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Keywords = relative stomatal limitation

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15 pages, 1291 KiB  
Article
Development and Validation of a Standardized Pseudotyped Virus-Based Neutralization Assay for Assessment of Anti-Nipah Virus Neutralizing Activity in Candidate Nipah Vaccines
by Muntasir Alam, Md Jowel Rana, Asma Salauddin, Emma Bentley, Gathoni Kamuyu, Dipok Kumer Shill, Shafina Jahan, Mohammad Mamun Alam, Md Abu Raihan, Mohammed Ziaur Rahman, Rubhana Raqib, Ali Azizi and Mustafizur Rahman
Vaccines 2025, 13(7), 753; https://doi.org/10.3390/vaccines13070753 - 15 Jul 2025
Viewed by 1703
Abstract
Background: An effective vaccine against Nipah virus (NiV) is crucial due to its high fatality rate and recurrent outbreaks in South and Southeast Asia. Vaccine development is challenged by the lack of validated accessible neutralization assays, as virus culture requires BSL-4 facilities, restricting [...] Read more.
Background: An effective vaccine against Nipah virus (NiV) is crucial due to its high fatality rate and recurrent outbreaks in South and Southeast Asia. Vaccine development is challenged by the lack of validated accessible neutralization assays, as virus culture requires BSL-4 facilities, restricting implementation in resource-limited settings. To address this, we standardized and validated a pseudotyped virus neutralization assay (PNA) for assessing NiV-neutralizing antibodies in BSL-2 laboratories. Methods: The NiV-PNA was validated following international regulatory standards, using a replication-defective recombinant Vesicular stomatitis virus (rVSV) backbone dependent pseudotyped virus. Assessments included sensitivity, specificity, dilutional linearity, relative accuracy, precision, and robustness. The assay was calibrated using the WHO International Standard for anti-NiV antibodies and characterized reference sera to ensure reliable performance. Findings: Preliminary evaluation of the developed NiV-PNA showed 100% sensitivity and specificity across 10 serum samples (5 positive, 5 negative), with a positive correlation to a calibrated reference assay (R2 = 0.8461). Dilutional linearity (R2 = 0.9940) and accuracy (98.18%) were confirmed across the analytical titer range of 11-1728 IU/mL. The assay also exhibited high precision, with intra-assay and intermediate precision geometric coefficients of variation of 6.66% and 15.63%, respectively. Robustness testing demonstrated minimal variation across different pseudotyped virus lots, incubation times, and cell counts. Conclusions: The validated NiV-PNA is a reproducible and scalable assay platform for quantifying NiV neutralizing antibodies, offering a safer alternative to virus culture. Its validation and integration into the CEPI Centralized Laboratory Network will enhance global capacity for vaccine evaluation and outbreak preparedness. Full article
(This article belongs to the Section Vaccines against Infectious Diseases)
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17 pages, 1778 KiB  
Article
Stomatal–Hydraulic Coordination Mechanisms of Wheat in Response to Atmospheric–Soil Drought and Rewatering
by Lijuan Wang, Yanqun Zhang, Hao Li, Xinlong Hu, Pancen Feng, Yan Mo and Shihong Gong
Agriculture 2025, 15(13), 1375; https://doi.org/10.3390/agriculture15131375 - 27 Jun 2025
Viewed by 332
Abstract
Drought stress severely limits agricultural productivity, with atmospheric and soil water deficits often occurring simultaneously in field conditions. While plant responses to individual drought factors are well-documented, recovery mechanisms following combined atmospheric–soil drought remain poorly understood, hindering drought resistance strategies and irrigation optimization. [...] Read more.
Drought stress severely limits agricultural productivity, with atmospheric and soil water deficits often occurring simultaneously in field conditions. While plant responses to individual drought factors are well-documented, recovery mechanisms following combined atmospheric–soil drought remain poorly understood, hindering drought resistance strategies and irrigation optimization. We set up two VPD treatments (low and high vapor pressure deficit) and two soil moisture treatments (CK: control soil moisture with sufficient irrigation, 85–95% field capacity; drought: soil moisture with deficit irrigation, 50–60% field capacity) in the pot experiment. We investigated wheat’s hydraulic transport (leaf hydraulic conductance, Kleaf) and gas exchange (stomatal conductance, gs; photosynthetic rate, An) responses to combined drought stress from atmospheric and soil conditions at the heading stage, as well as rewatering 55 days after treatment initiation. The results revealed that: (1) high VPD and soil drought significantly reduced leaf hydraulic conductance (Kleaf), with a high VPD decreasing Kleaf by 31.6% and soil drought reducing Kleaf by 33.2%; The high VPD decreased stomatal conductance (gs) by 43.6% but the photosynthetic rate (An) by only 12.3%; (2) After rewatering, gs and An of atmospheric and soil drought recovered relatively rapidly, while Kleaf did not; (3) Atmospheric and soil drought stress led to adaptive changes in wheat’s stomatal regulation strategies, with an increasing severity of drought stress characterized by a shift from non-conservative to conservative water regulation behavior. These findings elucidate wheat’s hydraulic–stomatal coordination mechanisms under drought stress and their differential recovery patterns, providing theoretical foundation for improved irrigation management practices. Full article
(This article belongs to the Section Agricultural Water Management)
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13 pages, 1107 KiB  
Article
Physiological Response of Citrus reticulata Blanco var. Gonggan Seedlings to High-Temperature Stress
by Shaoping Wu, Jinyan Liao, Chunxing Ye, Shanyi Chen, Yingshan Wang, Xiaochun Zhang, Junwen Huang and Cong Chen
Life 2025, 15(5), 806; https://doi.org/10.3390/life15050806 - 19 May 2025
Viewed by 480
Abstract
The physiological and biochemical responses of Citrus reticulata Blanco var. Gonggan (Gonggan) to high-temperature stress were explored in the present study, offering valuable insights into the growth of this plant in elevated temperature scenarios. Plants were exposed to daytime temperatures of 22 °C, 40 [...] Read more.
