Various Types Of Environmental Stress Research Articles

Mitochondrial targeting of Candida albicans SPFH proteins and requirement of stomatins for SDS-induced stress tolerance.

Stomatins and prohibitins coordinate respiration and stress adaptation in fungi. Invasive mycoses caused by Candida albicans are a significant cause of morbidity, and candidemia patients show high mortality rates worldwide. Mitochondria are essential for C. albicans commensalism and virulence, and mitochondrial proteins are targets for antifungal interventions. C. albicans encodes five SPFH proteins: two stomatin-like proteins and three prohibitins. We have previously shown that Slp3 is important for C. albicans adaptation to various types of environmental stress. Moreover, synthetic compounds that bind to mammalian prohibitins inhibit C. albicans filamentation and are fungicidal. However, there is limited information available regarding the remaining SPFH proteins. Our findings show that mitochondrial localization of SPFH proteins is conserved in C. albicans. In addition, we demonstrate the importance of stomatins in plasma membrane and mitochondrial stress tolerance.

Peroxisomal Localization of Benzyl Alcohol O-Benzoyltransferase HSR201 Is Mediated by a Non-canonical Peroxisomal Targeting Signal and Required for Salicylic Acid Biosynthesis.

The phytohormone salicylic acid (SA) regulates plant responses to various types of environmental stress, particularly pathogen infections. We previously revealed that the benzyl alcohol O-benzoyltransferase HSR201 was required for pathogen signal-induced SA synthesis, and its overexpression together with NtCNL, encoding a cinnamate-coenzyme A ligase, was sufficient for the production of significant amounts of SA in tobacco. We herein examined the subcellular localization of HSR201 and found that it fused to a yellow fluorescent protein localized in peroxisomes. Most peroxisomal matrix proteins possess peroxisomal targeting signal type-1 (PTS1) located at the extreme C terminus or PTS2 located at the N terminus; however, a bioinformatics analysis failed to identify similar signals for HSR201. Deletion and mutation analyses of HSR201 identified one essential (extreme C-terminal Leu46°) and three important (Ile455, Ile456 and Ala459) amino acid residues for its peroxisomal localization. The virus-induced gene silencing (VIGS) of PEX5, a PTS1 receptor, but not PEX7, a PTS2 receptor, compromised the peroxisomal targeting of HSR201 in Nicotiana benthamiana. When overexpressed with NtCNL, HSR201 mutants with reduced or non-peroxisomal targeting induced lower SA levels than the wild type; however, these mutations did not affect the protein stability or activity of HSR201. VIGS of the HSR201 homolog compromised pathogen signal-induced SA accumulation in N. benthamiana, which was complemented by the HSR201 wild type, but not the mutant with non-peroxisomal targeting. These results suggest that the peroxisomal localization of HSR201 is mediated by a non-canonical PTS1 and required for SA biosynthesis.

Potassium silicate enhances drought tolerance of Bellis perennis by improving antioxidant activity and osmotic regulators

Ornamental plants can usually encounter various types of environmental stress, which reduce plant productivity. A proper application of fertilizers can improve plantsʼ tolerance to drought stress. Nutrients such as potassium and silicon are known to have beneficial effects. This study aimed to evaluate the growth of Bellis perennis under drought stress (80, 70, and 60% FC) and with the application of potassium silicate (0, 2, and 4 mM). The results showed that potassium silicate (2 and 4 mM) increased K and Si accumulation in plants under drought stress. Plants treated with potassium silicate under drought stress exhibited a lower degree of electrolyte leakage and less MDA accumulation in the following order: 2 and 4 mM potassium silicate. An increase in relative water content and chlorophyll was observed with application of potassium silicate under drought stress. Regardless of potassium silicate, the plant enzymatic defense system was significantly improved compared to non-stressed plants. Potassium silicate enhanced the amount of osmotic regulators (carbohydrate and proline) and secondary metabolites (flavonoids and phenols) compared to control plants regardless of drought stress. The anthocyanin content in the flowers significantly decreased by 32.2% when the plants were treated with 4 mM potassium silicate at 60% FC, compared to 80% FC. In conclusion, potassium silicate mitigated the effects of drought stress, enhanced plant tolerance to drought stress, increased the activity of antioxidant enzymes, and improved the amounts of osmotic regulators and secondary metabolites.

