 10 ml. Moreover, the analysis has been further refined by turning off the photomultiplier system electronically during irradiation leading to the first measurements of induced light emission in the cells after less than 10 micros instead of more than 100 milliseconds. These significant changes lead to an improvement factor up to 106 in comparison to classical detection procedures. In addition, different skin cells as fibroblasts and keratinocytes stemming from the same donor were measured using this new highly sensitive method in order to find new biophysical insight of light pathways. This is important in view to develop new strategies in biophotonics especially for use in alternative therapies.     

Response of sugar beet plants to ultraviolet-B (280–320 nm) radiation and Cercospom leaf spot disease

Sugar beet ( Beta vulgaris L.) plants injected with Cercospora beticota Sace. as well as non-infected plants were grown under visible light with or without ultraviolet-B (UV-B, 280–320 nm) radiation for 40 days. An interaction between UV-B radiation and Cercospora leaf spot disease was observed, resulting in a large reduction in leaf chlorophyll content, dry weight of leaf laminae, petioles and storage roots. Lipid peraxidation in leaves also increased the most under the combined treatments. This was also true for ultraweak luminescence from both adaxial and abaxial leaf surfaces. However, no correlation between lipid peroxidation and ultraweak luminescence was observed. Ultraviolet-B radiation given alone appeared to have either a stimulating effect, giving an increase in dry weight of laminae and reducing lipid peroxidation, or no effect. This lack of effect was seen in the absence of change in dry weight of storage roots and chlorophyll content relative to controls. The :study demonstrated a harmful interaction between UV-B radiation and Cercospom leaf spot disease on sugar beet.     

Statistical and frequency-amplitude characteristics of ultra weak emissions of the loach eggs and embryos under the normal conditions and during their optic interactions. I. Characteristics of ultra weak emission in normal development and the optic role of egg envelope

Ultraweak emissions of groups comprising several dozens of unfertilized and fertilized loach eggs, embryos, larvae, and their egg envelopes were measured on a photomultiplier tube. The envelopes absorbed the light from external sources but readily gave it back in the absence of embryos. We carried out statistical and frequency-amplitude analyses of ultraweak emissions and studied the autocorrelation structure of their frequency spectra. The frequencies of signals with different intensity underwent regular changes during development. Cascades of short-term (< or = 1 ms) flashes timed (during cleavage) to furrowing were a characteristic element of ultraweak emission. The Fourier spectra of developing embryos had pronounced frequency-amplitude peaks and higher, than in unfertilized eggs and inanimate samples, mutual correlation during successive time intervals. Stage-specific translational symmetry of the frequency spectra of ultraweak emissions was demonstrated, which suggests the presence in groups of embryos of a coordinated system of harmonic oscillators. The latter underwent regular changes during development. The measurement of ultraweak emissions represents a unique non-invasive method of analysis of these oscillators.     

N-methyl-N'-nitro-N-nitrosoguanidine-induced light emission in Chinese hamster cell cultures: correlation with enhancement of chromosomal aberrations.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) was found to induce an ultraweak photon emission in cultures of Chinese hamster fibroblasts (CHL). Measurements suggest that the light emission is due to a reaction between MNNG and cellular metabolites. The light emission depended on the concentration of MNNG and was oxygen-dependent, disappearing in a nitrogen atmosphere. Superoxide dismutase (SOD) or sodium azide decreased the emission intensity. The production of chromosomal aberrations in CHL by MNNG was correlated with the light emission intensity and was inhibited in the presence of SOD.     

Characterization of intermediate biotypes in atrazine-susceptible populations of Chenopodium polyspermum L. and Amaranthus bouchonii thell. in Hungary

Intermediate biotypes for atrazine herbicide resistance in Chenopodium polyspermum and Amaranthus bouchonii were characterized by a peculiar chlorophyll fluorescence induction curve. The intermediate biotypes were isolated from progenies of susceptible plants in maize grown in alternate years without atrazine. The lethal dose in seedling treatments was lower than that of the resistant plants but higher than for susceptible plants. Atrazine at 10 μM was near the I₅₀-value for in vivo nitrite reductase activity in both intermediate biotypes. The activity of nitrite reducttase in the intermediate biotypes was about 75% of that of susceptible biotypes. These characteristics of intermediate biotypes were maternally inherited in crosses.     

