Environmental Stress Conditions Research Articles

ASYMMETRIC LEAVES2 repression confers lobed leaves by regulating lignin biosynthesis of leaf veins in Betula pendula

Lobed leaves are a desirable phenotypic trait in conditions of high irradiance and environmental stresses. Betula pendula 'Dalecarlica', an intraspecific variation of B. pendula, shows a unique leaf shape with deeply lobed leaves in contrast to the serrated ovate leaves of B.pendula. The leaf vein pattern is critically important for the formation of leaf lobes. However, the underlying regulatory mechanisms remain elusive. In this study, we investigated a gene regulatory network using RNA-seq data from different development stages of midveins in B.pendula 'Dalecarlica'. We identified BpAS2 as a key negative regulator in vein development of lobed leaves. RNA-seq analysis revealed that genes related to lignin biosynthesis were significantly upregulated in bpas2 mutant plants created using the CRISPR/Cas9 genome editing system. Loss-of-function of BpAS2 gene results in overdeveloped veins in lobed leaves. Furthermore, ChIP assay confirms that BpAS2 physically binds the promoter of BpKNAT1, and represses its gene expression of BpKNAT1 which is a molecular regulator of leaf dissection and lignin biosynthesis. Our results indicate that BpAS2 represses BpKNAT1 to downregulate lignin biosynthesis, thereby, inhibiting the development of leaf vein patterns and the formation of lobed leaves.

Evolutionary Insights and Expression Dynamics of the Glutathione Peroxidase (GPX) Gene Family in Water lily (Nymphaea colorata) in Response to Multiple Abiotic Stresses

The glutathione peroxidase (GPX) family in plants contains various isoenzymes, each with distinct subcellular localizations, tissue-specific expression patterns, and responses to environmental stress. In current study, we conducted genome-wide bioinformatics analyses of the GPX gene family in Nymphaea colorata, identifying five putative NcGPX genes dispersed across five of the fourteen chromosomes. Examination of the protein sequences revealed that NcGPXs comprehend three conserved cysteine residues, with predicted in-silico subcellular localizations in chloroplast, extracellular, or cytoplasm. We reported that NcGPX genes protein lengths and molecular weight (MW) ranged from 171-248 amino acids (aa) and 18.798-27.076 kDa, respectively. A comparative neighbor-joining phylogenetic study revealed that GPX genes were clustered into four main groups (Group A– D) from water lily and two closely related plant species, alongside with Arabidopsis thaliana. The universal analysis showed that segmental duplications occurred within the NcGPX gene family. Investigation of gene structure and motifs suggested that most NcGPX genes have relatively conserved exon-intron structures and motif arrangements. Promoter region exploration of NcGPX genes revealed numerous cis-acting regulatory elements associated with development, stress, and hormone responses. The identified 3D protein structures showed that water lily GPXs form conserved dimeric protein signatures. Finally, gene expression and enzymes accumulation of NcGPXs in response to different abiotic stresses, in leaves of N. colorata were analysed using real-time RT-qPCR and spectrophotometry. The results indicate that different members of the GPX gene family are co-ordinately regulated under specific environmental stress conditions, establishing a foundation for studying their gene functions and improving abiotic stress tolerance in water lily genetic breeding.

