How plants sense temperature

Environmental adaptation and reproductive mechanisms of Codium fragile subsp. fragile in the Bohai Bay

Bohai Bay, a typical semi-enclosed bay with limited water exchange capacity, has seen increasing demand for large-scale seaweed cultivation as a sustainable resource. Codium fragile subsp. fragile (Suringar) Hariot has established stable populations in artificial diversion channels within Bohai Bay, demonstrating strong environmental adaptability and commercial cultivation potential. This study systematically evaluates the effects of temperature, salinity, and light intensity on the growth, antioxidant activity, and photosynthetic performance of Codium fragile subsp. fragile under controlled conditions. The results identified the optimal growth conditions as 20°C, salinity of 30, and light intensity of 3000 Lux. Additionally, the highest gamete release rate was observed at 25°C, salinity of 20, and light intensity of 1000 Lux, while optimal conditions for sporeling growth were 20°C, salinity of 30, and 1000 Lux. Transcriptomic analysis revealed significant temperature-dependent effects (20°C and 25°C) on both growth and reproduction, with 2668 differentially expressed genes (DEGs), of which 1663 were upregulated. At 20°C, genes associated with photosynthesis, carbon metabolism, and nucleic acid synthesis were upregulated, promoting growth and reproductive development. In contrast, at 25°C, the upregulation of heat shock proteins and antioxidant enzymes indicated enhanced stress tolerance. By integrating physiological and transcriptomic data, this study provides new insights into the environmental adaptation strategies of Codium fragile subsp. fragile, supporting its artificial cultivation and commercial applications.

Breaking new ground: First AquaCrop calibration and climate change impact assessment on Arabica coffee

Climate change threatens global coffee yield stability, especially in Brazil, the largest Arabica exporter. Yield modeling is key to climate-resilient strategies and effective planning. To this end, the AquaCrop model was parameterized, calibrated, and validated for Arabica coffee in Brazil and subsequently applied to project yield under future climate scenarios. These processes were carried out across 58 municipalities in Brazil's two largest coffee-growing regions, covering the growing years from 2014 to 2019. AquaCrop accurately simulated Arabica coffee yield during calibration and validation processes, with root mean square error values of ∼0.15 t ha-1, mean bias error of ∼0.007 t ha-1, and d-index of ∼0.76. To project yield, AquaCrop used as input daily near-surface air temperature (minimum and maximum), precipitation, and reference evapotranspiration data from 9 General Circulation Models (GCMs) from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP), which are derived from the Coupled Model Intercomparison Project Phase 6 (CMIP6), under three Shared Socioeconomic Pathways scenarios (SSP2-4.5, SSP3-7.0 and SSP5-8.5). Under future climate conditions, reductions in the coffee growing cycle duration and heterogeneous yield changes are projected, with increases (between 0.25 and 0.55 t ha-1) along a belt extending from southeastern São Paulo to southern Minas Gerais, and decreases (between -0.05 and -0.15 t ha-1) in northeastern Minas Gerais. Even though yield increases are projected for much of the study region, adopting effective adaptive measures will be essential to address climate change threats.

Characterization of the heat shock factor RcHsfA6 in Rosa chinensis and function in the thermotolerance of Arabidopsis

BACKGROUND

Environmental stresses, especially high temperatures, severely limit the growth and development of many horticultural plants. As a woody ornamental flower with rich flower colors and flower types, rose (R. chinensis) leaves wilt and shriveled petals at high temperatures, which severely affects its growth and ornamental value. The defense mechanism of rose plants against high-temperature stress has not been fully elucidated.

RESULTS

In the present study, the transcriptomes of rose petals at normal (25 °C) and high (35 °C) temperature were compared. A total of 2519 differentially expressed genes (DEGs) were identified, including 1491 upregulated DEGs and 1028 downregulated DEGs. The plant hormone signal transduction pathway, especially the abscisic acid (ABA) signaling pathway, was the most enriched signaling pathway for DEGs in rose at high temperature. Heat shock factors (Hsfs), especially class A Hsfs, have been confirmed to be involved in thermotolerance mechanisms. Among the DEGs, eight genes were annotated as Hsfs, including 5 upregulated Hsfs at high temperature. RcHsfA6 is rapidly induced by high temperatures and is a candidate regulatory factor in the plant ABA signaling pathway. Therefore, we focused on RcHsfA6. RcHsfA6 encodes a protein containing 308 amino acids and contains typical Hsf domains, such as the DNA-binding domain (DBD), the N-terminal oligomerization domain (OD), the nuclear localization signal (NLS) and AHA motifs at the C-terminal activator domain (CTAD). The heterologous overexpression of RcHsfA6 in Arabidopsis increased the thermotolerance of Arabidopsis seeds. In addition, RcHsfA6 overexpression increased the ABA content and the expression of ABA biosynthetic gene AtABI5 and signal transduction gene AtPYL12, thereby inhibiting the germination of Arabidopsis seeds under exogenous ABA conditions.

CONCLUSIONS

Taken together, our results suggest that RcHsfA6 is involved in the high-temperature response of rose and its heterologous overexpression in Arabidopsis increased the thermotolerance of Arabidopsis at high temperatures via the ABA signaling pathway.

Effect of temperature on the physiology and phytoremediation capacity of Spirodela polyrhiza exposed to atrazine and S-metolachlor

Environmental toxicity of pesticides to aquatic plants can vary with temperature, as temperature affects plant metabolic processes. We exposed the globally distributed duckweed Spirodela polyrhiza to environmentally relevant concentrations (40 µg/L) of atrazine and S-metolachlor at temperatures typical of surface freshwater in temperate zones (10, 15, and 21 °C). Our objective was to assess the effects of low temperatures and herbicide concentration, and their interactions, on growth, photosynthesis, pigments, antioxidant enzymes, and phytoremediation capacity. Lower temperatures (10 °C) intensified the adverse effects of both herbicides on the quantum yield of photosystem II in S. polyrhiza, with photosynthesis being a more sensitive endpoint than biomass growth rate. Both in the control and herbicide treatments, plants exposed to 10 °C exhibited lower concentrations of photosynthetic pigments (chlorophylls and carotenoids) and reduced ascorbate peroxidase activity, which may have contributed to the intensified negative effects on photosynthesis at this temperature. The removal of S-metolachlor was lower at 10 and 15 °C (3-8 %) compared to 21 °C (17 %), while no difference was observed between the three tested temperatures for atrazine (2-8 %). Our findings suggest that conducting pesticide toxicity tests at around 25 °C may underestimate the contaminants' inhibitory effects on aquatic plants during colder seasons and in temperate regions. Additionally, lower temperatures pose a challenge to the effectiveness of atrazine and S-metolachlor phytoremediation in aquatic environments.

Design and Research of a New Cold Storage: The Phase-Temperature Storage (PTS) to Reduce Evaporator Frosting

This paper introduces a novel cold storage: phase-temperature storage, which is characterized by its distinctive coupling jacket structure that connects the sub-storehouse units to the main storehouse. This innovative design facilitates heat transfer while effectively inhibiting mass transfer. Experimental results indicate that polyethylene film, with a thermal conductivity of 0.42 W/m·K, is a more suitable material for constructing sub-storehouses. Enhancing the surface area of the sub-storehouse and increasing convective wind speed are identified as key factors for improving convective heat transfer within the sub-storehouse. Moreover, the optimized design ensures a more uniform temperature distribution inside the sub-storehouse. In contrast to conventional cold storage, the defrosting unit in phase-temperature storage consumes only 5.72 units of energy under equivalent conditions, compared to 154.02 units for conventional cold storage. This demonstrates that the energy expenditure during the defrosting process of phase temperature storage is less than 4% of that required by conventional cold storage, achieving an energy savings rate exceeding 96%. Under identical circumstances, conventional cold storage consumes a total of 36.359 units of electrical energy for defrosting, with 34.231 units being released as defrosting waste heat into the cold storage environment, resulting in a loss rate of approximately 94.13%. Based on apple preservation experiments, phase-temperature storage exhibited significantly superior performance compared to conventional cold storage in terms of apple respiratory peak, weight loss rate, hardness, and TSS content, with respective values of 17.05 CO2 mg·kg-1·h-1, 2.89%, 9.29 N, and 16.3%. In contrast, the conventional cold storage group recorded values of 18.15 CO2 mg·kg-1·h-1, 5.16%, 8.42 N, and 14.9%. These results highlight the exceptional freshness-retention capabilities of phase-temperature storage, underscoring its considerable potential for application in storage systems.

