• Korean journal of applied entomology
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• v.36 no.3
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• pp.249-255
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• 1997

The sublethal temperature (5$^{\circ}$C for 2hr) led the fifth instar larvae of beet armyworm, Spodoprern exigucr (Hiibner), to increase cold tolerance to subzero lethal temperatures ( 'rapid cold hardening' ). The strength of rapid cold hardening was, however, varied among different populations which showed different cold tolerance in response to cold temperatures. To analyse the physiological factors affecting the rapid cold hardening, hernolymph osmolalities. supercooling points, glycerol contents, and cold stress proteins were measured by treating the fifth instar larvae with the sublethal low temperatures. The treated larvae showed increase of hemolymph osmolalities and glycerol contents. Changes of the osmolalities were greater in cold-hardy strains than in cold-susceptible strains. The sublethal temperature also induced them to express the cold-stress proteins (I0 - 20kD) in the hemolymph. but did not to change supercooling points.

• Plant Breeding and Biotechnology
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• v.1 no.1
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• pp.1-8
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• 2013

Low-temperature stress is an important factor controlling the growth and development of rice (Oryza sativa L.) in temperate region. In this study, a molecular linkage map consisting of 136 SSR markers was employed to identify QTL associated with cold tolerance at the seedling stage. 80 recombinant inbred lines (RILs) from an intersubspecific cross between Milyang23 (O. sativa ssp. Indica) and Hapcheonaengmi3, a japonica weedy rice and the parents were evaluated for leaf discoloration and SAPD value of seedlings. Rice plants were grown for 15 days in the low-temperature condition (13/20℃ day/night) and the control condition (25/20℃ day/night) in the growth chamber. The degree of leaf discoloration showed a highly significant correlation with the SPAD value in the low-temperature plot (r = -0.708, P < 0.0001). A total of four QTLs for SPAD were identified and the phenotypic variance explained by each QTL ranged from 5.4 to 16.0%. Two QTLs detected in the control condition were located on chromosomes 2 and 5, respectively. Two QTL on chromosomes 1 and 4 were detected at the low-temperature condition and Hapcheonaengmi3 alleles increased the SPAD values at these loci. Substitution mapping was conducted to delimit the position of qSPA-4 using introgression lines derived from the same cross. Results indicated that qSPA-4 was located in a 810-Kb region flanked by RM16333 and RM16368. The results indicated that Hapcheonaengmi3 contains QTL alleles that are likely to improve cold tolerance of Indica rice.

• Molecules and Cells
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• v.39 no.3
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• pp.250-257
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• 2016

Abiotic stresses such as drought and low temperature critically restrict plant growth, reproduction, and productivity. Higher plants have developed various defense strategies against these unfavorable conditions. CaPUB1 (Capsicum annuum Putative U-box protein 1) is a hot pepper U-box E3 Ub ligase. Transgenic Arabidopsis plants that constitutively expressed CaPUB1 exhibited drought-sensitive phenotypes, suggesting that it functions as a negative regulator of the drought stress response. In this study, CaPUB1 was over-expressed in rice (Oryza sativa L.), and the phenotypic properties of transgenic rice plants were examined in terms of their drought and cold stress tolerance. Ubi:CaPUB1 T3 transgenic rice plants displayed phenotypes hypersensitive to dehydration, suggesting that its role in the negative regulation of drought stress response is conserved in dicot Arabidopsis and monocot rice plants. In contrast, Ubi:CaPUB1 progeny exhibited phenotypes markedly tolerant to prolonged low temperature ($4^{\circ}C$) treatment, compared to those of wild-type plants, as determined by survival rates, electrolyte leakage, and total chlorophyll content. Cold stress-induced marker genes, including DREB1A, DREB1B, DREB1C, and Cytochrome P450, were more up-regulated by cold treatment in Ubi:CaPUB1 plants than in wild-type plants. These results suggest that CaPUB1 serves as both a negative regulator of the drought stress response and a positive regulator of the cold stress response in transgenic rice plants. This raises the possibility that CaPUB1 participates in the cross-talk between drought and low-temperature signaling pathways.

