Effect Of Cold Hardening Research Articles

Rapid cold hardening response of the phytoseiid mite Neoseiulus striatus: increased cold tolerance but not reduced predation

The predatory mite Neoseiulus striatus (Wu) (Acari: Phytoseiidae), which has been found on maize plants in Inner Mongolia, is regarded as a promising biological control agent of small sucking pests, especially Tetranychid mites. Temperature is an important abiotic factor, and a sudden drop in temperature may affect its performance when released in areas with big circadian temperature differences. Rapid cold hardening is a type of phenotypic plasticity that allows ectotherms to quickly enhance their cold tolerance in response to a brief chilling exposure. However, it is not clear whether N. striatus possesses such plasticity. To understand how this species of phytoseiid mite copes with short-term low-temperature stress, its rapid cold hardening response was studied in the laboratory by first exploring its critical temperature. Then, the effects of exposure to a series of temperatures (0, 5, 10, 15, and 20°C) for different durations on the survival of N. striatus were investigated to determine the optimal temperature and duration for cold hardening. Moreover, the effect of cold hardening on the consumption of Tetranychus urticae by N. striatus was also investigated, as was the response of immature stages. The critical temperature for N. striatus was - 15°C, at which its survival dropped below 10%. An exposure to 5°C for 2h was optimal for rapid cold hardening, efficiently increasing survival in N. striatus. Rapid cold hardening was found in all developmental stages of N. striatus, and there was no significant effect of exposure on the consumption of spider mites. Our study shows that exposure to low temperatures during a limited period can enhance the cold hardiness but not reduce predation by N. striatus, which will be advantageous to its field applications during a period of large diurnal temperature fluctuations.

State of antioxidant system in triticale seedlings at cold hardening of varieties of different frost resistance

Effect of cold hardening on state of antioxidant system (AOS) of triticale (× Triticosecale Wittmack) seedlings of varieties, differed in frost resistance, namely Buket and Raritet (winter, high-frost-resistant), and Alexandra and Pidzymok Kharkovskiy (facultative, less resistant) was studied. In absence of cold hardening, a clear connection between studied indicators of the AOS state and frost resistance of the varieties was not observed. After hardening of seedlings at 2–4 °C for 6 days, the activity of superoxide dismutase (SOD) and catalase increased in the high-frost-resistant varieties Buket and Raritet. In less resistant ones—Alexandra and Pidzymok Kharkovskiy—the activity of these enzymes changed less significantly. At the same time, the activity of guaiacol peroxidase increased more noticeably after hardening in these varieties. Hardened seedlings of the Buket, Raritet and Alexandra varieties had significantly higher sugar content than the Pidzymok Kharkovskiy. The proline content in response to cold hardening increased in all varieties, while the absolute values in the varieties Buket, Raritet and Pidzymok Kharkovskiy were significantly higher than in the Alexandra. Cold hardening caused a significant increase in the content of anthocyanins and flavonoids, absorbing in UV-B, in the Buket, Raritet and Alexandra, but not in the Pidzymok Kharkovskiy. The content of lipid peroxidation product malondialdehyde after a 6-h damaging action of − 7 °C increased in the varieties Alexandra and Pidzymok Kharkovskiy and slightly changed in the Buket and Raritet. In general, a positive relationship was found between AOS activity and frost resistance of hardened triticale seedlings. This relationship was most clearly manifested for indicators of SOD activity and flavonoid content.

Cold-modulated small proteins abundance in winter triticale (x Triticosecale, Wittm.) seedlings tolerant to the pink snow mould (Microdochium nivale, Samuels and Hallett) infection.

