Search

Twenty Pinus taeda L. families from both the Coastal Plain and Piedmont provenances in the southeastern United States were planted on an upper Piedmont site that experienced a severe ice storm at age 3 years. Storm damage and defect rates through age 11 years were compared with the seed transfer distance and the seed parents' breeding values to develop prediction models for storm damage and rates of forking, stem break, and sawtimber potential. Warmer-source families had higher probability of limb or stem breaks and foliage injury from the storm. Taller trees were more likely to experience breaks and foliage injury, even after accounting for seed transfer distance. Trees with forks or fusiform rust (Cronartium quercuum f. sp. fusiforme) infection had a higher probability of breaks. Trees with limb breaks or foliage injury did not have reduced sawtimber potential, but broken stems reduced sawtimber potential. The storm did not cause immediate mortality, but trees with major limb breaks, stem breaks, or foliage injury were less likely to be alive at age 8 years. At age 11 years, families with the best combination of breeding values for forking, straightness, and rust resistance had a predicted 60% of stems having sawtimber potential, whereas families with the worst combination had 30%. Study Implications : Planting warmer-source Pinus taeda (loblolly pine) families farther north and inland may lead to greater growth but poses a risk of damage from cold temperatures and ice storms. Trees grown for solid-wood products must be relatively defect-free and require a longer rotation, whereas bioenergy and pulpwood can use smaller, defective trees. This analysis presents predictions of defect rates through age 11 years based on the seed source and breeding values using data from a planting in the upper Piedmont of North Carolina. Land managers can use these models to weigh the benefits and risks when choosing families for reforestation. [ABSTRACT FROM AUTHOR]

Abstract Background Understanding adaptation involves establishing connections between selective agents and beneficial population responses. However, relatively little attention has been paid to seasonal adaptation, in part, because it requires complex and integrative knowledge about seasonally fluctuating environmental factors, the effects of variable phenology on exposure to those factors, and evidence for temporal specialization. In the European corn borer moth, Ostrinia nubilalis, sympatric pheromone strains exploit the same host plant (Zea mays) but may genetically differ in phenology and be reproductively “isolated by time.” Z strain populations in eastern North America have been shown to have a prolonged larval diapause and produce one annual mating flight (July), whereas E strain populations complete an earlier (June) and a later (August) mating flight by shortening diapause duration. Here, we find evidence consistent with seasonal “adaptation by time” between these ecotypes. Results We use 12 years of field observation of adult seasonal abundance to estimate phenology of ecotype life cycles and to quantify life-stage specific climatic conditions. We find that the observed reduction of diapause duration in the E strain leads their non-diapausing, active life stages to experience a ~ 4 °C colder environment compared to the equivalent life stages in the Z strain. For a representative pair of populations under controlled laboratory conditions, we compare life-stage specific cold tolerance and find non-diapausing, active life stages in the E strain have as much as a 60% greater capacity to survive rapid cold shock. Enhanced cold hardiness appears unrelated to life-stage specific changes in the temperature at which tissues freeze. Conclusions Our results suggest that isolation by time and adaptation by time may both contribute to population divergence, and they argue for expanded study in this species of allochronic populations in nature experiencing the full spectrum of seasonal environments. Cyclical selective pressures are inherent properties of seasonal habitats. Diverse fluctuating selective agents across each year (temperature, predation, competition, precipitation, etc.) may therefore be underappreciated drivers of biological diversity.

The winter months are challenging for many animal species, which often enter a state of dormancy or hypometabolism to "wait out" the cold weather, food scarcity, reduced daylight, and restricted mobility that can characterize the season. To survive, many species use metabolic rate depression (MRD) to suppress nonessential metabolic processes, conserving energy and limiting tissue atrophy particularly of skeletal and cardiac muscles. Mammalian hibernation is the best recognized example of winter MRD, but some turtle species spend the winter unable to breathe air and use MRD to survive with little or no oxygen (hypoxia/anoxia), and various frogs endure the freezing of about two-thirds of their total body water as extracellular ice. These winter survival strategies are highly effective, but create physiological and metabolic challenges that require specific biochemical adaptive strategies. Gene-related processes as well as epigenetic processes can lower the risk of atrophy during prolonged inactivity and limited nutrient stores, and DNA modifications, mRNA storage, and microRNA action are enacted to maintain and preserve muscle. This review article focuses on epigenetic controls on muscle metabolism that regulate MRD to avoid muscle atrophy and support winter survival in model species of hibernating mammals, anoxia-tolerant turtles and freeze-tolerant frogs. Such research may lead to human applications including muscle-wasting disorders such as sarcopenia, or other conditions of limited mobility. [ABSTRACT FROM AUTHOR]

1. Ant colonies passing through the period of winter dormancy are subject to the two conflicting selective pressures: (i) on escaping the coldest temperatures during the winter by hiding deep into the soil and (ii) on the reactivation after overwintering as soon as the weather conditions become favourable and the soil surface is warm enough. 2. If selective pressures associated with overwintering are affected differently by the spatial variation in the climate conditions then different overwintering strategies can be expected to occur across geographical gradients. 3. In this study, Formica fusca colonies were excavated in north‐eastern Poland to examine the spatial distribution of overwintering ants. It has been found that queens, accompanied by part of the workers, shelter themselves at a depth close to the colony's lower limit. However, workers were clustered at different depths along the soil profile, including a few centimetres from the soil surface. 4. Natural selection might promote to allocate individuals who are less valuable to the colony to more risky tasks (e.g. those performed outside the nest). Thus, playing the role of a forager should be associated with the occupation of more risky positions during overwintering. However, no statistically significant difference has been found between workers overwintering in the upper and lower soil strata in their propensity to explore the experimental arena. 5. The observed pattern of the spatial distribution of overwintering ants indicates the existence of a trade‐off between winter mortality, costs of physiological adaptations, and the time needed for a colony to reactivate in response to temperature increase. [ABSTRACT FROM AUTHOR]

