The Experts below are selected from a list of 9918 Experts worldwide ranked by ideXlab platform
Iwona Adamska - One of the best experts on this subject based on the ideXlab platform.
-
Light Stress Proteins in Viruses, Cyanobacteria and Photosynthetic Eukaryota
Photosynthesis, 2011Co-Authors: Mounia Heddad, Johannes Engelken, Iwona AdamskaAbstract:Plants in Nature frequently perceive environmental extremes such as Light Stress. To maintain their physiological functions under Light Stress conditions plants have developed different protection strategies that operate at morphological, anatomical and subcellular levels. The accumulation of Light Stress proteins from the ELIP (early Light-induced protein) family can be considered to be a part of such photoprotective responses. ELIPs are distant relatives of the chlorophyll a/b-binding proteins of photosystem I and II that accumulate only transiently in thylakoid membranes under certain physiological Stress conditions. Based on predicted secondary structure ELIP family members are divided into three-helix ELIPs, two-helix SEPs (Stress-enhanced proteins) and one-helix OHPs (one-helix proteins), called also HLIPs (high Light-induced proteins) or SCPs (small chlorophyll-binding-like proteins) in cyanobacteria and viruses. It is believed that these proteins play a protective role within the chloroplast under Light Stress conditions either by transient binding of free chlorophylls and preventing the formation of free radicals and/or by acting as sinks for excitation energy. Expanding functional genomics provided new tools for the identification of genes and proteins structurally and/or functionally related to ELIP family members that escaped previous detection by classical molecular biology or biochemical methods. This chapter provides an overview of “classical” ELIP family members, discusses their evolution and photoprotective functions and introduces novel types of ELIP-like proteins in algae and land plants.
-
Light Stress photodynamics of chlorophyll-binding proteins in Arabidopsis thaliana thylakoid membranes revealed by high-resolution mass spectrometric studies
Russian Journal of Bioorganic Chemistry, 2011Co-Authors: Dmitry Galetskiy, Iwona Adamska, Jens N. Lohscheider, Alexey Kononikhin, Oleg N. Kharybin, Igor Popov, Eugene N. NikolaevAbstract:In higher plants the Light energy is captured by the photosynthetic pigments that are bound to photosystem I and II and their Light-harvesting complex (LHC) subunits. In this study, we examined the photodynamic changes within chlorophyll-protein complexes in the thylakoid membrane of Arabidopsis thaliana leaves adapted to low Light and subsequently exposed to Light Stress. Chlorophyll-protein complexes were isolated using sucrose density gradient centrifugation and blue-native polyacrylamid gel electrophoresis (BN-PAGE). Proteome analysis was performed using SDS-PAGE, HPLC, and high resolution mass spectrometry. We identified several rarely expressed and Stress-induced chlorophyll-binding proteins, showed changes in localization of early Light-induced protein family and LHC protein family members between different photosynthetic complexes and assembled/disassembled subcomplexes under Light Stress conditions and discuss their role in a variety of Light Stress-related processes.
-
Identification of genes expressed in response to Light Stress in leaves of Arabidopsis thaliana using RNA differential display.