Metabolic engineering of lipids for crop resilience and nutritional improvements towards sustainable agriculture

Metabolic engineering of lipids in crops presents a promising strategy to enhance resilience against environmental stressors while improving nutritional quality. By manipulating key enzymes in lipid metabolism, introducing novel genes, and utilizing genome editing technologies, researchers have improved crop tolerance to abiotic stresses such as drought, salinity, and extreme temperatures. Additionally, modified lipid pathways contribute to resistance against biotic stresses, including pathogen attacks and pest infestations. Engineering multiple stress-resistance traits through lipid metabolism offers a holistic approach to strengthening crop resilience amid changing environmental conditions. Beyond stress tolerance, lipid engineering enhances the nutritional profile of crops by increasing beneficial lipids such as omega-3 fatty acids, vitamins, and antioxidants. This dual approach not only improves crop yield and quality but also supports global food security by ensuring sustainable agricultural production. Integrating advanced biotechnological tools with a deeper understanding of lipid biology paves the way for developing resilient, nutrient-rich crops capable of withstanding climate change and feeding a growing population.

The Arabidopsis thaliana core splicing factor PORCUPINE/SmE1 requires intron-mediated expression

Plants are prone to genome duplications and tend to preserve multiple gene copies. This is also the case for the genes encoding the Sm proteins of Arabidopsis thaliana (L). The Sm proteins are best known for their roles in RNA processing such as pre-mRNA splicing and nonsense-mediated mRNA decay. In this study, we have taken a closer look at the phylogeny and differential regulation of the SmE-coding genes found in A. thaliana, PCP/SmE1, best known for its cold-sensitive phenotype, and its paralog, PCPL/SmE2. The phylogeny of the PCP homologs in the green lineage shows that SmE duplications happened multiple times independently in different plant clades and that the duplication that gave rise to PCP and PCPL occurred only in the Brassicaceae family. Our analysis revealed that A. thaliana PCP and PCPL proteins, which only differ in two amino acids, exhibit a very high level of functional conservation and can perform the same function in the cell. However, our results indicate that PCP is the prevailing copy of the two SmE genes in A. thaliana as it is more highly expressed and that the main difference between PCP and PCPL resides in their transcriptional regulation, which is strongly linked to intronic sequences. Our results provide insight into the complex mechanisms that underlie the differentiation of the paralogous gene expression as an adaptation to stress.

Heat stress in plants: sensing, signalling, and ferroptosis

In the current context of global warming, high temperature events are becoming more frequent and intense in many places around the world. In this context, understanding how plants sense and respond to heat is essential to develop new tools to prevent plant damage and address global food security, as high temperature events are threatening agricultural sustainability. This review summarizes and integrates our current understanding underlying the cellular, physiological, biochemical, and molecular regulatory pathways triggered in plants under moderately high and extremely high temperature conditions. Given that extremely high temperatures can also trigger ferroptosis, the study of this cell death mechanism constitutes a strategic approach to understand how plants might overcome otherwise lethal temperature events.

Exogenous tryptophan enhances cold resistance of soybean seedlings by promoting melatonin biosynthesis

Given the global climate change, soybean production is highly susceptible to low temperature. Although tryptophan, the synthesis precursors of melatonin and auxin, exhibited a positive effect in regulating plant growth, it is still unclear whether tryptophan could improve the tolerance of soybean to low temperature stress through endogenous melatonin synthesis. Therefore, the effect of tryptophan on the resistance of two varieties of soybean seedlings to low temperature (4°C) was evaluated, and the main regulation pathway of tryptophan was verified with melatonin synthesis inhibitors. The results revealed that low temperature stress significantly inhibited the growth of soybean, while the application of exogenous tryptophan significantly enhanced the antioxidant activity of soybean seedlings to reduce the content of reactive oxygen species, including O2 - (11.3%) and H2O2 (17.8%), and effectively protected the photosynthetic capacity of leaves, involving net photosynthetic rate (22.94%), transpiration rate (15.31%), stomatal conductance (20.27%). And the application of tryptophan significantly increased the leaf area (16.63%), plant height (7.14%), root surface area (24.37%), root volume (22.92%) and root tip number (29.67%) of seedlings at low temperature. However, p-chlorophenylalanine inhibited the synthesis of melatonin and eliminated the effect of tryptophan. In conclusion, tryptophan mainly improved the cold tolerance of soybean seedlings by promoting endogenous melatonin synthesis, which provided a theoretical basis for tryptophan to enhance the cold tolerance of soybean in field production.

How to survive mild winters: Cold acclimation, deacclimation, and reacclimation in winter wheat and barley

Cold acclimation and vernalization represent the major evolutionary adaptive responses to ensure winter survival of temperate plants. Due to climate change, mild winters can paradoxically worsen plant winter survival due to cold deacclimation induced by warm periods during winter. It seems that the ability of cold reacclimation in overwintering Triticeae cereals is limited, especially in vernalized plants. In the present review, the major factors determining cold acclimation (CA), deacclimation (DA) and reacclimation (RA) processes in winter-type Triticeae, namely wheat and barley, are discussed. Recent knowledge on cold sensing and signaling is briefly summarized. The impacts of chilling temperatures, photoperiod and light spectrum quality as the major environmental factors, and the roles of soluble proteins and sugars (carbohydrates) as well as cold stress memory molecular mechanisms as the major plant-based factors determining CA, DA, and RA processes are discussed. The roles of plant stress memory mechanisms and development processes, namely vernalization, in winter Triticeae reacclimation are elucidated. Recent findings about the role of O-glucose N-acetylation of target proteins during vernalization and their impacts on the expression of VRN1 gene and other target proteins resulting in cold-responsive modules reprogramming are presented.

BcWRKY53 promotes chlorophyll biosynthesis and cold tolerance of non-heading Chinese cabbage under cold stress

WRKY transcription factors are widely involved in plant responses to biotic and abiotic stresses, including cold stress. However, they have not been well studied in the regulation of chlorophyll synthesis and cold tolerance. So it is meaningful to analyze the mechanism under cold stress in non-heading Chinese cabbage. Here, BcWRKY53, a transcriptional activator WRKY-III gene, was identified by a screen upstream of the key chlorophyll synthesis genes BcCHLH and BcGUN4. BcWRKY53 was localized in the cell nucleus and induced to a significant extent by cold treatment. Ectopic expression of BcWRKY53 in Arabidopsis not only increased the chlorophyll content under cold stress, but also improved the cold tolerance. After silencing of BcWRKY53, there was a decrease in chlorophyll content and an increase in cold sensitivity. BcWRKY53 could inhibit self-expression by binding W-boxes in its own promoter. In addition, histone deacetylase 9 (BcHDA9) interacted with BcWRKY53 to inhibit BcWRKY53-mediated transcriptional activation. When ectopically overexpressed, BcHDA9 negatively regulates chlorophyll content and cold tolerance under cold treatment. Taken together, this study demonstrated that the cold-inducible transcription factor BcWRKY53 positively regulates BcCHLH and BcGUN4 under the regulation of self-regulation and BcHDA9 interactions. In this way, BcWRKY53 is actively involved in chlorophyll synthesis and the establishment of cold tolerance, which providing practical theoretical support in molecular characterization of cold tolerance and variety selection of non-heading Chinese cabbage.

Climate Change and Plant Foods: The Influence of Environmental Stressors on Plant Metabolites and Future Food Sources

Climate change is reshaping global agriculture by altering temperature regimes and other environmental conditions, with profound implications for food security and agricultural productivity. This review examines how key environmental stressors-such as extreme temperatures, water scarcity, increased salinity, UV-B radiation, and elevated concentrations of ozone and CO2-impact the nutritional quality and bioactive compounds in plant-based foods. These stressors can modify the composition of essential nutrients, particularly phytochemicals, which directly affect the viability of specific crops in certain regions and subsequently influence human dietary patterns by shifting the availability of key food resources. To address these challenges, there is growing interest in resilient plant species, including those with natural tolerance to stress and genetically modified variants, as well as in alternative protein sources derived from plants. Additionally, unconventional food sources, such as invasive plant species and algae, are being explored as sustainable solutions for future nutrition.

Individual and interactive effects of temperature and blue light on canola growth, lignin biosynthesis and methane emissions

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the mechanisms of methane production in plants, its potential precursors, and the factors that are involved in the process are not fully understood. Few studies have considered the effects of blue light on methane emissions from plants; however, the combined effects of temperature and blue light have not been studied. We studied the effects of two temperature regimes (22/18 °C and 28/24 °C; 16 h light/8 h dark), and three blue light levels (0, 4, and 8 mW cm-2; 400-500 nm) on the growth, lignin, and methane emissions of canola (Brassica napus). Plants were grown under experimental conditions for three weeks, and then methane, monolignols and other plant traits, including growth, biomass, growth index, photosynthesis, chlorophyll fluorescence, and photosynthetic pigments, were measured. Blue light significantly increased methane emissions, stem height, and growth rate, but decreased stem diameter, leaf number and area, biomass, specific leaf mass, leaf area ratio, shoot/root mass ratio, photosynthetic pigments, sinapyl alcohol, and coniferyl aldehyde. Higher temperature significantly decreased stem diameter, non-photochemical quenching, sinapyl alcohol, and coniferyl aldehyde. Methane emission was negatively correlated with plant dry mass, leaf area per plant, and maximum quantum yield of photosystem II. However, no significant relationships were found between methane and monolignols. In conclusion, plants emitted more methane under stress conditions; however, further studies are required to understand the potential precursors of methane and the mechanism of its synthesis in plants.

