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Background: Drought constitutes a major abiotic stress factor adversely affecting plant growth and productivity. Plant-microbe symbiotic associations have evolved regulatory mechanisms to adapt to environmental stress conditions. However, the interactive effects of different fungi on host growth and stress tolerance under drought conditions remain unclear. Objective: This study explored the effects of varying polyethylene glycol (PEG-6000) concentrations (0%, 15%, 25%, and 35%) on the growth and physiological responses of two ectomycorrhizal fungi (Suillus granulatus (Sg) and Pisolithus tinctorius (Pt)) and two dark septate endophytes (Pleotrichocladium opacum (Po) and Pseudopyrenochaeta sp. (Ps)) isolated from the root system of Pinus tabuliformis. Specifically, the study aimed to evaluate six inoculation treatments, including no inoculation (CK), single inoculations with Sg, Pt, Po, Ps, and a mixed inoculation (Sg: Pt : Po: Ps = 1:1:1:1), on the growth and physiological characteristics of P. tabuliformis seedlings under different water regimes: well-watered at 70% ± 5%, light drought at 50% ± 5%, and severe drought at 30% ± 5% of the maximum field water holding capacity. Results: All four fungi exhibited the capacity to cope with drought stress by enhancing antioxidant activities and regulating osmotic balance. Upon successful root colonization, they increased plant height, shoot biomass, root biomass, total biomass, and mycorrhizal growth response in P. tabuliformis seedlings. Under drought stress conditions, fungal inoculation improved seedling drought resistance by increasing superoxide dismutase and catalase activities, free proline and soluble protein contents, and promoting nitrogen and phosphorus uptake. Notably, mixed inoculation treatments significantly enhanced antioxidant capacity, osmotic adjustment, and nutrient acquisition abilities, leading to superior growth promotion effects under drought stress compared to single inoculation treatments. Conclusion: All four fungi tolerated PEG-induced drought stress, with increased antioxidant enzyme activities and osmotic adjustment substances and they promoted the growth and enhanced drought resistance of P. tabuliformis seedlings.
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Polyploid varieties have been suggested as an alternative approach to promote drought tolerance in citrus crops. In this study, we compared the responses of diploid and tetraploid Sunki 'Tropical' rootstocks to water deficit when grafted onto 'Valencia' sweet orange trees and subjected to water withholding in isolation or competition experiments under potted conditions. Our results revealed that, when grown in isolation, tetraploid rootstocks took longer to show drought symptoms, but this advantage disappeared when grown in competition under the same soil moisture conditions. The differences in drought responses were mainly associated with variations in endogenous leaf levels of abscisic acid (ABA), hydrogen peroxide (H2O2) and carbohydrates among treatments. Overall, tetraploids were more affected by drought in individual experiments, showing higher H2O2 production, and in competition experiments, rapidly increasing ABA production to regulate stomatal closure and reduce water loss through transpiration. Therefore, our results highlight the crucial importance of evaluating diploid and tetraploid rootstocks under the same soil moisture conditions to better simulate field conditions, providing important insights to improve selection strategies for more resilient citrus rootstocks.
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Drought stress (DS) is one of the abiotic stresses that plants encounter commonly in nature, which affects their life, reduces agricultural output, and prevents crops from growing in certain areas. To enhance plant tolerance against DS, abundant exogenous substances (ESs) have been attempted and proven to be effective in helping plants relieve DS. Understanding the effect of each ES on alleviation of plant DS and mechanisms involved in the DS relieving process has become a research focus and hotspot that has drawn much attention in the field of botany, agronomy, and ecology. With an extensive and comprehensive review and summary of hundred publications, this paper groups various ESs based on their individual effects on alleviating plant/crop DS with details of the underlying mechanisms involved in the DS-relieving process of: (1) synthesizing more osmotic adjustment substances; (2) improving antioxidant pathways; (3) promoting photosynthesis; (4) improving plant nutritional status; and (5) regulating phytohormones. Moreover, a detailed discussion and perspective are given in terms of how to meet the challenges imposed by erratic and severe droughts in the agrosystem through using promising and effective ESs in the right way and at the right time.
