[Biophysical methods of ecological monitoring. Photosynthetic characteristics of tree plants growing in Moscow city].

In this work, we studied an influence of ecological factors (a distance from the highway) on photosynthetic characteristics of leaves of four species of tree plants growing in Moscow city. Photosynthetic activity of leaves was assayed by instrumental methods of probing the functional state of photosynthetic apparatus, using electron paramagnetic resonance method for measuring the kinetics of photooxidation of P700 centers, thermoluminescence, and slow induction of chlorophyll fluorescence. It has been shown that kinetic parameters of the induction curves, as measured from the kinetics of photooxidation of P700 and slow induction of chlorophyll fluorescence in dark-adapted leaves, are sensible to variations of plant growing conditions. These parameters can be used as informative characteristics for ecological monitoring of the environment.

[Luminescence characteristics of strawberry leaves in early stages of their injury by arachnoidal mite].

In this work, we have investigated how the luminescence characteristics and a total content of antioxidants in leaves of strawberry (Fragaria x ananassa Duch.) change after infestation of plants by spider mite (Tetranychus atlanticus McGregor). At the earlier stage of plant injury, the chlorophyll concentration remained unchanged. However, the total amount of antioxidants decreased and the intensity of high-temperature band (60 divided by 100 degrees C) of thermoluminescence increased, indicating a degradation of membrane lipids caused by oxidative stress. In infected leaves, the light-induced rise of non-photochemical quenching of chlorophyll fluorescence was slower, while the relaxation of non-photochemical quenching in the dark was faster than in control samples of leaves. These data might indicate that the thylakoid membranes in infested leaves were more permeable for ions than in control leaves.

Investigation of the low-affinity oxidation site for exogenous electron donors in the Mn-depleted photosystem II complexes.

In the manganese-depleted photosystem II (PSII[-Mn]) preparations, oxidation of exogenous electron donors is carried out through the high-affinity (HA) and the low-affinity (LA) sites. This paper investigates the LA oxidation site in the PSII(-Mn) preparations where the HA, Mn-binding site was blocked with ferric cations [[11] B.K. Semin, M.L. Ghirardi, M. Seibert, Blocking of electron donation by Mn(II) to Y(Z)(*) following incubation of Mn-depleted photosystem II membranes with Fe(II) in the light, Biochemistry 41 (2002) 5854-5864.]. In blocked (PSII[-Mn,+Fe]) preparations electron donation by Mn(II) cations to Y(Z)(*) was not detected at Mn(II) concentration 10 microM (corresponds to K(m) for Mn(II) oxidation at the HA site), but detected at Mn concentration 100 microM (corresponds to K(m) for the LA site) by fluorescence measurements. Comparison of pH-dependencies of electron donation by Mn(II) through the HA and the LA sites revealed the similar pK(a) equal to 6.8. Comparison of K(m) for diphenylcarbazide (DPC) oxidation at the LA site and K(d) for A(T) thermoluminescence band suppression by DPC in PSII(-Mn,+Fe) samples suggests that there is relationship between the LA site and A(T) band formation. The role of D1-His190 as an oxidant of exogenous electron donors at the LA site is discussed. In contrast to electrogenic electron transfer from Mn(II) at the HA site to Y(Z)(*), photovoltage due to Mn(II) oxidation in iron-blocked PSII(-Mn) core particles was not detected.

[Slow fluorescence induction and CO2-exchange in bean leaves treated with Reynoutria sachalinensis extract].

It has been shown that the treatment of bean seedlings with a water extract of Reynoutria sachalinensis increases visible photosynthesis and the activity of dark respiration of plants. The increase in CO2-uptake under relatively high light illumination (10000 1x) correlates with an increase in the fluorescence parameter (F(M) - F(T))/F(T).

[Luminescent indicators in various parts of wheat leaves in ontogenesis]. / Liuminestsentnye pokazateli v raznykh uchastkakh lista pshenitsy v ontogeneze.

A comparative study of slow fluorescence induction, fluorescence spectra, thermoluminescence, photosynthetic activity and chlorophyll content in ontogenesis of wheat seedlings (Triticum aestivum L, cv. Yubileinayd) grown in the laboratory conditions was carried out. It was shown that (FM-FT)/FT values of slow fluorescence induction increased with the age of leaf part, reached a maximum (for 2-week-old seedlings), and then decreased. Changes in (FM-FT)/FT positively correlated with the changes in photosynthetic activity per chlorophyll unit (delta O2/(delta t.chlorophyll)); the coefficient of correlation r = 0.84, p > 0.999. The F685/F730 ratio of the intensities of fluorescence spectrum decreased with the increase in chlorophyll content. The relative light sum SA/S(tot) of band A of thermoluminescence changed in the same direction as delta O2/(delta t-chlorophyll), the relative light sum (SC/S(tot) of band C of thermoluminescence decreased during leaf maturation. The regularities revealed in the experiments are discussed in terms of changes in the structural and functional organization of the photosynthetic apparatus known from the literature.

Comparative study of effects of artificial electron donors on the AT-band of photosystem II thermoluminescence.