Background and Aims Most perennial plants memorize cold stress for a certain period and retrieve the memories for cold acclimation and deacclimation, which leads to seasonal changes in cold-hardiness. Therefore, a model for evaluating cold stress memories is required for predicting cold-hardiness and for future frost risk assessments under warming climates. In this study we develop a new dynamic model of cold-hardiness by introducing a function imitating past temperature memory in the processes of cold acclimation and deacclimation. Methods We formulated the past temperature memory for plants using thermal time weighted by a forgetting function, and thereby proposed a dynamic model of cold-hardiness. We used the buds of tea plants (Camellia sinensis) from two cultivars, 'Yabukita' and 'Yutakamidori', to calibrate and validate this model based on 10 years of observed cold-hardiness data. Key Results The model captured more than 90 % of the observed variation in cold-hardiness and predicted accurate values for both cultivars, with root mean square errors of ~1.0 °C. The optimized forgetting function indicated that the tea buds memorized both short-term (recent days) and long-term (previous months) temperatures. The memories can drive short-term processes such as increasing/decreasing the content of carbohydrates, proteins and antioxidants in the buds, as well as long-term processes such as determining the bud phenological stage, both of which vary with cold-hardiness. Conclusions The use of a forgetting function is an effective means of understanding temperature memories in plants and will aid in developing reliable predictions of cold-hardiness for various plant species under global climate warming. [ABSTRACT FROM AUTHOR]

Extreme winter temperatures during the 2018-2019 dormant season contributed to trunk collapse and complete trunk death of numerous genotypes throughout a diverse grapevine planting in eastern North Dakota, USA. Through the early portion of the dormant season, 12 genotypes were screened to identify lethal temperature exotherms of primary buds; from these results, none were anticipated to be fully prepared to survive the -37 °C minimum temperature recorded in the region. Trunk collapse, death, and survival were monitored for 35 replicated genotypes. New trunks were retrained from suckers and monitored for growth following trunk removal. Only five genotypes exceeded 50% trunk survival at the end of the 2019 growing season, 'Valiant', 'King of the North', 'John Viola', 'Baltica', and 'Bluebell'. Following re-establishment, 'La Crescent' was the most vigorous genotype with the largest sucker circumference, sucker length, and internode length. Nearly all genotypes evaluated produced suckers with lengths approaching the high-wire trellis height (1.8 m), designating their potential for cordon retraining in 2020. Cumulatively, however, the lethal temperature exotherm results and the trunk survival examination indicate a harrowing need for investigation of new management practices (such as protected training systems) and the generation of new cold-hardy genotypes to enhance productivity under standard unprotected systems. [ABSTRACT FROM AUTHOR]

A dynamic thermal time model (DTTM) has been developed to predict cold-hardiness in dormant grapevine buds, which uses daily mean temperatures as the only input variable. However, it has been recently reported that cold-hardiness in grapevine buds depends not only on low temperatures (LTs), but also on the content of the plant phytohormone abscisic acid (ABA). An important parameter in the DTTM is the ecodormancy boundary (EDB), which represents the chilling degree days (DDc) required for the transition of the buds from endo to ecodormancy. In this study, the bud cold-hardiness of grapevines was measured by the low-temperature exotherm (LTE) in the subtropical Elqui and in the temperate Maipo valleys of Chile, and the values fitted to the DTTM. Moreover, the ABA content was determined in dormant buds throughout the dormant season. The results demonstrated that the DTTM worked better in the Maipo than in the Elqui valley, and that the content of ABA in the buds was higher in the vines grown in the Elqui valley. On the other hand, the optimized EDB parameter value varied from year to year when it was estimated as chilling accumulated, but when it was estimated as time, it remained constant in the Maipo valley. Based on the results, we conclude the following: (a) the proper functioning of the DTTM requires that the ABA content profile in the dormant buds should be kept constant from year to year, (b) the highest content of ABA in the buds collected in the Elqui valley is probably due to abiotic stresses, (c) the EDB parameter corresponds to the accumulated cold until before the buds begin their deacclimation process and not until they release from endodormancy, (d) the release of the buds from endodormancy does not depend on the accumulated cold, but on the elapsed time. [ABSTRACT FROM AUTHOR]

Background: Understanding adaptation involves establishing connections between selective agents and beneficial population responses. However, relatively little attention has been paid to seasonal adaptation, in part, because it requires complex and integrative knowledge about seasonally fluctuating environmental factors, the effects of variable phenology on exposure to those factors, and evidence for temporal specialization. In the European corn borer moth, Ostrinia nubilalis, sympatric pheromone strains exploit the same host plant (Zea mays) but may genetically differ in phenology and be reproductively "isolated by time." Z strain populations in eastern North America have been shown to have a prolonged larval diapause and produce one annual mating flight (July), whereas E strain populations complete an earlier (June) and a later (August) mating flight by shortening diapause duration. Here, we find evidence consistent with seasonal "adaptation by time" between these ecotypes. Results: We use 12 years of field observation of adult seasonal abundance to estimate phenology of ecotype life cycles and to quantify life-stage specific climatic conditions. We find that the observed reduction of diapause duration in the E strain leads their non-diapausing, active life stages to experience a ~ 4 °C colder environment compared to the equivalent life stages in the Z strain. For a representative pair of populations under controlled laboratory conditions, we compare life-stage specific cold tolerance and find non-diapausing, active life stages in the E strain have as much as a 60% greater capacity to survive rapid cold shock. Enhanced cold hardiness appears unrelated to life-stage specific changes in the temperature at which tissues freeze. Conclusions: Our results suggest that isolation by time and adaptation by time may both contribute to population divergence, and they argue for expanded study in this species of allochronic populations in nature experiencing the full spectrum of seasonal environments. Cyclical selective pressures are inherent properties of seasonal habitats. Diverse fluctuating selective agents across each year (temperature, predation, competition, precipitation, etc.) may therefore be underappreciated drivers of biological diversity. [ABSTRACT FROM AUTHOR]