European journal of biochemistry, 2001Co-Authors: Marina Dunaeva, Iwona AdamskaAbstract:The plant cell responds to Light Stress by the expression of genes encoding specific Stress proteins with possible protective functions. Five genes, the mRNA levels of which increased drastically in response to Light Stress in mature green leaves of Arabidopsis thaliana were identified and isolated by the differential display technique. These genes were designated Lsr1-Lsr5 (Light Stress-regulated). Northern blot analysis demonstrated that the transcript level of Lsr1-Lsr5 increased 4- to 17-fold under Light Stress conditions as compared with leaves incubated at low intensity Light. Further analysis of the Lsr1-Lsr5 transcript level under cold Stress, heat shock, wounding, desiccation, salt Stress, oxidative Stress and UV-A irradiation showed that the expression of all five genes was triggered by more than one Stress factor. Thus, it was expected that isolated genes encode proteins involved in general Stress responses. Homology searches revealed that all of the isolated cDNAs were represented in the GenBank in genomic DNAs and expressed sequence tag (EST) cDNA clones. The Lsr1-Lsr4 genes encoded cytoplasmic proteins with assigned identities, such as ERD15 (early responsive to dehydration), ACT2 (actin 2), LEA14 (late embryogenesis abundant) and MT1a (metallothionein class 1a), respectively. Light Stress had not yet been reported to induce or enhance the expression of these genes. The Lsr5 clone encoded a novel protein with high similarity to beta-1,3-galactosyltransferases from human and primates predicted to be located in the Golgi body. Three ORFs homologous to the Lsr5 gene were found on chromosome I and IV of Arabidopsis indicating that a multigene family of these proteins exists in plants. The possible role of Lsr gene products in Light Stress defences is discussed.
-
Proteolytic Enzymes in the Chloroplast Related to Light Stress Conditions
Photosynthesis: Mechanisms and Effects, 1998Co-Authors: Iwona AdamskaAbstract:Exposure of plants to Light intensities which are higher than those required to saturate photosynthesis leads to reduction in photosynthetic capacity. This effect is known as photoinhibition or Light Stress syndrome (1, 2). The main target of the Light Stress is the chloroplast. Because of oxygen production by photosystem II the oxygen concentration in the chloroplast in the Light is very high and this can result in the release of reactive intermediates of reduced dioxygen, such as superoxide radicals, hydroxy radicals, hydrogen peroxide or singlet oxygen (3). These free radicals might participate in destruction of carotenoids, bleaching of chlorophylls or might lead to an increased lipid peroxidation. In order to maintain their normal function under Light Stress conditions chloroplasts have developed multiple repair and protection systems. One of the repair systems involves the degradation of damaged, non-functional proteins and their replacement by de novo synthesized, functional molecules. Very fast and efficient degradation of proteins in the chloroplast under Light Stress conditions implies that this organelle contains multiple proteolytic systems that can selectively recognize and degrade damaged proteins. Our present knowledge concerning proteolytic processes in the chloroplast and proteases involved in these processes is very limited (4). Only few of the proteolytic enzymes localized in the chloroplasts has been isolated and characterized (4, 5, 6). Here I would like to present a group of proteases which are active in the thylakoid membranes and thylakoid lumen under Light Stress conditions and which function might be related to the degradation of damaged proteins.
-
Degradation of the Light-Stress protein is mediated by an ATP-independent, serine-type protease under low-Light conditions.
European journal of biochemistry, 1996Co-Authors: Iwona Adamska, Marika Lindahl, Margrit Roobol-boza, Bertil AnderssonAbstract:Green plants respond to Light Stress by induction of the Light-Stress proteins (ELIPs). These proteins are stable as long as the Light Stress persists but are very rapidly degraded during subsequent low Light conditions [Adamska, I., Kloppstech, K. & Ohad, I. (1993) J. Biol. Chem. 268, 5438–5444]. Here we report that the degradation of ELIPs is mediated by an extrinsic, thylakoid-associated protease which is already present in the membranes during Light Stress conditions. Partial purification of the protease by perfusion chromatography indicates that this proteolytic activity may be represented by a protein with an apparent molecular mass of 65 kDa. The ELIP-directed protease is localized in the stroma lamellae of the thylakoid membranes and does not require ATP or additional stromal factors for proteolysis. The protease has an optimum activity at pH 7.5–9.5 and requires Mg2+ for its activity. The ELIP-degrading protease show an unusual temperature sensitivity and becomes reversibly inactivated at temperatures below 20°C and above 30°C. Studies with protease inhibitors indicate that this enzyme belongs to the serine class of proteases. The enhanced degradation of ELIP in isolated thylakoid membranes after addition of the ionophore nigericin suggests that a trans-thylakoid pH or changes in ionic strength may be involved in the mechanism of protease activation.