Effects of acute and chronic chromium stress on the expression of heat shock protein genes and activities of antioxidant enzymes in larvae of Orthetrum albistylum

The dragonfly species Orthetrum albistylum, can accumulate heavy metals from its aquatic environment and thus serves as a biological indicator for monitoring and evaluating water quality. Heat shock proteins (HSPs) play important biological roles in resistance to various types of environmental stress. The full-length cDNA sequences of the heat shock cognate (hsc) 70 and heat shock protein (hsp) 70 genes were cloned from O. albistylum larvae. Relative levels of expression of hsc70 and hsp70 in the head, epidermis, midgut, and adipose tissue were measured by qRT-PCR after chronic and acute contamination of 5–8 instar larvae with chromium (Cr) solution, and under control conditions. Activities of superoxide dismutase (SOD) and catalase (CAT) in chronically contaminated larvae were also measured. Phylogenetic analysis revealed that the cloned hsc70 and hsp70 genes were highly homologous to known HSP70 family members reported in other insects. The mRNA levels of hsc70 and hsp70 did not differ significantly in various larval tissues. Under chronic chromium stress, hsc70 and hsp70 expression were upregulated to a maximum and then downregulated; hsp70 mRNA levels were higher than those of hsc70 at all concentrations of chromium. Under acute chromium stress, hsc70 expression was inhibited at low chromium concentrations and upregulated at chromium concentrations higher than 125 mg/L. However, hsp70 expression was higher than that in the control group and markedly higher than that of hsc70. Changes in SOD and CAT activities displayed consistent trends for different chronic chromium concentrations, first increasing and then decreasing over time. Collectively, these findings demonstrated the response of the HSP family of genes and antioxidant enzymes following exposure to heavy metal stress, as well as their potential applicability as biomarkers for monitoring environmental pollutants.

The evolutionary patterns, expression profiles, and genetic diversity of expanded genes in barley.

Gene duplication resulting from whole-genome duplication (WGD), small-scale duplication (SSD), or unequal hybridization plays an important role in the expansion of gene families. Gene family expansion can also mediate species formation and adaptive evolution. Barley (Hordeum vulgare) is the world's fourth largest cereal crop, and it contains valuable genetic resources due to its ability to tolerate various types of environmental stress. In this study, 27,438 orthogroups in the genomes of seven Poaceae were identified, and 214 of them were significantly expanded in barley. The evolutionary rates, gene properties, expression profiles, and nucleotide diversity between expanded and non-expanded genes were compared. Expanded genes evolved more rapidly and experienced lower negative selection. Expanded genes, including their exons and introns, were shorter, they had fewer exons, their GC content was lower, and their first exons were longer compared with non-expanded genes. Codon usage bias was also lower for expanded genes than for non-expanded genes; the expression levels of expanded genes were lower than those of non-expanded genes, and the expression of expanded genes showed higher tissue specificity than that of non-expanded genes. Several stress-response-related genes/gene families were identified, and these genes could be used to breed barley plants with greater resistance to environmental stress. Overall, our analysis revealed evolutionary, structural, and functional differences between expanded and non-expanded genes in barley. Additional studies are needed to clarify the functions of the candidate genes identified in our study and evaluate their utility for breeding barley plants with greater stress resistance.

Phytochemical Screening and Antibacterial Activity of Bark Exudates in Selected Tree Species