The physiological and biochemical responses of Citrus reticulata Blanco var. Gonggan (Gonggan) to high-temperature stress were explored in the present study, offering valuable insights into the growth of this plant in elevated temperature scenarios. Plants were exposed to daytime temperatures of 22 °C, 40 °C, and 45 °C, with corresponding nighttime temperatures of 17 °C, 35 °C, and 40 °C, respectively. Each treatment was administered for 12 h, with a daytime light intensity of 14,400 lux. Key parameters such as the chlorophyll content, peroxidase activity, malondialdehyde content, cytoplasmic membrane permeability, and photosynthetic metrics were assessed. The results showed that the content of malondialdehyde decreased with the increase in temperature, with the highest content at 22 °C. After high-temperature treatment at 40 °C and 45 °C, there was a significant difference (p < 0.05) compared with the Gonggan plants treated at 22 °C. Peroxidase activity exhibited an increasing trend as the temperature increased, and there was a significant difference (p < 0.05) between the peroxidase activity at 22 °C and 45 °C. Similar trends are displayed for high-temperature stress, stomatal conductance, transpiration rate, and intercellular CO2, which initially decreased and then significantly increased. The net photosynthetic rate (Pn) showed a trend of first increasing and then decreasing. When plants were subjected to high-temperature stress at 40 °C, the net photosynthetic rate showed a significant increase compared to the control group at 22 °C, but in a 45 °C stress environment, the Pn showed a decreasing trend. In the experimental group, relative conductivity decreased with the increase in temperature. Meanwhile, Gonggan plants exhibited moderate heat tolerance to short-term or moderate high-temperature stress, primarily through antioxidant and repair mechanisms. However, their heat tolerance was limited under prolonged or extremely high-temperature conditions, characterized by significant membrane damage and photosynthetic inhibition. Overall, Gonggan plants demonstrate moderate heat tolerance, making them suitable for intermittent high-temperature environments rather than prolonged extreme heat conditions. These findings provide a foundation for understanding the adaptive strategies of Gonggan plants and their cultivation in high-temperature settings. Full article
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23 pages, 8466 KiB  
Article
Physiological and Flavonoid Metabolic Responses of Black Locust Leaves to Drought Stress in the Loess Plateau of China
by Yan Wang, Ning Peng, Binbin Liu, Yingbin Yang, Chao Yue, Wenfang Hao and Junhao He
Forests 2025, 16(4), 695; https://doi.org/10.3390/f16040695 - 17 Apr 2025
Viewed by 453
Abstract
Drought threatens the stability of artificial black locust forests on the Loess Plateau, yet there is limited research on the physiological and metabolic responses of mature black locust to drought stress. This study employed a throughfall exclusion system—i.e., moderate drought (40% throughfall reduction), [...] Read more.
Drought threatens the stability of artificial black locust forests on the Loess Plateau, yet there is limited research on the physiological and metabolic responses of mature black locust to drought stress. This study employed a throughfall exclusion system—i.e., moderate drought (40% throughfall reduction), extreme drought (80% throughfall reduction), and 0% throughfall reduction for control—to analyze leaf microstructure, relative water content (RWC), osmotic adjustment substances, hormone levels, and flavonoid metabolites in black locust under controlled drought stress. The results demonstrated that as drought stress intensified, stomatal aperture and density decreased, while trichome density and length exhibited significant increases. MDA, proline, IAA, and osmotic adjustment substances (soluble protein, reducing sugar, and total sugar) first increased and then decreased as drought stress intensified. A total of 245 flavonoid compounds were identified through metabolomic analysis, among which 91 exhibited differential expression under drought treatments. Notably, 37 flavonoids, including flavonols and glycosylated derivatives, were consistently upregulated. These findings suggest that drought stress can lead to the accumulation of flavonoids. This study explored the physiological and metabolic responses of mature black locust trees to drought stress, offering insights for selecting drought-resistant species in vegetation restoration and informing ecological management practices in arid regions. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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19 pages, 4421 KiB  
Article
Variations in Leaf Photosynthesis and Its Limitations at Different Canopy Positions in Mature Camphor Trees
by Hanbing Leng, Lingyan Zhou and Wei Yan
Forests 2025, 16(4), 581; https://doi.org/10.3390/f16040581 - 27 Mar 2025
Viewed by 357
Abstract
Urban forests play important roles in carbon sequestration and climate change mitigation. However, their adaptive mechanisms and limitations on photosynthesis throughout the canopy are poorly understood. This study takes the most widely distributed 50-year-old camphor plantations (Cinnamomum camphora) in Shanghai as [...] Read more.