Two winter triticale (x Triticosecale Wittmack) model cultivars: Hewo (tolerant to pink snow mould) and Magnat (sensitive) were used to test the effect of cold-hardening (4 weeks at 4°C) on soluble ≤50 kDa protein profiles of the seedling leaves. The presence and abundance of individual proteins were analysed via two-dimensional gel electrophoresis (2-DE) and Surface-Enhanced Laser Desorption/Ionization Time-of-Flight (SELDI-TOF). Up to now, no proteomics analysis of triticale response to hardening has been performed. Thus, the present paper is the first in the series describing the obtained results. In our experiments, the exposure to the low temperature-induced only quantitative changes in the leaves of both cultivars, causing either an increase or decrease of 4-50 kDa protein abundance. Among proteins which were cold-accumulated in cv. Hewo's leaves, we identified two thioredoxin peroxidases (chloroplastic thiol-specific antioxidant proteins) as well as mitochondrial- β-ATP synthase subunit and ADP-binding resistance protein. On the contrary, in hardened seedlings of this genotype, we observed the decreased level of chloroplastic RuBisCO small subunit PW9 and epidermal peroxidase 10. Simultaneous SELDI-TOF analysis revealed several low mass proteins better represented in cold-hardened plants of tolerant genotype in comparison to the sensitive one and the impact of both genotype and temperature on their level. Based on those results, we suggest that indicated proteins might be potential candidates for molecular markers of cold-induced snow mould resistance of winter triticale and their role is worth to be investigated in the further inoculation experiments.

The effects of cold-hardening and Microdochium nivale infection on oxidative stress and antioxidative protection of the two contrasting genotypes of winter triticale

Pink snow mould resulting from Microdochium nivale (Samuels and I.C. Hallett) regularly infects winter triticale (× Triticosecale, Wittm.). Therefore, in the present paper we aimed to identify biochemical markers potentially involved in the increased resistance against M. nivale of this valuable crop. In our experiment, we used two doubled haploid (DH) lines with the highest and the lowest cold-induced snow mould resistance, previously identified in cold chamber tests. The impact of cold-hardening (4 weeks at 4 °C) as well as covering plants with an artificial system to mimic snow covers and inoculation with M. nivale mycelium in leaves of seedlings, different genotypes on the thiobarbituric acid-reactive substance (TBARS) level and superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX) activities was assessed. Our studies indicate that, indeed, various genotypes differ in their response to the treatments in regard to the measured parameters. The leaf TBARS content was always lower in seedlings of snow mould-resistant DH1 line in comparison with susceptible DH92 ones, suggesting that tissue damage was more pronounced in plants of the second genotype. The activity of SOD and CAT had no correlation with the level of snow mould resistance. The cold-enhanced POX I activity was higher in DH1 seedlings under the snow-imitating covers with or without M. nivale inoculation in comparison with DH92 plants. Moreover, POX II activity was higher after cold-hardening in the resistant genotype. POX III activity was enhanced by abiotic stress in leaves of DH1 seedlings, while it was not detected in susceptible genotype in any experimental term.

Cold hardening protects cereals from oxidative stress and necrotrophic fungal pathogenesis

AbstractThe effects of cold hardening of cereals on their cross-tolerance to treatments leading to oxidative stress were investigated. Long-term exposure to low non-freezing temperatures provided partial protection to wheat and barley plants from the damage caused by paraquat and hydrogen peroxide treatments. It also conferred resistance in two barley cultivars to the necrotic symptoms and growth of the fungal phytopathogen Pyrenophora teres f. teres. Pathogen-induced oxidative burst was also reduced in cold hardened plants. The possible roles of host-derived redox factors and other signaling components in the observed forms of cereal cross-tolerance are discussed.

Measured and Predicted Static Friction for Real Rough Surfaces in Point Contact

A numerical model to predict static friction for metallic point contacts was developed and validated by comparison to experimental measurements using a specially designed test rig. Key aspects of the numerical model were the incorporation of a digitized real rough surface profile, application of discrete convolution fast Fourier transform (DC-FFT) to predict local asperity interference, and modification of the yield strength to capture the effect of cold hardening. It was found that these model features are critically important to quantitative prediction of static friction. The model significantly underestimated the static friction coefficient if randomly generated surfaces having statistical parameters the same as the measured rough surface were used; digitized real rough surfaces enabled accurate predictions. Further, the model was able to describe the static friction of worn surfaces after cold hardening was introduced through modification of material yield strength. This work illustrates the importance of incorporating the surface features and the change of those features with wear to accurately and reliably predict static friction.

