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International Journal of Molecular... May 2024Saline and alkaline stresses limit plant growth and reduce crop yield. Soil salinization and alkalization seriously threaten the sustainable development of agriculture...
Saline and alkaline stresses limit plant growth and reduce crop yield. Soil salinization and alkalization seriously threaten the sustainable development of agriculture and the virtuous cycle of ecology. Biofertilizers made from plant growth-promoting rhizobacteria (PGPR) not only enhance plant growth and stress tolerance, but also are environmentally friendly and cost-effective. There have been many studies on the mechanisms underlying PGPRs enhancing plant salt resistance. However, there is limited knowledge about the interaction between PGPR and plants under alkaline-sodic stress. To clarify the mechanisms underlying PGPR's improvement of plants' tolerance to alkaline-sodic stress, we screened PGPR from the rhizosphere microorganisms of local plants growing in alkaline-sodic land and selected an efficient strain, AD13-4, as the research object. Our results indicate that the strain AD13-4 can produce various growth-promoting substances to regulate plant endogenous hormone levels, cell division and differentiation, photosynthesis, antioxidant capacity, etc. Transcriptome analysis revealed that the strain AD13-4 significantly affected metabolism and secondary metabolism, signal transduction, photosynthesis, redox processes, and plant-pathogen interactions. Under alkaline-sodic conditions, inoculation of the strain AD13-4 significantly improved plant biomass and the contents of metabolites (e.g., soluble proteins and sugars) as well as secondary metabolites (e.g., phenols, flavonoids, and terpenoids). The 16S rRNA gene sequencing results indicated that the strain AD13-4 significantly affected the abundance and composition of the rhizospheric microbiota and improved soil activities and physiochemical properties. Our study provides theoretical support for the optimization of saline-alkali-tolerant PGPR and valuable information for elucidating the mechanism of plant alkaline-sodic tolerance.
Topics: Rhizosphere; Soil Microbiology; Medicago sativa; Bacillus; Alkalies; Microbiota; Stress, Physiological; Salt Tolerance; Soil
PubMed: 38891975
DOI: 10.3390/ijms25115785 -
International Journal of Molecular... May 2024AP2/ERF transcription factor genes play an important role in regulating the responses of plants to various abiotic stresses, such as cold, drought, high salinity, and...
AP2/ERF transcription factor genes play an important role in regulating the responses of plants to various abiotic stresses, such as cold, drought, high salinity, and high temperature. However, less is known about the function of oil palm AP2/ERF genes. We previously obtained 172 AP2/ERF genes of oil palm and found that the expression of was significantly up-regulated under salinity, cold, or drought stress conditions. In the present study, the sequence characterization and expression analysis for were conducted, showing that it was transiently over-expressed in L. The results indicated that transgenic tobacco plants over-expressing could have a stronger tolerance to salinity stress than wild-type tobacco plants. Compared with wild-type plants, the over-expression lines showed a significantly higher germination rate, better plant growth, and less chlorophyll damage. In addition, the improved salinity tolerance of transgenic plants was mainly attributed to higher antioxidant enzyme activities, increased proline and soluble sugar content, reduced HO production, and lower MDA accumulation. Furthermore, several stress-related marker genes, including , , , , , , and , were significantly up-regulated in transgenic tobacco plants subjected to salinity stress. Overall, over-expression of the gene significantly enhanced salinity stress tolerance in transgenic tobacco plants. This study lays a foundation for further exploration of the regulatory mechanism of the gene in conferring salinity tolerance in oil palm.
Topics: Nicotiana; Plants, Genetically Modified; Plant Proteins; Salt Tolerance; Gene Expression Regulation, Plant; Salt Stress; Stress, Physiological; Arecaceae; Germination
PubMed: 38891808
DOI: 10.3390/ijms25115621 -
BMC Plant Biology Jun 2024Nitrogen (N) availability is crucial in regulating plants' abiotic stress resistance, particularly at the seedling stage. Nevertheless, plant responses to N under...
BACKGROUND
Nitrogen (N) availability is crucial in regulating plants' abiotic stress resistance, particularly at the seedling stage. Nevertheless, plant responses to N under salinity conditions may vary depending on the soil's NH to NO ratio.
METHODS
In this study, we investigated the effects of different NH:NO ratios (100/0, 0/100, 25/75, 50/50, and 75/25) on the growth and physio-biochemical responses of soybean seedlings grown under controlled and saline stress conditions (0-, 50-, and 100-mM L NaCl and NaSO, at a 1:1 molar ratio).