Light-chilling Stress Causes Hyper-accumulation of Iron in Shoot, Exacerbating Leaf Oxidative Damage in Cucumber

Iron availability within the root system of plants fluctuates depending on various soil factors, which directly impacts plant growth. Simultaneously, various environmental stressors, such as high/low temperatures and high light intensity, affect plant photosynthesis in the leaves. However, the combined effects of iron nutrient conditions and abiotic stresses have not yet been clarified. In this study, we analyzed how iron nutrition conditions impact the chilling-induced damage on cucumber leaves (Cucumis sativus L.). When cucumbers were grown under different iron conditions and then exposed to chilling stress, plants grown under a high iron condition exhibited more severe chilling-induced damage than the control plants. Conversely, plants grown under a low-iron condition showed an alleviation of the chilling-induced damages. These differences were observed in a light-dependent manner, indicating that iron intensified the toxicity of reactive oxygen species generated by photosynthetic electron transport. In fact, plants grown under the low-iron condition showed less accumulation of malondialdehyde derived from lipid peroxidation after chilling stress. Notably, the plants grown under the high iron condition displayed a significant accumulation of iron and an increase in lipid peroxidation in the shoot, specifically after light-chilling stress, but not after dark-chilling stress. This indicated that increased root-to-shoot iron translocation, driven by light and low temperature, exacerbated leaf oxidative damage during chilling stress. These findings also highlight the importance of managing iron nutrition in the face of chilling stress and will facilitate crop breeding and cultivation strategies.

Construction and evaluation of a model for efficient identification of photothermal sensitivity of tobacco cultivars based on agronomic traits

The photothermal sensitivity of tobacco refers to the degree to which tobacco responds to changes in light and temperature conditions in its growth environment, which is crucial for determining the planting area of cultivars and improving tobacco yield and quality. In order to accurately and effectively evaluate the photothermal sensitivity of tobacco cultivars, this study selected five cultivars and their hybrid combinations with significant differences planted under different ecological conditions from 2021 to 2022 as materials. The experiment was conducted in two locations with significant differences in temperature and light. We measured the agronomic traits and biomass of the experimental materials, and constructed an effective tobacco photothermal sensitivity evaluation model using principal component analysis, membership function, and regression analysis. The reliability of the model was evaluated by utilizing the photosynthetic characteristics, chlorophyll content, and antioxidant enzyme system activity of the experimental materials. The results showed that tobacco biomass is the most important principal component in agricultural traits, and the comprehensive evaluation model for tobacco photothermal sensitivity is: y = 0.4571y1 + 0.2406y2 + 0.1725y3, where the fitting coefficients R2 of y1, y2, and y3 are 0.945, 0.851, and 0.977, respectively; The photothermal sensitivity of the experimental materials was calculated using this model, and the comprehensive ranking of the 11 experimental materials is: G3 < G5 < G10 < G9 < G11 < G6 < G7 < G2 < G4 < G8 < G1. Conventional identification methods have found that G2, G4, G6, G7, G8, and G11 are sensitive materials, G3, G5, and G10 are insensitive materials, and G1 and G9 are intermediate materials. The consistency rate of the evaluation results of the two methods reached 90.91%. And there is a significant correlation between the agronomic traits selected in the model and the physiological indicators selected by conventional evaluation methods, providing a scientific basis for evaluating the light temperature sensitivity of tobacco cultivars using agronomic traits in this study. The results indicate that the photothermal sensitivity evaluation model established in this study provides an efficient, convenient, and reliable method for evaluating the photothermal sensitivity of tobacco.

Application of Exogenous Ascorbic Acid Enhances Cold Tolerance in Tomato Seedlings through Molecular and Physiological Responses

Ascorbic acid (AsA), an essential non-enzymatic antioxidant in plants, regulates development growth and responses to abiotic and biotic stresses. However, research on AsA's role in cold tolerance remains largely unknown. Here, our study uncovered the positive role of AsA in improving cold stress tolerance in tomato seedlings. Physiological analysis showed that AsA significantly enhanced the enzyme activity of the antioxidant defense system in tomato seedling leaves and increased the contents of proline, sugar, abscisic acid (ABA), and endogenous AsA. In addition, we found that AsA is able to protect the photosynthetic system of tomato seedlings, thereby relieving the declining rate of chlorophyll fluorescence parameters. qRT-PCR analysis indicated that AsA significantly increased the expression of genes encoding antioxidant enzymes and involved in AsA synthesis, ABA biosynthesis/signal transduction, and low-temperature responses in tomato. In conclusion, the application of exogenous AsA enhances cold stress tolerance in tomato seedlings through various molecular and physiological responses. This provides a theoretical foundation for exploring the regulatory mechanisms underlying cold tolerance in tomato and offers practical guidance for enhancing cold tolerance in tomato cultivation.

Molecular and biochemical components associated with chilling tolerance in tomato: comparison of different developmental stages

The cultivated tomato, Solanum lycopersicum, is highly sensitive to cold stress (CS), resulting in significant losses during cultivation and postharvest fruit storage. Previously, we demonstrated the presence of substantial genetic variation in fruit chilling tolerance in a tomato recombinant inbred line (RIL) population derived from a cross between a chilling-sensitive tomato line and a chilling-tolerant accession of the wild species S. pimpinellifolium. Here, we investigated molecular and biochemical components associated with chilling tolerance in fruit and leaves, using contrasting groups of "chilling tolerant" and "chilling sensitive" RI lines. Transcriptomic analyses were conducted on fruit exposed to CS, and gene expressions and biochemical components were measured in fruit and leaves. The analyses revealed core responding genes specific to either the cold-tolerant or cold-sensitive RI lines, which were differentially regulated in similar fashion in both leaves and fruit within each group. These genes may be used as markers to determine tomato germplasm cold tolerance or sensitivity. This study demonstrated that tomato response to CS in different developmental stages, including seedling and postharvest fruit, might be mediated by common biological/genetic factors. Therefore, genetic selection for cold tolerance during early stages of plant development may lead to lines with greater postharvest fruit chilling tolerance.

Functions and Regulatory Mechanisms of bHLH Transcription Factors during the Responses to Biotic and Abiotic Stresses in Woody Plants

Environmental stresses, including abiotic and biotic stresses, have complex and diverse effects on the growth and development of woody plants, which have become a matter of contention due to concerns about the outcomes of climate change on plant resources, genetic diversity, and world food safety. Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes and play an important role in biotic and abiotic stress responses of woody plants. In recent years, an increasing body of studies have been conducted on the bHLH TFs in woody plants, and the roles of bHLH TFs in response to various stresses are increasingly clear and precise. Therefore, it is necessary to conduct a systematic and comprehensive review of the progress of the research of woody plants. In this review, the structural characteristics, research history and roles in the plant growth process of bHLH TFs are summarized, the gene families of bHLH TFs in woody plants are summarized, and the roles of bHLH TFs in biotic and abiotic stresses in woody plants are highlighted. Numerous studies mentioned in this review have shown that bHLH transcription factors play a crucial role in the response of woody plants to biotic and abiotic stresses. This review serves as a reference for further studies about enhancing the stress resistance and breeding of woody plants. Also, the future possible research directions of bHLH TFs in response to various stresses in woody plants will be discussed.

Foliar spraying with amino acids and their chitosan nanocomposites as promising way to alleviate abiotic stress in iceberg lettuce grown at different temperatures

We analyzed the effects of foliar spraying with amino acids, chitosan (CHS) and nanocomposites (NCs) of chitosan with the amino acids proline, L-cysteine and glycine betaine (CHS-Pro NCs; CHS-Cys NCs, CHS-GB NCs, respectively) on the changes in the physiological and biochemical parameters of iceberg lettuce grown at the control temperature (20 °C) and under chilling conditions (4 °C). The physicochemical parameters of the phospholipid monolayers (PLs) extracted from plants showed the effects of the treatments on the properties of the monolayers, namely, the packing density and flexibility. We observed increased accumulation of proline at 4 °C, and differences in the concentrations of sugars in most of the analyzed variants were a consequence of the lowered temperature and/or the use of organic compounds. A temperature of 4 °C caused a significant increase in the L-ascorbic acid level compared with that at 20 °C. Differences were also found in glutathione (GSH) content depending on the temperature and treatment with the tested organic compounds. CHS NCs loaded with Pro and GB were effective at increasing the amount of phenols under stress temperature conditions. We noted that a significant increase in the antioxidant activity of plants at 4 °C occurred after priming with Cys, CHS-Cys NCs, Pro and CHS-Pro NCs, and the CHS nanocomposites were more effective in this respect. Both low-temperature stress and foliar spraying of lettuce with various organic compounds caused changes in the activity of antioxidant enzymes. Two forms of dismutase (SOD), iron superoxide dismutase (FeSOD) and copper/zinc superoxide dismutase (Cu/ZnSOD), were identified in extracts from the leaves of iceberg lettuce seedlings. The application of the tested organic compounds, alone or in combination with CHS, increased the amount of malondialdehyde (MDA) in plants grown under controlled temperature conditions. Chilling caused an increase in the content of MDA, but some organic compounds mitigated the impact of low temperature. Compared with that of plants subjected to 20 °C, the fresh weight of plants exposed to chilling decreased. However, the tested compounds caused a decrease in fresh weight at 4 °C compared with the corresponding control samples. An interesting exception was the use of Cys, for which the difference in the fresh weight of plants grown at 20 °C and 4 °C was not statistically significant. After Cys application, the dry weight of the chilled plants was greater than that of the chilled control plants but was also greater than that of the other treated plants in this group. To our knowledge, this is the first report demonstrating that engineered chitosan-amino acid nanocomposites could be applied as innovative protective agents to mitigate the effects of chilling stress in crop plants.