Urban forests play important roles in carbon sequestration and climate change mitigation. However, their adaptive mechanisms and limitations on photosynthesis throughout the canopy are poorly understood. This study takes the most widely distributed 50-year-old camphor plantations (Cinnamomum camphora) in Shanghai as the research objects. We investigated the variations in leaf morphology and photosynthetic physiology and biochemistry at six different canopy positions during a summer and an autumn period. We discovered that on account of leaf nitrogen loss and water deficit, light-saturated photosynthesis (Amax) declined in upper sunlit leaves despite being exposed to high sunlight in the same fashion as stomatal and mesophyll conductance (gsw, gm), photochemical quenching coefficient and actual photochemical efficiency of PSII (ΦPSII, qP), and maximum rate of electron transport and carboxylation (Jmax, Vcmax) during the growing season. Although seasonal change had little effect on Amax, the relative importance of limitations varied temporally. Mesophyll and biochemical limitation were the major contributors to the decline in the Amax in upper sunlit leaves between summer and autumn, respectively. Our study highlights the constraints of carbon fixation capacity in dense stands of mature camphor trees and offers technical support for the accurate prediction of canopy photosynthesis and the enhancement of carbon sequestration management in urban forests. Full article
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27 pages, 2090 KiB  
Article
Nitrogen-Fixing Bacteria Promote the Growth of Fritillaria taipaiensis P. Y. Li by Regulating Physiological and Biochemical Reactions and Protecting Enzyme System-Related Gene Expression
by Mingyan Ye, Jiaqi Lang, Xiaotian Kong, Zhifen Shi, Fengjie Duan, Guiyong Qin, Hua Zhang, Dongqin Guo and Nong Zhou
Biology 2025, 14(4), 325; https://doi.org/10.3390/biology14040325 - 24 Mar 2025
Cited by 1 | Viewed by 708
Abstract
The widespread application of chemical fertilizers and pesticides has resulted in environmental pollution. With the growing emphasis on ecological agriculture in traditional Chinese medicine, microbial fertilizers are increasingly recognized for their potential. The aim of this study is to investigate the effect of [...] Read more.
The widespread application of chemical fertilizers and pesticides has resulted in environmental pollution. With the growing emphasis on ecological agriculture in traditional Chinese medicine, microbial fertilizers are increasingly recognized for their potential. The aim of this study is to investigate the effect of inoculating nitrogen-fixing bacteria on the soil (yellow loam, river sand, and organic fertilizer in a 2:1:1 ratio) of Fritillaria taipaiensis, with a focus on the leaf changes in terms of physiological parameters, antioxidant enzyme activity, and corresponding gene expression levels. The experiment involved three nitrogen-fixing bacteria, namely Rahnella aquatilis, Pseudomonas chlororaphis, and Paenibacillus stellifer, with a total of eight treatment groups. The objective was to assess how these bacterial treatments influenced physiological parameters, photosynthetic characteristics, pigment content, and both antioxidant enzyme activities and gene expression in the leaves of F. taipaiensis. The experimental results demonstrated statistically significant reductions (p < 0.05) in malondialdehyde (MDA) content and stomatal limitation value (LS) in F. taipaiensis leaves under treatment conditions relative to the control group (CK). The most substantial decreases were observed dual-inoculation with R. aquatilis and P. stellifer (N5), showing reductions of 38.24% and 20.94% in MDA and LS compared to CK values. Additionally, leaf area, leaf thickness, stem thickness, plant height, photosynthetic parameters, pigment content, soluble sugars, soluble proteins, proline levels, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) exhibited varying degrees of increase. Compared to the CK group, the SOD, POD, and CAT activities of the N5 group increased by 141.06%, 160.59%, and 106.23%, respectively. The relative gene expression patterns of SOD, POD, and CAT corresponded with the trends observed in their respective antioxidant enzyme activities. Pearson correlation analysis further demonstrated that leaf area and net photosynthetic rate (Pn) were significantly correlated with respect to SOD, POD, and CAT activities, as well as their corresponding gene expression levels. In conclusion, inoculation with nitrogen-fixing bacteria improved the growth and stress tolerance of F. taipaiensis, with the combined application of Rahnella aquatilis and Pseudomonas stellifer yielding the most effective results. This study establishes that different rhizosphere nitrogen-fixing bacteria, either individually or in combination, influence the photosynthetic characteristics, physiological and biochemical parameters, and protective enzyme systems of F. taipaiensis. These findings provide a theoretical foundation for the selection of nitrogen-fixing bacteria as biofertilizers in the artificial cultivation of F. taipaiensis and highlight their potential application in the cultivation of traditional Chinese medicinal materials. Full article
(This article belongs to the Section Genetics and Genomics)
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15 pages, 1738 KiB  
Article
The Kinetics of Mesophyll Conductance and Photorespiration During Light Induction
by Ningyu Liu, Jianxin Cao, Mingying Yang, Yiyun Li and Wei Huang
Plants 2025, 14(6), 850; https://doi.org/10.3390/plants14060850 - 8 Mar 2025
Viewed by 818
Abstract
Mesophyll conductance to CO2 (gm) act as a significant limiting factor influencing the CO2 assimilation rate (AN) during photosynthetic induction. However, the effect of vapor pressure deficit (VPD) on gm kinetics during light induction [...] Read more.