Plants have evolved multiple defense mechanisms against microbial pathogens and various types of environmental stress. Qualitative screening of phytochemical analysis from bark exudates of tree species (Cassia siamea, Araucaria, Artocarpus heterophyllus) were analysed. Tannins, alkaloids, steroids, saponins, reducing sugars, flavonoids, phenols, glycosides are present in aqueous and acetone extracts. But proteins and starch are present in acetone extracts of three bark samples. The maximum flavonoid content was observed in bark sample of Artocarpus heterophyllus, followed by Cassia siamea which was par with Araucaria. The highest amount of alkaloid and phenols were seen in Cassia followed by Artocarpus and Artocarpus heterophyllus. The maximum zone of inhibition were observed in aqueous and acetone extract of Cassia siamea by E. coli (20 mm) and Proteus vulgaris (18 mm). This was followed by acetone extract of Araucaria (15 mm) and Artocarpus heterophyllus (12 mm) by Proteus vulgaris. Whereas minimum zone of incubation were noted in aqueous extract of bark samples of Araucaria, Cassia (5.0 mm) and Artocarpus heterophyllus (4.0 mm) by E. coli and Bacillus subtilis. Bacterial antibiotic streptomycin which was used as positive controls were more effective compared to all the plant extracts tested against the bacterial pathogens. The aqueous extract of Cassia and Araucaria and acetone extract of Artocarpus heterophyllus showed the highest scavenging activity (Dark coloration) upon addition of FeCl3 which could be due to the high phenol content.

Identification of Genes Promoting Growth of Ustilago maydis on Biomolecules Released from Cells Killed by Oxidation.

Much headway has been made in understanding the numerous strategies that enable microorganisms to counteract various types of environmental stress, but little is known about how microbial populations recover after a massive death caused by exposure to extreme conditions. Using the yeast-like fungus Ustilago maydis as a model, our recent post-stress regrowth under starvation (RUS) studies have demonstrated that this organism reconstitutes devastated populations with remarkable efficiency. Subsequently, we have identified four RUS-gene products. Two of these, Did4 and Tbp1, play parallel roles in protecting the genome. To identify additional molecular components, we took a molecular-genetic and a transcriptomic approach. By employing a simple and novel screening method, we identified five RUS-deficient mutants (snf8, slm1, vrg4, snf5, hsf1), three of which (snf8, slm1, and hsf1) displayed sensitivity to different genotoxic agents, indicating that the corresponding gene products have roles in genome protection. The global transcriptomic changes of cells grown in supernatants derived from peroxide-treated cell suspensions revealed sets of uniquely expressed genes. Importantly, among the genes induced by the substrates was Chk1, which encodes a protein kinase required for checkpoint-mediated cell cycle arrest in response to DNA damage. Mutants of U. maydis deleted of Chk1 are severely incapacitated in RUS.

Effect of bacterial quorum sensing and mechanism of antimicrobial resistance

Biofilm is considered to be the protective environment of a large number of sessile microcolonies that protect the cells from various types of environmental stresses. The sessile microcolonies communicate through a density-dependent communication system known as quorum sensing (Q.S.). This mechanism results in the development of various compounds associated with the development of antimicrobial resistance. Antimicrobial resistance is the condition where the microbes develop resistance to the drug. The microbes can show resistance toward the drug in various processes, such as inactivating the drug and preventing its uptake by going through certain modifications in its cell wall. It uses a special pump in which once the drug enters the microbes it will pump out the drug through a special membrane pump. These can be classified according to the antimicrobial activity mechanism. Most antimicrobial agents tend to Impede the cell wall synthesis and inhibit the protein, nucleic acid synthesis and metabolic pathways inhibiting. The capability of the microbes to resist the antimicrobial agents either acquired naturally or from other microbes.Furthermore, various factors affect antimicrobial resistance, such as overuse of common antibiotics and improper prescription in which the broad-spectrum drug is prescribed. Overdosage of the antimicrobial agent can increase the patient's risk of getting infected by the pathogen, showing sensitivity to the drug. This review will focus on the mechanism of quorum sensing and the cause of the development of antimicrobial.

Transcriptomic and Metabolomic Analyses of the Effects of Exogenous Trehalose on Heat Tolerance in Wheat.