RESULTS
We observed that shoot length, root length, and leaf-stem-root dry weight decreased significantly with increased saline stress levels compared to control. Moreover, there was a significant accumulation of Na, Cl, hydrogen peroxide (HO), and malondialdehyde (MDA) but impaired ascorbate-glutathione pools (AsA-GSH). They also displayed lower photosynthetic pigments (chlorophyll-a and chlorophyll-b), K ion, K/Na ratio, and weakened O-HO-scavenging enzymes such as superoxide dismutase, catalase, peroxidase, monodehydroascorbate reductase, glutathione reductase under both saline stress levels, while reduced ascorbate peroxidase, and dehydroascorbate reductase under 100-mM stress, demonstrating their sensitivity to a saline environment. Moreover, the concentrations of proline, glycine betaine, total phenolic, flavonoids, and abscisic acid increased under both stresses compared to the control. They also exhibited lower indole acetic acid, gibberellic acid, cytokinins, and zeatine riboside, which may account for their reduced biomass. However, NH:NO ratios caused a differential response to alleviate saline stress toxicity. Soybean seedlings supplemented with optimal ratios of NH:NO (T3 = 25:75 and T = 4 50:50) displayed lower Na and Cl and ABA but improved K and K/Na, pigments, growth hormones, and biomass compared to higher NH:NO ratios. They also exhibited higher O-HO-scavenging enzymes and optimized HO, MDA, and AsA-GSH pools status in favor of the higher biomass of seedlings.
CONCLUSIONS
In summary, the NH and NO ratios followed the order of 50:50 > 25:75 > 0:100 > 75:25 > 100:0 for regulating the morpho-physio-biochemical responses in seedlings under SS conditions. Accordingly, we suggest that applying optimal ratios of NH and NO (25/75 and 50:50) can improve the resistance of soybean seedlings grown in saline conditions.
Topics: Glycine max; Seedlings; Antioxidants; Plant Growth Regulators; Salt Tolerance; Nitrates; Ammonium Compounds; Salt Stress; Ions
PubMed: 38890574
DOI: 10.1186/s12870-024-05294-z -
Proceedings. Biological Sciences Jun 2024Hyperoxia has been shown to expand the aerobic capacity of some fishes, although there have been very few studies examining the underlying mechanisms and how they vary...
Hyperoxia has been shown to expand the aerobic capacity of some fishes, although there have been very few studies examining the underlying mechanisms and how they vary across different exposure durations. Here, we investigated the cardiorespiratory function of yellowtail kingfish () acutely (~20 h) and chronically (3-5 weeks) acclimated to hyperoxia (~200% air saturation). Our results show that the aerobic performance of kingfish is limited in normoxia and increases with environmental hyperoxia. The aerobic scope was elevated in both hyperoxia treatments driven by a ~33% increase in maximum O uptake (MO), although the mechanisms differed across treatments. Fish acutely transferred to hyperoxia primarily elevated tissue O extraction, while increased stroke volume-mediated maximum cardiac output was the main driving factor in chronically acclimated fish. Still, an improved O delivery to the heart in chronic hyperoxia was not the only explanatory factor as such. Here, maximum cardiac output only increased in chronic hyperoxia compared with normoxia when plastic ventricular growth occurred, as increased stroke volume was partly enabled by an ~8%-12% larger relative ventricular mass. Our findings suggest that hyperoxia may be used long term to boost cardiorespiratory function potentially rendering fish more resilient to metabolically challenging events and stages in their life cycle.
Topics: Animals; Perciformes; Oxygen Consumption; Hyperoxia; Acclimatization; Oxygen; Cardiac Output
PubMed: 38889794
DOI: 10.1098/rspb.2023.2557 -
PeerJ 2024is a D-genome donor of hexaploid wheat and is a potential source of genes for various biotic and abiotic stresses including heat and drought. In the present study, we...