Comparative Growth of Triazine-susceptible and -resistant Biotypes ofSolanum nigrumat Different Light Levels

Effects of variation in light intensity on growth of plantsfrom five different populations of triazine-susceptible and-resistantSolanum nigrumwere studied in growth chambers at threelight levels. Plants were grown without intraspecific competitionand with optimal mineral nutrition. After 29 d, the mean biomassof resistant biotypes was about 25% less than that of susceptiblebiotypes at all light levels. Curve-fitting growth analysisshowed that this was the result of a lower initial biomass ofthe resistant biotype at the start of the experiment, as therelative growth rates (RGR) of the susceptible and resistantbiotypes in the early growth phase were equal. Specific leafarea (SLA) was higher for the resistant biotype but this wascompensated for by a lower net assimilation rate (NAR). Thefraction of dry matter invested in leaves was the same for bothbiotypes, but the resistant biotype produced more leaf areaper unit leaf weight. The equal RGR of the susceptible and resistantbiotypes in the early growth phase may have implications forthe competitive ability and population dynamics of a populationwith resistant biotypes.Copyright 1999 Annals of Botany Company Black nightshade, growth analysis, light level, management strategies, RGR, SLA,Solanum nigrum, triazine resistance, weed control.     

On the Mechanism of Resistance to Paraquat in Hordeum glaucum and H. leporinum: Delayed Inhibition of Photosynthetic O(2) Evolution after Paraquat Application

The mechanism of resistance to paraquat was investigated in biotypes of Hordeum glaucum Steud. and H. leporinum Link. with high levels of resistance. Inhibition of photosynthetic O₂ evolution after herbicide application was used to monitor the presence of paraquat at the active site. Inhibition of photosynthetic O₂ evolution after paraquat application was delayed in both resistant biotypes compared with the susceptible biotypes; however, this differential was more pronounced in the case of H. glaucum than in H. leporinum. Similar results could be obtained with the related herbicide diquat. Examination of the concentration dependence of paraquat-induced inhibition of O₂ evolution showed that the resistant H. glaucum biotype was less affected by herbicide compared with the susceptible biotype 3 h after treatment at most rates. The resistant H. leporinum biotype, in contrast, was as inhibited as the susceptible biotype except at the higher rates. In all cases photosynthetic O₂ evolution was dramatically inhibited 24 h after treatment. Measurement of the amount of paraquat transported to the young tissue of these plants 24 h after treatment showed 57% and 53% reductions in the amount of herbicide transported in the case of the resistant H. glaucum and H. leporinum biotypes, respectively, compared with the susceptible biotypes. This was associated with 62% and 66% decreases in photosynthetic O₂ evolution of young leaves in the susceptible H. glaucum and H. leporinum biotypes, respectively, a 39% decrease in activity for the resistant H. leporinum biotype, but no change in the resistant H. glaucum biotype. Photosynthetic O₂ evolution of leaf slices from resistant H. glaucum was not as inhibited by paraquat compared with the susceptible biotype; however, those of resistant and susceptible biotypes of H. leporinum were equally inhibited by paraquat. Paraquat resistance in these two biotypes appears to be a consequence of reduced movement of the herbicide in the resistant plants; however, the mechanism involved is not the same in H. glaucum as in H. leporinum.     

Temperature dependence of ultraweak photon emission in fibroblastic differentiation after irradiation with artificial sunlight

Yield of ultraweak photon emission in a cell culture model for biophotonic measurements using fibroblastic differentiation depended on the temperature of photonic measurement. The ultraweak photon emission of medium was significantly higher at 37 degrees C than at 25 degrees C and after UVB-irradiation this difference was even more pronounced. While with cells in the medium no temperature dependence could be determined in unirradiated samples, after UVB-irradiation of cells an increase of biophotonic emission was observed in postmitotic fibroblasts. While after several UVB exposures normal cells begin to absorb the ultraviolet light, cells from patients with the disease Xeroderma Pigmentosum loose this capacity. In view that fibroblasts play an essential role in skin aging, skin carcinogenesis and wound healing, the biophotonic model using the fibroblastic differentiation system provides to be a new and powerful non-invasive tool for the development of skin science.     

自发和光诱导的生物超微弱发光图像的观测

本文报导一种最新研制的高探测灵敏度,低噪声的光子图像观测系统。利用该系统观测了绿豆芽,小葱和树叶等活体品的超弱发光图像。     

Endogenous enzyme reactions closely related to photon emission in the plant defense response

Lipoxygenase (LOX) and peroxidase (POD) reactions, which are involved in the production of reactive oxygen and radical species, are shown to be associated with ultraweak photon emission in plant defense mechanisms. These enzyme reactions induced high-level ultraweak photon emission in an in vitro reaction system. The application of LOX to sweet potato slices caused photon emission directly in plants. LOX substrate promoted photon emission in chitosan-treated sweet potato, and LOX inhibitor markedly suppressed this emission. Therefore, a LOX-related pathway, including LOX and other downstream reactions, is principally associated with photon emission in plant defense mechanisms.