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The predatory mite Neoseiulus longispinosus (Evans, 1952) isused as a specialized acariphage on vegetable, flower and berry crops inAsia. In protected ground of European agriculture, N. californicus is one ofthe effective predators of spider mites (Tetranychidae). The periodicity ofattacks on the victim depends on the temperature. The predator prefers tohunt immature individuals of T. urticae, often ignoring adult female spidermites if there is a choice. N. longispinosus does not show preferencebetween eggs and T. urticae nymphs. However, as the density of the spidermite population increases, the predatory mite switches its diet from theeggs to its larvae and nymphs. Adult females of N. californicus exhibit atype 2 functional response to both eggs and T. urticae nymphs. Pyrethroidand avermectin substances are highly toxic to predator populations, despitelow acute toxicity of many other insecticides (Actara, Envidor, etc.).

The redox interaction of exogenous cytochrome c550 (Cyt) with PSII isolated from spinach was studied. Illumination of PSII particles in the presence of Cyt led to: (1) Cyt photooxidation by PSII reaction center (demonstrated at the first time), (2) Cyt photoreduction via O2−• photoproduced on the acceptor side of PSII, and (3) Cyt photoreduction by reduced electron carriers of PSII. A step-by-step removal of components of water-oxidizing complex was accompanied by the appearance of Cyt photooxidation, an increase in the superoxide dismutase (SOD)-dependent Cyt photoreduction (related to O2−• formation), and a decrease in the SOD-independent Cyt photoreduction. Re-addition of PsbO protein diminished the Cyt-induced restoration of electron transfer in PSII. Addition of diuron led to inhibition of these photoprocesses, while exogenous Mn2+ inhibited only the Cyt c photooxidation. The results can be important for correct measurements of O2−• photoproduction in PSII and for elucidation of the role of cytochrome c550 in cyanobacterial PSII. [ABSTRACT FROM AUTHOR]

In this study tomato plants are affected by infecting stress factor and subjected to photonic pumping. The pathogen can cause symptoms of diseases that are dangerous for plants and are exibited on the level of organs of plant by changes in metabolism rates. The objective of this study is to trace the modification of transpiration parameters patterns of green tomato leaves under the influence of the stress factor, to provide means to assess damage and to further restore optimal parameters of plant growth and development.

The search and creation of agrochemicals of a new generation, similar to bioprotectors, for agriculture is an urgent task of today scientific findings. The applied high-tech agrochemicals, in addition to their protective properties, have positive effect on the growth and development of cereals. The initial stages of growth and development (stress phases) are passing better with the introduction of effective fertilizers, agrochemicals and growth regulators. However, the use of their concentrated solutions is ineffective due to losses or transitions to an inaccessible state. Prolonged gradual release of Fe (II) will provide the concentration required for plants in the soil.

The effect on transpiration in tomato on different tiers (Crisis tiers) was studied, which consisted of increasing transpiration parameters in option 1 (Standard) and option 2 (Load). The influence of regulated photosynthetic flow on the studied tomato under different conditions was studied. Changes in transpiration parameters (from 1.4*10-5 mol m-2 s-1 to 1.3*10-3 mol m-2 s-1) are reflected in the graphs. The portable LI-COR LI- 6800 system successfully measured several parameters in the same area of the leaf: photosynthesis (µmol m-2 s-1), transpiration (mol m-2 s-1), stomatal conductance (mol m-2 s -1). The average level of transpiration in the studied tomato on crisis tiers is different and is, in option 1 (Standard): 1.6 *10-4 mol m-2 s-1± 1*10-5 mol m-2 s-1, in option 2 (Load): 3.1 *10-4 mol m-2 s-1 ± 2*10-5 mol m-2 s-1. The average level of transpiration of the studied tomato on the control layer, in option 1 (standard) is 2.2 * 10-4 mol m-2 s-1 ± 3 * 10-6 mol m-2 s-1, in option 2 (Load) is 3.6 *10-4 mol m-2 s-1 ± 4 *10-6 mol m-2 s-1.

A study was carried out of the physiological parameters of the tomato variety “Barberry F1”, under the influence of an external factor, at night in the conditions of the Moscow region. Parameters such as transpiration were observed. According to the results of the experiment, there are significant differences between the two variants of the experiment (control and experiment). Under the influence of the limiting factor, there is a general increase in the efficiency of transpiration; in addition to the general increase, changes occur in the studied parameters under the conditions of dividing the plant into tiers. Thus, in the control plant, the middle leaves show significant differences from the upper and lower tier, whereas in the experiment this difference is significant only in some cases.