is a D-genome donor of hexaploid wheat and is a potential source of genes for various biotic and abiotic stresses including heat and drought. In the present study, we used multi-stage evaluation technique to understand the effects of heat and drought stresses on derived introgression lines (ILs). Preliminary evaluation (during stage-I) of 369 ILs for various agronomic traits identified 59 agronomically superior ILs. In the second stage (stage-II), selected ILs (, 59 ILs) were evaluated for seedling heat (at 30 °C and 35 °C) and drought (at 20% poly-ethylene glycol; PEG) stress tolerance under growth chambers (stage-II). Heat and drought stress significantly reduced the seedling vigour by 59.29 and 60.37 percent, respectively. Genotype × treatment interaction analysis for seedling vigour stress tolerance index (STI) identified IL-50, IL-56, and IL-68 as high-performing ILs under heat stress and IL-42 and IL-44 as high-performing ILs under drought stress. It also revealed IL-44 and IL-50 as the stable ILs under heat and drought stresses. Furthermore, in the third stage (stage-III), selected ILs were evaluated for heat and drought stress tolerance under field condition over two cropping seasons (viz., 2020-21 and 2021-22), which significantly reduced the grain yield by 72.79 and 48.70 percent, respectively. Stability analysis was performed to identify IL-47, IL-51, and IL-259 as the most stable ILs in stage-III. Tolerant ILs with specific and wider adaptability identified in this study can serve as the potential resources to understand the genetic basis of heat and drought stress tolerance in wheat and they can also be utilized in developing high-yielding wheat cultivars with enhanced heat and drought stress tolerance.
Topics: Triticum; Aegilops; Droughts; Thermotolerance; Heat-Shock Response; Adaptation, Physiological; Seedlings; Stress, Physiological; Genetic Introgression; Plant Breeding
PubMed: 38881860
DOI: 10.7717/peerj.17528 -
Scientific Reports Jun 2024High temperatures are a major stress factor that limit the growth of Pinellia ternata. WRKY proteins widely distribute in plants with the important roles in plant growth...
High temperatures are a major stress factor that limit the growth of Pinellia ternata. WRKY proteins widely distribute in plants with the important roles in plant growth and stress responses. However, WRKY genes have not been identified in P. ternata thus far. In this study, five PtWRKYs with four functional subgroups were identified in P. ternata. One group III WRKY transcription factor, PtWRKY2, was strongly induced by high temperatures, whereas the other four PtWRKYs were suppressed. Analysis of transcription factor characteristics revealed that PtWRKY2 localized to the nucleus and specifically bound to W-box elements without transcriptional activation activity. Overexpression of PtWRKY2 increased the heat tolerance of Arabidopsis, as shown by the higher percentage of seed germination and survival rate, and the longer root length of transgenic lines under high temperatures compared to the wild-type. Moreover, PtWRKY2 overexpression significantly decreased reactive oxygen species accumulation by increasing the catalase, superoxide dismutase, and peroxidase activities. Furthermore, the selected heat shock-associated genes, including five transcription factors (HSFA1A, HSFA7A, bZIP28, DREB2A, and DREB2B), two heat shock proteins (HSP70 and HSP17.4), and three antioxidant enzymes (POD34, CAT1, and SOD1), were all upregulated in transgenic Arabidopsis. The study identifies that PtWRKY2 functions as a key transcriptional regulator in the heat tolerance of P. ternata, which might provide new insights into the genetic improvement of P. ternata.
Topics: Arabidopsis; Transcription Factors; Gene Expression Regulation, Plant; Plant Proteins; Thermotolerance; Pinellia; Plants, Genetically Modified; Reactive Oxygen Species; Heat-Shock Response; Hot Temperature
PubMed: 38877055
DOI: 10.1038/s41598-024-64560-0 -
European Journal of Sport Science Jun 2024This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high... (Randomized Controlled Trial)
Randomized Controlled Trial
This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high altitudes (HA), considering the physiological challenges of hypoxic conditions. Overall, 121 lowlanders who had lived on the Tibetan Plateau for >2 years and were still living at HA during the measurements were randomly classified into four groups. Each individual of the low-intensity (LI), moderate-intensity (MI), and high-intensity (HI) groups performed 20 sessions of aerobic exercise at HA (3680 m) over 4 weeks, while the control group (CG) did not undergo any intervention. Physiological responses before and after the intervention were observed. The LI and MI groups experienced significant improvement in cardiopulmonary fitness (0.27 and 0.35 L/min increases in peak oxygen uptake [ O], both p < 0.05) after exercise intervention, while the hematocrit (HCT) remained unchanged (p > 0.05). However, HI exercise was less efficient for cardiopulmonary fitness of lowlanders (0.02 L/min decrease in O, p > 0.05), whereas both the HCT (1.74 %, p < 0.001) and glomerular filtration rate (18.41 mL/min, p < 0.001) increased with HI intervention. Therefore, LI and MI aerobic exercise, rather than HI, can help lowlanders in Tibet become more acclimated to the HA by increasing cardiopulmonary function and counteracting erythrocytosis.
