Physiological Adaptation Mechanisms Research Articles

Plant Coping with Cold Stress: Molecular and Physiological Adaptive Mechanisms with Future Perspectives

Cold stress strongly hinders plant growth and development. However, the molecular and physiological adaptive mechanisms of cold stress tolerance in plants are not well understood. Plants adopt several morpho-physiological changes to withstand cold stress. Plants have evolved various strategies to cope with cold stress. These strategies included changes in cellular membranes and chloroplast structure, regulating cold signals related to phytohormones and plant growth regulators (ABA, JA, GA, IAA, SA, BR, ET, CTK, and MET), reactive oxygen species (ROS), protein kinases, and inorganic ions. This review summarizes the mechanisms of how plants respond to cold stress, covering four main signal transduction pathways, including the abscisic acid (ABA) signal transduction pathway, Ca2+ signal transduction pathway, ROS signal transduction pathway, and mitogen-activated protein kinase (MAPK/MPK) cascade pathway. Some transcription factors, such as AP2/ERF, MYB, WRKY, NAC, and bZIP, not only act as calmodulin-binding proteins during cold perception but can also play important roles in the downstream chilling-signaling pathway. This review also highlights the analysis of those transcription factors such as bHLH, especially bHLH-type transcription factors ICE, and discusses their functions as phytohormone-responsive elements binding proteins in the promoter region under cold stress. In addition, a theoretical framework outlining plant responses to cold stress tolerance has been proposed. This theory aims to guide future research directions and inform agricultural production practices, ultimately enhancing crop resilience to cold stress.

A population dynamics approach to understand the invasiveness of the seaweed Rugulopteryx okamurae (Ochrophyta, Dictyotales)

The success of invasive species can be measured by invasiveness, which depicts intrinsic characteristics that enable them to thrive in new environments. In invasive seaweeds, for example, the persistence of multiple overlapping cohorts throughout the year plays a key role in increasing plant cover and exerting unrelenting pressure on invaded areas. The marine brown macroalgae Rugulopteryx okamurae has recently established abundant populations in the Mediterranean Sea and Atlantic Ocean, negatively affecting both biodiversity and socioeconomic factors by unprecedently aggressive invasive behaviour. The objective of the study is to understand the invasiveness of R. okamurae through its popu lation dynamics. For this, a year-round study was conducted in a protected habitat of Posidonia oceanica in southern Spain, revealing that R. okamurae uses alternating mechanisms for population maintenance. It achieves high density of young individuals in late summer and autumn, peaking at 3285 individuals per square metre. In spring and early summer, the population shifts towards fewer – but larger – individuals, with densities dropping to 888 individuals per square metre and biomass reaching a peak of 170 g dry weight (DW) per square metre. Six overlapping cohorts were identified by Gaussian curves. They persisted throughout the year, but they were not related to environmental factors, which indicates adaptive physiological mechanisms that sustain dense monospecific populations. Additionally, the association between cohorts and different morphotypes suggests that R. okamurae phenotypic plasticity enables its persistence in introduced areas. These findings provide valuable insights into the biological traits underpinning its invasiveness in P. oceanica meadows, revealing temporal windows of invasiveness driven by different mechanisms. This knowledge is crucial for developing effective conservation and management strategies aimed at mitigating the impact of this invasive species.

Genomic and physiological mechanisms of high-altitude adaptation in Ethiopian highlanders: a comparative perspective