Synergy effect of silicate fertilizer and iron slag: A sustainable approach for mitigating methane emission in rice farming

Although silicate fertilizer has been recently recognized for its ability to suppress methane (CH4) emissions in paddy fields, the effects of its consecutive application during the rice farming period are still a subject of debate. Moreover, while it was known that silicate fertilizer can mitigate CH4 emissions through several electron acceptors, the effect of additional application of electron acceptors have not been extensively studied. This study evaluated the effect of silicate fertilizer with varying concentrations of iron slag on CH4 emissions and rice yield over the 3 years rice farming period. Seasonal CH4 fluxes exhibited a significant decrease with the application of silicate fertilizer, with the treatment containing 2.5 % iron slag showing the maximum reduction of 35 % in 2020. Additionally, in 2021 and 2022, the application of silicate fertilizer with 2.5 % iron slag resulted in a decrease of total seasonal CH4 emission by 22 % and 23 %, respectively. Rice grain yield exhibited a significant increase with the inclusion of iron slag in the silicate fertilizer, which resulted in a 37 % and 16 % higher yield compared to no-silicate fertilization and no‑iron slag silicate fertilization, respectively. Therefore, iron slag-based silicate fertilizer could be a beneficial soil amendment to mitigate CH4 emissions in rice paddy fields and improve rice productivity without negative effects on the atmospheric and soil ecosystem.

Multi-scale analysis of heat stress acclimation in Arabidopsis seedlings highlights the primordial contribution of energy-transducing organelles

Much progress has been made in understanding the molecular mechanisms of plant adaptation to heat stress. However, the great diversity of models and stress conditions, and the fact that analyses are often limited to a small number of approaches, complicate the picture. We took advantage of a liquid culture system in which Arabidopsis seedlings are arrested in their development, thus avoiding interference with development and drought stress responses, to investigate through an integrative approach seedlings' global response to heat stress and acclimation. Seedlings perfectly tolerate a noxious heat shock (43°C) when subjected to a heat priming treatment at a lower temperature (38°C) the day before, displaying a thermotolerance comparable to that previously observed for Arabidopsis. A major effect of the pre-treatment was to partially protect energy metabolism under heat shock and favor its subsequent rapid recovery, which was correlated with the survival of seedlings. Rapid recovery of actin cytoskeleton and mitochondrial dynamics were another landmark of heat shock tolerance. The omics confirmed the role of the ubiquitous heat shock response actors but also revealed specific or overlapping responses to priming, heat shock, and their combination. Since only a few components or functions of chloroplast and mitochondria were highlighted in these analyses, the preservation and rapid recovery of their bioenergetic roles upon acute heat stress do not require extensive remodeling of the organelles. Protection of these organelles is rather integrated into the overall heat shock response, thus allowing them to provide the energy required to elaborate other cellular responses toward acclimation.

Climate warming worsens thermal resource utilization for practical rice cultivation in China

Rice production is sensitive to climate change and significantly affected by warming in recent years. To what extent climate warming shifted rice phenology and varied thermal resource condition were explored across five agro-ecological zones in China, based on up-to-date observations of meteorology and rice cultivation in 1981-2020. It was clearly signaled that there was a general advance of 0.3-3.8 days in observed sowing date and a delay of 0.4-3.5 days in observed maturity date in 2001-2020 relative to 1981-2000 in major zones. A vacant time slice of 2.6-28.8 days between observed sowing date and potential sowing date, and a lag of 15.4-56.7 days in potential maturity date compared to observed maturity date were identified in 2001-2020. Within longer growing season, useful accumulated temperature increased by 76.7-117.6 °C·d in 2001-2020 relative to 1981-2000, while disactive accumulated temperature also increased. In Northeast China, actual rice cultivation was undergoing earlier sowing date than potential sowing date and longer growing duration than potential duration, yet leading to upward disactive accumulated temperature. The decrease in the thermal resource utilization in 2001-2020 relative to 1981-2000 was highlighted at 55.3-78.3% stations in major zones, with a decrement of 0.006-0.018 in average magnitude. The changes in thermal resource utilization unveiled that the shifts in actual rice cultivation still could not compensate for the suitability in thermal resource utilization benefited from climate warming.

Exploring the potential of endophyte-plant interactions for improving crop sustainable yields in a changing climate

Climate change poses a major threat to global food security, significantly reducing crop yields as cause of abiotic stresses, and for boosting the spread of new and old pathogens and pests. Sustainable crop management as a route to mitigation poses the challenge of recruiting an array of solutions and tools for the new aims. Among these, the deployment of positive interactions between the micro-biotic components of agroecosystems and plants can play a highly significant role, as part of the agro-ecological revolution. Endophytic microorganisms have emerged as a promising solution to tackle this challenge. Among these, Arbuscular Mycorrhizal Fungi (AMF) and endophytic bacteria and fungi have demonstrated their potential to alleviate abiotic stresses such as drought and heat stress, as well as the impacts of biotic stresses. They can enhance crop yields in a sustainable way also by other mechanisms, such as improving the nutrient uptake, or by direct effects on plant physiology. In this review we summarize and update on the main types of endophytes, we highlight several studies that demonstrate their efficacy in improving sustainable yields and explore possible avenues for implementing crop-microbiota interactions. The mechanisms underlying these interactions are highly complex and require a comprehensive understanding. For this reason, omic technologies such as genomics, transcriptomics, proteomics, and metabolomics have been employed to unravel, by a higher level of information, the complex network of interactions between plants and microorganisms. Therefore, we also discuss the various omic approaches and techniques that have been used so far to study plant-endophyte interactions.

Transcriptomic and physiological analyses reveal different grape varieties response to high temperature stress

High temperatures affect grape yield and quality. Grapes can develop thermotolerance under extreme temperature stress. However, little is known about the changes in transcription that occur because of high-temperature stress. The heat resistance indices and transcriptome data of five grape cultivars, 'Xinyu' (XY), 'Miguang' (MG), 'Summer Black' (XH), 'Beihong' (BH), and 'Flame seedless' (FL), were compared in this study to evaluate the similarities and differences between the regulatory genes and to understand the mechanisms of heat stress resistance differences. High temperatures caused varying degrees of damage in five grape cultivars, with substantial changes observed in gene expression patterns and enriched pathway responses between natural environmental conditions (35 °C ± 2 °C) and extreme high temperature stress (40 °C ± 2 °C). Genes belonging to the HSPs, HSFs, WRKYs, MYBs, and NACs transcription factor families, and those involved in auxin (IAA) signaling, abscisic acid (ABA) signaling, starch and sucrose pathways, and protein processing in the endoplasmic reticulum pathway, were found to be differentially regulated and may play important roles in the response of grape plants to high-temperature stress. In conclusion, the comparison of transcriptional changes among the five grape cultivars revealed a significant variability in the activation of key pathways that influence grape response to high temperatures. This enhances our understanding of the molecular mechanisms underlying grape response to high-temperature stress.

Fungi beyond limits: The agricultural promise of extremophiles

Global climate changes threaten food security, necessitating urgent measures to enhance agricultural productivity and expand it into areas less for agronomy. This challenge is crucial in achieving Sustainable Development Goal 2 (Zero Hunger). Plant growth-promoting microorganisms (PGPM), bacteria and fungi, emerge as a promising solution to mitigate the impact of climate extremes on agriculture. The concept of the plant holobiont, encompassing the plant host and its symbiotic microbiota, underscores the intricate relationships with a diverse microbial community. PGPM, residing in the rhizosphere, phyllosphere, and endosphere, play vital roles in nutrient solubilization, nitrogen fixation, and biocontrol of pathogens. Novel ecological functions, including epigenetic modifications and suppression of virulence genes, extend our understanding of PGPM strategies. The diverse roles of PGPM as biofertilizers, biocontrollers, biomodulators, and more contribute to sustainable agriculture and environmental resilience. Despite fungi's remarkable plant growth-promoting functions, their potential is often overshadowed compared to bacteria. Arbuscular mycorrhizal fungi (AMF) form a mutualistic symbiosis with many terrestrial plants, enhancing plant nutrition, growth, and stress resistance. Other fungi, including filamentous, yeasts, and polymorphic, from endophytic, to saprophytic, offer unique attributes such as ubiquity, morphology, and endurance in harsh environments, positioning them as exceptional plant growth-promoting fungi (PGPF). Crops frequently face abiotic stresses like salinity, drought, high UV doses and extreme temperatures. Some extremotolerant fungi, including strains from genera like Trichoderma, Penicillium, Fusarium, and others, have been studied for their beneficial interactions with plants. Presented examples of their capabilities in alleviating salinity, drought, and other stresses underscore their potential applications in agriculture. In this context, extremotolerant and extremophilic fungi populating extreme natural environments are muchless investigated. They represent both new challenges and opportunities. As the global climate evolves, understanding and harnessing the intricate mechanisms of fungal-plant interactions, especially in extreme environments, is paramount for developing effective and safe plant probiotics and using fungi as biocontrollers against phytopathogens. Thorough assessments, comprehensive methodologies, and a cautious approach are crucial for leveraging the benefits of extremophilic fungi in the changing landscape of global agriculture, ensuring food security in the face of climate challenges.

