• BMB Reports
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• v.40 no.6
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• pp.986-1001
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• 2007

Cold acclimation improves freezing tolerance in plants. In higher plants, many advances have been made toward identifying the signaling and regulatory pathways that direct the low-temperature stress response; however, similar insights have not yet been gained for simple nonvascular plants, such as bryophytes. To elucidate the pathways that regulate cold acclimation in bryophytes, we used two PCR-based differential screening techniques, cDNA amplified fragment length polymorphism (cDNA-AFLP) and suppression subtractive hybridization (SSH), to isolate 510 ESTs that are differentially expressed during cold acclimation in Physcomitrella patens. We used realtime RT-PCR to further analyze expression of 29 of these transcripts during cold acclimation. Our results show that cold acclimation in the bryophyte Physcomitrella patens is not only largely similar to higher plants but also displays distinct differences, suggests significant alteration during the evolution of land plants.

• Journal of Ecology and Environment
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• v.34 no.3
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• pp.251-257
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• 2011

The purpose of this study was to investigate the acclimation responses of Tamarix chinensis to cold stress. We evaluated the acclimation responses by measuring biomass, daily elongation rate, chlorophyll content, and total soluble carbohydrate content. The plant samples comprised leaves from seedlings of 2 different ages (8 and 12 weeks); the leaves were collected 0, 2, and 4 weeks after cold treatment. We found that the cold-treated samples showed reduced daily elongation rates and chlorophyll content. Further, these samples showed more than 8-fold increase in the total soluble carbohydrate content. However, the seedling ages did not have a significant influence on the growth of cold-treated seedlings. On the basis of these findings, we can conclude that T. chinensis seedlings aged less than 1 year old show acclimation to cold stress by accumulating soluble carbohydrates. This study may help us understand how T. chinensis seedlings acclimatize to their first cold season.

• Journal of Ecology and Environment
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• v.31 no.4
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• pp.317-325
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• 2008

P. glehnii, an evergreen conifer found in northern areas, is known as a cold-resistant species. In this experiment, we measured the water content, PSⅡ efficiency, chlorophyll fluorescence, pigments of the xanthophyll-cycle and activity of enzymes of the ascorbate-glutathione cycle during cold acclimation and at subsequent low-temperature conditions to examine the importance of acclimation to cold tolerance. P. glehnii showed a decrease in PSⅡ efficiency (especially in Fv) during cold acclimation and at subsequent low temperatures. However, cold-acclimated needles showed higher PSⅡ efficiency at low temperatures than nonacclimated needles. In addition, 0-YON (first-year needles) showed an increase in $\beta$-carotene and lutein, while 1-YON (one-year-old needles) immediately developed an antioxidant mechanism in the ascorbate-gluthathione cycle as soon as they were exposed to low temperature and both 0-YON and 1-YON showed increased zeaxanthin and de-epoxidation ratios at continuous low temperature. Based on our results, we suggest that P. glehnii maintain PSⅡ efficiency at low temperature by effectively protecting the photosynthetic apparatus from photo-damage by rapid induction of an antioxidant mechanism in 1-YON and dissipation of excess energy by $\beta$-carotene and lutein in 0-YON.

• ALGAE
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• v.39 no.1
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• pp.17-30
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• 2024

Red macroalga Pyropia yezoensis is a high valuable cultivated marine crop. Its acclimation to cold stress is especially important for long cultivation period across winter in coasts of warm temperate zone in East Asia. In this study, the response of P. yezoensis thalli to low temperature was analyzed on physiology and transcriptome level, to explore its acclimation mechanism to cold stress. The results showed that the practical photosynthesis activity (indicated by Φ_PSII and qP) was depressed and pigment allophycocyanin content was decreased during the cold stress of 48 h. However, the F_v/F_m and non-photochemical quenching increased significantly after 24 h, and the average growth rate of thalli also rebounded from 24 to 48 h, indicating a certain extent of acclimation to cold stress. On transcriptionally, the low temperature promoted the expression of differentially expressed genes (DEGs) related to carbohydrate metabolism and energy metabolism, while genes related to photosynthetic system were depressed. The increased expression of DEGs involved in ribosomal biogenesis and lipid metabolism which could accelerate protein synthesis and enhance the degree of fatty acid unsaturation, might help P. yezoensis thallus cells to cope with cold stress. Further co-expression network analysis revealed differential expression trends along with stress time, and corresponding hub genes play important roles in the systemic acquired acclimation to cold stress. This study provides basic mechanisms of P. yezoensis acclimation to cold temperature and may aid in exploration of functional genes for genetic breeding of economic macroalgae.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.176-179
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• 1999