Peculiarities of Plant Mineral Composition in Semi-Desert Conditions

Plant–soil interactions in semi-desert conditions elicit the development of plant-specific adaptation strategies, including selective accumulation of macro- and microelements. Using an ICP-MS analysis of 12 plant species belonging to Asteraceae, Fabaceae, Poaceae, Ephedraceae, Amarantaceae, and Lamiaceae families of the Baskunchak Nature Reserve, remarkable species differences in accumulation of 22 macro- and microelements were recorded. The most common Artemisia species and Poaceae representatives belong to two different groups of plants with high content of Na, K, Zn, Cu, V and high antioxidant status and low Si typical for the former group and the opposite characteristics for the latter one. The mentioned phenomenon indicates two diverse powerful adaptation mechanisms based on the antioxidant defense and Si protection, respectively. The high frequency of remarkable levels of Se in plants with BCF exceeding 1 (Glycyrrhiza aspera, Phlomis pungens, Tanacetum nullifolium, Helichrysum nogaicum, and Jurinea ewersmannii), Zn in all species except Poa angustifolia, and Cu in the Asteraceae plants Phlomis pungens and Krascheninnikovia ceratoides suggests the significance of these elements in plant tolerance to environmental stresses. Plant–soil positive correlations were recorded for Sr (r = 0.866; p < 0.001); plant Sr, Fe, Co, Pb levels and soil salinity (r = 0.763, p < 0.001; r = 0.606, p < 0.03; r = 0.627, p < 0.02; r = 0.548, p < 0.05, respectively); and Cr only for Asteraceae species (r = 0.986, p < 0.001). The results obtained in this research may be used in plant adaptability evaluation in conditions of environmental stress.

The Population and Isolates of Potential ACC Deaminase-Producing Rhizobacteria from Rhizospheric Soil of Peanut under Different Moisture Levels

ACC deaminase-producing rhizobacteria play an important role in enhancing plant growth and health, particularly under environmental stress conditions. This study focused on isolating and determining the population of potential ACC deaminase-producing rhizobacteria from the rhizosphere of peanut plants (Arachis hypogea L.) grown under varying moisture levels. Bacterial populations were measured using the Standard Plate Count (SPC) method on Dworkin-Foster (DF) medium supplemented with ACC as the sole nitrogen source. The isolated bacteria were screened based on their ability to grow after 24 hours of incubation on the selective medium. Results showed that bacterial colonies on nutrient agar (NA) medium varied in color, while colonies on the selective medium were uniformly white. The total population of rhizobacteria generally declined as soil moisture decreased, nevertheless, the sample from 80% available water had fewer bacteria than those of the sample from 50%. In an additional experiment, 9 out of 11 selected isolates were found to potentially produce ACC deaminase, with 5 of these being diazotrophic bacteria. This study contributes valuable information for designing irrigation systems in sustainable land management, particularly concerning plant-beneficial microbes that produce ACC deaminase and help plants tolerate environmental stressors.

GmERFVII transcription factors upregulate PATHOGENESIS-RELATED10 and contribute to soybean cyst nematode resistance.

Low oxygen availability within plant cells arises during plant development but is exacerbated under environmental stress conditions. The group VII ETHYLENE RESPONSE FACTOR (ERFVII) transcription factors have been identified as pivotal regulators in the hypoxia response to abiotic stress. However, their roles in transcriptional regulation during biotic stresses remain less defined. In this study, we investigated the biological function and regulatory mechanism of soybean (Glycine max) ERFVII transcription factors during soybean cyst nematode (Heterodera glycines Ichinohe) infection. We provide evidence that soybean cyst nematode infection induces responses at the infection sites similar to those induced by hypoxia, characterized by the stabilization of ERFVII proteins and increased expression of hypoxia-responsive genes. Hypoxia pretreatment of soybeans enhances their resistance to nematode infection. We demonstrate that ERFVII members GmRAP2.12 and GmRAP2.3 act as transcriptional activators to drive the expression of GmPR10-09g, a member of the PR10 gene family highly induced by soybean cyst nematode and positively impacting nematode resistance. Transgenic hairy root analysis of nematode infection for either GmRAP2.12 or N-end rule pathway components (GmATE or GmPRT6) indicates a positive role of ERFVIIs in soybean defense responses against cyst nematode. The results of our study emphasize the important functions of GmERFVIIs in strengthening soybean's immune responses against cyst nematode by transcriptional activation of GmPR10.

Transcriptional profiling reveals the role of Candida albicans Rap1 in oxidative stress response.