Galactinol Regulates JA Biosynthesis to Enhance Tomato Cold Tolerance

Low temperatures can inhibit plant growth and development and reduce fruit yield. This study demonstrated that the expression of AnGolS1 from Ammopiptanthus nanus (A. nanus) encoding a galactinol synthase enhanced tomato cold tolerance. In AnGolS1-overexpressing plants, the jasmonic acid (JA) biosynthesis substrates 13-hydroperoxylinolenicacid and 12,13-epoxylinolenicacid were significantly accumulated, and the expression levels of the ethylene response factor (SlERF4-7) and serine protease inhibitor (SlSPI5) were increased. We speculated that there may be correlations among galactinol, ethylene signaling, the protease inhibitor, protease, and JA levels. The expression levels of SlERF4-7 and SlSPI5 as well as the JA content were significantly increased under exogenous galactinol treatment. Additionally, the expression of SlSPI5 was reduced in SlERF4-7-silenced plants, and SlERF4-7 was confirmed to bind to the dehydration-responsive element (DRE) of the SlSPI5 promoter. These results suggest that SlSPI5 is a target gene of the SlERF4-7 transcription factor. In addition, SlSPI5 interacted with cysteine protease (SlCPase), while SlCPase interacted with lipoxygenase (SlLOX5) and allene oxide synthase (SlAOS2). When SlCPase was silenced, JA levels increased and plant cold tolerance was enhanced. Therefore, galactinol regulates JA biosynthesis to enhance tomato cold tolerance through the SlERF4-7-SlSPI5-SlCPase-SlLOX5/SlAOS2 model. Overall, our study provides new perspectives on the role of galactinol in the JA regulatory network in plant adaptation to low-temperature stress.

Spatial distribution dynamics for Epimedium brevicornum Maxim. from 1970 to 2020

At different time scales, a species will experience diverse distribution changes. For Epimedium brevicornum Maxim, the phenomenon is obvious, but the understanding of the spatial dynamics of E. brevicornum under distinct time scales is poor. In this study, we modeled the potential distribution for E. brevicornum for five time scales, 1970-1979, 1980-1989, 1990-1999, 2000-2009, and 2010-2019, with different occurrence data, and the Kuenm package was used to optimize the parameter combination. Then, SDM tools and a Venn diagram were utilized to simulate the changes in highly suitable areas and spatial dynamics, respectively. Comprehensive results show that temperature seasonality (BIO4, 37.54%) has the greatest effect on the distribution of E. brevicornum, followed by minimum temperature (TMIN, 21.42%). The areas of distribution for E. brevicornum are 35.06 × 105 km2, 25.7 × 105 km2, 67.64 × 105 km2, 27.29 × 105 km2, and 9.87× 105 km2, which are mainly concentrated in Gansu, Shaanxi, Shanxi, and Henan, respectively. In addition, the largest regions for expansion, stability, and contraction under various time scales are 5.6 × 105 km2, 3.54 × 105 km2, and 3.47 × 105 km2, respectively. These changes indicate that approximately 7.96% of the regions are highly stable, and three critical counties, Wanyuan, Chenggu, and Hechuan, and Xixiang, have become significant areas for migration. Overall, our results indicate that there are different spatial distribution patterns and dynamics for E. brevicornum for different time scales. Given these results, this study also proposes comprehensive strategies for the conservation and management of E. brevicornum, which will further improve the current resource utilization status.

Antioxidative response of parthenocarpic tomato, iaa9-3 and iaa9-5, under heat stress condition

It has previously been shown that parthenocarpic tomato mutants, iaa9-3 and iaa9-5, can adapt, grow, and produce fruit under heat-stress conditions. However, the physiological processes in those two mutants especially for the enzymatic system that works to neutralize ROS are not clear. The objective of this research was to determine how the scavenging enzyme system responds to the heat stress in those mutants. The iaa9-3, iaa9-5, and WT-MT as a control were cultivated under two environmental conditions; normal and heat stress conditions. Vegetative and reproductive growth were observed during cultivation period. The activities of catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) were investigated in both wild-type and parthenocarpic tomato mutants under normal and heat stress conditions. The results showed that under heat stress condition, the mutants, iaa9-3 and iaa9-5, and WT-MT resulted in reduction of the vegetative growth, but those mutants showed better growth than WT-MT. Higher chlorophyll content in iaa9-3 and iaa9-5 was observed under normal or heat stress condition. Despite their growth reduction under heat stress conditions, iaa9-3 and iaa9-5 resulted in the significant higher CAT, APX and SOD activity than WT-MT. The results suggest that higher chlorophyll content and enhanced CAT, APX and SOD activity in the iaa9-3 and iaa9-5 mutants are adaptive strategies to survive in heat stress conditions.

Geomagnetic Anomaly in the Growth Response of Peat Moss Sphagnum riparium to Temperature

Temperature plays an essential role in a plant's life. The current investigation reveals that photoreceptors, whose activity is affected by the geomagnetic field, are a critical element of its perception. This knowledge suggests that plants' responses to temperature could shift in different geomagnetic conditions. To test this hypothesis, we studied the change in the growth response of the peat moss Sphagnum riparium to temperature with a gradual increase in the geomagnetic Kp index. Growth data for this species were collected from Karelian mires by detailed monitoring over eight full growing seasons. The growth of 209,490 shoots was measured and 1439 growth rates were obtained for this period. The analysis showed a strong positive dependence of sphagnum growth on temperature (r = 0.58; n = 1439; P = 1.7 × 10-119), which is strongest in the Kp range from 0.87 to 1.61 (r = 0.65; n = 464; P = 4.5 × 10-58). This Kp interval is clearer after removing the seasonal contributions from the growth rate and temperature and is preserved when diurnal temperature is used. Our results are consistent with the hypothesis and show the unknown contribution of the geomagnetic field to the temperature responses of plants.

Lipidomics-based insights into the physiological mechanism of wheat in response to heat stress

Lipids are the main components of plant cell biofilms and play a crucial role in plant growth, Understanding the modulation in lipid profiles under heat stress can contribute to understanding the heat tolerance mechanisms in wheat leaves. In the current study, two wheat cultivars with different heat tolerance levels were treated with optimum temperature (OT) and high temperature (HT) at the flowering stage, and the antioxidant enzyme activity in the leaves and the grain yield were determined. Further, lipidomics was studied to determine the changes in lipid composition in the leaves. The heat-tolerant cultivar ZM7698 exhibited higher antioxidant enzyme activity and lower malondialdehyde and H2O2 contents. High-temperature stress led to the remodeling of lipid profile in the two cultivars. The relative proportion of digalactosyl diacylglycerol (DGDG) and phosphatidylinositol (PI) components increased in the heat-tolerant cultivar under high-temperature stress, while it was decreased in the heat-sensitive cultivar. The lipid unsaturation levels of sulfoquinovosyl diacylglycerol (SQDG), monogalactosyl monoacylglycerol (MGMG), and phosphatidic acid (PA) decreased significantly in the heat-tolerant cultivar under high-temperature stress. The increase in unsaturation of monogalactosyl diacylglycerol (MGDG) and phosphatidylethanolamine (PE) in the heat-tolerant cultivar under high-temperature stress was lower than in the heat-sensitive cultivar. In addition, a high sitosterol/stigmasterol (SiE/StE) ratio was observed in heat-tolerant cultivar under high-temperature stress. Taken together, these results revealed that a heat-tolerant cultivar could enhance its ability to resist heat stress by modulating the composition and ratio of the lipid components and decreasing lipid unsaturation levels in wheat.

Response Mechanisms of Woody Plants to High-Temperature Stress

High-temperature stress is the main environmental stress that restricts the growth and development of woody plants, and the growth and development of woody plants are affected by high-temperature stress. The influence of high temperature on woody plants varies with the degree and duration of the high temperature and the species of woody plants. Woody plants have the mechanism of adapting to high temperature, and the mechanism for activating tolerance in woody plants mainly counteracts the biochemical and physiological changes induced by stress by regulating osmotic adjustment substances, antioxidant enzyme activities and transcription control factors. Under high-temperature stress, woody plants ability to perceive high-temperature stimuli and initiate the appropriate physiological, biochemical and genomic changes is the key to determining the survival of woody plants. The gene expression induced by high-temperature stress also greatly improves tolerance. Changes in the morphological structure, physiology, biochemistry and genomics of woody plants are usually used as indicators of high-temperature tolerance. In this paper, the effects of high-temperature stress on seed germination, plant morphology and anatomical structure characteristics, physiological and biochemical indicators, genomics and other aspects of woody plants are reviewed, which provides a reference for the study of the heat-tolerance mechanism of woody plants.