Change in the light-temperature characteristic of CO2 exchange of red clover under cold hardening conditions

The effect of cold hardening on CO2 exchange in plants of two red clover varieties is studied under controlled environmental conditions within the framework of a multifactor experiment. It is shown that hardening reduces the potential maximum net photosynthesis of plants, changing the light and temperature conditions that provide achieving it, and increases the dark respiration rate.

Effect of cold hardening on the phenolic complex of winter wheat leaves

The effect of hardening on the composition of phenolic compounds in winter wheat (Triticum aestivum L.) leaves was studied. It was shown that green tissues contained mainly flavonoids, especially flavons (C-and O-glycosides of apigenin and luteolin), and also ferulic acid derivatives. Among flavons, derivatives of luteolin dominated, including isoorientin, which comprised approximately a half of the content of all identified phenolic compounds. Low temperature induced the accumulation of phenolic compounds in winter wheat leaves, whereas their qualitative composition was not practically changed.

Effects of cold- and heat hardening on thermal resistance in Drosophila melanogaster

The effects of cold- and heat hardening on resistance to both low and high temperature stress was examined in Drosophila melanogaster lines selected for resistance to either cold or heat. The hardening effect was positive when the hardening was of the same type as the stress in all selection regimes. The effect of cold hardening on survival after heat stress was further examined in the lines selected for cold resistance and corresponding controls. A cross-protection effect (increased heat resistance after cold hardening) was present and this effect was lower in the lines selected for resistance to cold than in the controls. The level of Hsp70 expression induced by a non-lethal cold hardening was examined, showing that cold hardening induced Hsp70 expression. The results suggest that the cross-protection effect is at least partly due to Hsp70 expression induced by cold exposure.

Effects of Cold-Hardening on Chilling-Induced Photoinhibition of Photosynthesis and on Xanthophyll Cycle Pigments in Sweet Pepper

Two cultivars of Capsicum annuum L. were acclimated for 5 d at sub-optimal temperature (14 °C) and irradiance of 250 µmol m−2 s−1. This cold-hardening resulted in some reduction in the extent of photoinhibition during an 8 h exposure to high irradiance at 4 °C. Obvious differences were observed between non-hardened leaves (NHL) and cold-hardened leaves (CHL) in the recovery under low irradiance at room temperature. The CHL of both cultivars recovered faster than NHL, especially during the initial fast phase of recovery. Compared with NHL, the total content of carotenoids (Cars), based on chlorophyll, Chl (a+b), and the proportions of xanthophyll cycle pigments referred to total Cars increased in CHL, mainly due to an increase of violaxanthin (V) + antheraxanthin (A) + zeaxanthin (Z) content per mol Chl (a+b). Faster development and a higher non-photochemical quenching (NPQ) of Chl fluorescence, related to a stronger deepoxidation of the larger xanthophyll cycle pool in NHL, could act as a major defence mechanism to reduce the formation of reactive oxygen species during severe chilling. This is suggested by higher content of Z or Z+A in photoinhibition as well as by its rapid decline during the initial fast phase of recovery. In contrast to the chilling-sensitive cv. 0004, the chilling-tolerant cv. 1141 did more easily acclimate its photosynthetic apparatus to low temperatures.

Mapping of Genes Involved in Glutathione, Carbohydrate and COR14b Cold Induced Protein Accumulation during Cold Hardening in Wheat

Using some of the chromosome substitution lines developed from the crosses of the donor Cheyenne to Chinese Spring we showed that the accumulation of water soluble carbohydrates during different stages of hardening was time dependent. More over there was a significant correlation between the rate of carbohydrate accumulation and the frost tolerance. The expression and regulation of a wheat gene homologous to the barley cold regulated corl4b gene was compared in frost sensitive and frost tolerant wheat genotypes at different temperatures. Studies made with chromosome substitution lines showed that the threshold induction temperature polymorphism of the cor14b wheat homologous gene was controlled by loci located on chromosome 5A of wheat, while corl4b gene was mapped, in Triticum monococcum, onto the long arm of chromosome 2A“’. Our study on the effect of cold hardening on glutathione (GSH) metabolism showed that chromosome 5A of wheat has an influence on the GSH accumulation and on the ratio of reduced and oxidised glutathione as part of a complex regulatory function during cold hardening. In addition, the level of increase in GSH content during hardening may indicate the degree of the frost tolerance of wheat.