Background and Aims It has been reported that low temperatures (LTs) and the plant hormone abscisic acid (ABA) induce the expression of CBF/DREB1 transcription factors in vegetative tissues and seedlings of Vitis vinifera and Vitis riparia and that foliar applications of ABA to V. vinifera increase the freezing tolerance or cold-hardiness of dormant buds. However, the combined effect of ABA and LTs on the expression of CBF/DREB1 transcription factors and on the acquisition of freezing tolerance in dormant grapevine buds has not been investigated. The objective of this study was to analyse the combined effect of ABA and LT treatments on the expression of CBF/DREB transcription factors and the acquisition of freezing tolerance. Methods In vitro experiments with single-bud cuttings of grapevines were used to analyse the effect of ABA, ABA + LT and LT on the expression of CBF/DREB transcription factors, dehydrin and antioxidant genes, the acquisition of freezing tolerance and the endogenous content of ABA. Gene expression analysis was performed by quantitative real-time PCR and freezing tolerance was determined by measuring the low-temperature exotherm by differential thermal analysis. ABA levels were determined by gas chromatography coupled to an electron capture detector. Key Results The LT treatment and exogenous application of ABA to grapevine dormant buds increased the expression of the CBF/DREB1 transcription factors VvCBF2, VvCBF3, VvCBF4 and VvCBF6. The joint application of LT and ABA produced a huge increase in the expression of these transcription factors, which was greater than the sum of the increases produced by them individually, which indicates the existence of a synergistic effect between ABA and LT on the activation of these transcription factors. This synergic effect was also observed on the increase in bud cold-hardiness and on the expression of antioxidant and dehydrin genes. Conclusions The synergy between ABA and LT on the expression of CBF/DREB1 transcription factors VvCBF2, VvCBF3, VvCBF4 and VvCBF6 plays a key role in cold acclimatization of grapevine buds. The results highlight the importance of the combination of stimuli in the improvement of genetic and physiological responses and help us to understand the adaption of plants to complex environments. [ABSTRACT FROM AUTHOR]

Extreme winter temperatures during the 2018–2019 dormant season contributed to trunk collapse and complete trunk death of numerous genotypes throughout a diverse grapevine planting in eastern North Dakota, USA. Through the early portion of the dormant season, 12 genotypes were screened to identify lethal temperature exotherms of primary buds; from these results, none were anticipated to be fully prepared to survive the −37 °C minimum temperature recorded in the region. Trunk collapse, death, and survival were monitored for 35 replicated genotypes. New trunks were retrained from suckers and monitored for growth following trunk removal. Only five genotypes exceeded 50% trunk survival at the end of the 2019 growing season, ‘Valiant’, ‘King of the North’, ‘John Viola’, ‘Baltica’, and ‘Bluebell’. Following re-establishment, ‘La Crescent’ was the most vigorous genotype with the largest sucker circumference, sucker length, and internode length. Nearly all genotypes evaluated produced suckers with lengths approaching the high-wire trellis height (1.8 m), designating their potential for cordon retraining in 2020. Cumulatively, however, the lethal temperature exotherm results and the trunk survival examination indicate a harrowing need for investigation of new management practices (such as protected training systems) and the generation of new cold-hardy genotypes to enhance productivity under standard unprotected systems.

Global climate change may detrimentally affect future generations of numerous forest tree species, hampering their long-term sustainability if appropriate evolutionary responses remain lacking. To face these novel threats, conservation biologists are in need of a thorough understanding and identification of adaptive variation in key fitness traits. We here provide an elaborate synthesis of pre-existing and novel analyses of an association mapping, genecological and landscape genomic study integrating genotypic, environmental and phenotypic data to gain insights into the genetic basis of cold-hardiness adaptation in coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii). Data were collected across part of the natural range for a total of 643 individuals. A landscape genomic approach revealed 28 putative non-neutral genes, although a variance partitioning analysis indicated only moderate power of this gene set in explaining cold-hardiness-related phenotypic variation, and suggests many important genes await discovery. Integrating these results within the entire phenotype-genotype-environment spectrum allowed us to delineate the six most promising candidate genes under selection. By combining genomic, phenotypic and environmental data, this study attempts to gain insights in the genetic basis of key adaptations, which may ultimately aid forestry managers to establish resilient ecosystems in face of future climate change. [ABSTRACT FROM AUTHOR]

The common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), is a destructive pest in Asia. Although overwintering in the field has not been reported for this species, their larvae are capable of long-term survival in fluctuating temperatures, i.e., 5 °C (12 h) plus 13 °C (12 h), if food is available. With an increase in climate change due to global warming and the widespread use of greenhouses, further understanding of their cold survival strategy is needed to predict and control their population in the future. In this study, metabolomics was performed to analyze the metabolic features of S. litura larvae exposed to two typical low temperatures: 15 °C and 4 °C, at which the development, locomotion and feeding activities are maintained or halted, respectively. The results showed that the strategies that regulate lipid and amino acid metabolism were similar at 15 °C and 4 °C. Cold exposure induced a metabolic shift of energy from carbohydrate to lipid and decreased free amino acids level. Biosynthesis likely contributed to the decrease in amino acids levels even at 4 °C, a non-feeding temperature, suggesting an insufficient suppression of anabolism. This explains why food and high temperature pulses are necessary for their long-term cold survival. Glycometabolism was different between 15 °C and 4 °C. Carbohydrates were used rapidly at 15 °C, while trehalose accumulated at 4 °C. Interestingly, abundant trehalose and serine are prominent features of Spodoptera exigua larvae, an overwintering species, when compared to S. litura larvae. Exposure to 4 °C also induced up-regulation of carbohydrase and protease in the guts of S. litura . Therefore, it is likely that concurrence of food supplement and fluctuating temperatures could facilitate the cold survival of S. litura larvae. We also found that exposure to 4 °C could activate the mevalonate pathway in S. litura larvae, which might be related to glycometabolism at 4 °C. Overall, our study describes systematically the responses of a cold susceptible insect, S. litura , to low temperatures and explains how fluctuating temperatures facilitate their long-term cold survival indicating the possibility for overwintering of S. litura larvae with global warming and agricultural reforms. [ABSTRACT FROM AUTHOR]