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Sequías , Fotosíntesis , Estrés Fisiológico , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas/metabolismo , Antioxidantes/metabolismo , Productos Agrícolas , Fenómenos Fisiológicos de las PlantasRESUMEN
Drought stress triggers sugar accumulation in plants, providing energy and aiding in protection against oxidative damage. Plant hardening under mild stress conditions has been shown to enhance plant resistance to severe stress conditions. While sugar accumulation and metabolism under drought stress have been well-documented in crop plants, the effect of drought acclimation treatment on sugar accumulation and metabolism has not yet been explored. In this study, we investigated the impact of drought stress acclimation on sugar accumulation and metabolism in the leaves and root tissues of two commonly cultivated foxtail millet (Setaria italica L.) genotypes, 'PI 689680' and 'PI 662292'. Quantification of total sugars (soluble sugar, fructose, glucose, and sucrose), their related enzymes (SPS, SuSy, NI, and AI), and the regulation of their related transcripts (SiSPS1, SiSuSy1, SiSWEET6, SiA-INV, and SiC-INV) revealed that drought-acclimated (DA) plants exhibited levels of these indicators comparable to those of control plants. However, under subsequent drought stress conditions, both the leaves and roots of non-acclimated plants accumulated higher levels of total sugars, displayed increased activity of sugar metabolism enzymes, and showed elevated expression of sugar metabolism-related transcripts compared to drought-acclimated plants. Thus, acclimation-induced restriction of sugar accumulation, transport, and metabolism could be one of the metabolic processes contributing to enhanced drought tolerance in millet. This study advocates for the use of acclimation as an effective strategy to mitigate the negative impacts of drought-induced metabolic disturbances in millet, thereby enhancing global food security and promoting sustainable agricultural systems.
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Cotton is essential for the textile industry as a primary source of natural fibers. However, environmental factors like drought present significant challenges to its cultivation, adversely affecting both production levels and fiber quality. Enhancing cotton's drought resilience has the potential to reduce yield losses and support the growth of cotton farming. In this study, the cotton calcium-dependent protein kinase GhCDPK16 was characterized, and the transcription level of GhCDPK16 was significantly upregulated under drought and various stress-related hormone treatments. Physiological analyses revealed that the overexpression of GhCDPK16 improved drought stress resistance in Arabidopsis by enhancing osmotic adjustment capacity and boosting antioxidant enzyme activities. In contrast, silencing GhCDPK16 in cotton resulted in increased dehydration compared with the control. Furthermore, reduced antioxidant enzyme activities and downregulation of ABA-related genes were observed in GhCDPK16-silenced plants. These findings not only enhanced our understanding of the biological functions of GhCDPK16 and the mechanisms underlying drought stress resistance but also underscored the considerable potential of GhCDPK16 in improving drought resilience in cotton.
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Resistencia a la Sequía , Regulación de la Expresión Génica de las Plantas , Gossypium , Proteínas de Plantas , Proteínas Quinasas , Estrés Fisiológico , Arabidopsis/genética , Arabidopsis/fisiología , Resistencia a la Sequía/genética , Gossypium/genética , Gossypium/metabolismo , Gossypium/fisiología , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Proteínas Quinasas/metabolismo , Proteínas Quinasas/genéticaRESUMEN
The olive tree (Olea europaea L.) is an evergreen tree that occupies 19% of the woody crop area and is cultivated in 67 countries on five continents. The largest olive production region is concentrated in the Mediterranean basin, where the olive tree has had an enormous economic, cultural, and environmental impact since the 7th century BC. In the Mediterranean region, salinity stands out as one of the main abiotic stress factors significantly affecting agricultural production. Moreover, climate change is expected to lead to increased salinization in this region, threatening olive productivity. Salt stress causes combined damage by osmotic stress and ionic toxicity, restricting olive growth and interfering with multiple metabolic processes. A large variability in salinity tolerance among olive cultivars has been described. This paper aims to synthesize information from the published literature on olive adaptations to salt stress and its importance in salinity tolerance. The morphological, physiological, biochemical, and molecular mechanisms of olive tolerance to salt stress are reviewed.