High-altitude adaptation is a remarkable example of natural selection, yet the genomic and physiological adaptation mechanisms of Ethiopian highlanders remain poorly understood compared to their Andean and Tibetan counterparts. Ethiopian populations, such as the Amhara and Oromo, exhibit unique adaptive strategies characterized by moderate hemoglobin levels and enhanced arterial oxygen saturation, indicating distinct mechanisms of coping with chronic hypoxia. This review synthesizes current genomic insights into Ethiopian high-altitude adaptation, identifying key candidate genes involved in hypoxia tolerance and examining the influence of genetic diversity and historical admixture on adaptive responses. Furthermore, the review highlights significant research gaps, particularly the underrepresentation of Ethiopian populations in global genomic studies, the lack of comprehensive genotype-phenotype analyses, and inconsistencies in research methodologies. Addressing these gaps is crucial for advancing our understanding of the genetic basis of human adaptation to extreme environments and for developing a more complete picture of human physiological resilience. This review offers a comparative perspective with Tibetan and Andean highlanders, emphasizing the need for expanding genomic representation and refining methodologies to uncover the genetic mechanisms underlying high-altitude adaptation in Ethiopian populations.

Adaptive mechanism of submergence tolerance by Sub1 A

Among the various abiotic stresses affecting the growth, development, and yield of rice, submergence caused by continuous flooding without adequate drainage poses a significant threat. This stress is particularly detrimental in lowland areas with poor drainage, often near coastal regions, where excessive rainfall leads to prolonged waterlogging. Continuous waterlogging during germination severely impacts the germination of directly seeded rice crops, while seedling establishment suffers post-transplantation due to seedling decay and mortality. Submergence tolerance is an adaptive physiological and biochemical mechanism that has evolved in indica rice, enabling the plant to cope with the effects of anaerobic conditions caused by prolonged submergence. The putative progenitor Oryza rufipogon is well adapted to marshy environments. This study discusses the mechanisms of introgression of anaerobic germination and submergence tolerance from O. rufipogon through molecular analysis of genomic regions. It also explains the physiological and biochemical mechanisms that influence anaerobic germination and submergence tolerance. Lowland areas characterized by flooding due to excessive rainfall and inadequate drainage, particularly near coastal regions, require anaerobic germination and submergence tolerance for rice cultivation. Identifying new sources of submergence tolerance beyond the Sub1 gene, followed by genomic structural characterization for the development of pre-breeding genetic sources, is essential. Additionally, well-characterized quantitative trait loci (QTLs) and genes that confer submergence tolerance need to be transferred precisely.

Impact of modified atmospheres enriched with carbon dioxide on the survival, biological, and physiological aspects of Aleuroglyphus ovatus (Troupeau, 1878)

Aleuroglyphus ovatus (Troupeau, 1878), a prevalent mite within stored products, inflicts substantial economic and health risks. The use of fumigants and grain protectants as methods of stored grain pest management had resulted in resistance and environmental concerns, necessitating alternative strategies. This study explored the toxicity of modified atmospheres composed of CO2, as an environmentally friendly, residue-free, and viable disinfestation alternative. The mortality of A. ovatus increased significantly with an increase in either CO2 concentration or exposure duration. Complete adult mortality was recorded after 72 h of treatment with 95% CO2. The calculated LT50 value was 30.52 h under 35% CO2, and it decreased to 11.78 h under 95% CO2. Additionally, CO2 exposure led to changes in the activity of antioxidant and detoxification enzymes in A. ovatus, indicating its physiological adaptation mechanisms under varying CO2 concentrations and the impact of these changes on development and reproductive capacity. Enzymatic assays revealed a concentration-dependent decrease in superoxide dismutase activity and an increase in catalase activity. The detoxification enzymes, glutathione S-transferase, and carboxylesterase demonstrated adaptive upregulation. The development of A. ovatus was delayed, and its reproductive capacity was reduced under CO2 stress. Population parameters, including the net reproductive rate (R0) and intrinsic rate of increase (rm) were all significantly reduced under CO2 stress, with 35% CO2 showing the severer impact. The study concludes that CO2 can be an effective tool for pest management in stored products, with 35% CO2 showing potential as a more economical option for A. ovatus extermination.

