Spring frost is a major environmental stress caused by low temperature combined with dewpoints below freezing points (≤ 0°C), posing substantial economic threat on plants. While the terms “frost damage” and “freeze damage” are commonly used interchangeably, there are slight distinctions between them. Freeze damage is attributed to temperature below freezing points, whereas frost damage is caused by dewpoints below freezing points irrespective of temperature being at or below freezing points (Perry, 1998). However, the damage mechanisms at organ level are comparable in both cases. Consequently, for the purpose of this review, the term “freeze damage” will be employed. At the organ level, the damage occurs when water within plant tissues freezes, forming extracellular ice crystals that result in cell dehydration. Freezing-induced cellular dehydration is the predominant cause of damage in which the cell membranes are disrupted when the dehydration exceeds cell dehydration-tolerance (Pearce, 2001). The severity of damage is determined by multiple factors including plants species, their genetic makeup, dewpoint, surface moisture, probability of an extracellular ice nucleation event, pre-frost environmental conditions, and developmental stage – with flowering being the most susceptible developmental stage (Centinari et al., 2016). Crops can be exposed to two types of frost: radiation and advective – with the former being more common (Liu and Sherif, 2019). Radiation frost is a meteorological phenomenon resulting from the release of thermal energy stored in the soil. This thermal energy is radiated back into the atmosphere during the nocturnal period, characterized by a stable atmosphere and a low wind regime, allowing the formation of a temperature inversion. This atmospheric condition, in conjunction with a reduced dewpoint temperature, leads to a sharp reduction in the air temperature, which falls below the freezing point of water. Advective frost, on the other hand, occurs when a massive system of cold air moves into an area from polar and arctic regions, typically accompanied by wind ≥ 8 km/h. The resultant wind-driven turbulent mixing and cold advection lead to a significant reduction in the air temperature, resulting in the formation of frost.

Crop losses resulting from frost damage represent a significant economic threat to the crop production industry, with frost-related yield reduction being ranked highest among all weather-related disasters in the United States (Centinari et al., 2016; Snyder and de Melo-Abreu, 2005). For example, the one-week Easter freeze in 2007 led to over 2 billion dollars in economic losses due to reduced production of wheat (Triticum aestivum) by 19%, peach (Prunus persica) by 75%, apple (Malus domestica) by 67%, and pecan (Carya illinoinensis) by 66% (Liu et al., 2018). Additionally, based on our observations, even a brief frost event persisting only for a few hours can cause substantial damage to various crops. A recent hard freeze event in 2022, lasting 2.5 hours in Virginia, U.S., resulted in an 80% rate of damage to the sweet cherry crop, 15 – 35% damage to apple floral buds, and 15% damage to peach crops (Sherif, 2023). Climate change, leading to increasing global temperatures, exacerbates this threat (Liu et al., 2018), causing alterations in plant phenology such as shortened dormancy and early budburst and flowering (Augspurger, 2013; Ma et al., 2019). Economic losses vary in severity, ranging from partial to complete loss of valuable crops, and can have detrimental impacts on crop quality. Frost-related losses are not limited to specific regions or species; rather, they are a global phenomenon. Notable incidents such as the Easter freeze of 2007 (Liu et al., 2018), the Mother’s Day Freeze (2010), the Killer Frost (2012), and the Polar Vortex (2014) have inflicted billions of dollars in damages on the agricultural industry across North America.