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Water scarcity is a major environmental constraint on plant growth in arid regions. Soluble sugars and amino acids are essential osmolytes for plants to cope with osmotic stresses. Sweet sorghum is an important bioenergy crop and forage with strong adaptabilities to adverse environments; however, the accumulation pattern and biosynthesis basis of soluble sugars and amino acids in this species under osmotic stresses remain elusive. Here, we investigated the physiological responses of a sweet sorghum cultivar to PEG-induced osmotic stresses, analyzed differentially accumulated soluble sugars and amino acids after 20% PEG treatment using metabolome profiling, and identified key genes involved in the biosynthesis pathways of soluble sugars and amino acids using transcriptome sequencing. The results showed that the growth and photosynthesis of sweet sorghum seedlings were significantly inhibited by more than 20% PEG. After PEG treatments, the leaf osmotic adjustment ability was strengthened, while the contents of major inorganic osmolytes, including K+ and NO3-, remained stable. After 20% PEG treatment, a total of 119 and 188 differentially accumulated metabolites were identified in the stems and leaves, respectively, and the accumulations of soluble sugars such as raffinose, trehalose, glucose, sucrose, and melibiose, as well as amino acids such as proline, leucine, valine, serine, and arginine were significantly increased, suggesting that these metabolites should play key roles in osmotic adjustment of sweet sorghum. The transcriptome sequencing identified 1711 and 4978 DEGs in the stems, as well as 2061 and 6596 DEGs in the leaves after 20% PEG treatment for 6 and 48 h, respectively, among which the expressions of genes involved in biosynthesis pathways of sucrose (such as SUS1, SUS2, etc.), trehalose (including TPS6), raffinose (such as RAFS2 and GOLS2, etc.), proline (such as P5CS2 and P5CR), leucine and valine (including BCAT2), and arginine (such as ASS and ASL) were significantly upregulated. These genes should be responsible for the large accumulation of soluble sugars and amino acids under osmotic stresses. This study deepens our understanding of the important roles of individual soluble sugars and amino acids in the adaptation of sweet sorghum to water scarcity.
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Aminoácidos , Regulación de la Expresión Génica de las Plantas , Metaboloma , Presión Osmótica , Sorghum , Sorghum/metabolismo , Sorghum/genética , Aminoácidos/metabolismo , Azúcares/metabolismo , Perfilación de la Expresión Génica/métodos , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Transcriptoma , Vías Biosintéticas , FotosíntesisRESUMEN
Soil salinity is a significant abiotic stress and poses risks to environmental sustainability. Thus, the improvement of the time for recovering the salt-affect soil is crucial for the phytoextraction process using halophytes plants, especially regarding on nutritional management. We evaluated the responses of Atriplex nummularia Lindl. to nitrogen (N) and phosphorus (P) under different salinity levels. The treatments comprised doses of N (N1 = 80 kg ha-1) and P (P1 = 60 kg ha-1): (1) without N and P (N0P0) (control); (2) with N and without P (N1P0); (3) without N and with P (N0P1); and (4) with N and P (N1P1) and five levels of electrical conductivity from irrigation water: 0.08, 1.7, 4.8, 8.6, and 12.5 dS m-1. The. We evaluated dry biomass of leaves, stems, and roots 93 days after transplantation. We also assessed the leaf and osmotic water potential, the osmotic adjustment, and the nutrient contents (N, P, Na, and K). N application increased 22.3, 17.8, and 32.8% the leaf biomass, stem biomass, and osmotic adjustment, respectively; and consequently, boosts Na extraction in 27.8%. Thus, the time of the phytoextraction process can be improved with N fertilizer at a rate of 80 kg ha-1.
Very few studies have investigated the nutrient dynamics responses in Atriplex species in salt-affected soils; thus, this study represents a novelty. We tested the management of nitrogen (N) and phosphate (P) fertilizers to increase crop yield and optimize the phytoextraction process in salt-affected soils. We believe our results contribute to the improvement of the knowledge of this relevant topic, mainly in terms of the recovery of areas degraded by salinity. There is a paucity of studies associating salinity and nutritional management of soils worldwide.
