Journal of Experimental Botany, Vol. 52, No. 365, pp. 2367-2374,
December 1, 2001
© 2001 Oxford University Press
Original Papers |
Expression of a cold-responsive Lt-Cor gene and development of freezing tolerance during cold acclimation in wheat (Triticum aestivum L.)
Laboratory of Plant Genetics, Department of Biological and Environmental Science, Faculty of Agriculture, and Division of Life Science, Graduate School of Science and Technology, Kobe University, 1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Received 29 May 2001; Accepted 7 August 2001
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Time-courses of the development of freezing tolerance and the expression of a cold-responsive gene wlt10 were monitored during cold acclimation in wheat (Triticum aestivum L.). Bioassay showed that cold acclimation conferred much higher freezing tolerance on a winter cultivar than a spring cultivar. Northern blot analysis showed that the expression of wlt10 encoding a novel wheat member of a cereal-specific LT-COR protein family was specifically induced by low temperature. A freezing-tolerant winter cultivar accumulated the mRNA more rapidly and for a longer period than a susceptible spring cultivar. The increase in the amount of mRNA was temporary but the peak occurred at the time when the maximum level of freezing tolerance was attained. The mRNA accumulated more in the leaves than in the roots, and different light/dark regimes modulated the level of mRNA accumulation. Genomic Southern blot analyses using the nulli-tetrasomic series showed that the wlt10 homologues were located on the homologous group 2 chromosomes.
Key words: Cold acclimation, freezing tolerance, low temperature-responsive (Lt) gene, cold-responsive (Cor) gene, wheat (Triticum aestivum L.).
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Because plants are sessile to fixed habitats, they have evolved a variety of adaptive mechanisms for different environmental perturbations. Under low temperature stress, plant cells exhibit marked changes in biochemical and physiological processes, which lead to increased cold/freezing tolerance in overwintering temperate species. This adaptive process is generally referred to as cold/frost hardening or acclimation (Levitt, 1980
). Importantly, the process of cold acclimation is tightly associated with altered gene expression that is triggered during exposure to low but non-freezing temperature (Guy et al., 1985; Guy, 1990; Hughes and Dunn, 1990; Thomashow, 1998).
A considerable number of low-temperature-responsive or cold-responsive genes has been cloned and characterized in dicotyledonous and monocotyledonous species. A majority has also been shown to be responsive to dehydration and the phytohormone abscisic acid (ABA) (Palva, 1994; Hughes and Dunn, 1996; Bray, 1997; Thomashow, 1998). In cereals, a small gene family of Lt-Cor (Dunn et al., 1990; Grossi et al., 1998) is suggested to play an important role in freezing tolerance. A positive correlation has been observed between the Lt-Cor gene expression and freezing tolerance in different tissues, i.e. higher expression in more tolerant tissues than in more susceptible tissues (Pearce et al., 1998). Cultivars with different levels of freezing tolerance also showed different levels of Lt-Cor gene expression; however, their correlation was not necessarily apparent (Dunn et al., 1990; Zhang et al., 1993; Grossi et al., 1998).
To critically evaluate the relationship between the Lt-Cor gene expression and the development of freezing tolerance, these two processes have to be closely monitored during cold acclimation and deacclimation. The processes were compared using two wheat cultivars that show marked differences in their freezing tolerance. This study focused on one representative gene wlt10, which was isolated as a novel wheat member of a small family of cereal-specific Lt-Cor genes. These results showed that the expression of wlt10 was low temperature-specific and closely correlated with the development of freezing tolerance during cold acclimation in wheat.
|
Materials and methods |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Cloning of wlt10
A cDNA library was constructed from a cold-acclimated winter wheat (Triticum aestivum L.) cultivar ‘Mironovska 808’ (abbreviated as M808) as previously described (Tsvetanov et al., 2000
). M808 was bred in Mironovska Institute, Ukraine, and reported to be one of the hardiest wheat cultivars tested for freezing tolerance (Veisz and Stuka, 1990). The library was screened with a cold-responsive barley cDNA probe pao86 (Cattivelli and Bartel, 1990), which is a member of the barley blt14-Cor family (Dunn et al., 1990; Grossi et al., 1998). A selected wheat cDNA was subcloned into pUC19 and sequenced by the automated fluorescent dye deoxy terminator cycle sequencing system using ABI PRISMTM 310 Genetic Analyser (PE Applied Biosystems, USA). The DNA sequence and the deduced amino acid sequence were analysed by DNASIS (Hitachi, Japan), and the clone was designated as wlt10.
Bioassay for freezing tolerance
Seedlings of M808 and a standard common wheat cultivar ‘Chinese Spring’ (CS) were used. CS is a spring-type cultivar but possesses a weak winter habit. Fifty seeds from each of the two cultivars were imbibed under tap water for 5 h and kept overnight at 4 °C. Imbibed seeds were planted in a pot with soil and incubated for 5 d in a growth chamber under the following standard conditions: 25 °C with a 16 h photoperiod at a light intensity of 55–65 µE m-2 s-1 provided by cool white fluorescent lumps. The seedlings were watered every other day with 0.1% Hyponex solution (N:P:K=5:10:5 by vol., Hyponex Japan). The 5-d-old seedlings were cold-acclimated at 4 °C for 0–7 d, and then frozen at -20 °C for 3, 6 and 9 h in darkness. Some seedlings were deacclimated under the standard conditions for 1 d after 5 d cold acclimation before freezing treatment. The frozen seedlings were thawed overnight at 4 °C and transferred back to the standard conditions. At the 4 or 5th day after the transfer, numbers of surviving seedlings and their level of regrowth were recorded. The experiment was repeated 3–6 times, depending on combinations of the cold acclimation and freezing periods.