Extraction of the Mn-cluster from photosystem II (PS II) inhibits the main bands of thermoluminescence and induces a new AT-band at -20 degrees C. This band is attributed to the charge recombination between acceptor QA- and a redox-active histidine residue on the donor side of PS II. The effect of Mn(II) and Fe(II) cations as well as the artificial donors diphenylcarbazide and hydroxylamine on the AT-band of thermoluminescence was studied to elucidate the role of the redox-active His residue in binding to the Mn(II) and Fe(II). At the Mn/PS II reaction center (RC) ratio of 90 : 1 and Fe/PS II RC ratio of 120 : 1, treatment with Mn(II) and Fe(II) causes only 60% inhibition of the AT-band. Preliminary exposure of Mn-depleted PS II preparations to light in the presence of Mn(II) and Fe(II) causes binding of the cations to the high-affinity Mn-binding site, thereby inhibiting oxidation of the His residue involved in the AT-band formation. The efficiency of the AT-band quenching induced by diphenylcarbazide and hydroxylamine is almost an order of magnitude higher than the quenching efficiency of Mn(II) and Fe(II). Our results suggest that the redox-active His is not a ligand of the high-affinity site and does not participate in the electron transport from Mn(II) and Fe(II) to YZ. The concentration dependences of the AT-band inhibition by Mn(II) and Fe(II) coincide with each other, thereby implying specific interaction of Fe(II) with the donor side of PS II.

[Antifungal activity of aqueous extracts from the leaf of cowparsnip and comfrey]. / Fungitoksicheskaia aktivnost' vodnykh ékstraktov iz list'ev borshchevika i okopnika.

We found that extracts from the leaves of medicinal comfrey and cowparsnip strongly inhibit the germination of Erysiphe graminis conidia and uredospores of Puccinia graminis. Spraying wheat seedlings with these extracts, in contrast to the irrigation of soil, markedly diminished infection in plants with powdery mildew. Antifungal activity in vitro and protective activity (when plants were sprayed) correlated with the level of phenolic compounds in these extracts. Experiments with healthy plants have demonstrated that the photosynthetic apparatus of wheat plants is stimulated by extracts. Spraying seedlings with the extracts resulted in an increased rate of O2 evolution calculated per unit of chlorophyll, an increase in the ratio (FM-FT)/FT in the experiments that recorded slow fluorescence induction, an increase in the relative light intensity of band A, and a decrease of relative intensity of band C in experiments with thermoluminescence of wheat leaves. These results provide evidence that the protective activity of comfrey and cowparsnip extracts is associated with their action on the pathogenic fungus and with the activation of natural defense reactions of the host plant.

[Changes in induction of slow fluorescence in leaves of maple located near urban highways]. / Izmenenie medlennoi induktsii fluorestsentsii list'ev klena vblizi transportnykh magistralei.

The slow fluorescence induction parameter FM/FT was measured for green leaves from maple trees grown in the park, depending on the distance (5-65 m) between the tree and the highway cross. We concluded that the decrease in the value of FM/FT for trees grown in the vicinity of the road cross was caused by exhaust gases.

[Various luminescence characteristics of allocytoplasmic wheat hybrids]. / Nekotorye liuminestsentnye kharakteristiki allotsitoplazmaticheskikh gibridov pshenitsy.

Comparative studies of thermoluminescence and slow fluorescence induction were carried out on leaves of allocytoplasmic hybrids and standard regionalized wheat (cultivar Zarya). There are differences in luminescence indices between these objects correlated to the thermoluminescence and slow fluorescence induction methods. These differences allow estimation of the functional activity of the photosynthetic system. All studied allocytoplasmic hybrids exceeded the standard wheat in both luminescence indices FM/FT (slow fluorescence induction) and SA/Stot (thermoluminescence) and productivity (height of seedlings, number of ears and grains, grain mass, etc.). The highest values of FM/FT and SA/Stot and the lowest value of SC/Stot were recorded in the allocytoplasmic hybrid Igen 3 x Mironovskaya 808, which is characterized by the highest productivity.

[Effect of redox properties of the medium on the thermoluminescence of the chloroplasts of higher plants]. / Vliianie okislitel'no-vosstanovitel'nykh svoistv sredy na termoliuminestsentsiiu khloroplastov vysshikh rastenii.

The dependence of thermoluminescence characteristics of higher plants chloroplasts on the state of the electron transfer chain (ETC) was studied. The state of the ETC was changed with variation of the the redox state of the medium with different additions (mixture of ferri- and ferrocianide, DPIP, and DPIP in the presence of different concentrations of the ascorbate).

[Effect of light absorbed by photosystem 1 and photosystem 2 on the fluorescence yield of green leaves]. / Izmeneniia vykhoda fluorestsentsii zelenogo lista pod deistviem sveta, pogloshchaemogo fotosistemoi 1 i fotosistemoi 2

The influence of strong active light, which mainly excited the photosystem 1 (AL I) and photosystem 2 (AL II), on the fluorescence of weak detecting light under different intensities of active light has been investigated under aerobic and anaerobic conditions. It is shown that an increase or decrease in fluorescence can be observed under the influence of AL 1 according to the experimental conditions.