Upon virus infections, the rapid and comprehensive transcriptional reprogramming in host plant cells is critical to ward off virus attack. To uncover genes and defense pathways that are associated ...with virus resistance, we carried out the transcriptome-wide Illumina RNA-Seq analysis of pepper leaves harboring the L
resistance gene at 4, 8, 24 and 48 h post-inoculation (hpi) with two tobamoviruses. Obuda pepper virus (ObPV) inoculation led to hypersensitive reaction (incompatible interaction), while Pepper mild mottle virus (PMMoV) inoculation resulted in a systemic infection without visible symptoms (compatible interaction). ObPV induced robust changes in the pepper transcriptome, whereas PMMoV showed much weaker effects. ObPV markedly suppressed genes related to photosynthesis, carbon fixation and photorespiration. On the other hand, genes associated with energy producing pathways, immune receptors, signaling cascades, transcription factors, pathogenesis-related proteins, enzymes of terpenoid biosynthesis and ethylene metabolism as well as glutathione S-transferases were markedly activated by ObPV. Genes related to photosynthesis and carbon fixation were slightly suppressed also by PMMoV. However, PMMoV did not influence significantly the disease signaling and defense pathways. RNA-Seq results were validated by real-time qPCR for ten pepper genes. Our findings provide a deeper insight into defense mechanisms underlying tobamovirus resistance in pepper.
Light intensity and spectrum play a major role in the regulation of the growth, development, and stress response of plants. Changes in the light conditions affect the formation of reactive oxygen ...species, the activity of the antioxidants, and, consequently, the redox environment in the plant tissues. Many metabolic processes, thus the biogenesis and function of miRNAs, are redox-responsive. The miRNAs, in turn, can modulate various components of the redox system, and this process is also associated with the alteration in the intensity and spectrum of the light. In this review, we would like to summarise the possible regulatory mechanisms by which the alterations in the light conditions can influence miRNAs in a redox-dependent manner. Daily and seasonal fluctuations in the intensity and spectral composition of the light can affect the expression of miRNAs, which can fine-tune the various physiological and biochemical processes due to their effect on their target genes. The interactions between the redox system and miRNAs may be modulated by light conditions, and the proposed function of this regulatory network and its effect on the various biochemical and physiological processes will be introduced in plants.
The effects of various light intensities and spectral compositions on glutathione and amino acid metabolism were compared in wheat. Increase of light intensity (low-normal-high) was accompanied by a ...simultaneous increase in the shoot fresh weight, photosynthetic activity and glutathione content. These parameters were also affected by the modification of the ratios of blue, red and far-red components (referred to as blue, pink and far-red lights) compared to normal white light. The photosynthetic activity and the glutathione content decreased to 50% and the percentage of glutathione disulfide (characterising the redox state of the tissues) in the total glutathione pool doubled in far-red light. The alterations in the level and redox state of the antioxidant glutathione resulted from the effect of light on its synthesis as it could be concluded from the changes in the transcription of the related genes. Modification of the light conditions also greatly affected both the amount and the ratio of free amino acids. The total free amino acid content was greatly induced by the increase of light intensity and was greatly reduced in pink light compared to the normal intensity white light. The concentrations of most amino acids were similarly affected by the light conditions as described for the total free amino acid content but Pro, Met, Thr, ornithine and cystathionine showed unique response to light. As observed for the amino acid levels, the expression of several genes involved in their metabolism also enhanced due to increased light intensity. Interestingly, the modification of the spectrum greatly inhibited the expression of most of these genes. Correlation analysis of the investigated parameters indicates that changes in the light conditions may affect growth through the adjustment of photosynthesis and the glutathione-dependent redox state of the tissues. This process modifies the metabolism of glutathione and amino acids at transcriptional level.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The use of light-emitting diode (LED) technology for plant cultivation under controlled environmental conditions can result in significant reductions in energy consumption. However, there is still a ...lack of detailed information on the lighting conditions required for optimal growth of different plant species and the effects of light intensity and spectral composition on plant metabolism and nutritional quality. In the present study, wheat plants were grown under six regimens designed to compare the effects of LED and conventional fluorescent lights on growth and development, leaf photosynthesis, thiol and amino acid metabolism as well as grain yield and flour quality of wheat. Benefits of LED light sources over fluorescent lighting were manifested in both yield and quality of wheat. Elevated light intensities made possible with LEDs increased photosynthetic activity, the number of tillers, biomass and yield. At lower light intensities, blue, green and far-red light operated antagonistically during the stem elongation period. High photosynthetic activity was achieved when at least 50% of red light was applied during cultivation. A high proportion of blue light prolonged the juvenile phase, while the shortest flowering time was achieved when the blue to red ratio was around one. Blue and far-red light affected the glutathione- and proline-dependent redox environment in leaves. LEDs, especially in Blue, Pink and Red Low Light (RedLL) regimens improved flour quality by modifying starch and protein content, dough strength and extensibility as demonstrated by the ratios of high to low molecular weight glutenins, ratios of glutenins to gliadins and gluten spread values. These results clearly show that LEDs are efficient for experimental wheat cultivation, and make it possible to optimize the growth conditions and to manipulate metabolism, yield and quality through modification of light quality and quantity.
•L. minor extracted heavy metals more efficiently than S. natans or E. canadensis.•A considerable metal-induced phytochelatin synthesis was observed in L. minor only.•The length of produced ...phytochelatins was associated with metal removal capacity.