Dynamic expression of heat-shock and acid-tolerance related genes of Lactobacillus delbrueckii ssp. bulgaricus LBB.B5 in milk

Lactobacillus delbrueckii ssp. bulgaricus is a central species in the production of fermented dairy food. However, from the point of view of starter culture production this species is extremely sensitive to freeze-drying. Therefore, it is essential to understand the physiological processes and adaptation mechanisms of the bacterial cell, especially its response to factors such as heat-, cold- and acid stress. Here we report the results of the dynamic expression monitoring of heat/cold-shock related genes (hsp60 and cspA) and genes putatively contributing to acid-tolerance (ornB, thrB and thrC) in L. delbr. ssp. bulgaricus LBB.B5 grown in milk. These genes were selected as hsp60 and cspA encode a heat-shock and a cold-shock protein, respectively, while ornB encodes an ornithine decarboxylase, related to acid tolerance in this species. Genes thrB and thrC are involved in threonine synthesis and are of particular interest as unlike the majority of amino-acids, the threonine synthesis pathway is conserved in all L. delbr. ssp. bulgaricus strains. Expression levels were monitored by RT-qPCR for 7 hours of fermentation at 42oC and then until the 24th hour under cold storage at 4oC. Samples at 3h were used as control. Two distinct patterns in the expression dynamics of the analysed genes were observed. Genes cspA, ornB, thrB and thrC, followed a pattern with maximal expression at 5h of the fermentation with levels of 11.6, 6.8, 3.9 and 2.4 times the control, respectively. Maximal expression levels coincided with the transition of the culture from exponential to stationary phase at a pH threshold of 5.0. Gene hsp60 showed a different pattern with gradually increasing expression throughout the hole fermentation process, including after cold storage when expression level reached 6.4 times the control. The upregulation of threonine biosynthesis and of a cold-shock protein synthesis with the onset of the stationary phase may suggest that together with the activity of ornithine decarboxylase, they go beyond their function of serving the amino-acid anabolism or managing cold stress, but rather facilitate the transition of the cells to stationary phase and/or their adaptation to acidic conditions. The gradual upregulation of hsp60 on the other hand may reflect the adaptation of the cells to growth at higher temperature (42oC) and subsequent transfer to cold storage.

High-temperature stress in strawberry: understanding physiological, biochemical and molecular responses.

Heat stress reduces strawberry growth and fruit quality by impairing photosynthesis, disrupting hormone regulation, and altering mineral nutrition. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic and metabolomic under high temperatures. Garden strawberry is a globally cultivated, economically important fruit crop highly susceptible to episodic heat waves and chronically rising temperatures associated with climate change. Heat stress negatively affects the growth, development, and quality of strawberries. Elevated temperatures affect photosynthesis, respiration, water balance, hormone signaling, and carbohydrate metabolism in strawberries. Heat stress reduces the size and number of leaves, the number of crowns, the differentiation of flower buds, and the viability of pollen and fruit set, ultimately leading to a lower yield. On a physiological level, heat stress reduces membrane stability, increases the production of reactive oxygen species, and reduces the antioxidant capacity of strawberries. Heat-tolerant varieties have better physiological and biochemical adaptation mechanisms compared to heat-sensitive varieties. Breeding heat-tolerant strawberry cultivars involves selection for traits such as increased leaf temperature, membrane thermostability, and chlorophyll content. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic, metabolomic, and ionomic reprogramming at high temperatures. Integrative-omics approaches combine multiple omics datasets to obtain a systemic understanding of the responses to heat stress in strawberries. This article summarizes the deciphering of strawberry responses to heat stress using physiological, biochemical, and molecular approaches that will enable the development of resilient adaptation strategies that sustain strawberry production under global climate change.