Utilizing hydrothermal time models to assess the effects of temperature and osmotic stress on maize (Zea mays L.) germination and physiological responses

The application of germination models in economic crop management makes them extremely useful for predicting seed germination. Hence, we examined the effect of varying water potentials (Ψs; 0. - 0.3, - 0.6, - 0.9, - 1.2 MPa) and temperatures (Ts; 20, 25, 30, 35, 40 °C) on maize germination and enzymatic antioxidant mechanism. We observed that varying Ts and Ψs significantly influenced germination percentage (GP) and germination rate (GR), and other germination parameters, including germination rate index (GRI), germination index (GI), mean germination index (MGI), mean germination time (MGT), coefficient of the velocity of germination (CVG), and germination energy (GE) (p ≤ 0.01). Maximum (87.60) and minimum (55.20) hydro-time constant (θH) were reported at 35 °C and 20 °C, respectively. In addition, base water potential at 50 percentiles was highest at 30 °C (15.84 MPa) and lowest at 20 °C (15.46 MPa). Furthermore, the optimal, low, and ceiling T (To, Tb and Tc, respectively) were determined as 30 °C, 20 °C and 40 °C, respectively. The highest θT1 and θT2 were reported at 40 °C (0 MPa) and 20 °C (- 0.9 MPa), respectively. HTT has a higher value (R2 = 0.43 at 40 °C) at sub-optimal than supra-optimal temperatures (R2 = 0.41 at 40 °C). Antioxidant enzymes, including peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione peroxidase (GPX), increased with decreasing Ψs. In contrast, CAT and POD were higher at 20 °C and 40 °C but declined at 25, 30, and 35 °C. The APX and GPX remained unchanged at 20, 25, 30, and 40 °C but declined at 35 °C. Thus, maintaining enzymatic activity is a protective mechanism against oxidative stress. A decline in germination characteristics may result from energy diverting to anti-stress tools (antioxidant enzymes) necessary for eliminating reactive oxygen species (ROS) to reduce salinity-induced oxidative damage. The parameters examined in this study are easily applicable to simulation models of Z. mays L. germination under extreme environmental conditions characterized by water deficits and temperature fluctuations.

Examining the Transcriptomic and Biochemical Signatures of Bacillus subtilis Strains: Impacts on Plant Growth and Abiotic Stress Tolerance

Rhizobacteria from various ecological niches display variations in physiological characteristics. This study investigates the transcriptome profiling of two Bacillus subtilis strains, BsCP1 and BsPG1, each isolated from distinct environments. Gene expression linked to the synthesis of seven types of antibiotic compounds was detected in both BsCP1 and BsPG1 cultures. Among these, the genes associated with plipastatin synthesis were predominantly expressed in both bacterial strains. However, genes responsible for the synthesis of polyketide, subtilosin, and surfactin showed distinct transcriptional patterns. Additionally, genes involved in producing exopolysaccharides (EPS) showed higher expression levels in BsPG1 than in BsCP1. Consistently with this, a greater quantity of EPS was found in the BsPG1 culture compared to BsCP1. Both bacterial strains exhibited similar effects on Arabidopsis seedlings, promoting root branching and increasing seedling fresh weight. However, BsPG1 was a more potent enhancer of drought, heat, and copper stress tolerance than BsCP1. Treatment with BsPG1 had a greater impact on improving survival rates, increasing starch accumulation, and stabilizing chlorophyll content during the post-stress stage. qPCR analysis was used to measure transcriptional changes in Arabidopsis seedlings in response to BsCP1 and BsPG1 treatment. The results show that both bacterial strains had a similar impact on the expression of genes involved in the salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Likewise, genes associated with stress response, root development, and disease resistance showed comparable responses to both bacterial strains. However, treatment with BsCP1 and BsPG1 induced distinct activation of genes associated with the ABA signaling pathway. The results of this study demonstrate that bacterial strains from different ecological environments have varying abilities to produce beneficial metabolites for plant growth. Apart from the SA and JA signaling pathways, ABA signaling triggered by PGPR bacterial strains could play a crucial role in building an effective resistance to various abiotic stresses in the plants they colonize.

Photobiotechnology for abiotic stress resilient crops: Recent advances and prospects

Massive crop failures worldwide are caused by abiotic stress. In plants, adverse environmental conditions cause extensive damage to the overall physiology and agronomic yield at various levels. Phytochromes are photosensory phosphoproteins that absorb red (R)/far red (FR) light and play critical roles in different physiological and biochemical responses to light. Considering the role of phytochrome in essential plant developmental processes, genetically manipulating its expression offers a promising approach to crop improvement. Through modulated phytochrome-mediated signalling pathways, plants can become more resistant to environmental stresses by increasing photosynthetic efficiency, antioxidant activity, and expression of genes associated with stress resistance. Plant growth and development in adverse environments can be improved by understanding the roles of phytochromes in stress tolerance characteristics. A comprehensive overview of recent findings regarding the role of phytochromes in modulating abiotic stress by discussing biochemical and molecular aspects of these mechanisms of photoreceptors is offered in this review.

Investigating the impact of terminal heat stress on contrasting wheat cultivars: a comprehensive analysis of phenological, physiological, and biochemical traits

Terminal heat stress has become one of the major threats due to global climate change which is significantly affecting the production and productivity of wheat crop. Therefore, it is necessary to identify key traits and genotypes to breed heat-tolerant wheat. The present study was undertaken with the objective of comparing the effects of heat stress (HSE) and extended heat stress (EHSE) on phenological-physio-biochemical traits of contrasting heat-tolerant and heat-susceptible genotypes during the reproductive phase. Phenological traits exhibited significant reduction under EHSE compared to HSE. Heat-tolerant genotypes maintained balanced phenological-physio-biochemical traits, while heat-sensitive genotypes showed significant reductions under both stress regimes. Among phenological traits, DM (R2 = 0.52) and BY (R2 = 0.44) have shown a positive effect on seed yield, indicating that biomass and crop duration contributed to the yield advantage under stress. During the grain filling stage, both the normalized difference vegetation index (NDVI) and chlorophyll (Chl) exhibited consistently positive impacts on grain yield under both HSE and EHSE conditions. This could be attributed to the enhanced photosynthesis resulting from delayed senescence and improved assimilate remobilization under terminal heat stress. The biochemical activity of superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX) was induced in tolerant genotypes under HSE. The correlation of canopy temperature with phenological-physio-biochemical traits remained static under HSE and EHSE, suggesting CT as the best selection parameter for heat tolerance. The traits showing a positive association with yield and that are less affected under stress could be used for selecting tolerant genotypes under stress environments. These tolerant genotypes can be used to develop mapping populations to decipher the genes conferring tolerance as well as to study the molecular basis of tolerance.

Comparative heat stress responses of three hot pepper (Capsicum annuum L.) genotypes differing temperature sensitivity

As global temperatures have steadily increased over past decades, studying of the impacts of heat stress on morpho-physiological traits and economic yields of horticultural crops have been increasingly gained attentions by many scientists and farmers. Hot pepper (Capsicum annuum L.) is an important vegetable crop mostly grown in open-fields in South Korea. In this study, the impacts of prolonged heat stress on three hot pepper genotypes differing by levels of stress susceptibility were evaluated. The study was conducted in two different temperature-controlled greenhouses for 75 days. 48 days old plants were grown in control and heat-treated greenhouses where the temperatures had been set at 30 °C and 35 °C during the day for 75 days, respectively. Morphological, physiological, and nutrient characteristics of three accessions were measured. All hot pepper accessions were enabled to recover from prolonged heat stress exposures within approximately a month. The phenomenon of recovery was observed in some significant morphological and physiological characteristics. For example, the plant growth rate and photosynthesis rate significantly increased after 40th days of heat treatment. The heat stress sensitivity varied between genotypes. The plants that produced more fruits over biomass at early stage of heat treatment had relatively slow recovery, resulting in the largest yield loss. This key morphological characteristic can be used for future breeding program to adapt the prolonged heat stress.