The main function of small heat shock proteins (sHSPs) as molecular chaperones is to protect proteins fromdenaturation under adverse conditions. Molecular and physiological data were used to examine the sHSPs underlying cold-hardiness in Harmonia axyridis. Complementary DNA sequences were obtained for six H. axyridis sHSPs based on its transcriptome, and the expression of the genes coding for these sHSPs was evaluated by quantitative real-time PCR (qRT-PCR) in several developmental stages, under short-term cooling or heating conditions, and in black and yellow females of experimental and overwintering populations under low-temperature storage. In addition, we measured water content and the super cooling and freezing points (SCP and FP, respectively) of H. axyridis individuals from experimental and overwintering populations. The average water content was not significantly different between adults of both populations, but the SCP and FP of the overwintering population were significantly lower than that of the experimental population. Overall, the six sHSPs genes showed different expression patterns among developmental stages. In the short-term cooling treatment, Hsp16.25 and Hsp21.00 expressions first increased and then decreased, while Hsp10.87 and Hsp21.56 expressions increased during the entire process. Under short-term heating, the expressions of Hsp21.00, Hsp21.62, Hsp10.87, and Hsp16.25 showed an increasing trend, whereas Hsp36.77 first decreased and then increased. Under low-temperature storage conditions, the expression of Hsp36.77 decreased, while the expressions of Hsp21.00 and Hsp21.62 were higher than that of the control group in the experimental population. The expression of Hsp36.77 first increased and then decreased, whereas Hsp21.56 expression was always higher than that of the control group in the overwintering population. Thus, differences in sHSPs gene expression were correlated with the H. axyridis forms, suggesting that the mechanism of cold resistance might differ among them. Although, Hsp36.77, Hsp16.25, Hsp21.00, and Hsp21.62 regulated cold-hardiness, the only significant differences between overwintering and experimental populations were found for Hsp16.25 and Hsp21.00. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the relationship between antioxidant enzymes and reactive oxygen species production in diapausing larvae of the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae) kept at 5°C, -3°C and -16°C for two weeks. The amount of hydrogen peroxide (H2O2), activity of antioxidant enzymes, copper zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutases (MnSOD) and catalase (CAT) in whole body homogenates, as well as the electron paramagnetic resonance (EPR) spectroscopy of this insect's whole body were analysed. A higher level of melanin radical and lower CuZnSOD and CAT activities were found in larvae kept at -3°C than at 5°C and -16°C. At the same temperature (-3°C) an elevated H2O2 concentration was recorded. A possible regulatory role of H2O2 at -3°C, which is the temperature that triggers freezing tolerance, is suggested.

Great progress has recently been made in cryobiology. One field, however, has been neglected: the temporal sequence of the effects of photoperiod and temperature, and their relative importance in cold hardening. This is relevant to the question of importance of diapause in cold-hardiness. Denlinger (1991) outlined the categories of such relations and stressed a great need for further detailed research. A survey of studies done over the past decade revealed many gaps in the evidence and the ambiguous nature of the data on the photoperiodic regulation of cold-hardiness. We hope that this review will stimulate further research in this field. Among several directions where research is most needed we have stressed (1) simultaneous recording of changes in survival and dynamics of suspected cryoprotectants (stressed also by Danks, 1996), (2) checking the regulation of different phases of cold hardening, and (3) discrimination between direct and indirect (mediated via neuroendocrine system) effects of environmental cues on cold hardening.

The banded woolly bear caterpillar, Pyrrharctia isabella (Lepidoptera: Erebidae), overwinters in leaf litter and survives freezing under natural conditions. Following 18 weeks of cold acclimation at 5°C, all caterpillars could survive 1 week of continuous freezing at -20°C or seven cycles of freezing-thawing at -20°C, but none survived freezing at -80°C. Field-collected caterpillars had a temperature of crystallization of -7.7±0.5°C that decreased significantly to -9.5±0.6°C after 12 weeks of acclimation at 5°C. Hemolymph levels of free proline, total amino acids and proteins reached a peak during the first 4 weeks of acclimation; concomitantly, hemolymph osmolality increased markedly during this interval (from 364 to 1282 mosmol kg-1). In contrast, hemolymph pH decreased during the first 4 weeks of acclimation before this trend reversed and pH values gradually returned to initial values. However, pH reached its peak value following 1 week at -20°C, but decreased after longer periods of freezing. During cold acclimation, cholesterol levels decreased in the hemolymph and the membrane fraction of fat body but not in other tissues. Lethal freezing at -80°C reduced cell survival in foregut tissue and caused leakage of free proline, total amino acids and proteins from tissues into the hemolymph. The addition of glycerol to the bathing medium reduced freezing injury in fat body cells, as evidenced by reduced leakage of amino acids and proteins. [ABSTRACT FROM AUTHOR]

Cold-hardiness can be measured by supercooling points – the temperature at which spontaneous freezing occurs. Seasonal changes in supercooling point were assessed in field-collected predacious carabid beetle species: Carabus granulatus L., Pterostichus oblongopunctatus L. and Platynus assimilis Payk. (Coleoptera: Carabidae). Supercooling ability of these beetles changed seasonally. The tested carabid beetles proved to belong to freeze-avoiding cryotype.