Candida albicans is a member of the human commensal microbiota but can also cause opportunistic infections, including life-threatening invasive candidiasis, particularly in immunocompromised patients. One of the important features of C. albicans commensalism and virulence is its ability to adapt to diverse environmental stress conditions within the host. Rap1 is a DNA-binding protein identified in yeasts, protozoa, and mammalian cells, and it plays multiple functions, including telomere regulation. Intriguingly, our previous study showed that Rap1 is also involved in cell wall integrity, biofilm formation, and virulence in C. albicans. In this work, using RNA-seq analysis and other approaches, the role of C. albicans Rap1 in oxidative stress response was further revealed. The RAP1-deletion mutant exhibited greater resistance to the superoxide generator menadione, a lower level of intracellular reactive oxygen species (ROS) upon menadione treatment, and higher expression levels of superoxide dismutase genes, all in response to oxidative stress. Moreover, the association between Rap1-mediated oxidative stress response and the mitogen-activated protein kinase (MAPK) Hog1, the transcription factor Cap1 and the TOR signaling was also determined. Together, these findings expand our understanding of the complex signaling and transcriptional mechanisms regulating stress responses in C. albicans.

High temperature perturbs physicochemical parameters and fatty acids composition of safflower (Carthamus tinctorius L.)

Future climates will realise increasingly frequent extreme weather events, which will impact on the quantum and quality of crop production. While effects of extreme heat on crop production have been well studied hitherto, there remains a dearth of knowledge pertaining to the impacts of extreme heat on grain quality. As such, our purpose here was to evaluate the effects of terminal heat stress on the physicochemical properties and composition of seed oil of safflower plants. Using two contemporary cultivars with varying genetic tolerance to heat stress (Faraman and Sofeh), we found that exposure to extreme heat reduced grain yield by 53–57%. Four fatty acids (palmitic, stearic, oleic and linoleic acid) comprised 96–99% of total fatty acid methyl esters; relative composition varied in response to heat stress and other environmental conditions. In the first experimental year (2017-18), saturated fatty acids in Sofeh and Faraman cultivars increased by 69% and 18% respectively, while unsaturated fatty acids decreased by 9% and 4%, respectively. In the second experimental year (2018-19), saturated fatty acids increased by 10% in Sofeh and by less than 1% in Farman, while unsaturated fatty acids in both cultivars were not significantly altered. Physicochemical parameters differed across years and cultivars; exposure to high temperature increased chlorophyll and carotenoid content in Sofeh, but decreased the said parameters in Faraman. In 2017-18, effects of heat stress on thiobarbituric acid were variable, but in 2018-19, thiobarbituric acid increased in both cultivars. In all cases, saponification and iodine content increased in response to heat stress. In sum, the fatty acid profile of safflower exposed to terminal heat stress was less affected compared with oil physicochemical parameters, due to greater temperature sensitivity of the latter.

Leaf Anatomical Adaptation and Chloroplast Ultrastructure Changes Upon Magnesium Foliar Application of Faba Bean (Vicia faba L.) Grown Under Drought Stress

ABSTRACTBackgroundDrought stress (DS) impedes plant growth and development by impairing the uptake of nutrients, such as magnesium, which is central to many physiological processes, particularly photosynthesis. Leaf application was proposed to be an effective strategy to compensate for inadequate Mg2+ supply from the nutrient solution.AimThe present study is designed to investigate the role of Mg2+ leaf application in ameliorating leaf anatomy and chloroplast ultrastructure changes in faba beans grown under DS.MethodsHydroponically grown plants were subjected to DS under various levels of Mg2+, i.e. sufficient (0.5 mM), deficient (0 mM), and leaf‐application (250 mM). Light and transmission electron microscopy (TEM) were conducted to examine leaf anatomy and ultrastructural changes.ResultsMg2+ deficiency alone and under DS significantly affected plant biomass and photosynthesis. Additionally, sucrose concentration, oxidative stress, and lipid peroxidation were increased. Accordingly, the excessive deposition of photoassimilates in source organs due to the inhibition of phloem loading results in a disruption of the thylakoid structures leading to chloroplast damage. In the current study leaf application of Mg2+ partially ameliorated physiological functions, most notably chlorophyll concentration, photosynthesis and transpiration rate, plant biomass, and preservation of ultrastructure of the chloroplast.ConclusionAlthough the Mg application via roots enhanced drought tolerance, compared to Mg2+ leaf application. However, Mg2+ leaf application was proven to be an efficient strategy in mitigating DS in field trials. Therefore, Mg2+ foliar application should be prioritized for further investigation under relevant environmental stress conditions.