Uncovering the mechanisms of salicylic acid-mediated abiotic stress tolerance in horticultural crops

Salicylic acid (SA) has been recognized as a promising molecule for improving abiotic stress tolerance in plants due to its ability to enhance antioxidant defense system, and promote root architecture system. Recent research has focused on uncovering the mechanisms by which SA confers abiotic stress tolerance in horticultural crops. SA has been shown to act as a signaling molecule that triggers various physiological and morphological responses in plants. SA regulates the production of reactive oxygen species (ROS). Moreover, it can also act as signaling molecule that regulate the expression of stress-responsive genes. SA can directly interact with various hormones, proteins and enzymes involved in abiotic stress tolerance. SA regulates the antioxidant enzymes activities that scavenge toxic ROS, thereby reducing oxidative damage in plants. SA can also activate protein kinases that phosphorylate and activate transcription factors involved in stress responses. Understanding these mechanisms is essential for developing effective strategies to improve crop resilience in the face of changing environmental conditions. Current information provides valuable insights for farmers and plant researchers, offering new strategies to enhance crop resilience and productivity in the face of environmental challenges. By harnessing the power of SA and its signaling pathways, farmers can develop more effective stress management techniques and optimize crop performance. Plant researchers can also explore innovative approaches to breed or engineer crops with enhanced stress tolerance, thereby contributing to sustainable agriculture and food security.

Drought priming induced thermotolerance in wheat (Triticum aestivum L.) during reproductive stage; a multifaceted tolerance approach against terminal heat stress

In wheat (Triticum aestivum L.), terminal heat stress obstructs reproductive functioning eventually leading to yield loss. Drought priming during the vegetative stage can trigger a quicker and effective defense response against impending high temperature stress and improve crop production. In the present study, two contrasting wheat cultivars (PBW670 and C306) were subjected to moderate drought stress of 50-55% field capacity for eight days during the jointing stage to generate drought priming (DP) response. Fifteen days after anthesis heat stress (36 °C) was imposed for three days and physiological response of primed, and non-primed plants was assessed by analyzing membrane damage, water status and antioxidative enzymes. Heat shock transcription factors (14 TaHSFs), calmodulin (TaCaM5), antioxidative genes (TaSOD, TaPOX), polyamine biosynthesis genes and glutathione biosynthesis genes were analyzed. GC-MS based untargeted metabolite profiling was carried out to underpin the associated metabolic changes. Yield related parameters were recorded at maturity to finally assess the priming response. Heat stress response was visible from day one of exposure in terms of membrane damage and elevated antioxidative enzymes activity. DP reduced the impact of heat stress by lowering the membrane damage (ELI, MDA & LOX) and enhancing antioxidative enzyme activity except APX in both the cultivars. Drought priming upregulated the expression of HSFs, calmodulin, antioxidative genes, polyamines, and the glutathione biosynthesis genes. Drought priming altered key amino acids, carbohydrate, and fatty acid metabolism in PBW670 but also promoted thermotolerance in C306. Overall, DP provided a multifaceted approach against heat stress and positive association with yield.

Short- and long-term warming events on photosynthetic physiology, growth, and yields of field grown crops

Global temperatures are rising from increasing concentrations of greenhouse gases in the atmosphere associated with anthropogenic activities. Global warming includes a warmer shift in mean temperatures as well as increases in the probability of extreme heating events, termed heat waves. Despite the ability of plants to cope with temporal variations in temperature, global warming is increasingly presenting challenges to agroecosystems. The impact of warming on crop species has direct consequences on food security, therefore understanding impacts and opportunities to adapt crops to global warming necessitates experimentation that allows for modification of growth environments to represent global warming scenarios. Published studies addressing crop responses to warming are extensive, however, in-field studies where growth temperature is manipulated to mimic global warming are limited. Here, we provide an overview of in-field heating techniques employed to understand crop responses to warmer growth environments. We then focus on key results associated with season-long warming, as expected with rising global mean temperatures, and with heat waves, as a consequence of increasing temperature variability and rising global mean temperatures. We then discuss the role of rising temperatures on atmospheric water vapor pressure deficit and potential implications for crop photosynthesis and productivity. Finally, we review strategies by which crop photosynthetic processes might be optimized to adapt crops to the increasing temperatures and frequencies of heat waves. Key findings from this review are that higher temperatures consistently reduce photosynthesis and yields of crops even as atmospheric carbon dioxide increases, yet potential strategies to minimize losses from high-temperature exist.

Cold tolerance identification of nine Rosa L. materials and expression patterns of genes related to cold tolerance in Rosa hybrida

Members of the Rosa genus have a high ornamental value, but their cultivation area is limited by their sensitivity to cold temperatures. The aim of this study was to evaluate the cold tolerance of a range of Rosa materials, and then determine which genes were related to cold tolerance. Nine Rosa materials were subjected to a cold treatment. To identify genes related to cold tolerance, R. hybrida was treated at -15°C for 10 min, and leaves collected before and after this treatment were collected for RNA-Seq analyses. The transcript profiles of four DEGs (POD17, NDUFA9, PMA1, and b-Amy1) in R. hybrida were determined by qRT-PCR at 0 h, 1 h, 2 h, and 3 h at -15°C. Nine Rosa materials were subjected to a cold treatment, and the most cold-tolerant materials were identified as those that showed the lowest levels of electrolyte leakage and the best recovery after 30 d of growth. The most cold-tolerant materials were Rosa hybrida, Rosa rugosa 'Pingyin 12', and Rosa rugosa. In total, 204 significantly differentially expressed genes (DEGs) were identified, of which 88 were significantly up-regulated and 116 were significantly down-regulated under cold conditions. Gene Ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that the DEGs were enriched in 57 pathways, especially starch and sucrose metabolism, phenylpropane biosynthesis, MAPK signaling, fructose and mannose metabolism, and oxidative phosphorylation. By transcriptional analysis, PMA1, which was related to H⁺ ATPase activity, was continuously up-regulated, but the transcript levels of POD17, NDUFA9, and β-Amy1 fluctuated during the freezing treatment. This research uncovered scarce cold-resistant materials and layed the foundation for further research on the cold tolerance mechanism of Rosa plants and the breeding of cold-tolerant varieties.

Adaptive strategy of plant cells during chilling: Aspect of ultrastructural reorganization

The review is focused on a comparative analysis of the literature data on the ultrastructural reorganization of leaf cells of higher plants, which differ in their response to low sub-damaging temperatures. The importance of adaptive structural reorganization of cells as a special feature contributing to the surviving strategy of plants existing under changed conditions is emphasized. The adaptive strategy of cold-tolerant plants combines the structural, functional, metabolic, physiological and biochemical reorganization of cells and tissues. These changes constitute a unified program directed to protecting against dehydration and oxidative stress, as well as maintaining basic physiological processes, and above all, photosynthesis. The ultrastructural markers of cold-tolerant plants adaptation to low sub-damaging temperatures include some particular changes in cell morphology. Namely: the following: an increase in the volume of the cytoplasm; the formation of new membrane elements in it; an increase in the size and number of chloroplasts and mitochondria; concentration of mitochondria and peroxisomes near chloroplasts; polymorphism of mitochondria; an increase in the number of cristae in them; the appearance of outgrowths and invaginations in chloroplasts; lumen expansion in the thylakoids; the formation in chloroplasts "sun type" membrane system with reduction in the number and size of grana and domination of non-appressed thylakoids membranes. Due to this adaptive structural reorganization cold-tolerant plants are able to function actively during chilling. On the contrary, structural reorganization of leaf cells of cold-sensitive plants under chilling is aimed at maintaining the basic functions at a minimum level. Cold-sensitive plants "wait out" low temperature stress, and with prolonged exposure to cold, they die from dehydration and intensification of oxidative stress.

Actin Depolymerization Factor ADF1 Regulated by MYB30 Plays an Important Role in Plant Thermal Adaptation

Actin filaments are essential for plant adaptation to high temperatures. However, the molecular mechanisms of actin filaments in plant thermal adaptation remain unclear. Here, we found that the expression of Arabidopsis actin depolymerization factor 1 (AtADF1) was repressed by high temperatures. Compared with wild-type seedlings (WT), the mutation of AtADF1 and the overexpression of AtADF1 led to promoted and inhibited plant growth under high temperature conditions, respectively. Further, high temperatures induced the stability of actin filaments in plants. Compared with WT, Atadf1-1 mutant seedlings showed more stability of actin filaments under normal and high temperature conditions, while the AtADF1 overexpression seedlings showed the opposite results. Additionally, AtMYB30 directly bound to the promoter of AtADF1 at a known AtMYB30 binding site, AACAAAC, and promoted the transcription of AtADF1 under high temperature treatments. Genetic analysis further indicated that AtMYB30 regulated AtADF1 under high temperature treatments. Chinese cabbage ADF1 (BrADF1) was highly homologous with AtADF1. The expression of BrADF1 was inhibited by high temperatures. BrADF1 overexpression inhibited plant growth and reduced the percentage of actin cable and the average length of actin filaments in Arabidopsis, which were similar to those of AtADF1 overexpression seedlings. AtADF1 and BrADF1 also affected the expression of some key heat response genes. In conclusion, our results indicate that ADF1 plays an important role in plant thermal adaptation by blocking the high-temperature-induced stability of actin filaments and is directly regulated by MYB30.