The critical temperature at which crop damage occurs depends on multiple factors, including species specificity, duration of the frost event, and developmental stage (Centinari et al., 2016). For instance, the lower temperature limit at which 90% of floral buds are damaged ranges from -17.6˚C to -3.0˚C for tree fruits like apples, -19.4˚C to -2.8˚C for grapes, -6.1˚C to -0.6˚C for small fruits like strawberries, and -2.8˚C to -0.8˚C for citrus (Snyder and de Melo-Abreu, 2005). Plants at the dormant stage are less susceptible to low temperatures compared to advanced developmental stages. For example, apple floral buds at the silver-tip stage, characterized by slight separation and a shimmery gray color, can tolerate temperatures as low as -17.6˚C. However, at the post-bloom stage, 90% flower mortality can occur at -3˚C. Furthermore, the duration and severity of a frost event have a significant impact on the extent of damage – the more severe and longer it persists, the more damage occurs. Our research, involving a series of experiments investigating frost mitigation strategies, showed that a deleterious frost event in 2023, persisting for 1.5 hours, resulted in approximately 87% damage to apple floral buds, while a 2-hour long frost event in 2021 caused around 65% bud mortality. However, a relatively longer frost event in 2022, lasting around 2.5 hours, resulted in approximately 15 – 35% damage to floral buds. Interestingly, although the duration of frost in 2022 was relatively longer, it coincided with the early developmental stage of the crops, resulting in comparatively lower damage to the crops (Sherif, 2023). These observations suggest that crops at an early developmental stage exhibit increased resilience to extended frost exposure.

Frost protection methods for plants can be categorized into passive and active methods. Passive methods are considered preventive measures applied before the occurrence of frost events (Liu and Sherif, 2019). These methods are more economically efficient compared to active ones and are intended to provide protection over an extended period. Examples of passive methods include site selection, enhancing plant tolerance to frost through the application of cryoprotectant compounds and growth regulators, and the selection of frost-tolerant varieties (cold-hardy and/or late-blooming varieties). On the other hand, active frost protection methods are those applied during or immediately before a frost event with the aim of preventing the temperature from dropping below the freezing point. These methods involve various techniques including heaters (i.e., solid fuel, propane), wind machines, helicopters, surface irrigation, and sprinklers (i.e., over- and under-tree sprinklers). These approaches are designed to actively counteract the effects of frost in real-time.

Specific weather conditions, including wind speed, humidity, and the severity and duration of a frost event, significantly influence the efficacy of both active and passive methods of frost mitigation (Unterberger et al., 2018). For example, wind machines are beneficial for countering radiation frost, but they fail to provide protection against advective frost. Moreover, active methods frequently carry considerable costs, such as those involved in the acquisition and upkeep of necessary equipment. Implementing heaters is one such method, which, while effective, necessitates energy consumption and regular maintenance expenses. Another example is the use of helicopters, the operation and fueling of which can be significantly costly. Certain practical constraints may also emerge, causing some methods to be unsuitable in particular agricultural contexts. An example is the implementation of surface irrigation or sprinkler systems, which might not be feasible in regions with scarce water resources. In addition to these considerations, the environmental impact of these methods, particularly in terms of their energy and water usage, should be evaluated to determine their sustainability. A comprehensive understanding of these limitations is indispensable for making informed decisions about frost protection strategies, as this allows for the consideration of the specific needs and restrictions unique to each agricultural system.

A relatively recent strategy to mitigate frost damage in plants involves the application of chemical compounds, specifically plant growth regulators (PGRs). Over the past half-century, researchers have extensively probed PGRs for their potential in bolstering plant frost tolerance and delaying blooming periods, thereby averting late-spring freezes. Ethephon (2-chloroethylphosphonic acid), for example, is an ethylene-based PGR compound that has shown promising results in delaying bloom and increasing cold hardiness in various fruit and nut trees (Liu and Sherif, 2019; Liu et al., 2021a). Our research involved conducting a set of experiments to investigate the impact of ethephon applications on bloom delay. Our findings revealed that applying ethephon in the fall resulted in a bloom delay of 5-6 days in peaches, varying based on application timing and concentration (Liu et al., 2021a). Such a delay could notably lower the risk of frost damage. Furthermore, our results indicated that ethephon could enhance the cold hardiness of dormant buds, thereby promoting their survival through winter. However, ethephon application does have its drawbacks. For instance, it has been associated with adverse effects like gummosis, terminal dieback, and yield reduction (Liu et al., 2021a). Another frost damage mitigation approach involves applying exogenous cryoprotectant compounds. Yet, the specific physiological and molecular mechanisms that enable these compounds to offer frost protection remain relatively unclear. In this article, we present an in-depth overview of the physiological and molecular mechanisms associated with cryoprotectant compounds. However, gaining a robust understanding of these mechanisms requires a comprehensive grasp of plant cold-sensing mechanisms, natural plant defenses against freezing, and the damaging effects of freezing on plant tissues. Therefore, we also provide a detailed examination of these defense mechanisms and the impact of freezing on plants.