In this study, apoplastic antioxidant enzymes in the leaves of two strawberry cultivars ('Aromas' and 'Diamante') and their relationship to cold-hardiness were investigated. Fully expanded, uniformly sized leaves from 1-year-old field plants of the cultivars were collected at the hardening (late autumn, in November and winter, in January) and de-hardening (summer, in July) stages. Leaf samples were exposed to low temperatures of 5, -5, -10, -20 and -30°C for 12 h to determine their cold-hardiness (LT50; lethal temperature, where 50% of the plants were killed). Cold-acclimation produced a remarkable increase in cold-hardiness. It was found that 'Diamante' had higher cold-hardiness than 'Aromas'. Moreover, malondialdehyde and total carotenoid content increased during the hardening stage and decreased during the de-hardening stage. The activities of catalase, peroxidase and ascorbate peroxidase in the leaf apoplast and nicotinamide adenine dinucleotide phosphate oxidase activity in the leaf tissue were correlated with changes in cold-hardiness. The activities of these enzymes were higher in the hardening stage than in the de-hardening stage. The activities of apoplastic catalase, peroxidase and ascorbate peroxidase varied significantly depending on the cold-acclimation stage and the cold-hardiness level of the cultivars. This study indicates that elevated apoplastic antioxidative enzymes may be determinants of cold-hardiness in the strawberry plant. The lower malondialdehyde content and higher total carotenoid and apoplastic enzyme activities in 'Diamante' indicated an enhanced cold-hardiness capacity of this cultivar, serving to protect the plant from oxidative damage. [ABSTRACT FROM AUTHOR]

The effects of exogenous ABA on the expression of the cysteine proteinase (CP) gene and its inhibitor cystatin (WC3) in the leaves of winter wheat ( Triticum aestivum L.) seedlings that were hardened for 7 days at 5°C were studied. Seedling cold-hardiness was judged by the temperature causing death of 50% of palisade cells (LT) following 5-min freezing at the temperatures from −5 to −10°C. In the initial period of cooling, when seedling cold tolerance increased, the CP and WC3 gene expression increased considerably, but at the highest cold-hardiness the transcript levels of these genes returned to the control level. When ABA was applied exogenously, the CP gene expression grew by the order of magnitude already in 1-5 h from the onset of low temperature treatment and then abruptly dropped, but it was further maintained at a high level. In cold- and ABA-treated seedlings, the WC3 gene expression initially decreased, but it grew considerably in 3-7 days. It is concluded that the development of wheat cold-hardiness is related to ABA-regulated changes in the CP and WC3 gene expression. [ABSTRACT FROM AUTHOR]

The article focuses on a research conducted in order to investigate the effect of solid-stemmed wheat hosts on the overwintering mortality and cold-hardiness of the wheat stem sawfly, Cephus cinctus. It describes the host plant resistance in the form of solid-stemmed wheat cultivars as the main control strategy for C. cinctus. The study revealed the winter mortality as a minor factor in the population dynamics of wheat stem sawfly.

Abstract: The effects of transgenic Bt cotton on the overwintering generation of the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), are unknown. We hypothesized that a Bt cotton diet may adversely affect fitness of this generation and examined fresh weight, lipids, glycogens, low-molecular-weight sugars and SCPs (supercooling points) of pupae, as well as survival of larvae, diapausing pupae and adult emergence in comparison with controls. Field and laboratory experiments showed that larvae fed on Bt cotton had a decreased pupation rate, and fewer entered diapause and emerged as adults compared with larvae fed non-Bt cotton. Furthermore, larvae fed Bt cotton had reduced pupal weight, glycogen content and trehalose levels both in diapausing and in non-diapausing pupae, and only diapausing pupae had an increased SCP compared to controls. The SCPs of diapausing pupae reared on Bt cotton were significantly higher than those reared on non-Bt cotton. The trehalose levels of diapausing pupae reared on Bt cotton were significantly lower than those of larvae reared on non-Bt cotton. Thus, these results suggest that a Bt cotton diet weakens the preparedness of cotton bollworm for overwintering and reduces survival of the overwintering generation, which will in turn reduce the density of the first generation in the following year. Effects of transgenic Bt cotton on the overwintering generation of cotton bollworm appear to have significantly contributed to the suppression of cotton bollworm observed throughout northern China in the past decade. [Copyright &y& Elsevier]

The article focuses on CinnDak, a cultivar of Betula costata, a deciduous woody tree in the family Betulaceae with subgenus Neurobetula. It highlights that the members of costate birches includes Betula calcicola, Betula chichibuenis and Betula potaninii. It also informs about the selection of CinnDak' (dwarf Korean birch) from a population of seedlings grown at the North Dakota State University Horticulture Research Farm.

Summer storms along the Antarctic Peninsula can cause microhabitats of the terrestrial midge Belgica antarctica to become periodically inundated with seawater from tidal spray. As microhabitats dry, larvae may be exposed to increasing concentrations of seawater. Alternatively, as a result of melting snow or following rain, larvae may be immersed in freshwater for extended periods. The present study assessed the tolerance and physiological response of B. antarctica larvae to salinity exposure, and examined the effect of seawater acclimation on their subsequent tolerance of freezing, dehydration and heat shock. Midge larvae tolerated extended exposure to hyperosmotic seawater; nearly 50% of larvae survived a 10-day exposure to 1000 mOsm kg-1 seawater and -25% of larvae survived 6 days in 2000 mOsm kg-1 seawater. Exposure to seawater drastically reduced larval body water content and increased hemolymph osmolality. By contrast, immersion in freshwater did not affect water content or hemolymph osmolality. Hyperosmotic seawater exposure, and the accompanying osmotic dehydration, resulted in a significant correlation between the rate of oxygen consumption and larval water content and induced the de novo synthesis and accumulation of several organic osmolytes. A 3-day exposure of larvae to hyperosmotic seawater increased freezing tolerance relative to freshwater-acclimated larvae. Even after rehydration, the freezing survival of larvae acclimated to seawater was greater than freshwater-acclimated larvae. Additionally, seawater exposure increased the subsequent tolerance of larvae to dehydration. Our results further illustrate the similarities between these related, yet distinct, forms of osmotic stress and add to the suite of physiological responses used by larvae to enhance survival in the harsh and unpredictable Antarctic environment. [ABSTRACT FROM AUTHOR]