• Journal of Korean Society of Forest Science
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• v.111 no.2
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• pp.251-262
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• 2022

We selected a cold-tolerant tea tree (Camellia sinensis L.) through reliable evaluation using a number of cold-tolerance indicators targeting tea tree cultivars such as "Chamnok," "Bohyang," "Sangnok," and "Myungnok" in response to climate change. We conducted a low-temperature damage investigation, "Chamnok" and "Bohyang" were damaged investigated with small amounts of green and bright green. "Sangnok" and "Myungnok" were damaged investigated red and dark red at -10℃. The extent of electrolyte leakage increased as the treatment temperature decreased in all cultivars. We predicted lethal temperatures through non-linear regression analysis, finding relatively higher tolerance to low temperature in "Chamnok" (-9.344℃) and "Bohyang" (- 8.883℃) than that in "Myungnok" (-8.092 ℃) and"Sangnok" (-7.632℃). "Bohyang" showed higher levels of antioxidant activity compared to other cultivars. The lipid peroxidation reaction revealed that "Sangnok" and "Myungnok" had higher MDA content than that of other cultivars when treated at low temperatures. Consequently, predictions of the lethal temperature through non-linear regression analysis of "Chamnok" and "Bohyang" were consistent with their tolerance to low-temperature damage, and antioxidant activity and lipid peroxidation reactions were likewise consistent. The results of this study can be used not only for evaluation and selection of cold-tolerance of tea trees in response to climate change, but also in the cultivation of cold-tolerant plants.

• Journal of Plant Biotechnology
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• v.43 no.2
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• pp.255-260
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• 2016

This research was conducted to improve the cold tolerance of the gerbera cv. Gold Eye by introduction of the Arabidopsis $Ca^{2+}/H^+$ antiporter gene (CAX1) via Agrobacterium-mediated transformation. Prior to genetic transformation, we optimized a combination of plant growth regulators; $1.0mgl^{-1}$ 6-Benzyladenine (BA) and $0.1mgl^{-1}$3-indole-acetic acid (IAA) were found to lead to proper in vitro shoot regeneration from petiole explants. In addition, $50mgl^{-1}$ kanamycin was determined to be the minimal concentration useful for selection of putative transgenic plants. In this study, transgenic gerbera expressing the Arabidopsis $Ca^{2+}/H^+$ antiporter gene (CAX1) were obtained using the optimized concentrations. We expect that introduction of the gene to the cultivar will improve cold tolerance, which will be important in the winter months.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.4
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• pp.210-216
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• 2018

This experiment was carried out to study the effect of difference in cold-tolerance and growth characteristics of variety on forage productivity of Italian ryegrass(IRG) in middle region of Korea from 2017 to 2018. Cold-tolerance of IRG was significant different between varieties(p<0.05). Overwinter rate of domestic variety of IRG was higher than that of foreign variety(p<0.05). Among early-maturing varieties, overwinter rate of Kowinearly was highest as 68% that was 33% higher than that of Florida 80. Among middle-maturing varieties, overwinter rate of Kowinmaster was highest as 70% that was 28% higher than that of Tam 90. DM yield of IRG was significant different between varieties(p<0.05). Among early-maturing varieties, DM yield of Kowinearly and Greenfarm 2 was about 3 to 3.5 ton/ha more than that of Florida 80. Among middle-maturing varieties, DM yield of Kowinmaster was about 2ton/ha more than that of winter-hawk or Tam 90. There is a direct correlation between forage productivity and cold-tolerance of IRG variety(p<0.01). These results suggested that choice of early- or middle-maturing variety with cold-tolerant is more important for increasing the forage productivity of IRG If harvesting for roughage have to be finished in the middle ten days of May in middle region of Korea.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.193-199
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• 2021