High ecostoichiometric stability and accumulating SiO2 and NO3− as main physiological adaptive mechanisms for reed to adverse environments

Previous studies have shown that nutrients accumulation played important roles in resisting to stress resistance of plants. Our study examined the ecostoichiometric internal stability (EIS) of nutrients accumulation and, concomitantly identified the main resistant regulating substances and their contributions to stress resistance of reed (Gramineae) in arid desert areas. Plants (digging method) and soil samples (quartering method)) obtained from sand dune (SD), desert steppe (DP), interdune lowland (IL), saline meadow (SM) and wetland (W) habitats were brought back to the lab for nutrients analysis. Results indicated that soil nutrients differed obviously, while reed maintained relatively stable ratios of SiO2:N, N:K, and P:K when the eco-environments changed in different habitats. Furthermore, reed exhibits common adaptive characteristics by mainly accumulating large amounts of SiO2 (122.6–174.0 g/kg) and NO3− (166.1–216.6 g/kg), as well as moderate levels of soluble sugar (SS: 24.0–55.0 g/kg), which are mainly stored in leaves for stress resistance. The contribution of ions to stress resistance was 80.03%–91.15% (with SiO2 and NO3− accounting for 54.91%–63.10%), whereas the contribution of solutes was only 8.85%–19.97% (with SS contributing to 5.14%–10.91%) in different habitats. These findings suggest that maintaining relatively high EIS, while still accumulating SiO2 and NO3− as main physiological regulators might be an effective strategy for reed to positively respond to adverse habitats, which provide a strong theoretical basis and technical reference for searching useful methods for restoration and reconstruction of the degraded ecosystems in desert oasis regions.

Combined Analysis of Transcriptome and Metabolome Provides Insights in Response Mechanism under Heat Stress in Avocado (Persea americana Mill.)

Plants generate a range of physiological and molecular responses to sustain their growth and development when suffering heat stress. Avocado is a type of tropical fruit tree with high economic value. Most avocado cultivars delete, wither, or even die when exposed to heat stress for a long time, which seriously restricts the introduction and cultivation of avocados. In this study, samples of a heat-intolerant variety (‘Hass’) were treated under heat stress, and the transcriptomics and metabolomics were analyzed, with the expectation of providing information on the variety improvement and domestication of avocados. The differentially expressed genes identified using transcriptome analysis mainly involved metabolic pathways such as plant hormone signal transduction, plant–pathogen interaction, and protein processing in the endoplasmic reticulum. Combined transcriptome and metabolome analysis indicated that the down-regulation of Hass.g03.10206 and Hass.g03.10205 in heat shock-like proteins may result in the reduced Trehalose and Sinapoyl aldehyde content. Metabolomics analysis results indicated that the decrease in Trehalose and Sinapoyl aldehyde content may be an important factor for heat intolerance. These results provide important clues for understanding the physiological mechanisms of adaptation to heat stress in avocados.

Salt Tolerance of Fungi and Prospects for Mycodiagnostics of Contamination in Saline Soils

The review is devoted to the analysis of the characteristics of salt-tolerant fungi in order to identify the possibility of their use for indicating chemical contamination of highly mineralized soils and the search for potential test species for laboratory mycotesting. A list of representatives of halophilic and halotolerant genera of micromycetes is given, which can serve as indicators of pollution by heavy metals, oil products and other toxicants against the background of increased mineralization of soil substrates. For biotesting of soils with an average level of mineralization, micromycetes belonging to moderate halotolerant species are proposed as promising. The morphological, physiological and molecular mechanisms of adaptation of halophilic and halotolerant fungi to conditions of increased salinity of habitats are analyzed. The effects on fungal communities, which are caused by a combination of salinity with chemical pollution of different nature, are considered. Methodological aspects of the practical use of salt-tolerant fungi for biodiagnostics of the degree of unfavourability of saline soils are considered: the composition of media, cultivation conditions, and test reactions of fungal cultures that are optimal for an adequate assessment of the degree of halotolerance of fungi and ecotoxicity of soil samples.

Effects of Social Group Housing on the Behavioral and Physiological Responses of Captive Sub-Adult Giant Pandas.