Novel Populations of Mycobacterium smegmatis Under Hypoxia and Starvation: Some Insights on Cell Viability and Morphological Changes.

The general features of the shift to a dormant state in mycobacterial species include several phenotypic changes, reduced metabolic activities, and increased resistance to host and environmental stress conditions. In this study, we aimed to provide novel insights into the viability state and morphological changes in dormant M. smegmatis that contribute to its long-term survival under starvation or hypoxia. To this end, we conducted assays to evaluate cell viability, morphological changes and gene expression. During starvation, M. smegmatis exhibited a reduction in cell length, the presence of viable but non-culturable (VBNC) cells and the formation of anucleated small cells, potentially due to a phenomenon known as reductive cell division. Under hypoxia, a novel population of pleomorphic mycobacteria with a rough surface before the cells reached nonreplicating persistence 1 (NRP1) was identified. This population exhibited VBNC-like behaviour, with a loss of cell wall rigidity and the presence of lipid-body-like structures. Based on dosR and hspX expression, we suggest that M. smegmatis encounters reductive stress conditions during starvation, while lipid storage may induce oxidative stress during hypoxia. These insights into the heterogeneous populations presented here could offer valuable opportunities for developing new therapeutic strategies to control dormant mycobacterial populations.

Study of the Genetic Mechanisms of Siberian Stone Pine (Pinus sibirica Du Tour) Adaptation to the Climatic and Pest Outbreak Stresses Using Dendrogenomic Approach.

A joint analysis of dendrochronological and genomic data was performed to identify genetic mechanisms of adaptation and assess the adaptive genetic potential of Siberian stone pine (Pinus sibirica Du Tour) populations. The data obtained are necessary for predicting the effect of climate change and mitigating its negative consequences. Presented are the results of an association analysis of the variation of 84,853 genetic markers (single nucleotide polymorphisms-SNPs) obtained by double digest restriction-site associated DNA sequencing (ddRADseq) and 110 individual phenotypic traits, including dendrophenotypes based on the dynamics of tree-ring widths (TRWs) of 234 individual trees in six natural populations of Siberian stone pine, which have a history of extreme climatic stresses (e.g., droughts) and outbreaks of defoliators (e.g., pine sawfly [Neodiprion sertifer Geoff.]). The genetic structure of studied populations was relatively weak; samples are poorly differentiated and belong to genetically similar populations. Genotype-dendrophenotype associations were analyzed using three different approaches and corresponding models: General Linear Model (GLM), Bayesian Sparse Linear Mixed Model (BSLMM), and Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK), respectively. Thirty SNPs were detected by at least two different approaches, and two SNPs by all three. In addition, three SNPs associated with mean values of recovery dendrophenotype (Rc) averaged across multiple years of climatic stresses were also found by all three methods. The sequences containing these SNPs were annotated using genome annotation of a very closely related species, whitebark pine (P. albicaulis Engelm.). We found that most of the SNPs with supposedly adaptive variation were located in intergenic regions. Three dendrophenotype-associated SNPs were located within the 10 Kbp regions and one in the intron of the genes encoding proteins that play a crucial role in ensuring the integrity of the plant's genetic information, particularly under environmental stress conditions that can induce DNA damage. In addition, we found a correlation of individual heterozygosity with some dendrophenotypes. Heterosis was observed in most of these statistically significant cases; signs of homeostasis were also detected. Although most of the identified SNPs were not assigned to a particular gene, their high polymorphism and association with adaptive traits likely indicate high adaptive potential that can facilitate adaptation of Siberian stone pine populations to the climatic stresses and climate change.