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Creeping bentgrass (Agrostis stolonifera) is an excellent cool-season turfgrass that is widely used in urban gardening, landscaping, and golf turf. Triennial field experiments from 2017 to 2019 were conducted to investigate effects of the foliar application of chitosan (CTS), γ-aminobutyric acid (GABA), or sodium chloride (NaCl) on mitigating summer bentgrass decline (SBD) and exploring the CTS, GABA, or NaCl regulatory mechanism of tolerance to summer heat stress associated with changes in chlorophyll (Chl) loss and photosynthetic capacity, osmotic adjustment (OA), oxidative damage, and cell membrane stability. The findings demonstrated that persistent ambient high temperatures above 30 °C during the summer months of 2017, 2018, and 2019 significantly reduced the turf quality (TQ), Chl content, photochemical efficiency of PSII (Fv/Fm and PIABS), leaf relative water content, and osmotic potential (OP) but significantly increased electrolyte leakage (EL) and the accumulations of free proline, water-soluble carbohydrate (WSC), hydrogen peroxide (H2O2), and malondialdehyde (MDA). The foliar application of CTS, GABA, or NaCl could significantly alleviate SBD, as reflected by improved TQ and delayed Chl loss during hot summer months. Heat-induced declines in Fv/Fm, PIABS, the net photosynthetic rate (Pn), the transpiration rate (Tr), and water use efficiency (WUE) could be significantly mitigated by the exogenous application of CTS, GABA, or NaCl. In addition, the foliar application of CTS, GABA, or NaCl also significantly improved the accumulations of free proline and WSC but reduced the EL, OP, and H2O2 content and the MDA content in leaves of creeping bentgrass in favor of water and redox homeostasis in summer. Based on the comprehensive evaluation of the subordinate function value analysis (SFVA), the CTS had the best effect on the mitigation of SBD, followed by GABA and NaCl in 2017, 2018, and 2019. The current study indicates that the foliar application of an appropriate dose of GABA, CTS, or NaCl provides a cost-effective strategy for mitigating SBD.
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Introduction: Drought stress usually inhibits plant growth, which may increase the difficulty of greening slopes. Methods: In this study, we systematically investigated the effects of arbuscular mycorrhizal (AM) fungi on the growth and drought tolerance of two plant species, Festuca elata and Cassia glauca, in a vegetation concrete environment by exogenously inoculating AM fungi and setting three drought levels: well water, moderate drought and severe drought. The results showed that plant growth was significantly inhibited under drought stress; however, AM fungi inoculation significantly promoted plant height, root length, and above- and belowground biomass in these two plant species. Results: Compared with, those in the CK treatment, the greatest increases in the net photosynthesis rate, stomatal conductance and transpiration rate in the AM treatment group were 36.72%, 210.08%, and 66.41%, respectively. Moreover, inoculation with AM fungi increased plant superoxide dismutase and catalase activities by 4.70-150.73% and 9.10-95.70%, respectively, and reduced leaf malondialdehyde content by 2.79-55.01%, which alleviated the damage caused by oxidative stress. These effects alleviated the damage caused by oxidative stress and increased the content of soluble sugars and soluble proteins in plant leaves by 1.52-65.44% and 4.67-97.54%, respectively, which further increased the drought adaptability of plants. However, inoculation with AM fungi had different effects on different plants. Conclusion: In summary, this study demonstrated that the inoculation of AM fungi in vegetation concrete environments can significantly increase plant growth and drought tolerance. The plants that formed a symbiotic structure with AM fungi had a larger root uptake area, greater water uptake capacity, and greater photosynthesis and gas exchange efficiency. In addition, AM fungi inoculation further increased the drought adaptability of the plants by increasing their antioxidant enzyme activity and regulating their metabolite content. These findings are highly important for promoting plant growth and increasing drought tolerance under drought conditions, especially for potential practical applications in areas such as slope protection, and provide useful references for future ecological engineering and sustainable development.