Mesophyll conductance to CO2 (gm) act as a significant limiting factor influencing the CO2 assimilation rate (AN) during photosynthetic induction. However, the effect of vapor pressure deficit (VPD) on gm kinetics during light induction is not well clarified. We combined gas exchange with chlorophyll fluorescence measurements to assess the induction kinetics of gm during light induction under contrasting vapor pressure deficit (VPD) in two tree species with different stomatal conductance (gs) behavior, Catalpa fargesii and Pterocarya stenoptera. Our results revealed three key findings: (1) the coordination of gm and gs kinetics during light induction occurred in C. fargesii but not in P. stenoptera, and the model of gs kinetics largely determines whether the coordination of gs and gm exist in a given species; (2) a high VPD induced simultaneous changes in gs and gm kinetics in C. fargesii but had separated effects on gs and gm kinetics in P. stenoptera, indicating that the response of gm kinetics during light induction to VPD differs between species; and (3) the relative contribution of photorespiration to total electron flow was flexible in response to the change in relative diffusional and biochemical limitations, pointing out that photorespiration has a significant role in the regulation of photosynthetic electron flow during light induction. These results provide new sight into the species-dependent kinetics of gm and photorespiration during light induction. Full article
(This article belongs to the Section Plant Physiology and Metabolism)
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19 pages, 2196 KiB  
Article
Physiological and Biochemical Effects of Potassium Deficiency on Apple Tree Growth
by Evangelia-Vasiliki Ladikou, Gerasimos Daras, Marco Landi, Theocharis Chatzistathis, Thomas Sotiropoulos, Stamatis Rigas and Ioannis E. Papadakis
Horticulturae 2025, 11(1), 42; https://doi.org/10.3390/horticulturae11010042 - 6 Jan 2025
Cited by 1 | Viewed by 1579
Abstract
Potassium (K) is an essential mineral element that supports numerous plant processes, including photosynthesis, enzyme activation, osmoregulation, and nutrient balance. This study investigated how K deficiency impacts growth, physiological performance, and carbohydrate metabolism in ‘Granny Smith’ apple trees grafted onto M9 rootstock. The [...] Read more.
Potassium (K) is an essential mineral element that supports numerous plant processes, including photosynthesis, enzyme activation, osmoregulation, and nutrient balance. This study investigated how K deficiency impacts growth, physiological performance, and carbohydrate metabolism in ‘Granny Smith’ apple trees grafted onto M9 rootstock. The experimental material was cultivated hydroponically in a greenhouse under four K regimes, including 0.00, 0.75, 1.50, and 3.00 mM K, over 159 days. Deficiency symptoms such as chlorosis and necrosis were observed primarily in basal leaves. A reduced net photosynthetic rate in top and basal leaves was linked to a decreased stomatal conductance, thus limiting CO2 uptake (stomatal limitations of photosynthesis). Photosynthetic pigments, including chlorophyll a, chlorophyll b, and carotenoids, were also significantly reduced in K-limited leaves. Furthermore, photochemical performance of PSII also declined under K deficiency, with lower electron transport rates, PSII efficiency, and photochemical quenching (non-stomatal limitations of photosynthesis). While the photosynthetic rate declined under K deficiency conditions, the carbohydrate metabolism remained relatively stable without significant variation in total, translocating, or non-translocating sugars. Notably, an increase in sucrose-to-hexose ratio under low K suggests changes in sugar partitioning and utilization. Biomass allocation was also affected, with a notable decrease in the shoot-to-root ratio, mainly due to increased dry weight of roots, likely reflecting an adaptive response to enhance K uptake. Our study provides valuable insights into sustainable K fertilization practices aiming to maximize photosynthetic capacity, pigment content, and biomass production. These findings emphasize the importance of considering rootstock/scion interactions in future research to enhance apple tree vigor and productivity. Full article
(This article belongs to the Section Fruit Production Systems)
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16 pages, 3259 KiB  
Article
Elevated CO2 Shifts Photosynthetic Constraint from Stomatal to Biochemical Limitations During Induction in Populus tomentosa and Eucalyptus robusta
by Xianhui Tang, Jie Zhao, Jiayu Zhou, Qingchen Zhu, Xiyang Sheng and Chao Yue
Plants 2025, 14(1), 47; https://doi.org/10.3390/plants14010047 - 27 Dec 2024
Cited by 1 | Viewed by 912
Abstract
The relative impacts of biochemical and stomatal limitations on photosynthesis during photosynthetic induction have been well studied for diverse plants under ambient CO2 concentration (Ca). However, a knowledge gap remains regarding how the various photosynthetic components limit duction efficiency [...] Read more.