An LRR-RLK protein modulates drought- and salt-stress responses in maize

Maize (Zea mays), which is a vital source of food, feed, and energy feedstock globally, has significant potential for higher yields. However, environmental stress conditions, including drought and salt stress, severely restrict maize plant growth and development, leading to great yield losses. Leucine-rich repeat receptor-like kinases (LRR-RLKs) function in biotic and abiotic stress responses in the model plant Arabidopsis (Arabidopsis thaliana), but their roles in abiotic stress responses in maize are not entirely understood. In this study, we determine that the LRR-RLK ZmMIK2, a homolog of the Arabidopsis LRR-RK MALE DISCOVERER 1 (MDIS1)- INTERACTING RECEPTOR LIKE KINASE 2 (MIK2), functions in resistance to both drought and salt stress in maize. Zmmik2 plants exhibit enhanced resistance to both stresses, whereas overexpressing ZmMIK2 confers the opposite phenotypes. Furthermore, we identify C2-DOMAIN-CONTAINING PROTEIN 1 (ZmC2DP1), which interacts with the intracellular region of ZmMIK2. Notably, that region of ZmMIK2 mediates the phosphorylation of ZmC2DP1, likely by increasing its stability. Both ZmMIK2 and ZmC2DP1 are mainly expressed in roots. As with ZmMIK2, knockout of ZmC2DP1 enhanced resistance to both drought and salt stress. We conclude that ZmMIK2–ZmC2DP1 act as a negative regulatory module in maize drought- and salt-stress responses.

Inoculation of Arthrobacter sp. improves the growth of Acanthocalycium sp. and the fruits nutraceutical quality and the flowers longevity

Research objective: The aim of this work is on the inoculation in the growing medium of Arthrobacter sp. and its effects on the growth, flower quality and longevity of cactus plants. To this end, the study of biometric parameters, i.e. plants and flowers (height, weight, number and duration), as well as root growth (weight), and the presence of disease were quantified as measures of plant productivity and compared with those obtained from non-inoculated plants. The use of alginate microspheres as a means of bacterial inoculation was also considered. Materials and Methods: Seedlings of Acanthocalycium (2 years old) Ferrarii, A. Glaucum and A. Violaceum were immediately planted in pots after purchase, in substrate containing (sand 20%, pumice 20% and peat 60%; pH 7; electrical conductivity 0.7 dS/m; total porosity 80% (v/v). A randomised complete block design was applied for the experiments: the pots were randomly divided into two series, one series was inoculated with the bacteria and the other non-inoculated was used as a control. Each month, plant growth was assessed according to (1) plant height, (2) vegetative and root weight, (3) number of flowers per plant (4) flower duration. In addition, the occurrence of possible diseases, in particular Fusarium sp. and Verticillium sp., was assessed. Total flavonoids, total phenols and antioxidant activity were also analysed. Results and Discussion: The experiment showed that the use of Arthrobacter sp. can indeed significantly improve the vegetative and root growth of Acanthocalycium sp. cacti. In addition, there was a significant improvement in the number and floral longevity as well as in the phenol, flavonoid and antioxidant content of the fruits of the inoculated plants compared to the untreated control. The experiment also showed that mortality due to the pathogens Fusarium sp. and Verticillium sp. was significantly reduced in the treated plant. In agreement with these authors, we found that PGPB treatments increased agronomic parameters and improved Fusarium and Verticillium resistance. In general, the application of biostimulants can increase the synthesis of bioactive compounds in plants by increasing resistance to phytopathologies. Inoculation with Arthrobacter sp. led to a significant reduction in the number of dead plants with respect to the diseases analysed. As a result of the stimulating action demonstrated in Acanthocalycium, bioproducts suitable for nutraceutical purposes may be developed in the future. Therefore, new microbe-assisted technologies can help plants to resist stress conditions, improving their tolerance and productivity. Conclusions: Due to its ‘multifunctionality’, the genus Acanthocalycium is considered as one of the species of the future, for ornamental use and medicinal aspects, and new results may help reveal its potential in the context of the bio-economy and circular economy. As natural resources and cultural practices are crucial in defining the quality of flowers when destined for food/nutraceutical applications, the inoculation of Acanthocalycium with Arthrobacter sp. can be envisaged to provide better plant growth under conditions of environmental stress, or as a soil fertiliser, but also to improve the synthesis of natural products used for therapeutic applications.