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Salt stress is one of the major factors limiting plant growth and productivity. Many studies have shown that serine hydroxymethyltransferase (SHMT) gene play an important role in growth, development and stress response in plants. However, to date, there have been few studies on whether SHMT3 can enhance salt tolerance in plants. Therefore, the effects of overexpression or silencing of CsSHMT3 gene on cucumber seedling growth under salt stress were investigated in this study. The results showed that overexpression of CsSHMT3 gene in cucumber seedlings resulted in a significant increase in chlorophyll content, photosynthetic rate and proline (Pro) content, and antioxidant enzyme activity under salt stress condition; whereas the content of malondialdehyde (MDA), superoxide anion (H2O2), hydrogen peroxide (O2·-) and relative conductivity were significantly decreased when CsSHMT3 gene was overexpressed. However, the content of chlorophyll and Pro, photosynthetic rate, and antioxidant enzyme activity of the silenced CsSHMT3 gene lines under salt stress were significantly reduced, while MDA, H2O2, O2·- content and relative conductivity showed higher level in the silenced CsSHMT3 gene lines. It was further found that the expression of stress-related genes SOD, CAT, SOS1, SOS2, NHX, and HKT was significantly up-regulated by overexpressing CsSHMT3 gene in cucumber seedlings; while stress-related gene expression showed significant decrease in silenced CsSHMT3 gene seedlings under salt stress. This suggests that overexpression of CsSHMT3 gene increased the salt tolerance of cucumber seedlings, while silencing of CsSHMT3 gene decreased the salt tolerance. In conclusion, CsSHMT3 gene might positively regulate salt stress tolerance in cucumber and be involved in regulating antioxidant activity, osmotic adjustment, and photosynthesis under salt stress. KEY MESSAGE: CsSHMT3 gene may positively regulate the expression of osmotic system, photosynthesis, antioxidant system and stress-related genes in cucumber.
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Clorofila , Cucumis sativus , Regulación de la Expresión Génica de las Plantas , Fotosíntesis , Estrés Salino , Tolerancia a la Sal , Plantones , Cucumis sativus/genética , Cucumis sativus/crecimiento & desarrollo , Cucumis sativus/fisiología , Cucumis sativus/efectos de los fármacos , Plantones/genética , Plantones/crecimiento & desarrollo , Plantones/efectos de los fármacos , Plantones/fisiología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Tolerancia a la Sal/genética , Estrés Salino/genética , Clorofila/metabolismo , Fotosíntesis/genética , Fotosíntesis/efectos de los fármacos , Peróxido de Hidrógeno/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Glicina Hidroximetiltransferasa/genética , Glicina Hidroximetiltransferasa/metabolismo , Antioxidantes/metabolismo , Malondialdehído/metabolismo , Plantas Modificadas Genéticamente , Silenciador del GenRESUMEN
The use of bio-nanotechnology in agriculture-such as the biological applications of metal oxide nanoparticles (NPs)-greatly improves crop yield and quality under different abiotic stress factors including soil metal contamination. Here, we explore the effectiveness of zinc oxide (ZnO)-NPs (0, 50 mg/L) foliar spraying to ameliorate the detrimental effects of cadmium (Cd) on the water transport and nitrogen metabolism in tomato (Solanum lycopersicum Mill. cv. Chibli F1) plants grown on a Cd-supplied (CdCl2; 0, 10, 40 µM) Hoagland nutrient solution. The results depicted that the individually studied factors (ZnO-NPs and Cd) had a significant impact on all the physiological parameters analyzed. Independently to the Cd concentration, ZnO-NPs-sprayed plants showed significantly higher dry weight (DW) in both leaves and roots compared to the non-sprayed ones, which was in consonance with higher and lower levels of Zn2+ and Cd2+ ions, respectively, in these organs. Interestingly, ZnO-NPs spraying improved water status in all Cd-treated plants as evidenced by the increase in root hydraulic conductance (L0), apoplastic water pathway percentage, and leaf and root relative water content (RWC), compared to the non-sprayed plants. This improved water balance was associated with a significant accumulation of osmoprotectant osmolytes, such as proline and soluble sugars in the plant organs, reducing electrolyte leakage (EL), and osmotic potential (ψπ). Also, ZnO-NPs spraying significantly improved NO3- and NH4+ assimilation in the leaf and root tissues of all Cd-treated plants, leading to a reduction in NH4+ toxicity. Our findings point out new insights into how ZnO-NPs affect water transport and nitrogen metabolism in Cd-stressed plants and support their use to improve crop resilience against Cd-contaminated soils.