Plants have evolved intricate mechanisms to identify and respond to abiotic stresses such as cold stress. They perceive shifts in their physical and chemical surroundings like water availability, ion concentration, and temperature, and translate these changes into a biological signal via primary sensory mechanisms (Lamers et al., 2020). Each sensor is typically designed to detect a specific feature of the stress, potentially playing a role in a unique branch of the stress signaling pathway. In this context, the cold-signaling pathway is our focal point for this article. Plants deploy sophisticated multilevel processes in response to a decrease in temperature (Örvar et al., 2000). At the cellular level, cold stress signals are perceived via a variety of receptors that include plasma membrane (PM) rigidification, PM-bound G-protein-associated receptors, and other cold sensors such as Ca²⁺ influx channels, two-component histidine kinases, and changes in protein and nucleic acid conformations or metabolite concentrations ( Figure 1 ) (Kazemi-Shahandashti and Maali-Amiri, 2018). These signals give rise to secondary messengers like Ca²⁺, ROS, and inositol phosphates. These messengers subsequently adjust the intracellular Ca²⁺ level. Changes in the cytosolic Ca²⁺ level are detected by calcium-binding proteins, also known as Ca²⁺ sensors. These sensors engage with their target proteins to relay the calcium signal within the cell. These proteins coordinate the transfer of the cold stress signal, trigger protein phosphorylation cascades, and manage the expression of transcription factors and cold-regulated (COR) genes in plants ( Figure 1 , Table 1 ) (Drerup et al., 2013; Zhang et al., 2014; Ma et al., 2015; Zhu, 2016; Guo et al., 2018).

Plant cold signaling perception and transduction have been extensively studied in recent years, leading to significant advances in our understanding of this complex process (Zhang et al., 2017; Zhao et al., 2017; Ding et al., 2018; Guo et al., 2018). Plants perceive the environmental stimuli and transduce the signal into downstream biological responses by decreasing membrane fluidity, which in turn affects membrane-associated cellular functions (Hou et al., 2014). Different microdomains with specific lipid compositions, including sphingolipids in the plasma membrane, have been identified for their crucial roles in sensing particular temperature ranges (Fabri et al., 2020). Additionally, multiple cold sensors associated with sending temperature changes and cold signaling, such as putative calcium channels, PM-bound G-protein-associated receptors, and plasma membrane-localized receptor-like kinases (RLKs), have been identified in plants ( Figure 1 ). Calcium ions enter the cell primarily through transmembrane proteins complex, known as calcium channels, which are crucial sensors for abiotic stress (Görlach et al., 2015). The rigidification of the membrane due to cold stress activates mechanosensitive or ligand-activated calcium channels, leading to a transient Ca²⁺ influx into the cytosol (Wei et al., 2021).

After perceiving cold stress, plants initiate a series of intricate signal transduction events within the cytosol and nucleus. These events rely on secondary messengers like Ca²⁺, ROS, and nitric oxide (NO) to facilitate intracellular signaling and cell-to-cell communication (Marcec et al., 2019). Cold stress-induced Ca²⁺ signatures are deciphered through various pathways involving specific groups of Ca²⁺ sensors such as CaM (calmodulin) and CMLs (CaM-like), CDPKs (Ca²⁺-dependent protein kinases), CCaMK (Ca²⁺-and Ca²⁺/CaM-dependent protein kinase), CAMTA (CaM-binding transcription activator), CBLs (calcineurin B-like proteins) and CIPKs (CBL-interacting protein kinases) (Kudla et al., 2018). The Calcium/CaM-Regulated Receptor-Like Kinase 1, CRLK1, actively modulates MAPK kinase activity and exerts regulatory control over C-repeat Binding Factors (CBFs) regulons, as well as freezing tolerance (Yang et al., 2010). Subsequent downstream reactions in plants are triggered by cold stress encompass the ICE-CBF/DREB1 pathway, the intricate regulation of cold-responsive genes (Miura and Furumoto, 2013), and post-transcriptional and post-translational modifications (Vyse et al., 2020).