Biological traits of a commercial mussel species Mytilus platensis from the South Atlantic Ocean: Environmental drivers affecting on its intertidal population

Population density, morphometric relationships, maximum age and shell growth rate were studied in an intertidal commercial mytilid species, the blue mussel Mytilus platensis d’Orbigny, 1842, at Villa Gesell (37° 15′S; 56° 57′W), Argentina, Southwest Atlantic Ocean. The population density and mean shell length showed variation across the year, i.e., the month with the highest density (December) was mostly characterized by smaller sized individuals, representing the newly settled recruits during the austral summer months. Shell cross sections and acetate peels of M. platensis revealed an internal shell growth pattern alternating broad opaque and narrow translucent bands, corresponding to fast and slow-growing periods, respectively. Translucent bands representing external rings were formed mostly during July, coinciding with a decrease in sea water temperature (austral winter) and gonadal maturation processes. Data confirmed the annual formation of translucent bands in this species, showing a maximum age of 8 years. The generalized von Bertalanffy growth curve showed values of SL∞ = 38.46 mm, k = 0.28 yr−1 and t0 = −0.57 yr−1 (R2 = 0.80). Compared to studies of subtidal populations, lower shell growth rate in this intertidal population were observed, which may be associated with the stressful environmental conditions in this habitat, such as desiccation, exposure to waves and fluctuating sea water temperature. The characteristics described throughout the study highlight that the variability associated with intertidal environments could limit the sustainability of commercial exploitation of M. platensis in these ecosystems compared with conspecific subtidal populations.

Effects of mineral fertilization (NPK) on combined high temperature and ozone damage in rice

BackgroundIncreasing concern has recently been highlighted regarding crop damage due to extreme weather events caused by global warming and the increased production of ground-level ozone. Several studies have investigated rice growth in response to fertilization conditions under various environmental stress conditions; however, studies on growth development in response to fertilization conditions under combined high-temperature/ozone treatment conditions are scarce. In this study, we aimed investigate the growth and physiological development of rice under combined high temperature and ozone treatment conditions and to reveal the damage-mitigation effects of NPK fertilization treatments.ResultsThe plants were treated with varying levels of NPK [N2 (N-P-K: 9.0-4.5-4.0 kg/a), P2 (4.5-9.0-4.0 kg/a), K2 (4.5-4.5-8.0 kg/a), and control (4.5-4.5-4.0 kg/10a).] under combined high-temperature (35 ℃) and ozone (150 pb) treatment conditions. Analysis of the growth metrics, including plant height, leaf age, dry weight, and the plant height/leaf age (PH/L) ratio were revealed that combined high-temperature/ozone treatment promoted the phenological development indicated by increasing leaf age but decreased the plant height and dry weight indicating its negative effect on quantitative growth. The effects of this combined high-temperature/ozone treatment on growth were alleviated by NPK fertilization, particularly in K2 treatment but worsened in N2 treatment. Visible damage symptoms in rice leaves induced by exposure to the combined stressors was also alleviated by the K2 treatment. At the physiological level, K2 treatment reduced the expression of OsF3H2, which is associated with antioxidant activity, suggesting that potassium improved stress tolerance. Additionally, expression of genes related to abscisic acid (ABA) metabolism showed increased OsNECD (ABA synthesis) and decreased OsCYP707A3 (ABA degradation) in the K2 treatment, promoting a stronger adaptive stress response. Stomatal conductance measurements indicated a slight increase under K2 treatment, reflecting enhanced regulation of stomatal function during stress.ConclusionThe study highlights the potential of potassium fertilization to mitigate combined high-temperature and ozone stress in rice, suggesting it as a strategy to improve crop resilience and optimize fertilization. The findings offer insights into fertilization treatments and can guide future research on stress tolerance in crops.