Topics: Humans; Tibet; Exercise; Altitude; Male; Adult; Acclimatization; Oxygen Consumption; Cardiorespiratory Fitness; Female; Hematocrit; Young Adult; Glomerular Filtration Rate; Physical Fitness; Heart Rate
PubMed: 38874991
DOI: 10.1002/ejsc.12110 -
Science Advances Jun 2024Certain cyanobacteria alter their photosynthetic light absorption between green and red, a phenomenon called complementary chromatic acclimation. The acclimation is...
Certain cyanobacteria alter their photosynthetic light absorption between green and red, a phenomenon called complementary chromatic acclimation. The acclimation is regulated by a cyanobacteriochrome-class photosensor that reversibly photoconverts between green-absorbing (Pg) and red-absorbing (Pr) states. Here, we elucidated the structural basis of the green/red photocycle. In the Pg state, the bilin chromophore adopted the extended C15-, structure within a hydrophobic pocket. Upon photoconversion to the Pr state, the bilin is isomerized to the cyclic C15-, structure, forming a water channel in the pocket. The solvation/desolvation of the bilin causes changes in the protonation state and the stability of π-conjugation at the B ring, leading to a large absorption shift. These results advance our understanding of the enormous spectral diversity of the phytochrome superfamily.
Topics: Light; Cyanobacteria; Acclimatization; Photosynthesis; Phytochrome; Models, Molecular; Bile Pigments; Bacterial Proteins; Red Light
PubMed: 38865454
DOI: 10.1126/sciadv.adn8386 -
BMC Plant Biology Jun 2024BRVIS RADIX (BRX) family is a small gene family with the highly conserved plant-specific BRX domains, which plays important roles in plant development and response to...
BACKGROUND
BRVIS RADIX (BRX) family is a small gene family with the highly conserved plant-specific BRX domains, which plays important roles in plant development and response to abiotic stress. Although BRX protein has been studied in other plants, the biological function of cotton BRX-like (BRXL) gene family is still elusive.
RESULT
In this study, a total of 36 BRXL genes were identified in four cotton species. Whole genome or segmental duplications played the main role in the expansion of GhBRXL gene family during evolutionary process in cotton. These BRXL genes were clustered into 2 groups, α and β, in which structural and functional conservation within same groups but divergence among different groups were found. Promoter analysis indicated that cis-elements were associated with the phytohormone regulatory networks and the response to abiotic stress. Transcriptomic analysis indicated that GhBRXL2A/2D and GhBRXL5A/5D were up/down-regulated in response to the different stress. Silencing of GhBRXL5A gene via virus-induced gene silencing (VIGS) improved salt tolerance in cotton plants. Furthermore, yeast two hybrid analysis suggested homotypic and heterotypic interactions between GhBRXL1A and GhBRXL5D.
CONCLUSIONS
Overall, these results provide useful and valuable information for understanding the evolution of cotton GhBRXL genes and their functions in salt stress.
Topics: Gossypium; Multigene Family; Plant Proteins; Salt Stress; Gene Expression Regulation, Plant; Salt Tolerance; Phylogeny; Genes, Plant; Gene Expression Profiling
PubMed: 38862893
DOI: 10.1186/s12870-024-05220-3 -
Wilderness & Environmental Medicine Jun 2024Griffith Pugh, MD (1909-1994), was a pioneer in altitude physiology. During World War II, he developed training protocols in Lebanon to improve soldier performance at...
Griffith Pugh, MD (1909-1994), was a pioneer in altitude physiology. During World War II, he developed training protocols in Lebanon to improve soldier performance at altitude and in the cold. In 1951 he was chosen to join the British Everest team as a scientist. In preparation, he developed strategies for success on a training expedition on Cho Oyu in 1952. Results from Cho Oyu led to the use of supplemental oxygen at higher flow rates during ascent than used previously (4 L/min vs 2 L/min) and continued use (at a reduced rate of 2 L/min) during descent, enabling increased performance and improved mental acuity. Oxygen was also used during sleep, leading to improved sleep and warmth. Adequate hydration (∼3 L/day) was also stressed, and a more appealing diet led to improved nutrition and condition of the climbers. Improved hygiene practices and acclimatization protocols were also developed. These strategies contributed to the first successful summiting of Mount Everest in 1953. Pugh was then appointed as the lead scientist for a ground-breaking eight-and-a-half-month research expedition where the team was the first to overwinter at high altitude (5800 m) in the Himalayas. This current work summarizes Pugh's scientific contributions as they relate to success on Mount Everest and in inspiring future altitude research by generations of successful researchers.
PubMed: 38860547
DOI: 10.1177/10806032241259499