Ron Mittler - One of the best experts on this subject based on the ideXlab platform.
-
Vascular Bundles Mediate Systemic Reactive Oxygen Signaling during Light Stress.
The Plant cell, 2020Co-Authors: Sara I. Zandalinas, Yosef Fichman, Ron MittlerAbstract:Systemic signaling and systemic acquired acclimation (SAA) are essential for plant survival during episodes of environmental Stress. Recent studies highLighted a key role for reactive oxygen species (ROS) signaling in mediating systemic responses and SAA during Light Stress in Arabidopsis thaliana. These studies further identified the RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) protein as a key player in mediating rapid systemic ROS responses. However, the identity of the plant tissues and cells that transmit systemic ROS signals in plants, as well as the identity of other ROS-producing proteins involved in this process are currently unknown. Here, we report that tissue-specific expression of RBOHD in phloem or xylem parenchyma cells of the rbohD mutant restores systemic ROS signaling, systemic Stress-response transcript expression and SAA to a local treatment of Light Stress. We further demonstrate that RBOHD and RBOHF are both required for local and systemic ROS signaling at the vascular bundles of Arabidopsis. Taken together our findings highLight a key role for RBOHD-driven ROS production at the vascular bundles of Arabidopsis in mediating Light Stress-induced systemic signaling and SAA. In addition, they suggest that the integration of ROS, calcium, electric and hydraulic signals, during systemic signaling, occurs at the vascular bundles.
-
Phytochrome B Is Required for Systemic Stomatal Responses and Reactive Oxygen Species Signaling during Light Stress.
Plant physiology, 2020Co-Authors: Amith R. Devireddy, Emmanuel Liscum, Ron MittlerAbstract:Perception of a change in Light intensity leads to the activation of multiple physiological, metabolic, and molecular responses in plants. These responses allow acclimation to fluctuating Light conditions, e.g. sunflecks in field grown plants, preventing cellular damage associated with excess Light Stress. Perception of Light Stress by a single Arabidopsis (Arabidopsis thaliana) leaf was recently shown to activate different local and systemic responses that include rapid changes in stomatal aperture size; these were found to be coordinated by a systemic process of reactive oxygen species (ROS)-derived ROS production (i.e. the ROS wave). How Light intensity is perceived, and how long the ROS wave stays "on" during this process are, however, unknown. Here we show that triggering of the ROS wave by a local excess Light Stress treatment results in the induction and maintenance of high levels of systemic ROS for up to 6 h. Despite these high systemic ROS levels, stomatal aperture size returns to control size within 3 h, and the systemic stomatal response can be retriggered within 6 h. These findings suggest that the ROS wave triggers a systemic Stress memory mechanism that lasts for 3 to 6 h, but that within 3 h of its activation, stomata become insensitive to ROS and open. We further show that the excess Light Stress-triggered ROS wave, as well as the excess Light Stress-triggered local and systemic stomatal aperture closure responses, are dependent on phytochrome B function. Our findings reveal a delicate interplay between excess Light Stress, phytochrome B, ROS production, and rapid systemic stomatal responses.
-
Rapid Accumulation of Glutathione During Light Stress in Arabidopsis.
Plant & cell physiology, 2018Co-Authors: Feroza K Choudhury, Amith R. Devireddy, Rajeev K. Azad, Vladimir Shulaev, Ron MittlerAbstract:Environmental Stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in Light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. We previously reported that in response to rapid changes in Light intensity (0-60 s), Arabidopsis thaliana plants mount a large-scale transcriptomic response that includes several different transcripts essential for Light Stress acclimation. Here, we expand our analysis of the rapid response of Arabidopsis to Light Stress using a metabolomics approach and identify 111 metabolites that show a significant alteration in their level during the first 90 s of Light Stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during Light Stress in Arabidopsis and that the accumulation of total glutathione during Light Stress is associated with an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could augment the rapid response of plants to abiotic Stress. In addition, it highLights the important role of glutathione in these responses.