Genetic study of glutathione accumulation during cold hardening in wheat.

The effect of cold hardening on the accumulation of glutathione (GSH) and its precursors was studied in the shoots and roots of wheat (Triticum aestivum L.) cv. Cheyenne (Ch, frost-tolerant) and cv. Chinese Spring (CS, moderately frost-sensitive), in a T. spelta L. accession (Tsp, frost-sensitive) and in chromosome substitution lines CS (Ch 5A) and CS (Tsp 5A). The fast induction of total glutathione accumulation was detected during the first 3 d of hardening in the shoots, especially in the frost-tolerant Ch and CS (Ch 5A). This observation was corroborated by the study of de novo GSH synthesis using [(35)S]sulfate. In Ch and CS (Ch 5A) the total cysteine, gamma-glutamylcysteine (precursors of GSH), hydroxymethylglutathione and GSH contents were greater during the 51-d treatment than in the sensitive genotypes. After 35 d hardening, when the maximum frost tolerance was observed, greater ratios of reduced to oxidised hydroxymethylglutathione and glutathione were detected in Ch and CS (Ch 5A) compared to the sensitive genotypes. A correspondingly greater glutathione reductase (EC 1.6.4.2) activity was also found in Ch and CS (Ch 5A). It can be assumed that chromosome 5A of wheat has an influence on GSH accumulation and on the ratio of reduced to oxidised glutathione as part of a complex regulatory function during hardening. Consequently, GSH may contribute to the enhancement of frost tolerance in wheat.

Frost hardiness depending on carbohydrate changes during cold acclimation in wheat

The effect of cold hardening on the dynamics of frost tolerance and on carbohydrate metabolism was studied in the frost-sensitive Chinese Spring and the frost tolerant Cheyenne genotypes, and in some of the chromosome substitution lines, derived from the crosses of the donor Cheyenne to Chinese Spring. Total water-soluble carbohydrate, glucose, fructose, sucrose and fructan contents were measured in the leaves. Differences in the accumulation of carbohydrates associated with cold tolerance occurred early in response to low temperature. Total water-soluble carbohydrates and total fructan content increased continuously during the cold treatment in all genotypes, resulting in higher contents in tolerant genotypes than in sensitive ones. Their rate of accumulation correlated significantly with the frost tolerance after 19 days of cold treatment. During the cold acclimation, the maximum of fructose accumulation proceeded that of sucrose. Significant correlation was detected between fructose and sucrose content and frost hardiness on the 43rd day of cold treatment. Fructose accumulated to a greater extent in the most tolerant genotypes with a sharp peak on the 35th day of cold hardening, followed by a decrease. In the chromosome substitution lines, the considerable sucrose accumulation started after the 11th day with a maximum on the 43rd day of cold hardening, coinciding with the tolerance test.

Cryopreservation Approach for the Germplasm Conservation of the Tropical Forest Tree Species

Cryopreservation approach for the germplasm conservation of three useful tropical forest tree species (Cedrela odorata L., Guazuma crinita Mart., and Jacaranda mimosaefolia D. Don.) were carried out using shoot-tip or roottip explants from in vitro-grown plantlets by four cryopreservation methods ((1) simple freezing, (2) rapid freezing, (3) slow pre-freezing, and (4) dehydration method). The effects of cold hardening treatments (5, 10, 15, and 20/10°C) and pre-culture (dehydration treatments) were also studied.The best results were achieved when the shoot-tips were cooled by slow pre-freezing before immersion in liquid nitrogen (LN). Survival and plant recovery rates of 50 and 20%; and, 50 and 15%; were obtained in cryopreserved shoot-tips of C. odorata and G. crinita, respectively. Although the effects of cold hardening and/or pre-culture treatments are not clear, apparently they were not effective in enhancing the survival or plant recovery rate after immersion in LN because these species may be intolerant of low temperature treatments of long duration and/or to drastic dehydration treatments.The cryopreservation of shoot-tips from tissue-cultured plants can be considered as a feasible alternative for the long-term storage of C. odorata, G. crinita, and J. mimosaefolia germplasm.