Trehalose can improve the tolerance of plants to various types of environmental stress. Nonetheless, information respecting the molecular networks of wheat seedlings to exogenous trehalose under heat stress is limited. Here, two wheat varieties pretreated with exogenous trehalose were selected to explore the molecular mechanism by which trehalose improves the heat tolerance of wheat (Triticum aestivum L.). The results indicated that exogenous trehalose improved the physiological state of wheat seedlings under heat stress. Through RNA sequencing and metabolomics analysis, the genes and metabolites specifically expressed in trehalose pretreatment were identified. After heat stress, there were 18,352 differentially expressed genes (DEGs) in the control and trehalose-treated (H_vs_TreH) groups of Yangmai 18 and 9045 DEGs in Yannong 19. Functional annotation and enrichment analyses showed that the DEGs in the two wheat varieties were mainly involved in carbohydrate metabolism and biosynthesis of secondary metabolites. Through a liquid chromatography–mass spectrometry platform, 183 differential metabolites in H_vs_TreH groups of Yangmai 18 and 77 differential metabolites in Yannong 19 were identified. Compared with the control group, many protective metabolites, such as amino acids, purines, phenylpropanoids and flavonoids, showed significant differences under heat stress. The results indicated that exogenous trehalose protected the wheat biomembrane system, enhanced carbohydrate metabolism and signal transduction, strengthened the activity of the tricarboxylic acid cycle (TCA cycle), regulated purine metabolism, gene expression and metabolite accumulation in the phenylpropanoid biosynthesis and flavonoid biosynthesis pathways, thus improving the heat tolerance of wheat.

ADAPTIVE COMPONENTS OF Cyperus exaltatus UNDER HARSH SALINE ENVIRONMENT

Among the environmental problems, salinity is one of the major threats to agriculture around the globe which affects more than 6% of the available land on earth. However halophytes are blessed with the ability to cope with high salinity by various mechanisms. The present study was aimed to explore adaptive components of Cyperus exaltatus which is now growing widely at a number of saline areas across the Pakistan. Extensive trips were made across the country to collect the populations of Cyperus exaltatus from all sorts of environments with varying levels of salinity. The morphological study of ecotypes showed that many growth parameters were affected negatively under higher salinity. However, root length, shoot length, plant height, shoot fresh and dry weight showed a high association with hyper saline sites. Moreover the physiological parameters such as proline content, total soluble proteins and total soluble sugars were accumulated in higher concentrations among populations at hyper saline sites while in lower concentrations at moderately saline and less saline sits which may have supported the production of higher biomass under salinity. The results show that the plants like Cyperus exaltatus can be grown under various types of environmental stresses especially under salinity. Thus the barren saline lands can be used to produce fodder as well as the growth of plants may also help to reduce the levels of salinity in such areas.

Antioxidative enzymes in root and leaf of Rumex obtusifolius L. grown on ash amended soil

Antioxidant enzymes are one of the most important links in the plant defense system to various types of environmental stress, so their response to a particular type of stress may indicate the sensitivity or tolerance of the plant species. Our paper studied the difference in antioxidative enzyme [catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD, EC 1.15.1.1) and Class III peroxidases (POD, EC 1.11.1.7)], isoenzyme pattern and activities between Rumex obtusifolius L. (Polygonaceae) plants grown on ash amended and uncontaminated soil. Modified SDS-PAGE electrophoresis revealed the presence of a new POD isoform in leaf samples growing on ash-amended soil, although the activity of POD in the leaves did not change significantly compared to control plants. On the other hand, in the roots of ash-growing plants POD activity decreased by 90%. Single CAT isoform was detected in both leaf samples, and results indicate 47% higher CAT activity in leaves of ash growing plants. Native electrophoresis detected two SOD isoforms in leaves and roots from the control plant. SOD isoforms were inhibited in the roots of plants grown on ash. The paper indicates the possible role of CAT, SOD and POD in the adaptive response of R. obtusifolius plants on ash amended soil.

Epigenetic regulation of salinity stress responses in cereals.

Cereals are important crops and are exposed to various types of environmental stresses that affect the overall growth and yield. Among the various abiotic stresses, salt stress is a major environmental factor that influences the genetic, physiological, and biochemical responses of cereal crops. Epigenetic regulation which includes DNA methylation, histone modification, and chromatin remodelling plays an important role in salt stress tolerance. Recent studies in rice genomics have highlighted that the epigenetic changes are heritable and therefore can be considered as molecular signatures. An epigenetic mechanism under salinity induces phenotypic responses involving modulations in gene expression. Association between histone modification and altered DNA methylation patterns and differential gene expression has been evidenced for salt sensitivity in rice and other cereal crops. In addition, epigenetics also creates stress memory that helps the plant to better combat future stress exposure. In the present review, we have discussed epigenetic influences in stress tolerance, adaptation, and evolution processes. Understanding the epigenetic regulation of salinity could help for designing salt-tolerant varieties leading to improved crop productivity.