Wild giant pandas are inherently solitary creatures, however, the ex-situ conservation efforts significantly alter the living circumstances of their captive counterparts. Following the breeding period, giant pandas in captivity may be maintained in social groups. Currently, there is a lack of research on the effects of group housing on the physiology, behavior, and gut microbiota of captive giant pandas. This study divided six captive giant pandas into two groups following the breeding period. By comparing the behavior, physiology, and microorganisms of the two groups, we aim to investigate the behavioral responses and physiological adaptation mechanisms exhibited by captive giant pandas in a "group living" state. Our findings indicate that sub-adult giant pandas housed in group settings exhibit a significantly longer duration of playing behavior (including interactive and non-interactive play) compared to their counterparts housed separately (p < 0.001) while also demonstrating a significantly lower duration of stereotyped behavior than their separately housed counterparts. Additionally, an analysis of urine cortisol and heart rate variability between the two groups revealed no significant differences. Simultaneously, the group housing strategy markedly elevated the β diversity of gut microbiota in sub-adult giant pandas. In conclusion, the group-rearing model during the sub-adult stage has been shown to significantly alter the behavioral patterns of captive giant pandas. In conclusion, within the present captive setting, the group-rearing approach during the sub-adult stage proved to be less distressing for adult captive giant pandas.

Thermal balance in Andean lizards: A perspective from the high mountains

AbstractHigh Andean lizards in the Andes face numerous challenges in high‐altitude environments characterized by significant temperature, spatial and temporal variations. These factors greatly influence their thermal characteristics and adaptive strategies for coping with temperature fluctuations. This study aims were to investigate the thermal biology of high mountain lizards (&gt;2000 m) inhabiting the Andes Mountain range, using information from existing literature, and to identify the potential impacts of the original climate change scenarios developed in this study. Within the Andes, high‐altitude species are primarily found in families like Liolaemidae, Gymnophthalmidae, Tropiduridae, Anolidae and Leiourisauridae. Notably, we found in the literature that the higher body temperatures and maximum critical temperatures in southern species compared to those closer to the tropics. Typically, diurnal and seasonal temperature variations have a significant impact on the body temperature of these high‐altitude lizards, but their adaptive behaviours and physiological mechanisms enhance their resistance to extreme temperatures. Populations situated below the equator often exhibit higher body temperatures and maximum critical temperatures, largely due to their exposure to higher ambient temperatures during summer. With all global warming scenarios indicating temperature increases in latitudinal regions, tropical high‐altitude lizards, historically less thermally adaptable, may be particularly susceptible to these temperature rises. It is crucial to consider that additional factors, such as species activity patterns, thermal resource availability and diminishing suitable thermal habitats, will also play a pivotal role in shaping the future of these lizard species, making the situation even more complex and challenging.

Physiological response to low-nitrogen stress and comprehensive evaluation in four rice varieties.

Rice (Oryza sativa L.) research has rarely focused on the response to low-nitrogen stress in different subtypes previously and lacked a low-nitrogen tolerance evaluation system. Here, we investigated the physiological characteristics under moderate and low-nitrogen stress conditions in two japonica cultivars (NG46 and NG9108) and two indica cultivars (LYP9 and 9311). Using subordinate function analysis and principal component analysis, the low-nitrogen tolerance of four rice varieties was comprehensively evaluated; stomatal conductance, total carotenoid content, and nitrate reductase NR activity were taken as the low-nitrogen tolerance evaluation system. Among the four rice cultivars, NG46 and LYP9 had significant advantages in photosynthetic gas-exchange capacity, optimizing the balance between light-harvesting capacity, the ratio of reaction center inactivation, the magnitude of decrease in heat dissipation, and nitrogen-metabolism enzyme activities. The results investigated the physiological mechanisms of rice adaptation to low-nitrogen stress and offered a reliable method for assessing low-nitrogen tolerance in rice.