Trinexapac-ethyl[ 4-(cyclopropyl- $\alpha$ -hydroxy-methylene)-3,5-dioxocyclohexane carboxylic acid ethylester] is a growth-retardant for plants by inhibiting a key step in biosynthesis of GA. A treatment of trinexapacethyl generally induces a reduction in vegetative growth and also inhibits heading. In addition, the trinexapacethyl was known to enhance the freeze-tolerance in annual bluegrass, however, the mechanism is not known yet. One possible reason for the enhanced freeze-tolerance may be the antifreeze protein known to be accumulated in intercellular space of the leaf during cold acclimation. In order to see the possible in-duction of the synthesis of antifreeze proteins by trinexacpacethyl, the apoplastic proteins extracted from Kentucky bluegrass treated with trinexapacethyl were analyzed by SDS-PAGE and the presence of the antifreeze protein was observed. In addition, western analysis showed the identity of the protein induced by both a cold acclimation and a trinexapacethyl treatment. It appears that an enhanced freeze-tolerance of the turf grass by trinexapacethyl is due to the synthesis and/or accumulation of the antifreeze protein similar to the enhanced freeze tolerance induced by cold acclimation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.3
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• pp.172-178
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• 1998

Freezing-resistant plants can survive subzero temperatures by withstanding extracellular ice formation. During cold acclimation, their leaves accumulate antifreeze proteins (AFPs) that are secreted into the apoplast and have the ability to modify the normal growth of ice crystals. Three barley, two wheat and two rye cultivars were grown under two different temperature regimes (20/16$^{\circ}C$ and 5/2$^{\circ}C$, day/night). Apoplastic proteins from winter cereals were separated by SDS-PAGE and detected with antisera to AFPs from winter rye. Apoplastic proteins accumulated to much higher levels in cold-acclimated (CA) leaves compared with nonacclimated (NA) ones in winter cereals. After cold acclimation, the protein concentration of apoplastic extracts increased significantly from 0.088 $mgmL^{-1}$ to 0.448 $mgmL^{-1}$, with about 5-fold increment. Also, the apoplastic protein content per gram leaf fresh weight in CA leaves ranged from 31 $\mu\textrm{g}$ $(gFW)^{-1}$ to 120 $\mu\textrm{g}$ $(gFW)^{-1}$ with an averaged value of 77 $\mu\textrm{g}$ $(gFW)^{-1}$, and coefficients of variation of 54.9%. The CA leaves in Musketeer (a Canadian winter rye cultivar) showed the greatest AFPs and antifreeze activity followed by 'Geurumil' (a Korean winter wheat cultivar), and 'Dongbori l' (Korean facultative barley cultivar). The proteins secreted into the wheat leaf apoplast at CA condition were more numerous than those observed in winter rye, where two $\beta$-1,3-glucanase-like proteins (GLPs), two chitinase-like proteins (CLPs) and two thaumatin-like proteins (TLPs) accumulated during cold acclimation. The proteins in barley leaf apoplast at CA conditions were a little different from those in wheat leaves. The AFPs were various among and within species. More freezing-resistant cultivars had more clear and numerous bands than less freezing-resistant ones. The high determination coefficient ($R^2$ =91 %) between freezing resistance and AFPs per gram leaf fresh weight indicated that the amount of AFPs was highly related to freezing resistance in winter cereal crops.