The paper present the historical scope of the triterpene acids usage in agriculture and industry. On the territory of the Russian Federation, according to data for 2023, 4 agrochemicals based on triterpene acids are registered: “Biosil”, “Alfastim”, “Verva”, “Novosil”. Experimental studies carried out in laboratory conditions using original techniques and GLP- practices allow to determine effective concentrations systematically improving the state of organs and tissues of cereals at different stages of ontogenesis. Both triterpene-containing and chelated forms of trace elements shown to affect the effective development of roots and stems. Work in this direction is laborious, however, it expands the variability of knowledge on crop quality and volume management and requires expanding of the research.

The effect of coatings containing upconversion luminescent nanoparticles on the cultivation of Solanum lycopersicum has been studied. Sr0.76Ba0.20Yb0.02Er0.02F2.04 particles capable of converting infrared radiation into visible light (λem = 660 nm, 545 nm, and 525 nm) were used as the phosphor. It was shown that the cultivation of tomatoes under photoconversion coatings accelerated the adaptation of plants to ultraviolet radiation. A more efficient distribution of the energy of absorbed light between the processes of photosynthesis and thermal dissipation under upconversion coatings was revealed. As a result, plants grown under photoconversion coatings increased the number and total leaf area, stem length, and leaf chlorophyll content.

Earlier, it was suggested that carotenoids in light-harvesting complexes 2 (LH2) can generate singlet oxygen, further oxidizing bacteriochlorophyll to 3-acetyl-chlorophyll. In the present work, it was found that illumination of isolated LH2 preparations of purple sulfur bacterium Ectothiorhodospira haloalkaliphila with light in the carotenoid absorption region leads to the photoconsumption of molecular oxygen, which is accompanied by the formation of hydroperoxides of organic molecules in the complexes. Photoformation of two types of organic hydroperoxides were revealed: highly lipophilic (12 molecules per one LH2) and relatively hydrophobic (68 per one LH2). It has been shown that illumination leads to damage to light-harvesting complexes. On the one hand, photobleaching of bacteriochlorophyll and a decrease in its fluorescence intensity are observed. On the other hand, the photoinduced increase in the hydrodynamic radius of the complexes, the reduction in their thermal stability, and the change in fluorescence intensity indicate conformational changes occurring in the protein molecules of the LH2 preparations. Inhibition of the processes described above upon the addition of singlet oxygen quenchers (L-histidine, Trolox, sodium L-ascorbate) may support the hypothesis that carotenoids in LH2 preparations are capable of generating singlet oxygen, which, in turn, damage to protein molecules., Competing Interests: The authors declare there are no competing interests., (©2024 Yanykin et al.)

Main Conclusion: This study describes a new role for hydroperoxide lyase branch of oxylipin biosynthesis pathway in protecting photosynthetic apparatus under high light conditions. Lipid-derived signaling molecules, oxylipins, produced by a multi-branch pathway are central in regulation of a wide range of functions. The two most known branches, allene oxide synthase (AOS) and 13-hydroperoxide lyase (HPL) pathways, are best recognized as producers of defense compounds against biotic challenges. In the present work, we examine the role of these two oxylipin branches in plant tolerance to the abiotic stress, namely excessive light. Towards this goal, we have analyzed variable chlorophyll fluorescence parameters of intact leaves of Arabidopsis thaliana genotypes with altered oxylipin profile, followed by examining the impact of exogenous application of selected oxylipins on functional activity of photosynthetic apparatus in intact leaves and isolated thylakoid membranes. Our findings unequivocally bridge the function of oxylipins to photosynthetic processes. Specifically, HPL overexpressing lines display enhanced adaptability in response to high light treatment as evidenced by lower rate constant of photosystem 2 (PS2) photoinhibition and higher rate constant of PS2 recovery after photoinhibition. In addition, exogenous application of linolenic acid, 13-hydroperoxy linolenic acid, 12-oxophytodienoic acid, and methyl jasmonate individually, suppresses photochemical activity of PS2 in intact plants and isolated thylakoid membranes, while application of HPL-branch metabolites-does not. Collectively these data implicate function of HPL branch of oxylipin biosynthesis pathway in guarding PS2 under high light conditions, potentially exerted through tight regulation of free linolenic acid and 13-hydroperoxy linolenic acid levels, as well as competition with production of metabolites by AOS-branch of the oxylipin pathway.