-
coordinating the overall stomatal response of plants rapid leaf to leaf communication during Light Stress
Science Signaling, 2018Co-Authors: Amith R. Devireddy, Sara I. Zandalinas, Aurelio Gomezcadenas, Eduardo Blumwald, Ron MittlerAbstract:The plant canopy functions as an aerial array of Light-harvesting antennas. To achieve maximal yield, each leaf within this array and the array as a whole need to rapidly adjust to naturally occurring fluctuations in Light intensity and quality. Excessive Light Stress triggers the closing of pores in leaves called stomata to minimize moisture loss. We found that different leaves within the canopy of an Arabidopsis thaliana plant, including leaves not directly exposed to Light, coordinated stomatal closure in response to Light Stress by sending and receiving rapid systemic signals. This response required the plant hormones abscisic acid and jasmonic acid and was mediated by a rapid autopropagating wave of reactive oxygen species (ROS) production. Furthermore, this response depended on the function of genes encoding the ROS-generating NADPH oxidase RBOHD and various stomatal regulators, such as the anion channel SLAC1, GHR1 (guard cell hydrogen peroxide resistant 1), and lipoxygenase 1 (LOX1). Our findings reveal that plants function as highly dynamic and coordinated organisms, optimizing the overall response of their canopies to fluctuating Light intensities.
-
Ultra-fast alterations in mRNA levels uncover multiple players in Light Stress acclimation in plants
The Plant journal : for cell and molecular biology, 2015Co-Authors: Nobuhiro Suzuki, Amith R. Devireddy, Rajeev K. Azad, Vladimir Shulaev, Madhuri A. Inupakutika, Aaron Baxter, Gad Miller, Luhua Song, Elena Shulaev, Ron MittlerAbstract:The acclimation of plants to changes in Light intensity requires rapid responses at several different levels. These include biochemical and biophysical responses as well as alterations in the steady-state level of different transcripts and proteins. Recent studies utilizing promoter::reporter constructs suggested that transcriptional responses to changes in Light intensity could occur within seconds, rates for which changes in mRNA expression are not routinely measured or functionally studied. To identify and characterize rapid changes in the steady-state level of different transcripts in response to Light Stress we performed RNA sequencing analysis of Arabidopsis thaliana plants subjected to Light Stress. Here we report that mRNA accumulation of 731 transcripts occurs as early as 20-60 sec following Light Stress application, and that at least five of these early response transcripts play an important biological role in the acclimation of plants to Light Stress. More than 20% of transcripts accumulating in plants within 20-60 sec of initiation of Light Stress are H2 O2 - and ABA-response transcripts, and the accumulation of several of these transcripts is inhibited by transcriptional inhibitors. In accordance with the association of rapid response transcripts with H2 O2 and ABA signaling, a mutant impaired in ABA sensing (abi-1) was found to be more tolerant to Light Stress, and the response of several of the rapid response transcripts was altered in mutants impaired in reactive oxygen metabolism. Our findings reveal that transcriptome reprogramming in plants could occur within seconds of initiation of abiotic Stress and that this response could invoke known as well as unknown proteins and pathways.
Amith R. Devireddy - One of the best experts on this subject based on the ideXlab platform.
-
Phytochrome B Is Required for Systemic Stomatal Responses and Reactive Oxygen Species Signaling during Light Stress.