The relative impacts of biochemical and stomatal limitations on photosynthesis during photosynthetic induction have been well studied for diverse plants under ambient CO2 concentration (Ca). However, a knowledge gap remains regarding how the various photosynthetic components limit duction efficiency under elevated CO2. In this study, we experimentally investigated the influence of elevated CO2 (from 400 to 800 μmol mol–1) on photosynthetic induction dynamics and its associated limitation components in two broadleaved tree species, Populus tomentosa and Eucalyptus robusta. The results show that elevated CO2 increased the steady-state photosynthesis rate (A) and decreased stomatal conductance (gs) and the maximum carboxylation rate (Vcmax) in both species. While E. robusta exhibited a decrease in the linear electron transport rate (J) and the fraction of open reaction centers in photosynthesis II (qL), P. tomentosa showed a significant increase in non-photochemical quenching (NPQ). With respect to non-steady-state photosynthesis, elevated CO2 significantly reduced the induction time of A following a shift from low to high light intensity in both species. Time-integrated limitation analysis during induction revealed that elevated CO2 reduces the relative impacts of stomatal limitations in both species, consequently shifting the predominant limitation on induction efficiency from stomatal to biochemical components. Additionally, species-specific changes in qL and NPQ suggest that elevated CO2 may increase biochemical limitation by affecting energy allocation between carbon fixation and photoprotection. These findings suggest that, in a future CO2-rich atmosphere, plants productivity under fluctuating light may be primarily constrained by photochemical and non-photochemical quenching. Full article
(This article belongs to the Special Issue Biological Signaling in Plant Development)
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29 pages, 5366 KiB  
Article
Multi-Trait Index-Based Selection of Drought Tolerant Wheat: Physiological and Biochemical Profiling
by Mohammed Mohi-Ud-Din, Md. Alamgir Hossain, Md. Motiar Rohman, Md. Nesar Uddin, Md. Sabibul Haque, Mahmudul Hasan Tahery and Mirza Hasanuzzaman
Plants 2025, 14(1), 35; https://doi.org/10.3390/plants14010035 - 26 Dec 2024
Cited by 4 | Viewed by 1997
Abstract
Drought is a detrimental abiotic stress that severely limits wheat growth and productivity worldwide by altering several physiological processes. Thus, understanding the mechanisms of drought tolerance is essential for the selection of drought-resilient features and drought-tolerant cultivars for wheat breeding programs. This exploratory [...] Read more.
Drought is a detrimental abiotic stress that severely limits wheat growth and productivity worldwide by altering several physiological processes. Thus, understanding the mechanisms of drought tolerance is essential for the selection of drought-resilient features and drought-tolerant cultivars for wheat breeding programs. This exploratory study evaluated 14 wheat genotypes (13 relatively tolerant, one susceptible) for drought endurance based on flag leaf physiological and biochemical traits during the critical grain-filling stage in the field conditions. Measurements included six physiological, seven gas exchange, six photosystem II, six stomatal, three reactive species, seven metabolomic solutes, and two biomass traits. All parameters were significantly influenced by drought, with varying genotypic responses. Hierarchical cluster analysis (HCA) categorized genotypes into three drought tolerance groups based on trait performance. Seven genotypes in Cluster 2 (BARI Gom 26, BARI Gom 33, BD-631, BD-600, BD-9910, BD-9889, BD-637) exhibited superior drought tolerance, characterized by minimal changes in physiological traits and biomass accumulation, reduced oxidative stress markers, and increased accumulation of osmoprotectants. The innovative multi-trait genotype-ideotype distance index (MGIDI) further ranked wheat genotypes in regard to drought tolerance, identifying BARI Gom 33, BARI Gom 26, BD-9889, and BD-600 as top performers. Notably, all these top-ranking genotypes belonged to Cluster 2, previously identified as the highest-performing group in the HCA. The identified genotypes with superior drought tolerance offer valuable genetic resources for enhancing wheat productivity in water-limiting environments. Traits related to photosynthetic activity, biomass gain, leaf conductance, water stress, and osmoprotection showed high selection differentials and heritability in MGIDI analysis, indicating their potential as selection targets for drought-tolerant wheat. Overall, the strategic approaches have yielded novel insights into genotype screening that can be directly applied to deepen our understanding of drought tolerance mechanisms in wheat. Full article
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16 pages, 2738 KiB  
Article
The Physiological Response of Salix matsudana for Water Pollution by 2,4-Dinitrophenol
by Huicheng Xie, Yikang Fu, Degang Fu, Dengfeng Lin, Huimin Zhou, Guilong Fu, Hui Li, Jinxin Liu, Xiuguo Zheng and Kun Li
Toxics 2024, 12(10), 763; https://doi.org/10.3390/toxics12100763 - 20 Oct 2024
Viewed by 1271
Abstract
In this study, the effects of different concentrations of 2,4-dinitrophenol (2,4-DNP) stress on physiological parameters, as well as the uptake and removal of 2,4-DNP in Salix matsudana, were investigated using hydroponic simulation experiments to explore the potential of the use of Salix [...] Read more.