Effects of Drought on the Relationship Between Photosynthesis and Chlorophyll Fluorescence for Maize

Structural–physiological factors affect the accurate estimation of vegetation gross primary production (GPP) under various types of environmental stress. Solar-induced chlorophyll fluorescence (SIF), which is directly linked to photosynthesis, has been effectively used to estimate and monitor GPP. However, understanding of the physiological mechanism linking SIF to GPP under stress remains limited. In this article, the link between SIF and GPP at diurnal and seasonal timescales was explored for a maize field and its response to drought stress (as defined by the crop water stress index, CWSI) using three-years of continuous tower-based measurements was investigated. The results show that the ratio of GPP to SIF decreased with increasing drought stress levels, and the canopy stomata conductance (Gs) declined synchronously. Compared to two canopy structural factors (NDVI and NIRv), both the Pearson and partial correlation coefficients for the relationship between Gs and the ratio of GPP to the total SIF was higher (0.38, p ${{\bf \Phi }_F}$ tracked the changes in LUE well under drought conditions (CWSI > 0.6), which demonstrated that SIF can be a powerful parameter for estimating GPP under drought stress. However, there was a smaller drop in ${{\bf \Phi }_F}$ under drought stress (slope = –0.002) compared to the slope for the relationship between LUE and CWSI (–0.08). The response of light reactions to drought stress may be muted compared to the stomatal response. These findings confirm that the Gs is sensitive to drought and is important for the SIF-based GPP estimation model. It also provides reliable evidence that SIF data include a large amount of physiological information and can serve as a potential indicator for detecting drought and estimating GPP.

From the functional ecology of animals to the theory of the functioning of aquatic ecosystems. On the scientific heritage of A.F. Alimov

The article is devoted to the scientific heritage of the outstanding Russian hydrobiologist A.F. Alimov. Showing a deep scientific interest not only in the problems of aquatic ecology, but also in zoology, he laid the foundations of the functional ecology of animals as a common area of interest for ecology and zoology. Further, his views were successfully used in studying functional ecology of different groups of aquatic animals and on their basis important generalizations were carried out on productivity and energy flows through aquatic ecosystems and communities. An important stage in his scientific work was the development of a structurally functional approach to the study of the functioning of ecological systems of water bodies and watercourses. He showed that their structural and functional parameters are naturally interdependent. This approach allowed quantification of changes in the ecosystems of water bodies exposed to various types of environmental stress. To describe the response of aquatic ecosystems to external factors, A.F. Alimov proposed an original interpretation of the steadiness and endurance of ecological systems. As a result, he laid the foundation for a quantitative assessment of the influence of various factors, including anthropogenic, on aquatic ecosystems. The proposed measures of steadiness and endurance of populations, communities, and ecosystems made it possible to assess quantitatively the degree of influence of factors on aquatic communities and the ecosystem as a whole. A.F. Alimov made a great contribution to the development of theoretical ecology. He gave an original definition of the ecosystem and formulated the main provisions of the theory of the functioning of aquatic ecosystems. Of great importance for ecology and biology in general are the works of A.F. Alimov on the territoriality of animals and on mechanisms that determine the number of species in aquatic ecosystems depending on the morphometry of water bodies, their trophic status, geographical location and degree of water mineralization. Of crucial importance for theoretical biology is a series of his works devoted to the biological (physiological) time of organisms. Based on strict mathematical analysis, he convincingly showed that organisms exist in their own internal time, the speed of which depends on the rate of the processes occurring in the body and is closely related to its mass.