Abstract: The availability of water is recognized as the most important determinant of the distribution and activity of terrestrial organisms within the maritime Antarctic. Within this environment, arthropods may be challenged by drought stress during both the austral summer, due to increased temperature, wind, insolation, and extended periods of reduced precipitation, and the winter, as a result of vapor pressure gradients between the surrounding icy environment and the body fluids. The purpose of the present study was to assess the desiccation tolerance of the Antarctic springtail, Cryptopygus antarcticus, under ecologically-relevant conditions characteristic of both summer and winter along the Antarctic Peninsula. In addition, this study examined the physiological changes and effects of mild drought acclimation on the subsequent desiccation tolerance of C. antarcticus. The collembolans possessed little resistance to water loss under dry air, as the rate of water loss was >20%h−1 at 0% relative humidity (RH) and 4°C. Even under ecologically-relevant desiccating conditions, the springtails lost water at all relative humidities below saturation (100% RH). However, slow dehydration at high RH dramatically increased the desiccation tolerance of C. antarcticus, as the springtails tolerated a greater loss of body water. Relative to animals maintained at 100% RH, a mild drought acclimation at 98.2% RH significantly increased subsequent desiccation tolerance. Drought acclimation was accompanied by the synthesis and accumulation of several sugars and polyols that could function to stabilize membranes and proteins during dehydration. Drought acclimation may permit C. antarcticus to maintain activity and thereby allow sufficient time to utilize behavioral strategies to reduce water loss during periods of reduced moisture availability. The springtails were also susceptible to desiccation at subzero temperatures in equilibrium with the vapor pressure of ice; they lost ∼40% of their total body water over 28d when cooled to −3.0°C. The concentration of solutes in the remaining body fluids as a result of dehydration, together with the synthesis of several osmolytes, dramatically increased the body fluid osmotic pressure. This increase corresponded to a depression of the melting point to approximately −2.2°C, and may therefore allow C. antarcticus to survive much of the Antarctic winter in a cryoprotectively dehydrated state. [Copyright &y& Elsevier]

To investigate geographic adaptation of the migratory locust Locusta migratoria in China, locusts were collected from six localities, ranging from 47.4°N to 19.2°N. Using offspring from the various populations, we compared embryonic diapause, reproductive traits, cold-hardiness and adult body size. The incidence of embryonic diapause was influenced by the genetic makeup, parental photoperiod, and incubation temperature of the eggs. The northern strain (47.4°N) produced diapause eggs under all photoperiodic conditions, whereas the other strains produced a higher proportion of diapause eggs when exposed to a short photoperiod. The incubation temperature greatly influenced diapause induction. At a low temperature, all eggs entered diapause, even some of those from a tropical strain (19.2°N) in which no diapause was induced at high temperatures. Photoperiodic changes during the parental generation affected the incidence of embryonic diapause. Diapause intensity decreased with decreasing original latitude. Cold hardiness was compared by exposing eggs in diapause to either −10 or −20°C for various periods; the northern strain was more cold-hardy than the southern strain, although some eggs in the tropical strain were probably not in a state of diapause. Adult body size and head width showed a complicated pattern of variation along the latitudinal gradient, whereas egg pod size (egg pod width and egg number) and hatchling weight tended to decrease with decreasing latitude. These results reveal that L. migratoria has adapted to local environments and that the latitudinal gradient appears to play an important role in shaping L. migratoria life cycle and development. [ABSTRACT FROM AUTHOR]

The effects of three plant growth regulators (PGRs) (prohexadione-calcium, paclobutrazol, and flurprimidol) on the resistance of Fraser fir (Abies fraseri) and Colorado blue spruce (Picea pungens) to cold injuries were investigated. Treated and untreated seedlings were first allowed to harden before exposure to warm temperatures in a greenhouse. The seedlings were then subjected to an artificial freezing test to simulate the return to normal winter conditions. Chlorophyll fluorescence, relative electrolyte leakage, bud survival, and posttreatment plant survival were recorded to evaluate the effectiveness of the treatments. Results showed that treatments with paclobutrazol and flurprimidol maintained the photosynthetic ability of the plants and reduced the extent of needle cold injuries. There was no effect on bud and plant survival, possibly as a result of the timing of the PGR application. Further studies with adjustment of the timing and rates of PGR treatments are needed to validate these results. [ABSTRACT FROM AUTHOR]

Chorispora bungeana Fisch. & C.A. Mey (Chorispora bungeana) is a rare alpine subnival plant species that is highly capable of resisting freezing environment. In this paper, we attempted to explore a possible mechanism of its adaptation to the alpine subnival environment. The results of Ca2+ level measured by energy-dispersive X-ray detector (EDS) showed that the Ca2+ content in the wild species was higher than that of regenerated plants, and chilling induction at 0°C could increase Ca2+ contents in the regenerated plants. Further, the distribution and accumulation of Ca2+ in tissues was investigated by X-ray micro-domains analysis with scanning electron microscope (SEM), the results showed that Ca2+ levels were different in various tissues and organs of the wild species. However, Ca2+ levels did not show significant difference among tested tissues of the regenerated plants. Laser-scanning confocal microscopy (LSCM) revealed that, after 10th day of the chilling induction at 0°C, the free Ca2+ levels increased in the mesophyll protoplasts from the regenerated plants. In addition, the results of electric conductivity (EC) suggested that the chilling induction initially affected the permeability of cellular membrane, and it was restored to stable level with extending treatment. The mitochondria of the cells also maintained its normal function after the chilling induction by Rhodamine-123 detection. Taken together, the membrane remained its integrity and its mitochondria was functional at the condition of the chilling induction, which was essentially the requirement for alive cells as well as its whole entire plants. These findings suggested that distribution and accumulation of Ca2+ connected with the cold-hardiness of C. bungeana were different among the various tissues and organs in the wild species. Also, these results demonstrated that the difference in Ca2+ distribution was a response of C. bungeana in adapting itself to the alpine subnival environment and the accumulation of Ca2+ could play an important role in its active cold-hardiness. [Copyright &y& Elsevier]