Plant physiology, 2020Co-Authors: Amith R. Devireddy, Emmanuel Liscum, Ron MittlerAbstract:Perception of a change in Light intensity leads to the activation of multiple physiological, metabolic, and molecular responses in plants. These responses allow acclimation to fluctuating Light conditions, e.g. sunflecks in field grown plants, preventing cellular damage associated with excess Light Stress. Perception of Light Stress by a single Arabidopsis (Arabidopsis thaliana) leaf was recently shown to activate different local and systemic responses that include rapid changes in stomatal aperture size; these were found to be coordinated by a systemic process of reactive oxygen species (ROS)-derived ROS production (i.e. the ROS wave). How Light intensity is perceived, and how long the ROS wave stays "on" during this process are, however, unknown. Here we show that triggering of the ROS wave by a local excess Light Stress treatment results in the induction and maintenance of high levels of systemic ROS for up to 6 h. Despite these high systemic ROS levels, stomatal aperture size returns to control size within 3 h, and the systemic stomatal response can be retriggered within 6 h. These findings suggest that the ROS wave triggers a systemic Stress memory mechanism that lasts for 3 to 6 h, but that within 3 h of its activation, stomata become insensitive to ROS and open. We further show that the excess Light Stress-triggered ROS wave, as well as the excess Light Stress-triggered local and systemic stomatal aperture closure responses, are dependent on phytochrome B function. Our findings reveal a delicate interplay between excess Light Stress, phytochrome B, ROS production, and rapid systemic stomatal responses.
-
Rapid Accumulation of Glutathione During Light Stress in Arabidopsis.
Plant & cell physiology, 2018Co-Authors: Feroza K Choudhury, Amith R. Devireddy, Rajeev K. Azad, Vladimir Shulaev, Ron MittlerAbstract:Environmental Stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in Light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. We previously reported that in response to rapid changes in Light intensity (0-60 s), Arabidopsis thaliana plants mount a large-scale transcriptomic response that includes several different transcripts essential for Light Stress acclimation. Here, we expand our analysis of the rapid response of Arabidopsis to Light Stress using a metabolomics approach and identify 111 metabolites that show a significant alteration in their level during the first 90 s of Light Stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during Light Stress in Arabidopsis and that the accumulation of total glutathione during Light Stress is associated with an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could augment the rapid response of plants to abiotic Stress. In addition, it highLights the important role of glutathione in these responses.
-
coordinating the overall stomatal response of plants rapid leaf to leaf communication during Light Stress
Science Signaling, 2018Co-Authors: Amith R. Devireddy, Sara I. Zandalinas, Aurelio Gomezcadenas, Eduardo Blumwald, Ron MittlerAbstract:The plant canopy functions as an aerial array of Light-harvesting antennas. To achieve maximal yield, each leaf within this array and the array as a whole need to rapidly adjust to naturally occurring fluctuations in Light intensity and quality. Excessive Light Stress triggers the closing of pores in leaves called stomata to minimize moisture loss. We found that different leaves within the canopy of an Arabidopsis thaliana plant, including leaves not directly exposed to Light, coordinated stomatal closure in response to Light Stress by sending and receiving rapid systemic signals. This response required the plant hormones abscisic acid and jasmonic acid and was mediated by a rapid autopropagating wave of reactive oxygen species (ROS) production. Furthermore, this response depended on the function of genes encoding the ROS-generating NADPH oxidase RBOHD and various stomatal regulators, such as the anion channel SLAC1, GHR1 (guard cell hydrogen peroxide resistant 1), and lipoxygenase 1 (LOX1). Our findings reveal that plants function as highly dynamic and coordinated organisms, optimizing the overall response of their canopies to fluctuating Light intensities.
