Monitoring expression profiles of Arabidopsis genes during cold acclimation and deacclimation using DNA microarrays

A comparative analysis of gene expression profiles during cold acclimation and deacclimation is necessary to elucidate the molecular mechanisms of cold stress responses in higher plants. We analyzed gene expression profiles in the process of cold acclimation and deacclimation (recovery from cold stress) using two microarray systems, the 7K RAFL cDNA microarray and the Agilent 22K oligonucleotide array. By both microarray analyses, we identified 292 genes up-regulated and 320 genes down-regulated during deacclimation, and 445 cold up-regulated genes and 341 cold down-regulated genes during cold acclimation. Many genes up-regulated during deacclimation were found to be down-regulated during cold acclimation, and vice versa. The genes up-regulated during deacclimation were classified into (1) regulatory proteins involved in further regulation of signal transduction and gene expression and (2) functional proteins involved in the recovery process from cold-stress-induced damages and plant growth. We also applied expression profiling studies to identify the key genes involved in the biosynthesis of carbohydrates and amino acids that are known to play important roles in cold acclimation. We compared genes that are regulated during deacclimation with those regulated during rehydration after dehydration to discuss the similarity and difference of each recovery process.Electronic Supplementary Material Supplementary materials are available for this article at     

Inheritance of the photoperiodically induced cold acclimation response in Cornus sericea L., red-osier dogwood

Summary Cold acclimation responses of latitudinal ecotypes of Cornus sericea L. (C. stolonifera Michx.) and F₁, F₂ and BC₁ hybrid progenies were measured under natural photoperiod conditions in St. Paul, MN and artificially shortened photoperiods in the glass-house. The 65 °N and 62 °N ecotypes (Alaska and Northwest Territories, respectively) were characterized by a short night length for hardiness induction, the 42 °N ecotype (Utah A and B) by a long night length for hardiness induction, while the F₁ was intermediate to the parents. Results from reciprocal crosses indicated there was no significant unilateral maternal influence on cold acclimation. Acclimation responses of the F₂ were highly variable but generally ranged between the parental extremes. However, three individuals from the 42 ° × 62 °N crosses exhibited greater cold resistance than the northern parent on two successive freezing test dates. F₂ plants were also found with less freezing resistance than the southern parent. Backcrosses to the southern parent produced progeny with acclimation patterns resembling that of the southern parent and were significantly less hardy than the F₂ in early freezing tests.Scientific Journal Series Paper No. 12,075 of the Minnesota Agricultural Experiment Station     

In vitro screening for cold hardiness of raspberry cultivars

Raspberry (Rubus idaeus L.) cultivars ‘Festival’, ‘Titan’ and ‘Willamette’ were cultured in vitro on three different media: (A) MS medium supplemented with 1.0 mg l^-1 BAP and 0.1 mg l^-1 IBA, (B) MS medium without growth regulators, and (C) MS medium with reduced sucrose (10 g l^-1), and exposed to different low temperature acclimation treatments: (1) control, no acclimation, (2) 1 week at +15 °C, 1 week at +2 °C, 24 h at -2 °C and 3 days at +2 °C, and (3) 2 weeks at +15 °C, 2 weeks at +2 °C, 24 h at −2 °C and 3 days at +2 °C. After acclimation, shoot moisture content was measured, and cold hardiness (LT₅₀) was determined by controlled freezing. Shoot moisture content was generally lower on culture medium B compared to the other media, but not affected by acclimation treatment. In non-acclimated plants, medium composition had no effect on cold hardiness and no cultivar differences in hardiness were observed. After acclimation, plants on culture medium B were on average more cold hardy than on the other media. Acclimation treatment 3 on media A and B allowed the best discrimination between the hardy cultivar ‘Festival’ and less cold hardy ‘Titan’ and ‘Willamette’. When acclimation treatments were tested further using 11 raspberry cultivars with different levels of cold hardiness, discrimination between cultivars was satisfactory only after acclimation treatment 3 on culture medium B. This revised version was published online in June 2006 with corrections to the Cover Date.     