Recently, it has been shown that the addition of 1M trehalose leads to the increase of the rate of oxygen photoconsumption associated with activation of electron transport in the reaction center of photosystem 2 (PS2) in Mn-depleted PS2 membranes (apo-WOC-PS2) [37]. In the present work the effect of trehalose on photoinhibition of apo-WOC-PS2 preparations (which are characterized by a high sensitivity to the donor side photoinhibition of PS2) was investigated. The degree of photoinhibition was estimated by the loss of the capability of exogenous electron donor (sodium ascorbate) to reactivate the electron transport (measured by light-induced changes of chlorophyll fluorescence yield (∆F)) in apo-WOC-PS2. It was found that 1M trehalose enhanced the Mn 2+ -dependent suppression of photoinhibition of apo-WOC-PS2: in the presence of trehalose the addition of 0.2μM Mn 2+ (corresponding to 2 Mn 2+ per one reaction center) was sufficient for an almost complete suppression of the donor side photoinhibition of the complex. In the absence of trehalose it was necessary to add 100μM Mn 2+ to achieve a similar result. The effect of trehalose was observed during photoinhibition of apo-WOC-PS2 at low (15μmolphotons -1 m -2 ) and high (200μmolphotons -1 m -2 ) light intensity. When Mn 2+ was replaced by other PS2 electron donors (ferrocyanide, DPC) as well as by Ca 2+ the protective effect of trehalose was not observed. It was also found that 1M trehalose decreased photoinhibition of apo-WOC-PS2 if the samples contained endogenous manganese (1-2 Mn ions per one RC was enough for the maximum protection effect). It is concluded that structural changes in PS2 caused by the addition of trehalose enhance the capability of photochemical reaction centers of apo-WOC-PS2 to accept electrons from manganese (both exogenous and endogenous), which in turn leads to a considerable suppression of the donor side photoinhibition of PS2., (Copyright © 2016 Elsevier B.V. All rights reserved.)

It has been shown earlier (Khorobrykh and Klimov, 2015) that molecular oxygen is directly involved in the general mechanism of the donor side photoinhibition of photosystem II (PSII) membranes. In the present work the effect of oxygen on photoassembly ("photoactivation") of the functionally active inorganic core of the water-oxidizing complex (WOC) in Mn-depleted PSII preparations (apo-WOC-PSII) in the presence of exogenous Mn(2+), Ca(2+) as well as ferricyanide was investigated. It was revealed that the efficiency of the photoassembly of the WOC was considerably increased upon removal of oxygen from the medium during photoactivation procedure using the enzymatic oxygen trap or argon flow. The lowering of O2 concentration from 250μM to 75μM, 10μM and near 0μM results in 29%, 71% and 92%, respectively, stimulation of the rate of O2 evolution measured after the photoactivation. The increase in the intensity of light used during the photoactivation was accompanied by a decrease of both the efficiency of photoassembly of the WOC and the stimulation effect of removal of O2 (that may be due to the enhancement of the processes leading to the photodamage to PSII). It is concluded that the enhancement in photoactivation of oxygen-evolving activity of apo-WOC-PSII induced by oxygen removal from the medium is due to the suppression of the donor side photoinhibition of PSII in which molecular oxygen can be involved., (Copyright © 2016 Elsevier B.V. All rights reserved.)

It is known that the removal of manganese from the water-oxidizing complex (WOC) of photosystem 2 (PS2) leads to activation of oxygen photoconsumption (OPC) [Khorobrykh et al., 2002; Yanykin et al., 2010] that is accompanied by the formation of organic hydroperoxides on the electron-donor side of PS2 [Khorobrykh et al., 2011]. In the present work the effect of trehalose on the OPC in Mn-depleted PS2 preparations (apo-WOC-PS2) was investigated. A more than two-fold increase of the OPC is revealed upon the addition of 1M trehalose. Drastic (30%-70%) inhibition of the OPC upon the addition of either electron acceptor or electron donor indicates that the trehalose-induced activation of the OPC occurs on both donor and acceptor sides of PS2. A two-fold increase in the rate of superoxide-anion radical photoproduction on the electron-acceptor side of PS2 was also shown. Applying the "variable" chlorophyll fluorescence (ΔF) it was shown that the addition of trehalose induces: (i) a significant increase in the ability of exogenous Mn(2+) to donate electrons to the reaction center of PS2, (ii) slowing down the photoaccumulation of the primary quinone electron acceptor of PS2 (QA(-)) under aerobic conditions, (iii) acceleration of the reoxidation of QA(-) by QB (and by QB(-)) as well as the replacement of QB(2-) by a fully oxidized plastoquinone, and (iv) restoration of the electron transfer between the quinone electron carriers in the so-called "closed reaction centers of PS2" (their content in the apo-WOC-PS2 is 41%). It is suggested that the trehalose-induced increase in efficiency of the O2 interaction with the electron-donor and electron-acceptor sides of apo-WOC-PS2 is due to structural changes leading to both a decrease in the proportion of the "closed PS2 reaction centers" and an increase in the electron transfer rate in PS2., (Copyright © 2015 Elsevier B.V. All rights reserved.)