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Cadmio , Nitrógeno , Plantones , Solanum lycopersicum , Óxido de Zinc , Solanum lycopersicum/efectos de los fármacos , Solanum lycopersicum/metabolismo , Plantones/efectos de los fármacos , Agua , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Nanopartículas , Nanopartículas del Metal/toxicidadRESUMEN
Cultivated crops are generally expected to have less abiotic stress tolerance than their wild relatives. However, this assumption is not well supported by empirical literature and may depend on the type of stress and how it is imposed, as well as the measure of tolerance being used. Here, we investigated whether wild and cultivated accessions of Helianthus annuus differed in stress tolerance assessed as proportional decline in biomass due to drought and whether wild and cultivated accessions differed in trait responses to drought and trait associations with tolerance. In a greenhouse study, H. annuus accessions in the two domestication classes (eight cultivated and eight wild accessions) received two treatments: a well-watered control and a moderate drought implemented as a dry down followed by maintenance at a predetermined soil moisture level with automated irrigation. Treatments were imposed at the seedling stage, and plants were harvested after 2 weeks of treatment. The proportional biomass decline in response to drought was 24% for cultivated H. annuus accessions but was not significant for the wild accessions. Thus, using the metric of proportional biomass decline, the cultivated accessions had less drought tolerance. Among accessions, there was no tradeoff between drought tolerance and vigor assessed as biomass in the control treatment. In a multivariate analysis, wild and cultivated accessions did not differ from each other or in response to drought for a subset of morphological, physiological, and allocational traits. Analyzed individually, traits varied in response to drought in wild and/or cultivated accessions, including declines in specific leaf area, leaf theoretical maximum stomatal conductance (gsmax), and stomatal pore length, but there was no treatment response for stomatal density, succulence, or the ability to osmotically adjust. Focusing on traits associations with tolerance, plasticity in gsmax was the most interesting because its association with tolerance differed by domestication class (although the effects were relatively weak) and thus might contribute to lower tolerance of cultivated sunflower. Our H. annuus results support the expectation that stress tolerance is lower in crops than wild relatives under some conditions. However, determining the key traits that underpin differences in moderate drought tolerance between wild and cultivated H. annuus remains elusive.
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The growth and development of apricot flower organs are severely impacted by spring frosts. To better understand this process, apricot flowers were exposed to temperatures ranging from 0 °C to -8 °C, including a control at 18 °C, in artificial incubators to mimic diverse low-temperature environments. We aimed to examine their physiological reactions to cold stress, with an emphasis on changes in phenotype, membrane stability, osmotic substance levels, and antioxidant enzyme performance. Results reveal that cold stress induces significant browning and cellular damage, with a sharp increase in browning rate and membrane permeability below -5 °C. Soluble sugars and proteins initially rise as osmoprotectants, but their content decreases at lower temperatures. Proline content consistently increases, suggesting a protective role. Antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and ascorbate peroxidase (APX), exhibit a complex pattern, with initial increases followed by declines at more severe cold conditions. Correlation and principal component analyses highlight the interplay between these responses, indicating a multifaceted adaptation strategy. The findings contribute to the understanding of apricot cold tolerance and inform breeding efforts for improved crop resilience.
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BACKGROUND AND AIMS: Many agricultural areas are expected to face hotter, drier conditions from climate change. Understanding the mechanisms that crops use to mitigate these stresses can guide breeding for more tolerant plant material. We tested relationships between traits, physiological function in hot conditions and historical climate associations to evaluate these mechanisms for winegrapes. We expected a more negative leaf osmotic potential at full hydration (πo), which reduces leaf turgor loss during drought, and either a metabolically cheaper or more osmoprotectant leaf chemical composition, to allow cultivars associated with hot, dry regions to maintain greater gas exchange in hot growing conditions. METHODS: We measured πo, gas exchange and leaf chemistry for seven commercially important winegrape cultivars that vary widely in historical climate associations. Vines were grown in common-garden field conditions in a hot wine-growing region (Davis, CA, USA) and measured over the hottest period of the growing season (July-September). KEY RESULTS: The value of πo varied significantly between cultivars, and all cultivars significantly reduced πo (osmotically adjusted) over the study period, although osmotic adjustment did not vary across cultivars. The value of πo was correlated with gas exchange and climate associations, but in the direction opposite to expected. Photosynthesis and πo were higher in the cultivars associated with hotter, less humid regions. Leaf chemical composition varied between cultivars but was not related to climate associations. CONCLUSIONS: These findings suggest that maintenance of leaf turgor is not a primary limitation on grapevine adaptation to hot or atmospherically dry growing conditions. Thus, selecting for a more negative πo or greater osmotic adjustment is not a promising strategy to develop more climate-resilient grape varieties, contrary to findings for other crops. Future work is needed to identify the mechanisms increasing photosynthesis in the cultivars associated with hot, dry regions.