Effect of PCBs on Production Characteristics and Fucoxanthin / Fatty Acid Content of Cylindrotheca closterium (Ehrenberg) Reimann et Lewin Diatom Enrichment Culture

Background: Since the mid-20th century, polychlorinated biphenyls (PCBs) have emerged as one of the foremost anthropogenic organic pollutants in aquatic environments. Microphytobenthic algae of the genus Cylindrotheca have been recurrently employed in laboratory experiments to assess sediment toxicity. Recently, a novel strain of benthic diatoms belonging to the genus Cylindrotheca has been identified and characterized from PCB-contaminated sediments in the coastal region of Sevastopol Bay (Black Sea). This species of algae has high biomass productivity, the ability to synthesize fucoxanthin, and a variety of fatty acids. Cylindrotheca closterium is capable of metabolizing organic pollutants in bottom sediments. Objective: The objective of the study was to investigate the effects of PCBs on the growth patterns and physiological responses of C. closterium through a 9-day experiment, subjecting the microalgae to varying concentrations of PCBs ranging from 0.0003 to 100 mg/L. Results: The experiments revealed that C. closterium could grow in environments containing concentrations of PCBs ranging from 0.0003 to 10 mg/L, indicating its resilience to moderate levels of PCB exposure. Additionally, adaptive biochemical processes were observed in C. closterium under PCB exposure. Notably, on the sixth day of the experiment, the culture transitioned into a stationary growth phase, accompanied by significant increases in total lipid content by 1.6 times and fucoxanthin by 4.6 times compared to the control. However, a pronounced decrease in culture growth was observed at a PCB concentration of 100 mg/L, coinciding with reductions in total lipid and fucoxanthin content, suggesting a tolerance threshold of C. closterium between 10 and 100 mg/L PCB concentrations. Furthermore, alterations in the fatty acid profile of C. closterium were noted, characterized by a decrease in polyene content and an increase in monoene fatty acids, under PCB exposure. Conclusion: The study underscores the resilience of C. closterium to moderate PCB concentrations and highlights the complex physiological responses and adaptive mechanisms initiated in response to PCB exposure. The findings contribute to understanding the toxic effects of PCBs on C. closterium and provide insights into potential mechanisms underlying these effects.

Physiological Adaptation of Fenneropenaeus chinensis in Response to Saline-Alkaline Stress Revealed by a Combined Proteomics and Metabolomics Method.

The rapid development of the mariculture industry has been hindered by limited coastal aquaculture space. To utilize the abundant inland saline-alkaline water, we studied the physiological effects of high carbonate alkalinity stress and high pH stress on Fenneropenaeus chinensis. The study employed quantitative proteomics by tandem mass tag (TMT) and non-targeted metabolomics analysis using a liquid chromatograph mass spectrometer (LC-MS) to understand the physiological and biochemical adaptive mechanisms of the hepatopancreas of F. chinensis in response to saline-alkaline stress at the molecular level. We designed two stress groups as follows: a high carbonate alkalinity (CA) group and a combined high carbonate alkalinity and high pH (CP) group. The study found that the protein and metabolic profiles of the two stress groups were changed, and the CP group, which was exposed to dual stresses, incurred more severe damage to the hepatopancreas compared to that of the CA group. After exposure to CA and CP, the hepatopancreas of F. chinensis showed significant alterations in 455 proteins and 50 metabolites, and 1988 proteins and 272 metabolites, respectively. In addition, F. chinensis upregulated the level of energy metabolism in the hepatopancreas to defend against osmotic imbalance caused by CA or CP stress, which was demonstrated by the significant upregulation of important proteins and metabolites in glycolysis, pyruvate metabolism, TCA cycle, and fatty acid oxidation. Additionally, pattern recognition receptors, the phenol oxidase system, and various immune-related metabolic enzymes and metabolites were also affected. The immune homeostasis of F. chinensis was affected by the alteration of the antioxidant system following exposure to CA or CP. These findings provide valuable information for F. chinensis saline-alkaline water cultivation practices.

Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes.