Abstract: Terrestrially hibernating reptiles that live in seasonally cold climates need effective strategies of cold hardiness to survive the winter. Use of thermally buffered hibernacula is very important but when exposure to temperatures below 0°C cannot be avoided, either freeze avoidance (supercooling) or freeze tolerance strategies can be employed, sometimes by the same species depending on environmental conditions. Several reptile species display ecologically relevant freeze tolerance, surviving for extended times with 50% or more of their total body water frozen. The use of colligative cryoprotectants by reptiles is poorly developed but metabolic and enzymatic adaptations providing anoxia tolerance and antioxidant defense are important aids to freezing survival. New studies using DNA array screening are examining the role of freeze-responsive gene expression. Three categories of freeze responsive genes have been identified from recent screenings of liver and heart from freeze-exposed (5h post-nucleation at −2.5°C) hatchling painted turtles, Chrysemys picta marginata. These genes encode (a) proteins involved in iron binding, (b) enzymes of antioxidant defense, and (c) serine protease inhibitors. The same genes were up-regulated by anoxia exposure (4h of N2 gas exposure at 5°C) of the hatchlings which suggests that these defenses for freeze tolerance are aimed at counteracting the injurious effects of the ischemia imposed by plasma freezing. [Copyright &y& Elsevier]

Quantitative trait locus (QTL) analyses are used by geneticists to characterize the genetic architecture of quantitative traits, provide a foundation for marker-aided-selection (MAS), and provide a framework for positional selection of candidate genes. The most useful QTL for breeding applications are those that have been verified in time, space, and/or genetic background. In this study, spring cold-hardiness of Douglas-fir foliar tissues was evaluated in two clonally replicated (n=170 and 383 clones) full-sib cohorts derived from the same parental cross in two different years (made 5 years apart). The cohorts were established in widely separated forest test sites and tissues were artificially freeze tested using different cold injury assessment methods. Four of six unique QTL detected for spring cold-hardiness in needles of Cohort 1 were tentatively verified in the second cohort. Four additional QTL were detected in Cohort 2, two on linkage groups (LGs) not previously represented in the smaller cohort. In total, 10 unique QTL were identified across both cohorts. Seventeen of twenty-nine putative cold-hardiness candidate genes (Douglas-fir ESTs) placed on the Douglas-fir linkage map locate within the 95% confidence intervals of spring needle cold-hardiness QTL from the two cohorts and thus represent priority targets for initiating association mapping in Douglas-fir. [ABSTRACT FROM AUTHOR]

Cold exposure and freezing may affect ion distribution in several ways and reduce physiologically important ionic gradients. Both freeze-avoiding and freeze-tolerant organisms have developed mechanisms to handle this stress. Supercooled insects seem to be able to maintain their ionic gradients even at temperatures far below zero. When freeze-tolerant insects freeze, ions diffuse down their concentration gradients across the cell membranes and reach electrochemical equilibrium. They quickly reverse this transmembrane diffusion when they are thawed.Trace metals may affect mechanisms for cold-hardening in different ways and reduce cold-hardiness. Freezing may give rise to toxic concentrations of metal ions, and freeze-tolerant organisms probably need to inactivate toxic trace metals. Ice nucleating agents may be important in this context. [Copyright &y& Elsevier]

Abstract Respiration, mitochondrial (mt)DNA content, and mitochondrial-specific RNA expression in fat body cells from active and cold-adapted larvae of the goldenrod gall fly, Eurosta solidaginis , and the Arctic woolly bear caterpillar, Gynaephora groenlandica , were compared. Reduced amounts of mtDNA were observed in cold-adapted larvae of both E. solidaginis and G. groenlandica collected in fall or winter, compared with summer-collected larvae. mtDNA increased to levels similar to those of summer-collected larvae after incubation at 10 °C or 15 °C for 5 h. Mitochondrial-specific RNAs (COI and 16S) were observed in fat body cells of both active and cold-adapted E. solidaginis larvae. Our results suggest that mitochondrial proteins required for respiration may be restored rapidly from stable RNAs present in overwintering larvae. [ABSTRACT FROM AUTHOR]

Conifers in the temperate zone are subject to extremes in climatic conditions, such as low temperatures and water deficits. Under such conditions chloroplast antenna pigments can absorb more light energy than can be utilized in photosynthesis. If the plant is unable to dissipate this excess energy by combined radiationless decay (heat), fluorescence emission and carotenoid quenching, photodamage can result. Potentially damaging conditions exist during winter when low temperatures often occur simultaneously with intense light levels and desiccation. Photodamage is caused when regulatory controls on the production of toxic oxygen species produced in the chloroplast and the capacity of scavenging systems to dispose of them are exceeded. By becoming cold-hardened and dormant, conifer species can resist all but the most severe effects of the winter climates to which they are adapted. Mechanisms which protect chloroplasts from photodamage appear to be among the essential adaptations enabling temperate conifers to resist the effects of drought and low winter temperatures, especially when light levels are high. [ABSTRACT FROM AUTHOR]

Seasonal cold-acclimation patterns and the effects of photoperiod and temperature on coldhardiness of Hibiscus rosa-sinensis L. and Hibiscus syriacus L. were determined. Field-grown H. rosasinensis consistently failed to survive freezing at-2°C. Two genotypes of field-and container-grown H. syriacus initiated cold-acclimation in mid September, in response to decreasing daylength, and continued to an ultimate midwinter hardiness level of -27°C in early February. Controlled environment experiments using combinations of short days (SD) and cool day/night temperatures were unable to induce even minimal cold acclimation of H. rosasinensis. In controlled environments, H. syriacus attained a moderate amount of cold tolerance at warm temperatures and long days (LD). Low night temperature combined with LD, warm day produced the same degree of cold-acclimation as the SD treatments. While not essential, SD enhanced H. syriacus cold-acclimation in controlled environments. A-5°C frost treatment of intact plants did not enhance cold-hardiness of H. syriacus. [ABSTRACT FROM AUTHOR]