Androgen blockage impairs proliferation and function of Sertoli cells via Wee1 and Lfng

BackgroundAndrogens are essential hormones for testicular development and the maintenance of male fertility. Environmental factors, stress, aging, and psychological conditions can disrupt androgen production, impacting the androgen signaling pathway and consequently spermatogenesis. Within the testes, testosterone is produced by Leydig cells and acts on Sertoli cells by activating the androgen receptor (AR), which then translocates to the nucleus to function as a transcription factor. Despite clinical correlations between low testosterone levels and diminished sperm quality, the precise mechanism remains unclear.MethodsThis study explores the hypothesis that reduced androgen levels impair Sertoli cell function by disrupting AR transcriptional regulation. Using an androgen blockade model with enzalutamide, we investigated the impact of low androgen levels on AR target genes in Sertoli cells through ChIP-seq and RNA-seq assays.ResultsOur results reveal that androgen blockage increases AR enrichment on the promoter region of Wee1, promoting Wee1 expression, while decreasing binding to the promoter region of Lfng, inhibiting its expression. Increased WEE1 protein inhibits Sertoli cell proliferation, whereas reduced LFNG affects Notch modification, leading to decreased production of glial cell line-derived neurotrophic factor (GDNF), a key growth factor for spermatogonial stem cell self-renewal.ConclusionsThese findings provide new insights into the molecular mechanisms by which low androgen levels interfere with Sertoli cell functions, offering novel perspectives for the clinical treatment of male reproductive disorders.

Rhizosheath Formation and Its Role in Plant Adaptation to Abiotic Stress

The rhizosheath, the layer of soil tightly attached to the roots, protects plants against abiotic stress and other adverse conditions by providing a bridge from the plant root system to the soil. It reduces the formation of air gaps between the root and soil and facilitates the transportation of water at the root–soil interface. It also serves as a favourable niche for plant-growth-promoting rhizobacteria in the surrounding soil, which facilitate the absorption of soil water and nutrients. This review compares the difference between the rhizosheath and rhizosphere, and summarises the molecular and physiological mechanisms of rhizosheath formation, and identifying the causes of rhizosheath formation/non-formation in plants. We summarise the chemical and physical factors (root hair, soil-related factors, root exudates, and microorganisms) that determine rhizosheath formation, and focus on the important functions of the rhizosheath in plants under abiotic stress, especially in drought stress, phosphorus deficiency, aluminium stress, and salinity stress. Understanding the roles played by the rhizosheath and the mechanisms of its formation provides new perspectives for improving plant stress tolerance in the field, which will mitigate the increasing environmental stress conditions associated with on-going global climate change.

An ecological and evolutionary approach to arboreal communities under different environmental stress conditions

Biodiversity distribution patterns and the ecological processes underlying them reflect how organisms respond to abiotic and biotic factors that interact across both space and time. In this study, we aimed to test the hypothesis that small-scale environmental variations shape ecological and phylogenetic patterns in arboreal communities through environmental filters created by the specific conditions of each environment examined. We investigated a mosaic of Atlantic forest environments, analyzing species composition, community dynamics, and phylogenetic relationships among the various environments. This approach provided valuable insight into how environmental factors influence the ecological differentiation of these communities. Variations in conditions and resources produced environmental filters that resulted in significant small-scale heterogeneity in species composition, community dynamics, and evolutionary relationships among the environments. By considering the dynamic interations between biotic and abiotic factors, we conclude that the prevailing environmental conditions at these sites play a crucial role in shaping the behavior and distribution of the species that inhabit them.