This review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, defined as "SPARKS", will have a beneficial effect on the function and regeneration processes of the gut-brain-muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, defined as "SMOULDER", will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the significance of these factors for overall well-being, suggesting that adopting the "SPARKS" approach may benefit not only athletes but also older adults and individuals with health conditions.

Characterization of carbon and oxygen isotopes of plant on climate and plant physiology at the southeastern margin of Qinghai-Tibet Plateau, China

To investigate the correlation between carbon and oxygen isotope compositions of plant cellulose and climatic factors as well as plant physiological indices on the southeastern margin of the Qinghai-Tibet Plateau, we examined plant species in eight sampling sites with similar latitudes and different longitudes in this region. Through the characteristics of δ13C and δ18O values, fractionation values (Δ13C and Δ18O) in leaf cellulose, we discussed water use efficiency (WUE) and the environmental factors, the variation of carbon and oxygen isotopes in the southeastern margin of the Qinghai-Tibet Plateau with elevation and longitude, and revealed the indication degrees of isotopic signals to different environments and vegetation physiology. By using the semi-quantitative model of carbon and oxygen dual isotopes, we investigated the physiological adaptation mechanisms of plants to varying environmental conditions. The results demonstrated that both Δ13C and Δ18O of cellulose decreased with increasing elevation and longitude, and Δ13C was more influenced by longitude, while Δ18O was more susceptible to elevation variation. Additionally, Δ13C and Δ18O were significantly and positively correlated with temperature (TEM), precipitation (PRE), potential evapotranspiration (PET), and relative humidity (RH). PRE was the dominant meteorological factor driving the variation of Δ13C, while RH was the dominant meteorological factor influencing Δ18O variation. In contrast to Δ13C, WUE showed a stronger correlation with elevation than with longitude, which increased as elevation and longitude increased. According to the carbon-oxygen model, plant stomatal conductance (gs) and photosynthetic capacity (Amax) decreased with increasing precipitation and relative humidity, while the values increased with increasing elevation and longitude. The combined analysis of carbon and oxygen isotopes of organic matters would yield additional environmental and gas exchange information for studies on climate tracing and vegetation physiology studies on the southeastern margin of the Qinghai-Tibet Plateau.

Liver transcriptome and physiological analyses preliminarily revealed the adaptation mechanisms of Amur grayling (Thymallus arcticus grubei, Dybowski, 1869) fry for dietary lipid nutrition.

The Amur grayling (Thymallus arcticus grubei Dybowski, 1869), a species of potentially economic and research value, is renowned for its tender meat, exquisite flavor, and high nutritional contents. This study was conducted to investigate the physiological adaptation mechanisms to dietary lipids in Amur grayling fry (with average initial weight 4.64±0.03 g). This study involved a 56-day feeding trial with diets containing varying lipid levels (9.07%, 12.17%, 15.26%, 18.09%, 21.16%, and 24.07%, designated as GL1 through GL6, respectively) to explore the impact of dietary lipids on growth performance, intestinal digestion, liver antioxidative function, and transcriptomic profiles. Results showed that The group receiving 18% dietary lipid exhibited a markedly higher weight gain rate (WGR) and specific growth rate compared to other groups, alongside a reduced feed conversion ratio (FCR), except in comparison to the 15% lipid group. Activities of lipase in pancreatic secretion and amylase in stomach mucosa peaked in the 18% lipid treatment group, indicating enhanced digestive efficiency. The liver of fish in this group also showed increased activities of antioxidative enzymes and higher levels of glutathione and total antioxidative capacity, along with reduced malondialdehyde content compared to the 9% and 24% lipid treatments. Additionally, serum high-density lipoprotein cholesterol levels were highest in the 18% group. Transcriptomic analysis revealed four significant metabolic pathways affected: Cholesterol metabolism, Fat digestion and absorption, PPAR signaling, and Fatty acid degradation, involving key genes such as Lipase, Lipoprotein lipase, Fatty acid-binding protein, and Carnitine palmitoyltransferase I. These findings suggest that the liver of Amur grayling employs adaptive mechanisms to manage excessive dietary lipids. Quadratic regression analysis determined the optimal dietary lipid levels to be 16.62% and 16.52%, based on WGR and FCR, respectively. The optimal dietary lipid level for juvenile Amur grayling appears to be around 18%, as evidenced by improved growth performance, digestive function, balanced serum lipid profile, and enhanced liver antioxidative capacity. Exceeding this lipid threshold triggers both adaptive and potentially detrimental liver responses.