The supercooling capacity of nine laboratory-held species of ticks originating from different geographical areas, as well as five field-collected species from Germany, was investigated. All but one tick species showed mean supercooling points between about-17 and -23°C, suggesting that the capacity to supercool to temperatures of ≤17°C might be an inherent property of many tick species unrelated to their geographic orgin. Photoperiod did not influence the mean supercooling point in any of the species and there was also no distinct seasonal pattern of supercooling in seasonally acclimatized Dermacentor marginatus. Thus, the supercooling ability was independent of the presence/absence of diapause. The finding of thermal hysteresis in D. marginatus hemolymph raises the question of whether or not anti-freeze proteins are involved in the supercooling capacity of that species. An interspecies comparison revealed a weak negative correlation between relative water content and supercooling point of the ticks and an even weaker correlation between body mass or body water mass and the supercooling point. Since the ticks exhibited low supercooling points both before and shortly after feeding, the blood used as food should lack potent ice nucleators. [ABSTRACT FROM AUTHOR]

The European common lizard ( Lacerta vivipara) is widely distributed throughout Eurasia and is one of the few Palaearctic reptiles occurring above the Arctic Circle. We investigated the cold-hardiness of L. vivipara from France which routinely encounter subzero temperatures within their shallow hibernation burrows. In the laboratory, cold-acclimated lizards exposed to subfreezing temperatures as low as -3.5°C could remain unfrozen (supercooled) for at least 3 weeks so long as their microenvironment was dry. In contrast, specimens cooled in contact with ambient ice crystals began to freeze within several hours. However, such susceptibility to inoculative freezing was not necessarily deleterious since L. vivipara readily tolerated the freezing of its tissues, with body surface temperatures as low as -3.0°C during trials lasting up to 3 days. Freezing survival was promoted by relatively low post-nucleation cooling rates (≤0.1°C·h) and apparently was associated with an accumulation of the putative cryoprotectant, glucose. The cold-hardiness strategy of L. vivipara may depend on both supercooling and freeze tolerance capacities, since this combination would afford the greatest likelihood of surviving winter in its dynamic thermal and hydric microenvironment. [ABSTRACT FROM AUTHOR]

Three species of free-living Antarctic fellfield nematodes, Eudorylaimus coniceps, E. spaulli and E. pseudocarteri exhibited differing degrees of both strategies of cold-hardiness; freeze-tolerance and freeze-avoidance. Bimodal distributions of supercooling points were obtained from monthly field samples of both E. coniceps and E. spaulli. Individuals found in the low group of this distribution (supercooling to <-15 °C) were capable of avoiding freezing by extensive supercoolint (to a mean temperature of ca-22 °C), sufficient to with-stand the environmental extremes of the maritime Antarctic. The high groups of both these species, and almost all E. pseudocarteri, were likely to have frozen at some stage during winter. Survival of freezing increased with the temperature at which nucleation occurred, and has been described by a Gompertz model. Estimates of the supercooling points at which survival fell to 50% were-10.4,-7.1 and-6.1 °C for E. coniceps, E. pseudocarteri and E. spaulli, respectively. [ABSTRACT FROM AUTHOR]

Anatalanta aptera is a wingless fly which lives in subantarctic islands, particularly in sea bird colonies. Developmental patterns of supercooling capacity were studied in an experimental population reared at 5°C and fed ad libitum. Mean supercooling points of the eggs, second and third instar larvae, pupae, teneral and mature adults were −28.0°C, −10.8°C, −8.8°C, 17.6°C, −16.6°C and −8.2°C respectively. Low mean supercooling points were found for inactive stages (eggs, pupae) and, unexpectedly among Diptera, teneral adults. Mature adults had a combination of low supercooling ability, high lipid content and physogastry. The results are compared with those obtained in winged species from other families of Diptera. [ABSTRACT FROM AUTHOR]

There is a range of egg size phenotypes in Mallards ( Anas platyrhynchos) that has a large genetic component. It was hypothesized that egg size variation could play an important role in survival of newly hatched ducklings during their first few days out of the nest when they are most susceptible to thermal stress and starvation. Precocial young must be physiologically capable of maintaining homeothermy in order to spend adequate time foraging. Duckling size at hatching was highly correlated with egg mass, and those hatching from heavier eggs were able to maintain homeothermy at colder environmental temperatures than those from lighter eggs. Heavy ducklings had significantly lower mass-specific cooling rates, but lower critical temperature did not vary significantly among ducklings of different size. Although insulation and energy reserves were not proportionally greater in larger ducklings, those hatching from heavier eggs can survive starvation longer than those from lighter eggs. The relative cold tolerance of young from light and heavy eggs will affect the ratio of time spent foraging to time spent being brooded by the female parent. Although there is no direct evidence that selection is acting on egg size, variation in this trait within a population could be maintained by fluctuating environmental conditions at hatch. [ABSTRACT FROM AUTHOR]

The winter months are challenging for many animal species, which often enter a state of dormancy or hypometabolism to "wait out" the cold weather, food scarcity, reduced daylight, and restricted mobility that can characterize the season. To survive, many species use metabolic rate depression (MRD) to suppress nonessential metabolic processes, conserving energy and limiting tissue atrophy particularly of skeletal and cardiac muscles. Mammalian hibernation is the best recognized example of winter MRD, but some turtle species spend the winter unable to breathe air and use MRD to survive with little or no oxygen (hypoxia/anoxia), and various frogs endure the freezing of about two-thirds of their total body water as extracellular ice. These winter survival strategies are highly effective, but create physiological and metabolic challenges that require specific biochemical adaptive strategies. Gene-related processes as well as epigenetic processes can lower the risk of atrophy during prolonged inactivity and limited nutrient stores, and DNA modifications, mRNA storage, and microRNA action are enacted to maintain and preserve muscle. This review article focuses on epigenetic controls on muscle metabolism that regulate MRD to avoid muscle atrophy and support winter survival in model species of hibernating mammals, anoxia-tolerant turtles and freeze-tolerant frogs. Such research may lead to human applications including muscle-wasting disorders such as sarcopenia, or other conditions of limited mobility.