In addition to the plasma membrane, chloroplasts may also serve as important sensors for ambient temperature. When temperatures drop, the equilibrium between the ability to capture light energy and the ability to disperse this energy through metabolic processes is disturbed. This disruption results in enhanced excitation pressure on photosystem II (PSII) and subsequently hinders the photosynthetic capacity by inhibiting it (Ivanov et al., 2012). This phenomenon, known as photoinhibition, results in redox imbalances in photosynthetic electron transport and photosynthetic carbon reduction cycles. Eventually, the photosynthetic apparatus is destroyed, and ROS are generated, serving as a secondary messenger (Bhattacharjee, 2019). Disruption of the photosynthesis process under cold-stress conditions significantly reduces crop yield through various mechanisms. The maximum attainable yield, which represents the optimal conversion of captured light energy into biomass, known as photosynthetic efficiency, is compromised under cold stress (Simkin et al., 2019). This reduction in photosynthetic efficiency is primarily attributed to the impairment of key enzymes involved in the carbon fixation cycle, namely fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-1,7-bisphosphatase (SBPase) (Sassenrath et al.,1990; Kingston-Smith et al., 1997; Hutchison et al., 2000). The decreased activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), the primary enzyme involved in carbon fixation, and the reduction in bisphosphate (RuBP) levels are processes observed at low temperatures. Multiple causes contribute to the diminished RuBP regeneration, such as limitations in linear electron transport, chronic photoinactivation, deactivation of stromal bisphosphatases, and end-product limitation. In the case of end-product limitation, the limited synthesis of sucrose, starch, and amino acids leads to the accumulation of phosphorylated intermediates, depletion of the inorganic phosphate pool, and inhibition of ATP synthesis (Leegood and Furbank, 1986; Sharkey et al., 1986; Lemoine et al., 2013). Furthermore, imbalances in the source-sink relationship, where the plant’s source activity surpasses the sink demand, result in decreased mRNA levels, degradation of photosynthetic proteins, and ultimately reduced productivity (Adams et al., 2013; Kurepin et al., 2015). These combined effects contribute to lower crop yields under cold stress conditions.

At freezing temperatures, the aggregation of water molecules within plant cells leads to the formation of stable ice nuclei, which is a critical step in initiating the freezing process. Ice nucleation occurs when these small ice nuclei form a group of membrane proteins known as ice-nucleating proteins (INPs), which act as nucleation sites. These sites promote the formation of extracellular ice crystals by facilitating the proper arrangement of water molecules. In the absence of ice-binding proteins (IBPs), large ice crystals form in the apoplast, which can physically damage plasma membranes. The formation of ice crystals and the subsequent sequestration of intracellular water create an osmotic gradient, leading to cellular dehydration. This loss of cell volume can result in cell collapse or rupture (Pearce, 2001; Larcher, 2003; Snyder and de Melo-Abreu 2005; Zhang et al., 2019). Freeze damage also occurs due to alterations in membrane fluidity caused by the transition of lipid components from liquid into a gel state. This transition reduces membrane selectivity, increases permeability, destabilizes metabolic activities, and inhibits photosynthesis (Larcher, 2003; Zhang et al., 2019).