Prior Accumulation of Phosphatidylglycerol high in Trans-03Hexadecenoic Acid Enhances the in vitro Stability of Oligomeric Light Harvesting Complex II

Summary The effects of cold-hardening (5 °C) and non-hardening (20 °C) temperatures on the greening of etiolated seedlings under intermittent light conditions was examined in winter rye (Secale cereale L. cv. Muskateer). Development at 5 °C resulted in 2-fold higher levels of chlorophyll a and a 3-fold higher chlorophyll a fluorescence emission at 725 nm than leaves developed at 20 °C. Exposure of etiolated seedlings to low intensity (1 OWE — m-z . s-1), intermittent light at 20 °C resulted in the formation of higher levels of the trans-A3-hexadecenoic acid content associated with phosphatidylglycerol compared to exposure of etiolated seedlings to intermittent light at 5 °C. Subsequent exposure of seedlings grown either at 20 °C or 5 °C in intermittent light to continuous light (200 /,E — m-z . s-') caused a decrease in the ratio of chlorophyll a, b from between 7-10 to about 3.0 with the concomitant appearance of light harvesting complex II. However, in vitro data indicate that the oligomeric form of light harvesting complex II predominates at 20 °C (oligomer , monomer = 1.64) whereas the monomeric form predominates at 5 °C (oligomer, monomer = 0.42). Also, at 20 °C a maximum ratio of oligomer, monomer of 1.6-1.7 was attained after only 24 h of continuous illumination in seedlings initially exposed to 48 cycles of intermittent light. In contrast, 72 h at 20 °C was required to attain the same ratio in etiolated seedlings that had not been exposed to intermittent light. We conclude that low, intermittent light can induce the accumulation of high levels of trans-A3-hexadecenoic acid in the absence of light harvesting complex II. The prior accumulation of trans-A3-hexadecenoic acid enhances the stabilization of the oligomeric form of light harvesting complex II. This is consistent with a sequential process for the accumulation of trans-A3-hexadecenoic acid and the stabilization of light harvesting complex II in its in vitro oligomeric form.

Effect of Cold Hardening on Growth and Essential Oil Content of Mentha piperita L.

AbstractDivisions of running rhizomes of peppermint plants were planted in loamy clay soil in the experimental farm of National Research Centre, Dokki, Cairo, Egypt. After 21 days, the plants were exposed to low temperature 4, 7°C for 6, 9 and 12 days in controlled chamber before transplanting to large pots in winter season. Three cuttings were taken from the plants of different treatments during the season after 4, 7 and 10 months from transplanting. Representative samples of 6 replicates from each treatment were taken for the determination of vegetative growth and oil content in the leaves and branches.The results obtained indicated that the highest fresh and dry weight of leaves and branches was recorded in the second cutting, however, it markedly decreased in the third one. The highest favourable effect of cold hardening on vegetative growth was observed at 4°C for 12 days exposure in the second cutting. The percentage of volatile oil in the leaves recorded the highest values in treatment of 7°C for 6 days in the second sampling date. Cold hardening either at 4°C or 7°C resulted in pronounced increase in the essential oil yield produced by the plant with the superiority of 4°C for 12 days which recorded the highest value.It can be concluded from the obtained results that hardening peppermint plants with low temperature, particularly 4°C for 12 days before transplanting improved plant growth and considerably increased the volatile oil content in plant leaves and branches.