Assessment of biochemical and physiological parameters of durum wheat genotypes at the seedling stage during polyethylene glycol-induced water stress

Wild and landrace progenitors of wheat are an important source of resistance to various types of environmental stress, which can be explored in wheat breeding. With the aim of providing genetic materials for breeding to generate drought-resistant varieties, 50 durum wheat landraces, breeding lines and local cultivars were evaluated at the seedling stage for biomass, physiological parameters (e.g. photosynthetic pigment and relative water contents) and activities of key enzymatic antioxidants [e.g. ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD)] under optimal and polyethylene glycol (PEG)-triggered water stress. We observed significant differences in the measured parameters among the durum wheat genotypes in response to PEG-induced water stress. Biomass and physiological traits showed a decreasing trend, whereas the antioxidant enzyme activities displayed an increasing trend in the investigated durum wheats under PEG-induced water stress. PEG-induced water stress decreased the average means of total soluble protein, chlorophyll a and total chlorophyll contents of the 50 investigated genotypes by 51.42, 36.77 and 26.15%, respectively, while the mean values of POD and SOD activities increased by 173.33 and 92.26%, respectively, relative to the control. A principal component analysis (PCA)-based biplot demonstrated that the stress tolerance index (STI) positively correlated with the root and shoot dry weights as well as CAT, SOD and APX activities. In conclusion, several breeding lines (e.g. G10, G19 and G20), Iranian landraces (e.g. G42 and G47) and local cultivar (G49) showed a better adaptive response to PEG-induced water stress than other tested genotypes, suggesting that these genotypes could be explored in various breeding programs to create new wheat cultivars with beneficial water stress-adaptive traits.

The up-regulation of proline synthesis in the meristematic tissues of wheat seedlings upon short-term exposure to osmotic stress

An increase in the cellular concentration of free proline is a common response of many plants to various types of environmental stress. In this study, we monitored the accumulation of proline and the activities of Δ1-pyrroline-5-carboxylate synthetase (P5CS) and Δ1-pyrroline-5-carboxylate reductase (P5CR), the key enzymes of proline biosynthesis, in different parts of 4-day-old seedlings of wheat (Triticum aestivum L. cv. Josef) in the course of the first 8 h after the application of osmotic stress to determine the primary sites of proline production under water deficit conditions. Our results show that proline accumulated rapidly over this stress period in the root tips (cell division and elongation zone) and the basal region of the leaves in a time-dependent manner. Parallel to the rise in proline content, the activities of P5CS and P5CR increased markedly in these growing tissues under osmotic stress. Dissection of the root tip and the leaf base demonstrated that after 8 h of water shortage the accumulation of proline and the activities of P5CS and P5CR were highest in the regions where active cell division takes place. In the mature parts of the root and the leaf, there was virtually no enhancement of proline metabolism during the early phase of water deprivation investigated here. These data indicate that at the initial stage of water stress proline production is primarily required for the protection of the meristematic tissues in the roots and leaves. Furthermore, a transient rise in nitric oxide (NO) production was detected in the root tips and the leaf base in response to osmotic stress just before proline synthesis was enhanced. Treatment with the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) reduced considerably the increase in the activities of P5CS and P5CR and suppressed the accumulation of proline by more than 85% in the stressed root tips and the leaf base. These results suggest that NO is involved as a signalling molecule in the up-regulation of proline synthesis in the growing tissues of young wheat seedlings in response to short-term water deprivation.

Priming Induction in Neighbouring Plants of Gossypium hirsutum under Salt Stress

Plants are subjected to various types of environmental stresses throughout their lifecycle. It has been found that plants are able to communicate with the neighbouring plants under stress conditions through volatile organic compounds. These volatiles act as signals for the neighbouring plants thus preparing them for the upcoming stress, a phenomenon known as priming. So, the present study explores the effects of salt stress on cotton plants and the resultant induction of priming in the nearby plants. For this purpose, salt tolerant cotton (Gossypium hirsutum) variety was used. Two concentration levels, 100 mM, and 150 mM of salt were used to study the impacts of the stress. The experiment was divided into two steps for each treatment. In the first step, a set of plants (emitters) was given salt stress. The second set of plants (receivers) was placed adjacent to the stressed plants (emitters), while the third set of plants was placed separately as a control for both the treatments. Various physiological and morphological parameters were measured at the beginning and the end of the first step. In the second step, the receiver plants now termed as "primed" were given the same levels of stress while a new set of non-primed plants was placed near the primed plants. These non-primed plants were now treated with 100mM and 150mM of NaCl respectively and the results were compared. The results show that plants were able to get signals from neighbouring stressed plants. Plants responded by altering morphology and physiology to prepare themselves for future stress conditions.