The magnitude of damage depends on the intensity and duration of freezing conditions and the developmental stage of the plant (Larcher, 2003; Centinari et al., 2016). In some cases, plants can delay the formation of extracellular ice crystals through a process called supercooling, where water in plant tissues remain in a liquid state below the freezing point of water. Supercooling in plants is a sophisticated process, involving various mechanisms working synergistically. It prevents the transition of intercellular water from a liquid to a solid state, effectively suppressing water nucleation and thereby avoiding ice crystallization (Wisniewski et al., 2004; Londo and Kovaleski, 2019). Supercooling is a common phenomenon in woody plants, manifesting in both leaves and the living cells of the xylem, including the xylem ray parenchyma cells. This phenomenon readily takes place in small volumes of water, where the free energy of water is influenced by surface properties, especially in the absence of nucleation particles or agents responsible for initiating ice-crystal formation. This process allows cells to maintain their function, albeit at a relatively reduced rate, and become more tolerant to freeze damage (Cavender-Bares, 2005). However, even in supercooled parts of the plant, progressive dehydration can still occur, indicating that the avoidance of freezing-induced dehydration through deep supercooling is only partial (Pearce, 2001; Larcher, 2003).

Another equally important factor that influences the extent of damage caused by dehydration is the ratio of bound water to free water within plant cells. As freezing-induced dehydration progresses, it can disrupt cell structures associated with the bound water compartment, which is involved in the structural organization of membranes, organelles, and proteins. This disruption can result in irreversible injury to the cells (Elliott et al., 2017). Negative osmotic pressure induces a net movement of water towards the extracellular space, reducing cell volume. In non-acclimated cells, this reduction in cell volume leads to invagination of the plasma membrane and formation of endocytic vesicles, resulting in loss of surface area of the plasma membrane. Upon rewarming, melted water from the extracellular space re-enters the cell, causing the cell to burst before it can regain its original volume (Ambroise et al., 2020).

The antioxidant system in plants also scavenges the excessive amount of ROS, including superoxide (O₂ ^{• −}), hydroxyl radicals (OH ^• ), hydrogen peroxide (H₂O₂) and singlet oxygen (¹O₂) in response to cold stress. The antioxidant compounds play a critical role in maintaining redox homeostasis during cold stress, as optimal levels of ROS are necessary for normal progression of fundamental biological processes including cellular proliferation and differentiation (Tsukagoshi et al., 2010; Mittler, 2017). Under normal conditions, excessive ROS is neutralized through various enzymatic and non-enzymatic antioxidative defense mechanisms. However, when plants are exposed to cold stress, the equilibrium between ROS production and scavenging is disrupted, leading to mitochondrial membrane rigidification (Saha et al., 2015), loss of complex IV (Prasad et al., 1994), DNA damage, and impaired regulation of physiological cell death (Xie et al., 2014; Berni et al., 2019). These disruptive events can cause severe damage to plant cells and their functions, which may affect their survival and reproduction.

Plants possess avoidance and tolerance strategies to mitigate the detrimental effects of freezing temperatures and prevent damage to their cellular structures (Larcher, 2003; Hoermiller et al., 2018). Avoidance mechanisms rely on a variety of cryoprotectant molecules to reduce the intracellular freezing temperature through a plant-specific process called supercooling (Francko et al., 2011). These molecules help maintain the intracellular liquids at sub-zero temperatures supercooled and delay or inhibit the formation of extracellular ice crystals (Larcher, 2003; Wisniewski et al., 2018). Certain plant species have developed sophisticated mechanisms to mitigate freezing damage by utilizing IBPs as a part of their survival strategy. IBPs, also known as antifreeze proteins (AFPs) or ice recrystallization inhibition (IRI) proteins, are a group of low temperature-associated proteins found in various cold-adapted organisms, including plants such as Lolium perenne, Loliurn perenne and Ammopiptanthus nanus (Yu et al., 2021), animals, and microorganisms. Plant IBPs possess unique structural features and functional properties that enable them to interact with ice crystals, thereby impeding their growth and inhibiting the movement of water molecules from the intracellular to extracellular space. This binding ability helps prevent cell dehydration and maintains cellular integrity during freezing conditions. Additionally, IBPs exhibit the ability to suppress ice recrystallization, a process that can lead to tissue damage and disrupt plasma membranes. By effectively limiting ice crystal growth and inhibiting ice recrystallization, IBPs play a crucial role in safeguarding plant tissues against freezing temperatures (Bredow and Walker, 2017; Wisniewski et al., 2020). Numerous AFPs have been identified in various plant species, highlighting the diversity of these ice-binding proteins. For example, fpAFP has been discovered in Festuca pratensis (Muthukumaran et al., 2011), LpAFP and LpIRI2/3 in Lolium perenne (Bredow et al., 2017), BdIRI1-7 in Brachypodium distachyon (Bredow et al., 2016), daAFP in Daucus carota (Cid et al., 2018) and rsAFP in Raphanus sativus (Wisniewski et al., 2020). These specific IBPs exemplify the adaptations of plants to withstand freezing stress and highlight the intricate molecular strategies employed by these organisms to protect themselves from the detrimental effects of low temperatures.