Effect of cold hardening, wilting and exogenously applied proline on leaf proline content and frost tolerance of several genotypes of Solanum

Frost tolerance and leaf proline content were examined in a number of potato hybrids selected for frost tolerance and in the cv. Astarte before and after hardening. Cold hardening (2°C for 20 days) in a dry environment (50/90% relative humidity, day/night) resulted in decreased water content, increased proline content and increased frost tolerance of the leaves of all genotypes. Frost tolerance before and after hardening was positively related to leaf proline content, but not to leaf water content. Drought stress alone, imposed by wilting excised leaves for 4 days, resulted in an accumulation of proline comparable to that after hardening in a dry environment, but the increase in frost tolerance was smaller. Cold hardening in a humid environment (90% relative humidity continuously) only caused a minor accumulation of proline and a small increase in frost tolerance, but the increase in frost tolerance was high in relation to the amount of proline accumulated. Proline, exogenously applied to one of the genotypes, was accumulated in the leaves of shoot cultures, resulting in an increase in frost tolerance. A possible role of proline in frost tolerance is discussed.

Effects of cold hardening on acyl lipids of citrus tissue

Cold hardened and unhardened 8- or 16-month-old citrus plants were examined for differences in fatty acid (FA) content. Unhardened leaves from 8-month-old Valencia scion budded on sour orange rootstock had 29% less FAs than leaves from seedling sour orange. After cold hardening triacylglycerol (TAG) FAs increased 4-fold in Valencia on sour orange and 6-fold in sour orange seedling. The percentage of FAs associated with TAGs for unhardened-hardened 16-month-old Valencia on sour orange tissues were: upper leaves 7–20, lower leaves 6–17, bark 6–9, and roots 57–73%. Cold hardening increased the amount of TAG FAs of 16-month-old Valencia on sour orange in upper leaves by 226% and in lower leaves by 173%. Concentrations of linoleic acid increased by 479% in upper leaves and by 303% in lower leaves. Quantities of lionolenic acid in monogalactosyl diacylglycerols declined by 27% in upper leaves and by 20% in lower leaves.

Uptake and Growth-promoting Activity of Indoleacetic Acid in Segments of Cold-hardened Wheat Coleoptiles

Seedings of winter wheat (Triticum aestivum L. cv. Kharkov MC 22) were grown at 24 C (unhardened) and 4 C (hardened). Indoleacetic acid (IAA) was added to excised coleoptile segments after lengthy incubation and their responses were determined by photometric auxanometry at both 25 C and 5 C. The segments' rates of uptake of (14)CIAA were also compared at both temperatures. Cold hardening had no significant effect on the rates of elongation and uptake in a saturating concentration of IAA (2 to 10 muM) at either temperature. Elongation was more sensitive to temperature of measurement than was uptake. At suboptimal concentrations of IAA and 25 C, hardened coleoptiles took up [2-(14)C]-IAA twice as fast but elongated half as fast as unhardened coleoptiles. This and the lack of effect of cold hardening on apparent uptake of [1-(14)C]-IAA raised the possibility that a higher rate of IAA-decarboxylation was coupled with the higher rate of uptake of IAA by hardened coleoptiles. Homeostatic hormonal regulation was also evident in the same endogenous rates of elongation of segments of cold-hardened and unhardened coleoptiles.

Effects of Cold Hardening and CCC Treatment on Hydration and Frost and Desiccation Hardiness of Plant Tissues

Treatment at 5 C or with CCC (2-chloroethyl-trimethylammonium chloride) has enhanced resistance to frost injury in the leaves of winter rape, Brassica napus L. var. oleifera cv. Górczański, grown in water culture in temperature-controlled rooms. The leaves of the treated plants were also more resistant to desiccation injury caused by a highly effective desiccant. They were able to lose water at a faster rate in the presence of the desiccant. This was coincident with a lower impedance of those leaves. On the other hand, the leaves of the treated plants have shown a smaller water saturation deficit (WSD) under prevailing culture conditions. The WSD changes were not accompanied by changes in the number of stomata, and only cold-hardened leaves had their stomata closed. Both treatments caused a decrease in permeability of root systems to forced water flow. The possible reasons for the described phenomena and a possible role of these phenomena in frost hardiness of plants are discussed.