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Sequías , Calor , Fotosíntesis , Hojas de la Planta , Vitis , Fotosíntesis/fisiología , Hojas de la Planta/fisiología , Vitis/fisiología , Vitis/crecimiento & desarrollo , Cambio Climático , Adaptación FisiológicaRESUMEN
The aim of the present study was to evaluate the morphological and physiological responses of P. maritima plants from five geographically isolated sites growing in habitats with different conditions to different substrate moisture levels in controlled conditions. Plants were produced from seed and cultivated in a greenhouse at four relatively constant soil moisture regimes: at 25, 50, and 75% soil water content and in soil flooded 3 cm above the surface (80% F). The two morphological traits that varied most strikingly among P. maritima accessions were the number of flower stalks and the number of leaves. Only plants from two accessions uniformly produced generative structures, and allocation to flowering was suppressed by both low moisture and flooding. Optimum shoot biomass accumulation for all accessions was at 50 and 75% soil moisture. The Performance Index Total was the most sensitive among the measured photosynthesis-related parameters, and it tended to decrease with an increase in soil water content for all P. maritima accessions. The initial hypothesis-that plants from relatively dry habitats will have a higher tolerance against low soil water levels, but plants from relatively wet habitats will have a higher tolerance against waterlogged or flooded soil-was not proven. The existence of three ecotypes of P. maritima within the five accessions from geographically isolated subpopulations on the eastern coast of the Baltic Sea at the level of morphological responses to soil water content can be proposed. P. maritima plants can be characterized as extremely tolerant to soil waterlogging and highly tolerant to soil flooding and low soil water content.
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Drought stress adversely affects growth, development, productivity, and fiber quality of cotton (Gossypium hirsutum L). Breeding strategies to enhance drought tolerance require an improved knowledge of plant drought responses necessitating proper identification of drought-tolerant genotypes of crops, including cotton. The objective of this study was to classify the selected cotton genotypes for their drought tolerance ability based on morpho-physio-biochemical traits using Hierarchical Ward's cluster analysis. Five genotypes of cotton (Takfa 3, Takfa 6, Takfa 7, Takfa 84-4, and Takfa 86-5) were selected as plant materials, and were grown under well-watered (WW; 98 ± 2% field capacity) and water-deficit (WD; 50 ± 2% field capacity) conditions for 16 days during the flower initiation stage. Data on morpho-physio-biochemical parameters and gene expression levels for these parameters were collected, and subsequently genotypes were classified either as a drought tolerant or drought susceptible one. Upregulation of GhPRP (proline-rich protein), GhP5CS (Δ1-pyrroline-5-carboxylate synthetase), and GhP5CR (Δ1-pyrroline-5-carboxylate reductase) in relation to free proline enrichment was observed in Takfa 3 genotype under WD condition. An accumulation of free proline, total soluble sugar, and potassium in plants under WD conditions was detected, which played a key role as major osmolytes controlling cellular osmotic potential. Magnesium and calcium concentrations were also enriched in leaves under WD conditions, functioning as essential elements and regulating photosynthetic abilities. Leaf greenness, net photosynthetic rate, stomatal conductance, and transpiration rate were also declined under WD conditions, leading to growth retardation, especially aboveground traits of Takfa 6, Takfa 7, Takfa 84-4, and Takfa 86-5 genotypes. An increase in leaf temperature (1.1 - 4.0 °C) and crop water stress index (CWSI > 0.75) in relation to stomatal closure and reduced transpiration rate was recorded in cotton genotypes under WD conditions compared with WW conditions. Based on the increase of free proline, soluble sugar, leaf temperature, and CWSI, as well as the decrease of aboveground growth traits and physiological attributes, five genotypes were categorized into two cluster groups: drought tolerant (Takfa 3) and drought susceptible (Takfa 6, Takfa 7, Takfa 84-4, and Takfa 86-5). The identified drought-tolerant cotton genotype, namely, Takfa 3, may be grown in areas experiencing drought conditions. It is recommended to further validate the yield traits of Takfa 3 under rainfed field conditions in drought-prone environments.