Cold tolerance mechanisms involve acquiring tolerance to low, non-freezing temperatures through a process known as cold acclimation. It is a complex physiological process where plants gradually adapt to decreasing temperatures, resulting in enhanced hardiness and adaptive responses that enable them to withstand freezing conditions. Cold acclimation encompasses coordinated molecular, physiological, and biochemical changes that enhance plant tolerance to cold stress, crucial for survival under low temperature conditions. These adaptations include diverse morphological modifications such as reduced plant height, decreased leaf number, and increased epidermal thickness. Biochemical alterations involve the accumulation of sugars, amino acids, and secondary metabolites. Physiological adjustments encompass decreased photosynthesis, reduced water use efficiency, and altered pigment synthesis. Collectively, these mechanisms enhance a plant’s ability to thrive in cold environments (Fürtauer et al., 2019; Wang et al., 2020; Fang et al., 2021; Guo et al., 2021; Liu et al., 2021b; Satyakam et al., 2022). The regulation of gene expression during cold stress response is a complex network triggered by multiple factors including Ca²⁺ and plant hormones, particularly brassinosteroids (BRs), gibberellins, abscisic acid, jasmonic acid, and ethylene (Arias et al., 2015; Eremina et al., 2016; Hu et al., 2017; Li et al., 2017:1; Juurakko et al., 2021; Mishra et al., 2022; Sarkar and Sadhukhan, 2022). Additionally, plants synthesize secondary metabolites in response to cold stress, such as proline, betaine, and putrescine. These osmolytes act as protective compounds, helping to mitigate the effects of cold stress on plant cells (Lee et al., 2019). Plants also accumulate low-molecular-weight compatible solutes or osmolyte cryoprotectants, such as sucrose, glucose, raffinose, fructose and trehalose. These molecules assist in maintaining cellular osmotic balance and protect cellular structures from cold-induced damage (Karabudak et al., 2014; Lunn et al., 2014; Judy and Kishore, 2016; Roychoudhury and Banerjee, 2016; Suo et al., 2017; Siddique et al., 2018; Liu et al., 2019; Chen et al., 2022). In addition, plants respond to cold stress by increasing the accumulation of suberin and lignin, which contribute to the reinforcement of cell walls and the protection of plant tissues against freezing injury. These modifications are essential for reducing the adverse effects of cold stress on plant growth and development (Trache et al., 2017; Jian et al., 2020; Sun et al., 2021).

The process of cold acclimation in plants also involves plasma membrane rigidification and rearrangement of the cytoskeleton (Knight and Knight, 2012; Ambroise et al., 2020; Satyakam et al., 2022). These alterations trigger increased metabolic activities, initiating signaling pathways that regulate the expression of COR genes (Iqbal et al., 2022; Satyakam et al., 2022). The induction of COR genes is mediated by transcriptional activators known as C-repeat Binding Factors (CBFs), which are controlled by the regulatory module involving the Inducer of CBF Expression (ICE). This regulatory module, referred to as ICE-CBF-COR, represents a central pathway responsible for initiating the cold response in plants (Chinnusamy et al., 2003; Jin et al., 2018). Upon activation, COR genes regulate the synthesis of various protective molecules, including compatible solutes such as soluble sugars and proline, pigments like xanthophylls and carotenoids, amino acids, and cold-responsive proteins such as AFPs, late embryogenesis abundant (LEA) proteins, heat shock proteins (HSPs), cold shock proteins (CSPs), as well as antioxidants and stabilizing proteins like chaperones and dehydrins (DHNs) (Rinehart et al., 2007; Latowski et al., 2011; Yu et al., 2017; Meena et al., 2019; Ambroise et al., 2020). The synthesis and accumulation of these molecules collectively contribute to the development of cold tolerance in plants.