Phytochelatins (PCs) play important role in phytoremediation as heavy metal binding peptides. In the present study, the association between heavy metal removal capacity and phytochelatin synthesis was compared through the examination of three aquatic plants: Elodea canadensis, Salvinia natans and Lemna minor. In case of a Cd treatment, or a Cd treatment combined with Cu and Zn, the highest removal capacity was observed in L. minor. At the same time, E. canadensis showed the lowest removal capacity except for Zn. The heavy metal-induced (Cu+Zn+Cd) oxidative stress generated the highest ascorbate level in L. minor. Cd in itself or combined with the other two metals induced a 10–15-fold increase in the amount of ɣ-glutamylcysteine in L. minor while no or smaller changes were observed in the other two species. Correspondingly, the total PC content was 6–8-fold greater in L. minor. In addition, PCs with higher degree of polymerization were only observed in L. minor (PC4, PC6 and PC7) while PC2 and PC3 occurred in E. canadensis and S. natans only. The correlation analysis indicated that the higher phytoremediation capacity of L. minor was associated with the synthesis of PCs and their higher degree of polymerization.
Plant ascorbate and glutathione metabolism counteracts oxidative stress mediated, for example, by excess light. In this review, we discuss the properties of immunocytochemistry and transmission ...electron microscopy, redox-sensitive dyes or probes and bright-field microscopy, confocal microscopy or fluorescence microscopy for the visualization and quantification of glutathione at the cellular or subcellular level in plants and the quantification of glutathione from isolated organelles. In previous studies, we showed that subcellular ascorbate and glutathione levels in
Arabidopsis
are affected by high light stress. The use of light-emitting diodes (LEDs) is gaining increasing importance in growing indoor crops and ornamental plants. A combination of different LED types allows custom-made combinations of wavelengths and prevents damage related to high photon flux rates. In this review we provide an overview on how different light spectra and light intensities affect glutathione metabolism at the cellular and subcellular levels in plants. Findings obtained in our most recent study demonstrate that both light intensity and spectrum significantly affected glutathione metabolism in wheat at the transcriptional level and caused genotype-specific reactions in the investigated
Arabidopsis
lines.
•Environmental changes affect growth and development.•The environmental alterations influence metabolism through redox signalling.•Subcellular redox changes modify growth and development.•Redox ...changes and hormones regulate metabolism in a cross-talk.•Flowering is under redox control.
Redox changes determined by genetic and environmental factors display well-organized interactions in the control of plant growth and development. Diurnal and seasonal changes in the environmental conditions are important for the normal course of these physiological processes and, similarly to their mild irregular alterations, for stress adaptation. However, fast or large-scale environmental changes may lead to damage or death of sensitive plants. The spatial and temporal redox changes influence growth and development due to the reprogramming of metabolism. In this process reactive oxygen and nitrogen species and antioxidants are involved as components of signalling networks. The control of growth, development and flowering by reactive oxygen and nitrogen species and antioxidants in interaction with hormones at organ, tissue, cellular and subcellular level will be discussed in the present review. Unsolved problems of the field, among others the need for identification of new components and interactions in the redox regulatory network at various organization levels using systems biology approaches will be also indicated.
It is shown that plasma‐activated water (PAW) improves tolerance against combined low temperature and hypoxia stresses during germination. Due to PAW's effect on the antioxidant system, PAW ...pretreatment mitigates the reducing effect on plant growth of the hydroponically applied NaCl. PAW pretreatment reduces the salt‐stress‐induced decrease of the cysteine and γ‐glutamylcysteine content and improves the plant's recovery after NaCl stress. PAW pretreatment also modifies the NaCl‐induced changes in carotenoid content, especially, β‐carotenes and xanthophylls. These compounds, together with glutathione can reduce salt‐induced damage through the removal of excess reactive oxygen species, which could be the basis of the protective effect of PAW.
It is shown that PAW improves tolerance against combined low temperature and hypoxia stresses during germination, and it mitigates the reducing effect of hydroponically applied NaCl on plant growth. PAW modifies the NaCl‐induced changes in the concentrations of thiols and carotenoids, which can reduce salt‐induced damage through the removal of the excess of reactive oxygen species
The glutathione (GSH)/glutathione disulfide (GSSG) redox couple is involved in several physiologic processes in plants under both optimal and stress conditions. It participates in the maintenance of ...redox homeostasis in the cells. The redox state of the GSH/GSSG couple is defined by its reducing capacity and the half-cell reduction potential, and differs in the various organs, tissues, cells, and compartments, changing during the growth and development of the plants. When characterizing this redox couple, the synthesis, degradation, oxidation, and transport of GSH and its conjugation with the sulfhydryl groups of other compounds should be considered. Under optimal growth conditions, the high GSH/GSSG ratio results in a reducing environment in the cells which maintains the appropriate structure and activity of protein molecules because of the inhibition of the formation of intermolecular disulfide bridges. In response to abiotic stresses, the GSH/GSSG ratio decreases due to the oxidation of GSH during the detoxification of reactive oxygen species (ROS) and changes in its metabolism. The lower GSH/GSSG ratio activates various defense mechanisms through a redox signalling pathway, which includes several oxidants, antioxidants, and stress hormones. In addition, GSH may control gene expression and the activity of proteins through glutathionylation and thiol-disulfide conversion. This review discusses the size and redox state of the GSH pool, including their regulation, their role in redox signalling and defense processes, and the changes caused by abiotic stress.
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