Solenopsis japonica, which is belonging to Formicidae in Hymenoptera, is a native ant species in Korea. However, it had not been studied for cold hardiness of S. japonica to understand on its overwintering mechanisms in field so far. Cold tolerance on developmental stages was measured at different cold temperature with various exposure times. Workers showed more survival at 5℃ and 10℃ compared with other stages and elevated cold tolerance when workers were exposed at 15℃ for more than 12h incubation as a rapid cold hardening (RCH) condition. RCH treatment not only increased survival of workers at cold temperatures, but also decreased supercooling point (SCP) and freezing point (FP). RCH group increased the survival rate by 44% at 10℃ compared with Non-RCH group. SCP and FP were depressed from -10.0 to -14.2℃ and from -11.3 to -15.3℃, respectively, after RCH treatment. Cold temperature increased expression level of cold- and stress-related genes such as glycerol kinase and heat shock protein. These results indicate unacclimated cold tolerance of S. japonica and its acclimation to low temperature by RCH.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.203-211
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• 1995

This study was conducted to know how low temperature response of rice varieties is available for breeding lines adapted to cold weather. Some agronomic characters related to cold tolerance were evaluated for 188 varieties including three varietal types of Japonica, Tongil, and Indica. Cold tolerance of Japonica and Indica type varieties varied in leaf discoloration, heading delay, reduction of culm length, panicle number, spikelet number, panicle exsertion, spikelet fertility, and phenotypic acceptability at maturity, while Tongil type varieties were susceptible in most agronomic characters. In leaf discoloration, most Japonica type varieties were highly tolerant, while Indica type varieties showed various responses from tolerant to susceptibility. Not significant difference among three varietal types was observed on reduction of panicle number and spikelet number due to low temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.144-151
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• 1991

Composition and unsaturation ratio of fatty acids composing phospholipid which is the main constituent of biological membranes are known to be related to the response of plant to cold stress. In order to investigate a relationship between fatty acid unsaturation ratio of phospholipid and the range of cold tolerance of rice cultivars obtained in the field experiment, the lipid from the leaves of 32 rice cultivars were isolated and the fatty acid composition of phospholipid was determined by gas chromatography. In this experiment, composition and unsaturation ratio of fatty acids composing phopholipid on rice plants grown under natural condition and treated with chilling temperature were compared with the cold tolerance in the field for rice cultivars. The results obtained were summarized as follows ; 1. The phospholipids isolated from the leaves of 32 rice cultivars both grown under natural condition and chilling treatment contained palmitic, linoleic and linolenic acid as major components and palmitoleic, stearic and oleic acid as minor components. 2. The content of palmitic acid, a saturated fatty acid, was reduced in rice seedlings subjected to chilling treatment for 3 days at $15^{\circ}C$, and contents of linoleic and linolenic acid, unsaturated fatty acids, were increased. 3. The unsaturation ratio of fatty acid was increased by chilling treatment, and was high in cold-tolerant cultivars but low in cold-susceptible cultivars and the results were correlated with the range of cold tolerance investigated in the field. 4. The content of palmitic acids among fatty acids composing phospholipid was reduced and that of linolenic acid was increased by hardening treatment. 5. The unsaturation ratio of fatty acid was increased 18~24% by hardening treatment compared to control.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.1
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• pp.45-52
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• 1996

This study was conducted to know how cold tolerance of rice is inherited. Several crosses were made between cold tolerant and susceptible varieties, and their progenies were evaluated for days to heading, spikelet number per panicle and spikelet fertility under both cold water and natural conditions. In F$_1$ and F$_2$ generations, earlier heading, more number of spikelet per panicle and higher spikelet fertility under the cold condition were dominance, and less delay or reduction in heading days and spikelets per panicle by cold treatment were over dominance or partial dominance, while less reduction in spikelet fertility by cold-water irrigation was complete dominance. Heritability in most characters by cold treatment was high and there was less difference of heritabilities in heading days and spikelets per panicle between cold treatment and natural conditions, while there was much difference of heritability in spikelet fertility between two conditions. Heterosis in spikelet fertility was considerably high, while those in heading days and spikelets per panicle were relatively low. Heterosis in remote crosses was especially larger under the cold-water treatment condition compare with that under natural condition.