In this study, the effects of different concentrations of 2,4-dinitrophenol (2,4-DNP) stress on physiological parameters, as well as the uptake and removal of 2,4-DNP in Salix matsudana, were investigated using hydroponic simulation experiments to explore the potential of the use of Salix matsudana in the phytoremediation of wastewater polluted by 2,4-DNP. The results showed that PN (net photosynthetic rate), Tr (transpiration rate), Gs (stomatal conductance), Ls (stomatal limitation value), Fv/Fm (maximal quantum yield of PSII photochemistry), and qp (photochemical quenching coefficient) of Salix matsudana seedlings showed an overall decreasing trend, while Ci (intercellular CO2 concentration) showed an increasing trend with the increase in 2,4-DNP concentration. The net photosynthetic rate and intercellular carbon dioxide concentration showed an opposite trend in the leaves with the increase in 2,4-DNP stress concentration, and the inhibition of net photosynthesis by 2,4-DNP on Salix matsudana seedlings was mainly based on non-stomatal factors. In the 15 d incubation experiment, the values of SOD (superoxide dismutase), POD (peroxidase), and CAT (catalase) indexes were higher at low concentrations of 2,4-DNP stress, and all three enzymes reached their maximum values at 10 mg L−1 of 2,4-DNP and then decreased. Salix matsudana seedlings could tolerate 2,4-DNP stress well, which did not exceed 20 mg L−1. The toxicity of 2,4-DNP solution was significantly reduced after purification by Salix matsudana seedlings. The removal rate of 2,4-DNP was higher than 80% in each treatment group by Salix matsudana purified after 15 days. When the concentration of 2,4-DNP reached 20 mg L−1, the contents of MDA (malonicdialdehyde) were 55.62 mmol g−1, and the values of REC (relative conductivity) and LD (leaf damage) were 63.51% and 59.93%, respectively. The structure and function of the cell membrane in leaves were seriously damaged. With the increase in 2,4-DNP concentration, the removal of 2,4-DNP by Salix matsudana seedlings showed a decreasing trend. When the 2,4-DNP concentration was 5 mg L−1, the highest removal rate of 2,4-DNP by Salix matsudana seedlings was 95.98%, while when the 2,4-DNP concentration was 20 mg L−1, the highest removal rate was 86.76%. It is noted that the suitable, recommended concentration for the phytoremediation of 2,4-DNP contamination by Salix matsudana seedlings is between 8.81 and 13.78 mg L−1. Full article
(This article belongs to the Special Issue Bioremediation of Pollutants in Sewage Sludge)
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18 pages, 3740 KiB  
Article
Effects of Nitrogen Deficiency on the Photosynthesis, Chlorophyll a Fluorescence, Antioxidant System, and Sulfur Compounds in Oryza sativa
by Ling-Hua Chen, Ming Xu, Zuxin Cheng and Lin-Tong Yang
Int. J. Mol. Sci. 2024, 25(19), 10409; https://doi.org/10.3390/ijms251910409 - 27 Sep 2024
Cited by 10 | Viewed by 2909
Abstract
Decreasing nitrogen (N) supply affected the normal growth of Oryza sativa (O. sativa) seedlings, reducing CO2 assimilation, stomatal conductance (gs), the contents of chlorophylls (Chl) and the ratio of Chl a/Chl b, but increasing the intercellular CO2 [...] Read more.