A ThCAP gene from Tamarix hispida confers cold tolerance in transgenic Populus (P. davidiana?×?P. bolleana)

The ThCAP gene, which encodes a cold acclimation protein, was isolated from a Tamarix hispida NaCl-stress root cDNA library; its expression patterns were then assayed by qRT-PCR in different T. hispida tissues treated with low temperature (4°C), salt (400 mM NaCl), drought (20% PEG6000) and exogenous abscisic acid (100 μM). Induction of ThCAP gene was not only responsive to different stress conditions but was also organ specific. When transgenic Populus (P. davidiana × P. bolleana) plants were generated, expressing ThCAP under regulation of the cauliflower mosaic virus CaMV 35S promoter, they had a greater resistance to low temperature than non-transgenic seedlings, suggesting that ThCAP might play an important role in cold tolerance.     

Disruption of an Ice-nucleation Barrier in Cold Hardy Azalea Buds by Sublethal Heat Stress

Ice nucleating barriers of undetermined composition are knownto occur in floral buds of several cold hardy species, includingAzalea. Fluorescence microscopy indicated the presence of phenolic-nchareas within hardy Azalea flower buds, which could be ice barriers.Hardy buds were subjected to a sublethal heat stress of 45 °Cfor 2 h to disrupt barrier integrity. Two hours after treatmentthe low temperature exotherms (LTEs) of flowers were observedusing differential thermal analysis (DTA). The LTEs of budsexposed to heat stress were either fewer in number and/or occurredat higher temperatures than in controls. Visual assay of theflowers following DTA confirmed that heat-stressed flowers werekilled at higher temperatures than control flowers. Heat-stressedbuds also have lower resultant hardiness compared to controlsas demonstrated by controlled freezing experiments. Acclimation, phenolics, resistance, stress     

植物抗寒及其基因表达研究进展

植物经过逐渐降低的温度从而提高抗寒能力 ,这个过程被人们称为低温驯化。植物低温驯化过程是一个复杂的生理、生化和能量代谢变化过程 ,这些变化主要包括膜系统的稳定性、可溶性蛋白的积累和小分子渗透物质 ,比如脯氨酸、糖等 ,这些变化中的一些是植物抗寒必需的 ,而另外一些变化不是必需的。主要对冷害和低温生理生化变化、低温诱导表达基因的功能和作用、低温驯化的调节机制及其信号转导方面进行了综述。通过差别筛选 c DNA文库的方法已经鉴定了许多低温诱导表达、进而提高植物抗寒能力的基因 ,其中有脱水素、COR基因和 CBF1转录因子等。低温信号的感受、转导和调节表达是低温驯化的关键环节 ,低温信号的转导过程与干旱胁迫之间具有一定的交叉 ,这为利用 ABA等来提高植物抗寒能力成为可能 ,相信不久的将来人们可以通过提高植物抗寒能力从而增加经济产量成为现实。     

The state of water in acclimating vegetative buds from Malus and Amelanchier and its relationship to winter hardiness

The relationship between freezable water and cold hardiness during acclimation was studied using vegetative buds from several apple ( Malus domestica Borkh) cultivars and from one saskatoonberry ( Amelanchier alnifolia Nutt. cv. Smoky) cultivar. According to leakage data and visual assessments of cortical browning, vegetative buds of all cultivars were most tolerant to subfreezing temperatures in January. The hardy condition was also associated with maximum tolerance to desiccation. Qualitative features of freezing exotherms (number of peaks and temperature of the transition) were not correlated with the hardy condition in the tissues. However, the amount of unfrozen water, determined by quantifying the energy of the exotherms, increased with increasing hardiness. In buds that survived exposure to −45°C, freezing reduced the intracellular water content, but only to levels above the critical moisture content for desiccation damage. In buds that did not survive exposure to −45°C, freezing reduced the water content to levels equal to or less than the critical moisture content for desiccation damage. These observations suggest that the freezing of water in nonhardy tissue dried the tissue to moisture levels at which severe dehydration damage occurred. It appears that acclimation of vegetative apple buds involves at least two processes: (1) an increase in tolerance to dehydration and (2) an increase in the level of unfreezable water.     