Enhancing tomato fruit antioxidant potential through hydrogen nanobubble irrigation.

Eating fruits and vegetables loaded with natural antioxidants can boost human health considerably and help fight off diseases linked to oxidative stress. Hydrogen has unique antioxidant effects. However, its low-solubility and fast-diffusion has limited its applications in agriculture. Integration of hydrogen with nanobubble technology could address such problems. However, the physiological adaptation and response mechanism of crops to hydrogen nanobubbles is still poorly understood. Antioxidant concentrations of lycopene, ascorbic acid, flavonoids, and resveratrol in hydrogen nanobubble water drip-irrigated tomato fruits increased by 16.3-264.8% and 2.2-19.8%, respectively, compared to underground water and oxygen nanobubble water. Transcriptomic and metabolomic analyses were combined to investigate the regulatory mechanisms that differed from the controls. Comprehensive multi-omics analysis revealed differences in the abundances of genes responsible for hormonal control, hydrogenase genes, and necessary synthetic metabolites of antioxidants, which helped to clarify the observed improvements in antioxidants. This is the first case of hydrogen nanobubble water irrigation increasing numerous natural antioxidant parts in fruits. Considering the characteristics of hydrogen and the application of the nanobubble technology in agriculture, the findings of the present study could facilitate the understanding of the potential effects of hydrogen on biological processes and the mechanisms of action on plant growth and development.

Effects of Salt Stress on Salt-Repellent and Salt-Secreting Characteristics of Two Apple Rootstocks.

The effects of NaCl-induced salinity on biomass allocation, anatomical characteristics of leaves, ion accumulation, salt repellency, and salt secretion ability were investigated in two apple rootstock cultivars (Malus halliana '9-1-6' and Malus baccata), which revealed the physiological adaptive mechanisms of M. halliana '9-1-6' in response to salt stress factors. This experiment was conducted in a greenhouse using a nutrient solution pot. Salt stress was simulated by treating the plants with a 100 mM NaCl solution, while 1/2 Hoagland nutrient solution was used as a control (CK) instead of the NaCl solution. The results showed that the two rootstocks responded to salt environments by increasing the proportion of root biomass allocation. According to the stress susceptibility index, '9-1-6' exhibits a lower salt sensitivity index and a higher salt tolerance index. The thickness of the leaf, upper and lower epidermis, palisade tissue, and mesophyll tissue compactness (CTR) of the two rootstocks were significantly decreased, while the thickness of sponge tissue and mesophyll tissue looseness (SR) were significantly increased, and the range of '9-1-6' was smaller than that of M. baccata. With an extension of stress time, the accumulation of Na+ increased significantly, and the accumulation of K+ decreased gradually. The stem and leaves of '9-1-6' showed a lower accumulation of Na+ and a higher accumulation of K+, and the roots displayed a higher ability to reject Na+, as well as young and old leaves showed a stronger ability to secrete Na+. In conclusion, within a certain salt concentration range, the '9-1-6' root part can maintain lower salt sensitivity and a higher root-to-shoot ratio by increasing the proportion of root biomass allocation; the aerial part responds to salt stress through thicker leaves and a complete double-layer fence structure; the roots and stem bases can effectively reduce the transportation of Na+ to the aerial parts, as well as effectively secrete Na+ from the aerial parts through young and old leaves, thereby maintaining a higher K+/Na+ ratio in the aerial parts, showing a strong salt tolerance.