Over the past two decades, agrochemical companies have developed multiple cryoprotectants (such as KDL, Glacier, diKap, Anti-Stress 550, ThermoMax, FrostGard, etc.) for frost protection – a comprehensive list of the artificial cryoprotectants has recently been summarized in a review by (Román‐Figueroa et al., 2021). These compounds, when externally applied to plants, enhance plant’s freezing avoidance ability through various methods. They create a physical barrier around plant tissues, increase the concentration of endogenous cryoprotectants like metabolites and proteins, and boost the intercellular solute concentration. This elevated solute concentration leads to a depression in freezing point, preventing the formation of extracellular ice crystals and reducing cell dehydration-induced damage caused by apoplastic freezing. It has also been suggested that solute accumulation stabilizes cell membranes and macromolecules, either through direct interaction with the membrane surface or through strong interplay with the surrounding water. The precise mechanism by which these molecules prevent ice crystal formation and cell dehydration is intricate and varies depending on the specific type of cryoprotectant. In this summary, we outline some general mechanisms through which cryoprotectants alleviate freezing damage to plant tissues.

Plants utilize advanced molecular mechanisms to perceive and respond to cold stress. Transmembrane proteins function as initial sensors for cold stress signals, triggering a cascade of molecular events that involve the generation of secondary messengers such as calcium ions (Ca²⁺), reactive oxygen species (ROS), and inositol phosphates. Among these, calcium signaling plays a critical role, activating downstream phosphorylation cascades and inducing the transcription of cold-responsive genes, including the cold-regulated (COR) genes. Cold stress imposes significant challenges on plant tissues, leading to membrane rigidification and dehydration caused by freeze-induced damage. In an effort to mitigate these adverse effects, plants have evolved strategies encompassing both avoidance and tolerance mechanisms. Tolerance mechanisms involve the gradual acclimatization of plants to decreasing temperatures, allowing them to incrementally accumulate cold tolerance. In contrast, avoidance mechanisms are predicted on the presence of cryoprotectant molecules such as potassium ions (K⁺), proline, glycerol, and antifreeze proteins (AFPs).

Cryoprotectants operate by increasing intracellular solute concentration, thereby lowering the freezing point and obstructing ice formation. These molecules also exhibit potent antioxidant properties, efficiently scavenging ROS and preventing protein denaturation. By forming extensive hydrogen bonds with water molecules, cryoprotectants can also alter water properties, limiting intercellular water movement, and minimizing extracellular ice crystal formation ( Figure 2 ). This action consequently reduces cell dehydration and mitigates freeze-induced cellular damage. In addition, cryoprotectants aid in the preservation of plasma membrane fluidity and the reduction of electrolyte leakage, effectively shielding plant cells against freeze-induced injury. The intricate relationship between these cryoprotectant molecules and cellular processes enhances the plant’s resilience to cold stress and bolsters survival in freezing environments. Taken together, the deployment of cryoprotectants represents a sophisticated adaptive strategy utilized by plants to counter the damaging effects of cold stress, thereby facilitating their acclimation and survival in freezing conditions. Nevertheless, a comprehensive understanding of these mechanisms warrants further research. It is essential to elucidate the physiological and molecular mechanisms of these compounds and evaluate their potential impact on crop productivity and sustainability. Such efforts will undoubtedly contribute to the ongoing advancement of plant biology and the broader field of environmental science.

KJ conducted literature searches, prepared schematic diagrams, and wrote the first draft. AS contributed to figure preparation and literature review. SS oversaw the study, provided edits to improve clarity and readability, and ensured the overall quality of the manuscript. All authors contributed to the article and approved the submitted version.