Expression of SK3-type dehydrin in transporting organs is associated with cold acclimation in Solanum species

The expression of a gene, encoding a dehydrin protein designated as DHN24 was analyzed at the protein level in two groups of Solanum species differing in cold acclimation ability. The DHN24 protein displays consensus amino acid sequences of dehydrins, termed K- and S-segments. The S-segment precedes three K-segments, classifying the protein into SK₃-type dehydrins. A group of Solanum species able to cold acclimation constituted by S. sogarandinum and S. tuberosum, cv. Aster, and a second one composed of a S. sogarandinum line, that lost ability to cold acclimation, and of S. tuberosum, cv. Irga, displaying low ability to cold acclimation were studied. Under control conditions, noticeable levels of the DHN24 protein was observed in stems, tubers, and roots of Solanum species. No protein was detected in leaves. During low temperature treatment the DHN24 protein level substantially increased in tubers, in transporting organs and in apical parts, and only a small increase was observed in leaves. The increase in protein abundance was only observed in the plants able to cold acclimate and was found to parallel the acclimation capacity. Upon drought stress, the DHN24 level decreased in stems and in leaves, but increased in apical parts. These results suggest that Dhn24 expression is regulated by organ specific factors in the absence of stress and by factors related to cold acclimation processes during low temperature treatment in collaboration with organ-specific factors. A putative function of the SK₃-type dehydrin proteins during plant growth and in the tolerance to low temperature is discussed.     

Drought acclimation and lipid composition in Folsomia candida: implications for cold shock,heat shock and acute desiccation stress

Many of the physiological adaptations evolved in terrestrial invertebrates to resist desiccation have also been shown to enhance the survival of low temperatures. In this study we have examined temporal changes in the physiology of the collembolan Folsomia candida during acclimation to mild desiccation stress (98.2% RH), and how physiological changes correlate with resistance to subsequent cold shock, heat shock and acute desiccation stress. Drought-acclimation increased the resistance to cold and acute drought but reduced the resistance to heat shock. The composition of membrane phospholipid fatty acids (PLFA) changed during acclimation resulting in a higher degree of unsaturation by the end of the 192-h acclimation period. This resembles typical membrane alterations seen in ectothermic animals exposed to cold. Only small changes were seen in the neutral lipid fraction. The temporal changes in cold resistance and drought resistance correlated well with changes in PLFA composition and accumulation of sugars and polyols (’cryoprotectives’). It is proposed that the drought-induced PLFA desaturation, combined with the membrane protecting accumulation of cryoprotectives, are important physiological adaptations providing tolerance to both desiccation and cold.     

Programmed accumulation of LEA-like proteins during desiccation and cold acclimation of overwintering grape buds

Molecular investigation of the process of cold acclimation in woody plants has been limited by the superimposition of dormancy-related events on the process of cold tolerance development. To address this limitation, we have used the grape Vitis labruscana L. ev. Concord to develop a system in which the developmental programme of dormancy can be induced seperately from cold acclimation. Using this system we have characterized differential accumulation of several proteins in grape buds during the normally superimposed endodormancy and cold acclimation programmes, and in buds which have entered only the endodormancy programme. A set of 47 kD proteins accumulated during endodormancy without cold acclimation to a level similar to that found in endodormant and cold-acclimated buds, but without any associated increase in bud cold-acclimation level. However, a 27 kD LEA-like protein accumulated only in cold acclimated buds. We conclude that expression of the 47 kD glycoprotein is endodormancy-related, but is not strictly related to the development of cold acclimation, while the 27 kD protein appears to be more specific to cold acclimation. In addition to strengthening the association of LEA-like proteins with cold acclimation, this system allows more specific assessment of cold acclimation-associated phenomena in overwintering buds.