Biosynthesis of 2-Acetyl-1-pyrroline in Fragrant Rice: Recent Insights into Agro-management, Environmental Factors, and Functional Genomics

Rice is a staple food for more than half of the world's population, and rice fragrance is a key quality attribute which is highly desired by consumers and attracts premium prices in the international market. There are around 200 volatile compounds involved in rice fragrance, but 2-acetyl-1-pyrroline (2-AP) has been considered a master regulator of aroma in fragrant rice. Consequently, efforts were made to increase the 2-AP contents in the grain by managing agronomical practices or by using modern functional genomic tools, which successfully converted nonfragrant cultivars to fragrant rice. Furthermore, environmental factors were also reported to influence the 2-AP contents. However, a comprehensive analysis of 2-AP biosynthesis in response to agro-management practices, environmental factors, and the application of functional genomic tools for fragrant rice production was missing. In this Review, we summarize how micro/macronutrients, cultivation practices, amino acid precursors, growth regulators, and environmental factors, such as drought, salinity, light, and temperature, influence the 2-AP biosynthesis to modulate the aroma of fragrant rice. Furthermore, we also summarized the successful conversion of nonfragrant rice cultivars to fragrant rice using modern gene editing tools, such as RNAi, TALENS, and CRISPR-Cas9. Finally, we discussed and highlighted the future perspective and challenges related to the aroma of fragrant rice.

Alleviation of cold stress in wheat with psychrotrophic phosphorus solubilizing Acinetobacter rhizosphaerae EU-KL44

Low-temperature stress can seriously impair plant physiology. Chilling injury leads to a complex array of cellular dysfunctions, and symptoms include chlorosis, sterility, loss of vigor, wilting, and even death of the plants. Furthermore, phosphorus limitations additionally halt the growth of plants. Low-temperature adaptive plant growth-promoting microbes through various direct and indirect mechanisms help in the survival of plants under stress conditions. The present investigation deals with isolation of P-solubilizing psychrotrophic bacteria from diverse cultivars of wheat grown in the Keylong region of Himachal Pradesh. A total of 33 P-solubilizing bacterial isolates were obtained. P-solubilizers were screened for different plant growth-promoting (PGP) attributes of K and Zn solubilization, production of IAA, siderophores, and different hydrolytic enzymes. Among 33 P-solubilizers, 8 efficient strains exhibiting multiple PGP attributes were used as bioinoculants for wheat under low-temperature stress in different in vitro and in vivo experiments. The psychrotrophic bacterial isolates positively influenced the growth and physiological parameters as well as nutrient uptake and yield of wheat and efficiently alleviated low-temperature stress. The potential of low-temperature stress adaptive and PGP microbes can be utilized in agricultural sector for amelioration of low-temperature stress and plant growth promotion. The present study deals with the isolation of psychrotrophic P-solubilizers with multiple PGP attributes and their role in alleviation of cold stress in wheat.

Cadmium contributes to heat tolerance of a hyperaccumulator plant species Sedum alfredii

Hyperaccumulators are plant species that tolerate and accumulate very high concentrations of toxic metals, including Cd. Hyperaccumulation of heavy metals is reported to benefit plant biotic resistance; however, no prior study has examined the possible role of toxic metals on abiotic stress resistance in hyperaccumulators. A preliminary experiment found that Cd significantly improved plant growth of a hyperaccumulator, Sedum alfredii Hance, under heat stress. This study investigated the possible role of Cd in S. alfredii's heat resistance, using infrared thermography, transmission electron microscopy (TEM), real-time quantitative polymerase chain reaction (RTqPCR), and high-throughput sequencing. The results showed that high temperatures irreversibly damaged stomatal function, chloroplast structure, photosynthesis in S. alfredii, and lowered survival rates to 25%. However, Cd application significantly decreased the leaf temperature of S. alfredii and increased the survival rate to 75%. Cd penetrated the guard cells, restored stomatal function, and mitigated excessive water loss from S. alfredii under heat stress. Moreover, it activated antioxidant enzymes, promoted phytohormone biosynthesis, and upregulated a series of unigenes, thereby augmenting heat resistance in S. alfredii. These results indicate that Cd effectively improved thermotolerance in S. alfredii by regulating stomatal movement and antioxidant systems via upregulation of phytohormones and heat shock proteins.

Transcriptomic and hormonal analysis of the roots of maize seedlings grown hydroponically at low temperature

Prolonged cold stress has a strong effect on plant growth and development, especially in subtropical crops such as maize. Soil temperature limits primary root elongation, mainly during early seedling establishment. However, little is known about how moderate temperature fluctuations affect root growth at the molecular and physiological levels. We have studied root tips of young maize seedlings grown hydroponically at 30 ºC and after a short period (up to 24 h) of moderate cooling (20 ºC). We found that both cell division and cell elongation in the root apical meristem are affected by temperature. Time-course analyses of hormonal and transcriptomic profiles were achieved after temperature reduction from 30 ºC to 20 ºC. Our results highlighted a complex regulation of endogenous pathways leading to adaptive root responses to moderate cooling conditions.

Boosting Sustainable Agriculture by Arbuscular Mycorrhiza under Stress Condition: Mechanism and Future Prospective

Global agriculture is frequently subjected to stresses from increased salt content, drought, heavy metals, and other factors, which limit plant growth and production, deteriorate soil health, and constitute a severe danger to global food security. Development of environmentally acceptable mitigation techniques against stresses and restrictions on the use of chemical fertilizers in agricultural fields is essential. Therefore, eco-friendly practises must be kept to prevent the detrimental impacts of stress on agricultural regions. The advanced metabolic machinery needed to handle this issue is not now existent in plants to deal against the stresses. Research has shown that the key role and mechanisms of arbuscular mycorrhiza fungi (AMF) to enhance plant nutrient uptake, immobilisation and translocation of heavy metals, and plant growth-promoting attributes may be suitable agents for plant growth under diversed stressed condition. The successful symbiosis and the functional relationship between the plant and AMF may build the protective regulatory mechansm against the key challenge in particular stress. AMF's compatibility with hyperaccumulator plants has also been supported by studies on gene regulation and theoretical arguments. In order to address this account, the present review included reducing the impacts of biotic and abiotic stress through AMF, the mechanisms of AMF to improve the host plant's capacity to endure stress, and the strategies employed by AM fungus to support plant survival in stressful conditions.

Increasing Temperatures Potentiate the Damage of Rare Earth Element Yttrium to the Crop Plant Triticum aestivum L

Given that increasing temperature may aggravate the toxicity of pollutants, it is a daunting challenge to evaluate the realistic risks of rare earth elements (REEs) under global warming. Here, we studied how elevated temperatures (27 and 32 °C) impact the effect of yttrium (Y) on wheat plants (Triticum aestivum L.) at concentrations not causing effects (0, 0.5, and 1 μM) at the control temperature (22 °C) in a hydroponic system. After 14 days of exposure, significant inhibition (p < 0.05, 29.5%) of root elongation was observed only at 1 μM of Y at 32 °C. Exposure to Y at 27 °C showed no visible effects on root length, but induced significant (p < 0.05) metabolic disorders of a range of carbohydrates and amino acids related to galactose, phenylalanine, and glutamate metabolisms. Such cases were even shifted to substantial perturbation of the nucleotide pool reallocation involved in the disruption of purine and pyrimidine metabolism at 32 °C. These observations were regulated by sets of genes involved in these perturbed pathways. Using weighted gene co-expression network analysis, the disorder of nucleotide metabolism was shown to be responsible for the aggravated Y phytotoxicity at the extreme high temperature. Although the temperature fluctuation considered seems to be in an extreme range, unexpected implications driven by high temperature cannot be neglected. Our findings thus reduce the gaps of knowledge in REE toxicity to plants under future climate warming scenarios and highlight the importance of incorporating environmental temperature into the framework of the risk assessment of REEs.

Transcriptome and Metabolome Analysis Revealed That Exogenous Spermidine-Modulated Flavone Enhances the Heat Tolerance of Lettuce

Lettuce is sensitive to high temperature, and exogenous spermidine can improve heat tolerance in lettuce, but its intrinsic mechanism is still unclear. We analyzed the effects of exogenous spermidine on the leaf physiological metabolism, transcriptome and metabolome of lettuce seedlings under high-temperature stress using the heat-sensitive lettuce variety 'Beisansheng No. 3' as the material. The results showed that exogenous spermidine increased the total fresh weight, total dry weight, root length, chlorophyll content and total flavonoid content, increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and decreased malondialdehyde (MDA) content in lettuce under high temperature stress. Transcriptome and metabolome analyses revealed 818 differentially expressed genes (DEGs) and 393 metabolites between water spray and spermidine spray treatments under high temperature stress, and 75 genes from 13 transcription factors (TF) families were included in the DEGs. The Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis of DEG contains pathways for plant-pathogen interactions, photosynthesis-antennal proteins, mitogen-activated protein kinase (MAPK) signaling pathway and flavonoid biosynthesis. A total of 19 genes related to flavonoid synthesis were detected. Most of these 19 DEGs were down-regulated under high temperature stress and up-regulated after spermidine application, which may be responsible for the increase in total flavonoid content. We provide a possible source and conjecture for exploring the mechanism of exogenous spermidine-mediated heat tolerance in lettuce.