-
Ultra-fast alterations in mRNA levels uncover multiple players in Light Stress acclimation in plants
The Plant journal : for cell and molecular biology, 2015Co-Authors: Nobuhiro Suzuki, Amith R. Devireddy, Rajeev K. Azad, Vladimir Shulaev, Madhuri A. Inupakutika, Aaron Baxter, Gad Miller, Luhua Song, Elena Shulaev, Ron MittlerAbstract:The acclimation of plants to changes in Light intensity requires rapid responses at several different levels. These include biochemical and biophysical responses as well as alterations in the steady-state level of different transcripts and proteins. Recent studies utilizing promoter::reporter constructs suggested that transcriptional responses to changes in Light intensity could occur within seconds, rates for which changes in mRNA expression are not routinely measured or functionally studied. To identify and characterize rapid changes in the steady-state level of different transcripts in response to Light Stress we performed RNA sequencing analysis of Arabidopsis thaliana plants subjected to Light Stress. Here we report that mRNA accumulation of 731 transcripts occurs as early as 20-60 sec following Light Stress application, and that at least five of these early response transcripts play an important biological role in the acclimation of plants to Light Stress. More than 20% of transcripts accumulating in plants within 20-60 sec of initiation of Light Stress are H2 O2 - and ABA-response transcripts, and the accumulation of several of these transcripts is inhibited by transcriptional inhibitors. In accordance with the association of rapid response transcripts with H2 O2 and ABA signaling, a mutant impaired in ABA sensing (abi-1) was found to be more tolerant to Light Stress, and the response of several of the rapid response transcripts was altered in mutants impaired in reactive oxygen metabolism. Our findings reveal that transcriptome reprogramming in plants could occur within seconds of initiation of abiotic Stress and that this response could invoke known as well as unknown proteins and pathways.
Weijie Jiang - One of the best experts on this subject based on the ideXlab platform.
-
Effects of Exogenous Epibrassinolide on Photosynthetic Characteristics in Tomato (Lycopersicon esculentum Mill) Seedlings under Weak Light Stress
Journal of agricultural and food chemistry, 2010Co-Authors: Ming Wang, Weijie JiangAbstract:The effects of three concentrations (0.1, 0.01, 0.001 mg/kg) of exogenous 24-epibrassinolide on leaf photosynthesis, chlorophyll content, chlorophyll fluorescence, and parameters of Light response curve in tomato seedlings under 150 μmol·m−2·s−1 weak Light Stress were studied, with two tomato cultivars, ‘Zhongza9’, tolerant, and ‘Zhongshu6’, sensitive to weak Light Stress. The results showed that the net photosynthetic rate (Pn), maximal photochemical quantum efficiency of PSII (Fv/Fm), Light saturation point (LSP), and dark respiration rate (Rd) decreased remarkably under weak Light, but the chlorophyll content, especially chlorophyll b (chlb) content, increased obviously compared with normal Light intensity control. However, exogenous 24-epibrassinolide alleviated the decrease of leaf Pn and Fv/Fm and induced the further increase of chlb content as well as the further decrease of Rd and chla/chlb under weak Light Stress, which indicated that exogenous 24-epibrassinolide could enhance plant tolerance to ...
Klaus Kloppstech - One of the best experts on this subject based on the ideXlab platform.
-
Low temperature increases the abundance of early Light-inducible transcript under Light Stress conditions.
The Journal of biological chemistry, 1994Co-Authors: Iwona Adamska, Klaus KloppstechAbstract:Abstract Green pea plants respond to Light Stress by expression of a nuclear ELIP (early Light-inducible protein) gene. Here we report that the accumulation of ELIP transcript in pea plants during Light Stress is enhanced by low temperature treatment. The enhanced level of ELIP transcript during combined Light and cold Stress was found to be due to an increased stability of ELIP messenger RNA under these conditions. This transcript is translatable in vitro. In vivo, however, the amount of accumulated protein in the thylakoids declines with the decrease in the temperature because the translational activity is strongly reduced already at 10 degrees C. Plants exposed to Light Stress at temperatures that do not allow accumulation of ELIP transcript respond by induction of ELIP mRNA and protein during recovery at low Light intensity and ambient temperature. The amount of protein that accumulates as a result of this "memory effect" is, however, much lower than that which accumulates as a result of direct Light Stress. The memory of a perceived Light Stress persists in plants stored at low temperature for at least 3 h, and the Stress response can be released after an increase in temperature. Prolonged cold treatment, however, has a negative effect on the translatability of the ELIP transcript that accumulates during recovery.