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.1-11
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• 1997

In relations to cold acclimation, experiment was carried out to understand the seasonal changes in reserve substances of the mulberry. The shoot barks and leaves of three mulberry varieties(Kaeryangppong, Shinilppong and Yongcheonppong) were sampled, after that their reserve substances were analyzed. The cold hardiness of mulberry was investigated by DTA(Differential Thermal Analysis) method. To increase cold hardiness, gibberellin(100 ppm), kinetin(100 ppm) and Jambi 8 were sprayed on the mulberry leaves. After spraying, falling of the leaves of Yongcheonppong occured earier than the other varities. After the first frost, all of treatments except gibberellin were entirely fallen. Growth regulator extended the leaves fallen. After spraying, water of the shoot barks was not showed difference in the content among the treatments, but amino acid, carbohydrate and soluble protein increased from September to October. Starch content of the shoot barks and leaves was maximum in October, but thereafter decreased during wintering stage. In Shinilppong, Jambi 8 spray increased cold hardiness by 1-2$^{\circ}C$ more than no spray. It was concluded that the cold hardiness of the mulberry in midwinter is closely related to the reserve substances with spraying Jambi 8 on the mulberry leaves.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.212-217
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• 1995

This study was aimed for determining the biochemical mechanism of cold tolerance in crops and for searching the biochemical genetic marker related with cold tolerance by the analysis of isozyme pattern. We investigated various biochemical changes induced by the long-term cold acclimation in cold sensitive rape (B. napus) and in cold tolerant 'Sandongchae'(B. campestris) seedlings. The cold shock after long-term cold acclimation to B. napus and B. campestris greatly increased the activities of peroxidase 157% and 50% in root fraction and, 201% and 205% in hypocotyl, respectively. Simultaneously, the activity of superoxide dismutase was largely increased in hypocotyl fraction, too. Protein contents of hypocotyl fractions in B. napus and B. campestris were also increased by 11.4% and 57.8%, respectively. The band of pl 6.4 among peroxidase isozymes newly biosynthesized during long-term cold acclimation was emerged in the hypocotyl fraction of cold tolerant B. campestris as well as in the root of both species. From above and previous results, we presented a model of interconversions of molecular oxygen species due to the cold injury and biochemically inferred the mechanism of cold tolerance in crops.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.91-96
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• 1998

In relation to cold acclimation, this experiment was carried out to understand the changes of the cortical cells in the living barks of the mulberry during wintering period. The living barks of three mulberry varieties(Kaeryangppong, Shinilppong and Yongcheonppong) were sampled from December, 1995 to March, 1996. The result of this experiment was summarized as follows. The cortical cells in the living barks of the mulberry in December were filled with small vacuoles. Plastids and mitochondrias were located near the nucleus. At this time, almost all starch granules disappeared from the plastids. In January and February, mitochondria, palstids and microbodys of the cortical cell were observed. As increasing temperature from March, dictysomes and polysomes were sparse. Again, starch granules disappeared were observed in the plastids. From the above result. starch granules in plastide of the cortical cell of the mulberry disappeared during cold acclimation stage. After late January, Proplastid was observed in the cortical cell and the ultrastructures of cortical cell were actively changed.

• The Korean Journal of Zoology
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• v.7 no.1
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• pp.23-28
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• 1964

120 mice of both sexes weighing from 18 to 22 g. were used. These mice were divided nito 12 groups : control (non-restraint and restraint) , acclinmation (non-restraint and restraint , acclimation for 5 and 10 days) , adrenalectomized (non-restraint and restraint0 and acclimation-adrenalectomized (non-restraint and restraint, acclimation for 5 and 10 days) groups. The rectal temperature of each group were measured at 10, 30 and 50 min under environment of $0^{\circ}C$.Measurements were done with a microphrometer of B.T.-32 thermocorpules. The results obtained may be summarized as follows : 1) The rectal temperature in normal mice without restraint was higher than that of normal mice with restraint under environment of $0^{\circ}C$. 2) The rectal temperature in normal mice was higher than that of adrenalectomized mice at 20$^{\circ}$ C. But the rectal temperature in adrenalectomized mice without restraint was higher than that of adrenalectomized mice with restraint under cold-stress. This difference was in the order of 1.65$^{\circ}$ under environment of 20$^{\circ}$ and 10 $^{\circ}$ at 50 min under environment of 0$^{\circ}$. 3) The rectal temperature of normal mice with restraint was less than that of adrenalectomized mice (non-restraint) under cold-stress. 4) The rectal temperature of normal and adrenalectomized mice that acclimated under cold stress ($0^{\circ}C$) for 5 and 10 days was usually higher than that of normal and adrenalectomized mice of non-acclimation under environment of $0^{\circ}C$. 5) The tolerance in mice under cold-stress was increased on the acclimtion of cold.