Molecular and genetic mechanisms of sex determination in poplar

The study of molecular and genetic mechanisms of sex determination in poplar is of interest not only in the fundamental aspect, but also in the applied aspect. In landscaping of large settlements, it is advisable to use male individuals of Populus genus due to their hypoallergenicity and increased resistance to environmental pollution, stress conditions and pathogens. However, sex determination in poplars is complicated by the complex genetic structure of the sex-determining region of the genome (SDR). In this review, the emergence, evolution, structure and function of the SDR in the genus Populus are discussed. Current insights into the structure and function of the key regulator of sex selection in poplars, the orthologous ARR16/ARR17 gene, and the possible role of other genes differentially expressed between male and female plants, including microRNAs, in this process are discussed in detail. The great diversity of species and the high complexity of SDR organization justify the need for further study of the molecular mechanisms of sex determination in poplars.

Elucidating the downstream pathways triggered by H2S signaling in Arabidopsis thaliana under drought stress via transcriptome analysis

ABSTRACT Hydrogen sulfide (H2S) is a crucial signaling molecule in plants. Recent studies have shown that H2S plays an equally important role as nitric oxide (NO) and hydrogen peroxide (H2O2) in plant signaling. Previous studies have demonstrated the involvement of H2S in regulating drought and other stressful environmental conditions, but the exact downstream molecular mechanisms activated by the H2S signaling molecule remain unclear. In this study, we conducted a comprehensive genome-wide transcriptomic analysis of both wild type (WT) and double mutant (lcd/des1). Arabidopsis thaliana plants were exposed to 40% polyethylene glycol (PEG) to induce drought stress and 20 µM sodium hydrosulfide (NaHS). The resulting transcriptome data were analyzed for differentially significant genes and their statistical enrichments in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results indicated significant upregulation of genes related to photosynthesis, carbon fixation, plant secondary metabolite biosynthesis, inositol and phosphatidylinositol signaling pathways, and stress-responsive pathways in mutant plants under drought stress. Mutant plants with impaired H2S signaling mechanisms displayed greater susceptibility to drought stress compared to wild-type plants. In summary, all findings highlight the pivotal role of H2S signaling in stimulating other drought-responsive signaling pathways.

The Combined Effects of Temperature and pH to the Toxicity of the Water-Soluble Fraction of Gasoline (WSFG) to the Neotropical Yellow-Tail Tetra, Astyanax altiparanae.

Continental aquatic environments have undergone chemical pollution due to increased anthropogenic activities. Among those substances, petroleum hydrocarbons are a potential hazard for the aquatic animals. Additionally, alterations in the abiotic characteristics of the water, such as temperature and pH, can impose additional stress when those substances are present. We evaluate how alterations in water temperature and pH modified the acute (96h) toxicity of the water-soluble fraction of gasoline (WSFG) to Astyanax altiparanae through physiological analysis. We also investigated the physiological responses after the fish recovery from exposure (96h) in clean water. Both isolated and combined exposures to WSFG resulted in significant physiological changes. Alone, WSFG altered energetic metabolism and haematopoietic functions, potentially due to metabolic hypoxia. When combined with changes in water temperature (30°C) and pH (4.0), A. altiparanae activated additional physiological mechanisms to counterbalance osmoregulatory and acid-base imbalances, likely exacerbated by severe metabolic hypoxia. In both isolated and combined exposure scenarios, A. altiparanae maintained cellular hydration, suggesting a robust capacity to uphold homeostasis under environmental stress conditions. Following a recovery in clean water, energetic metabolism returned to control levels. Nevertheless, plasmatic Na+ and Cl- levels and haematological parameters remained affected by WSFG exposure. Our findings underscore the impact of interactions between WSFG contaminants, temperature and pH, leading to additional biological damage in A. altiparanae.