-
Effects of Light Stress on the expression of early Light‐inducible proteins in barley
European journal of biochemistry, 1993Co-Authors: Eyck Pötter, Klaus KloppstechAbstract:Treatment of six-day-old barley leaves with white Light of high intensity, 250–2000 W/m2, leads to a linear increase in the steady-state concentrations of early Light-inducible protein (ELIP) mRNA followed by an accumulation of the protein. Accumulation of ELIP mRNA, under Light Stress, is highest in the basal third of the leaf and declines to approximately 50% of this level in the apical segment. The amount of the accumulated protein decreases more steeply towards the tip than would be expected from mRNA levels. This finding, as well as the fact that during greening a massive accumulation of the protein starts only at a time when the steady-state concentrations of ELIP mRNA have declined to 10% of the maximal value, indicate post-transcriptional control. Accumulation is presumably achieved by stabilization of the protein. ELIP mRNA and protein levels, induced by a 2-h period of high-Light Stress, are lowest in the afternoon and highest at midnight and during the morning. The inducibility of ELIP by high Light is therefore under diurnal control. An increase of Light Stress, due to application of the carotenoid-biosynthesis inhibitor norfluorazon, results in a considerable induction of ELIP mRNA and protein. The plant hormone abscisic acid exerts only a small effect on the mRNA level. In all cases studied, the Light-induced increase in the amount of ELIP mRNA was accompanied by a corresponding decline in the mRNA levels for the apoprotein of the chlorophyll-alb-binding protein. Steady-state concentrations of mRNA for the small subunit of ribulose-1,5-bisphosphate carboxylase were hardly affected under all investigated Light intensities.
-
Early Light-inducible protein in pea is stable during Light Stress but is degraded during recovery at low Light intensity.
Journal of Biological Chemistry, 1993Co-Authors: Iwona Adamska, Klaus Kloppstech, Itzhak OhadAbstract:Abstract The nuclear-encoded, thylakoid-bound early Light-inducible protein (ELIP) reported to be related to the initial stages of chloroplast differentiation is synthesized in substantial amounts in leaves of mature plants exposed to Light Stress conditions (Adamska, I., Ohad, I., and Kloppstech, K. (1992b) Proc. Natl. Acad. Sci. U.S.A. 89, 2610-2613). Increase in ELIP content correlates with the photoinactivation of PSII, degradation of D1 protein, and changes in the level of pigments. Inhibition of phytoene desaturase and/or zeta-carotene desaturase during Light Stress drastically increases accumulation of the protein. ELIP mRNA is short-lived (t1/2 = 1 h). The thylakoid bound protein is stable in high Light exposed leaves and is degraded only during recovery from Light Stress at low Light intensity (40 microE/m2s). The lifetime of the protein during the recovery process increases with the extent of initial Light Stress condition. We propose that ELIP synthesis and degradation is related to the process of the plant response to Light Stress and recovery from photoinhibition.
-
UV Light Stress induces the synthesis of the early Light-inducible protein and prevents its degradation.
The Journal of biological chemistry, 1992Co-Authors: Iwona Adamska, Klaus Kloppstech, Itzhak OhadAbstract:Abstract ELIP is a nuclear-encoded protein localized in the thylakoid membranes. The protein is specifically induced by blue Light in mature, Light-grown plants (Adamska, I., Ohad, I., and Kloppstech, K. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 2610-2613), as well as in plants developed in the Light in which pigment synthesis and plastid development were inhibited by the bleaching herbicide norflurazon. ELIP transcription and protein accumulation are induced also by UVA but not by UVB Light. However, UVB Light allows ELIP synthesis induced by superimposed white Light. The protein is stable under Light Stress including UVA and UVB Light, but it is rapidly degraded upon cessation of the Light Stress conditions. ELIP synthesis and integration into the chloroplast membranes is related neither to chloroplast translation activity nor to photosynthetic electron flow. Inhibition of carotenoid synthesis by fluridone, a bleaching herbicide which causes extensive damage to the photosynthetic apparatus, does not affect induction of ELIP transcription during Light Stress but greatly enhances ELIP accumulation. Based on these results it is proposed that ELIP turnover is related to the Light Stress and recovery process in plants.