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Sequías , Regulación de la Expresión Génica de las Plantas , Genotipo , Gossypium , Proteínas de Plantas , Prolina , Prolina/metabolismo , Gossypium/genética , Gossypium/fisiología , Gossypium/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Adaptación Fisiológica/genética , Resistencia a la SequíaRESUMEN
The growth and physiological characteristics of four Magnoliaceae plants (Yulania biondii, Yulania denudata, and two varieties of Magnolia wufengensis (Jiaohong 1 and Jiaohong 2)) were investigated. Four Magnoliaceae plants were subjected to various concentrations of NaCl for 60 days: 0 mM, 60 mM, 120 mM, 180 mM, and 240 mM. The leaf water content (LWC), relative growth rate of plant height and stem diameter, photosynthetic pigments, and photosynthetic rate (Pn) decreased during the NaCl treatments, indicating slowed growth and photosynthesis. Malondialdehyde (MDA), Na+, superoxide dismutase (SOD) activity, peroxidase (POD) activity, ascorbic acid (AsA) content, and soluble sugar content all increased while K+ decreased. Ascorbate peroxidase (APX) activity, glutathione (GSH), soluble protein, and proline first increased after decreasing with increasing NaCl concentration. Principal component 1 (PC1) had larger loading values for growth and photosynthesis indices, while principal component 2 (PC2) exhibited larger loading values for antioxidant substances and osmotic adjustment substances; the correlation analysis showed that PC1 and PC2 had negative correlations. The four Magnoliaceae plants exhibited largely variable growth and physiological activities in response to NaCl. Yulania denudata exhibited greater reductions in growth and photosynthesis and greater decreases in antioxidant enzyme activities and osmotic adjustment substances, which indicated poor tolerance to salt stress. Among the four Magnoliaceae plants, Jiaohong 1 exhibited the greatest salt tolerance, followed by Jiaohong 2, Yulania biondii, and Yulania denudata.
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Sesuvium portulacastrum (L.) is a halophyte, adapted to grow naturally under saline environments. The ability to use Na and K interchangeably indicated its facultative halophyte nature. No significant growth reduction occurs in seedlings up to 250 mM NaCl, except for curling of the youngest leaf. Within 8 h of salt treatment, seedlings accumulate proline, glycine betaine and other amino acids in both root and shoot. Despite a continued increase of tissue Na content, the number of differentially expressed genes (DEGs) decreases between 8 and 24 h of salt exposure, indicating transcriptional restoration after the initial osmotic challenge. At 8 h, upregulated genes mainly encode transporters and transcription factors, while genes in growth-related pathways such as photosynthesis and ribosome-associated biogenesis are suppressed. Overexpression of SpRAB18 (an ABA-responsive dehydrin), one of the most strongly induced DEGs, in soybean was found to increase biomass in control conditions and the growth benefit was maintained when plants were grown in 100 mM NaCl, indicating conservation of function in halophyte and glycophyte. An open-access transcriptome database "SesuviumKB" (https://cb.imsc.res.in/sesuviumkb/) was developed to involve the scientific community in wide-scale functional studies of S. portulacastrum genes, that could pave the way to engineer salt tolerance in crops.
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Aizoaceae , Plantas Tolerantes a la Sal , Plantas Tolerantes a la Sal/genética , Plantas Tolerantes a la Sal/metabolismo , Cloruro de Sodio/farmacología , Cloruro de Sodio/metabolismo , Fotosíntesis , Tolerancia a la Sal/genética , Aizoaceae/genética , Aizoaceae/metabolismo , Sodio/metabolismoRESUMEN
Histone deacetylases have been demonstrated to play an important role in responding to low-temperature stress, but the related response mechanism in chrysanthemum remains unclear. In this study, we isolated a cold-induced gene, DgHDA6, from chrysanthemum (Chrysanthemum morifolium Ramat). DgHDA6 contains 474 amino acids and shares a typical deacetylation domain with RPD3/HDA1 family members. The overexpression of DgHDA6 enhanced cold resistance in chrysanthemums. After low-temperature stress, the overexpression lines showed a higher survival rate. The contents of proline, soluble proteins and sugars, and the activities of antioxidant enzymes were significantly increased while the contents of H2O2, O2- and MDA were lower. Moreover, cold-stress-responding genes such as DgCuZnSOD, DgCAT, DgP5CS, and DgFAD were upregulated after cold stress. These results suggest that the overexpression of DgHDA6 can improve cold tolerance in chrysanthemum by enhancing ROS scavenging capacity.