Decreasing nitrogen (N) supply affected the normal growth of Oryza sativa (O. sativa) seedlings, reducing CO2 assimilation, stomatal conductance (gs), the contents of chlorophylls (Chl) and the ratio of Chl a/Chl b, but increasing the intercellular CO2 concentration. Polyphasic chlorophyll a fluorescence transient and relative fluorescence parameters (JIP test) results indicated that N deficiency increased Fo, but decreased the maximum quantum yield of primary photochemistry (Fv/Fm) and the maximum of the IPphase, implying that N-limiting condition impaired the whole photo electron transport chain from the donor side of photosystem II (PSII) to the end acceptor side of PSI in O. sativa. N deficiency enhanced the activities of the antioxidant enzymes, such as ascorbate peroxidase (APX), guaiacol peroxidase (GuPX), dehydro–ascorbate reductase (DHAR), superoxide dismutase (SOD), glutathione peroxidase (GlPX), glutathione reductase (GR), glutathione S-transferase (GST) and O-acetylserine (thiol) lyase (OASTL), and the contents of antioxidant compounds including reduced glutathione (GSH), total glutathione (GSH+GSSG) and non-protein thiol compounds in O. sativa leaves. In contrast, the enhanced activities of catalase (CAT), DHAR, GR, GST and OASTL, the enhanced ASC–GSH cycle and content of sulfur-containing compounds might provide protective roles against oxidative stress in O. sativa roots under N-limiting conditions. Quantitative real-time PCR (qRT-PCR) analysis indicated that 70% of the enzymes have a consistence between the gene expression pattern and the dynamic of enzyme activity in O. sativa leaves under different N supplies, whereas only 60% of the enzymes have a consistence in O. sativa roots. Our results suggested that the antioxidant system and sulfur metabolism take part in the response of N limiting condition in O. sativa, and this response was different between leaves and roots. Future work should focus on the responsive mechanisms underlying the metabolism of sulfur-containing compounds in O. sativa under nutrient deficient especially N-limiting conditions. Full article
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17 pages, 12147 KiB  
Article
Exogenous Melatonin Alleviates NaCl Injury by Influencing Stomatal Morphology, Photosynthetic Performance, and Antioxidant Balance in Maize
by Fuqiang He, Xiaoqiang Zhao, Guoxiang Qi, Siqi Sun, Zhenzhen Shi, Yining Niu, Zefeng Wu and Wenqi Zhou
Int. J. Mol. Sci. 2024, 25(18), 10077; https://doi.org/10.3390/ijms251810077 - 19 Sep 2024
Cited by 4 | Viewed by 1274
Abstract
Maize (Zea mays L.) is sensitive to salt stress, especially during seed germination and seedling morphogenesis, which limits maize growth and productivity formation. As a novel recognized plant hormone, melatonin (MT) participates in multiple growth and developmental processes and mediates biotic/abiotic stress [...] Read more.
Maize (Zea mays L.) is sensitive to salt stress, especially during seed germination and seedling morphogenesis, which limits maize growth and productivity formation. As a novel recognized plant hormone, melatonin (MT) participates in multiple growth and developmental processes and mediates biotic/abiotic stress responses, yet the effects of salt stress on maize seedlings remain unclear. Herein, we investigated the effects of 150 μM exogenous MT on multiple phenotypes and physiologic metabolisms in three-leaf seedlings across eight maize inbred lines under 180 mM NaCl salt stress, including growth parameters, stomatal morphology, photosynthetic metabolisms, antioxidant enzyme activities, and reactive oxygen species (ROS). Meanwhile, the six gene expression levels controlling antioxidant enzyme activities and photosynthetic pigment biosynthesis in two materials with contrasting salt resistance were examined for all treatments to explore the possible molecular mechanism of exogenous MT alleviating salt injury in maize. The results showed that 150 μM exogenous MT application protected membrane integrity and reduced ROS accumulation by activating the antioxidant system in leaves of maize seedlings under salt stress, their relative conductivity and H2O2 level average reduced by 20.91% and 17.22%, while the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) averaged increased by 13.90%, 17.02%, 22.00%, and 14.24% relative to salt stress alone. The improvement of stomatal size and the deposition of photosynthetic pigments were more favorable to enhancing photosynthesis in leaves when these seedlings treated with MT application under salt stress, their stomatal size, chlorophyll content, and net photosynthetic rate averaged increased by 11.60%, 19.64%, and 27.62%. Additionally, Gene expression analysis showed that MT stimulation significantly increased the expression of antioxidant enzyme genes (Zm00001d009990, Zm00001d047479, Zm00001d014848, and Zm00001d007234) and photosynthetic pigment biosynthesis genes (Zm00001d011819 and Zm00001d017766) under salt stress. At the same time, 150 μM MT significantly promoted seedling growth and biomass accumulation. In conclusion, our study may unravel crucial evidence of the role of MT in maize seedlings against salt stress, which can provide a novel strategy for improving maize salt stress resistance. Full article
(This article belongs to the Special Issue Plant Development and Hormonal Signaling)
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16 pages, 3169 KiB  
Article
Morpho-Physiological Response of Four Native Accessions of Phaseolus vulgaris L. Subjected to Water Stress under Greenhouse Conditions in Northeastern Peru
by Anlly Santillan Huaman, José Jesús Tejada-Alvarado, Ligia García, Jheiner Vásquez-García, Elizabeth Fernandez, Nuri Carito Vilca-Valqui and Manuel Oliva-Cruz
Agronomy 2024, 14(9), 2044; https://doi.org/10.3390/agronomy14092044 - 6 Sep 2024
Viewed by 2232
Abstract
Phaseolus vulgaris L. is a legume of high nutraceutical value, widely cultivated and consumed. However, common bean production faces challenges such as water stress that severely affects its growth and yield. This study evaluated the morphological and physiological response of four native P. [...] Read more.