Enhancement of antioxidant activity and bioactive compound contents in yellow soybean by plant-extract-based products

Polyphenols present in different plant cell organelles increase the resistance of plants to various types of environmental stresses. We investigated the possibility of increasing the content of bioactive compounds in the seed of yellow soybean variety Laura. The soybean was treated during vegetation with five products based on plant extracts, on the assumption of enrichment of plants with various nutrients. Soybean flour extracts were screened spectrophotometrically for total phenolic content and antioxidant activity. The antioxidant activity was evaluated using three methods. The content of phenolic acids was determined by HPLC, and the raw protein content was estimated by the Kjeldahl method. Depending on the treatment, variations in the quantity of individual phenolic acids with up to 90% higher concentration as compared to the control were observed. Controlled usage of certain plant extracts can increase the concentration of the target group of bioactive compounds in the samples. The synergistic effect of proteins and phenolic compounds on the antioxidant activity of extracts was detected. The results of this study are not only important from the aspect of plant resistance to various types of stress, but also when considering soybean as a functional food. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31018, Grant no. 31037, Grant no. 37021 and Grant no. 172015]

Multilayer gyroid cubic membrane organization in green alga Zygnema.

Biological cubic membranes (CM), which are fluid membranes draped onto the 3D periodic parallel surface geometries with cubic symmetry, have been observed within subcellular organelles, including mitochondria, endoplasmic reticulum, and thylakoids. CM transition tends to occur under various stress conditions; however, multilayer CM organizations often appear associated with light stress conditions. This report is about the characterization of a projected gyroid CM in a transmission electron microscopy study of the chloroplast membranes within green alga Zygnema (LB923) whose lamellar form of thylakoid membrane started to fold into multilayer gyroid CM in the culture at the end of log phase of cell growth. Using the techniques of computer simulation of transmission electron microscopy (TEM) and a direct template matching method, we show that these CM are based on the gyroid parallel surfaces. The single, double, and multilayer gyroid CM morphologies are observed in which space is continuously divided into two, three, and more subvolumes by either one, two, or several parallel membranes. The gyroid CM are continuous with varying amount of pseudo-grana with lamellar-like morphology. The relative amount and order of these two membrane morphologies seem to vary with the age of cell culture and are insensitive to ambient light condition. In addition, thylakoid gyroid CM continuously interpenetrates the pyrenoid body through stalk, bundle-like, morphologies. Inside the pyrenoid body, the membranes re-folded into gyroid CM. The appearance of these CM rearrangements due to the consequence of Zygnema cell response to various types of environmental stresses will be discussed. These stresses include nutrient limitation, temperature fluctuation, and ultraviolet (UV) exposure.

Expression of Arabidopsis Bax Inhibitor-1 in transgenic sugarcane confers drought tolerance.

SummaryThe sustainability of global crop production is critically dependent on improving tolerance of crop plants to various types of environmental stress. Thus, identification of genes that confer stress tolerance in crops has become a top priority especially in view of expected changes in global climatic patterns. Drought stress is one of the abiotic stresses that can result in dramatic loss of crop productivity. In this work, we show that transgenic expression of a highly conserved cell death suppressor, Bax Inhibitor‐1 from Arabidopsis thaliana (AtBI‐1), can confer increased tolerance of sugarcane plants to long‐term (>20 days) water stress conditions. This robust trait is correlated with an increased tolerance of the transgenic sugarcane plants, especially in the roots, to induction of endoplasmic reticulum (ER) stress by the protein glycosylation inhibitor tunicamycin. Our findings suggest that suppression of ER stress in C4 grasses, which include important crops such as sorghum and maize, can be an effective means of conferring improved tolerance to long‐term water deficit. This result could potentially lead to improved resilience and yield of major crops in the world.