Phaseolus vulgaris L. is a legume of high nutraceutical value, widely cultivated and consumed. However, common bean production faces challenges such as water stress that severely affects its growth and yield. This study evaluated the morphological and physiological response of four native P. vulgaris accessions subjected to different irrigation treatments under greenhouse conditions. A completely randomized design with factorial arrangement was used, evaluating three irrigation frequencies (100%, 50%, 25%) in combination with four accessions (PER1003541, PER1003542, PER1003543, PER1003544). The results showed that with the 25% irrigation treatment, PER1003544 showed a 54.62% decrease in leaf area, while PER1003542 and PER1003543 experienced reductions of 56.56% and 59.24%, respectively. In addition, accession PER1003544 reported a smaller reduction in the number of flowers and pods, with decreases of 40.21% and 29.9%, in contrast to PER1003543, which showed decreases of 60.66% and 52.63%, respectively. Accessions PER1003541 and PER1003544 also recorded the lowest reductions in dry biomass, with 31.85% and 35.41%, respectively. Regarding yield, PER1003544 and PER1003541 experienced reductions of 59.01% and 69.79%, respectively, unlike PER1003543, which showed a 90% decrease. In relation to stomatal density, PER1003541 recorded a reduction of 28.28%, while PER1003544 had a decrease of 37.10%, and PER1003543 experienced a reduction of 47.05%; chlorophyll content showed a similar trend. Finally, PER1003544 maintained a relatively stable stomatal index, with a reduction of 29.01%, compared to PER1003543, which reduced by 60.99%. In conclusion, accession PER1003544 stands out as a promising variety for breeding programs focused on water stress tolerance, contributing to food security and agricultural sustainability in areas affected by limited water availability. However, PER1003541 would be a suitable additional option, offering farmers flexibility in their crop selection according to the specific conditions of their environment. Full article
(This article belongs to the Section Plant-Crop Biology and Biochemistry)
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15 pages, 8318 KiB  
Article
Exogenous Melatonin Alleviates Osmotic Stress by Enhancing Antioxidant Metabolism, Photosynthetic Maintenance, and Hormone Homeostasis in Forage Oat (Avena sativa) Seedlings
by Jingbo Yu, Xingyu Luo, Qingping Zhou, Zhou Li and Shiyong Chen
Grasses 2024, 3(3), 190-204; https://doi.org/10.3390/grasses3030014 - 3 Sep 2024
Viewed by 1678
Abstract
Melatonin (MT) is a multifunctional hormone that enhances crop resilience against various abiotic stresses. However, its regulatory mechanism of osmotic tolerance in forage oats (Avena sativa) plants under water-limited scenarios is still unclear. This study aimed to delineate the impact of [...] Read more.
Melatonin (MT) is a multifunctional hormone that enhances crop resilience against various abiotic stresses. However, its regulatory mechanism of osmotic tolerance in forage oats (Avena sativa) plants under water-limited scenarios is still unclear. This study aimed to delineate the impact of MT pretreatment on the morphological, physiological, and biochemical functions of oat seedlings under osmotic stress. Our findings demonstrated that exogenous treatment of MT noticeably elevated leaf area while decreasing the root/shoot ratio of oat seedlings subjected to osmotic stress. Osmotic-induced 38.22% or 48.37% decrease in relative water content could be significantly alleviated by MT pretreatment on day 7 or day 14, respectively. MT treatment also significantly mitigated osmotic-induced decreases in photosynthetic parameters including net photosynthetic rate, stomatic conductance, and intercellular CO2 concentration as well as various chlorophyll fluorescence parameters, which could contribute to enhanced accumulations of free proline and soluble sugars in seedlings after being subjected to a prolonged duration of osmotic stress. Furthermore, MT markedly improved antioxidant enzyme activities including superoxide dismutase, ascorbate peroxidase, catalase, and peroxidase along with the accumulation of ascorbic acid contributing to a significant reduction in reactive oxygen species under osmotic stress. In addition, the MT application induced a 978.12%, 33.54%, or 30.59% increase in endogenous MT, indole acetic acid, or gibberellic acid content under osmotic stress but did not affect the accumulation of abscisic acid. These findings suggest that an optimal concentration of MT (100 μmol·L−1) could relieve osmotic stress via improvement in osmotic adjustment, the enzymatic antioxidant defense system, and endogenous hormonal balance, thereby contributing to enhanced photosynthetic functions and growth of oat seedlings under water-limited conditions. Full article
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