Northern blot analysis
Northern blot analysis was conducted to monitor the expression of wlt10. Seedlings of M808 and CS were grown for 7 d under the standard conditions in pots with soil. Seedlings were cold-acclimated at 4 °C for 0–10 d. Some seedlings were deacclimated for 1 d after a 3 d acclimation. 7-d-old seedlings were also treated with abscisic acid (ABA), gibberellic acid (GA3), NaCl, and drought in the following manner. The above-ground tissues of the seedlings were sprayed with 20 µM ABA or GA3 solution containing 0.1% (w/v) Tween 20 and they were kept under the standard conditions for 1 h. The seedlings were removed from the soil and treated with 0.4 M NaCl solution for 1 h or kept on dry filter paper for 4 h under the standard conditions. Some seedlings were cold acclimated under continuous dark and also under different light/dark regimes (see Results). Total RNA was extracted by guanidine thiocyanate using sepasol (nacalai tesque, Japan) from 0.5 g (fresh weight) of the above-ground tissues of the cold acclimated and non-acclimated control seedlings and also from the seedling leaves and roots separately. The total RNA (20 µg) was fractionated by electrophoresis through 1.2% formaldehyde/agarose gel and transferred to a Hybond N+ nylon membrane (Amersham). The RNA blot was hybridized with the 32P-labelled whole sequence of wlt10 as a probe. Probe labelling, hybridization, washing, and autoradiography were performed as described earlier (Liu et al., 2000).
Southern blot analysis
DNA was extracted from a diploid species, T. monococcum, a tetraploid species, T. durum cv. ‘Langdon’, and M808. For chromosome assignment of wlt10, DNA was extracted from the nulli-tetrasomic series of CS (Sears, 1966). Each line of the nulli-tetrasomic series lacks a given pair of homologous A, B or D genome chromosomes (nullisomics) that are replaced by the corresponding homologous chromosome pair (tetrasomics). DNA was single-digested with BamHI, EcoRV and DraI. The digested DNA was fractionated by electrophoresis through 0.8% agarose gel and blotted by the alkaline method. Probe labelling, hybridization and autoradiography were performed in the same way as for the Northern blot analysis.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Cloning of wlt10
Using the M808 cDNA library and the barley cold-responsive cDNA probe pao86, one cDNA clone was selected from c. 9.000 pfu, subcloned into the EcoRI site of the vector pUC19 and sequenced. This cDNA clone was 548 bp in length and had an open reading frame of 303 nucleotides. The deduced polypeptide with 101 amino acids was neutral (pI=7.0) and hydrophobic with a molecular weight of c. 10 kDa, and thus the clone was designated as wlt10. WLT10 protein had nine contiguous repeats of a LPT triplet, similar to the barley LT-COR protein AO86 (Fig. 1
). WLT10 showed considerable homology with several other LT-COR proteins from barley and rye. They include BLT14 (Dunn et al., 1990), BLT14.1, BLT14.2 (Phillips et al., 1997), and AO29 (Grossi et al., 1998) of barley, and RLT1412 and RLT1421 (a partial sequence) of rye (Zhang et al., 1993).
|
Bioassay for freezing tolerance
The development of freezing tolerance during cold acclimation (4 °C) was monitored using the two wheat cultivars, M808 and CS. Since the winter hardiness of M808 was already proven by the standard freezing test (Veisz and Stuka, 1990), a simpler method was developed for evaluating freezing tolerance of the wheat cultivars. Cold-acclimated and non-acclimated seedlings were frozen at a single freezing temperature (–20 °C) for 3, 6 or 9 h and then returned back to the normal temperature condition (25 °C) for regrowth. The bioassay clearly showed that the cold acclimation conferred much higher levels of freezing tolerance on M808 than on CS (Fig. 2A). It was noted that the above-ground tissues of all the tested seedlings, irrespective of the cultivars, became wilted and withered within a day of transfer back to the standard temperature condition. The cold-acclimated M808 seedlings, however, showed a rapid recovery from the freezing stress and they developed new shoots from the surviving meristems within 1–2 d (Fig. 2B). Among the survivors, M808 seedlings grew normally but CS seedlings showed strongly retarded growth when the freezing treatment was given for more than 6 h.
|
Results of the bioassay for freezing tolerance are summarized in Table 1
. Both cultivars exhibited a considerable level of tolerance (over 50% survival) without cold acclimation against the freezing treatment for 3 h (data not shown). Some seedlings could survive 6 h of freezing without cold acclimation. M808 acquired a low but significantly higher level of freezing tolerance than CS after 1 d of acclimation. After 3–5 d of acclimation, M808 showed a nearly full level of freezing tolerance (more than 70% survival), while CS remained highly susceptible at this stage. About 60% seedlings of M808 survived 9 h of freezing after 5–7 d of acclimation, but less than 20% of CS seedlings could survive under this condition. A treatment of 1 d deacclimation after 5 d of acclimation almost completely abolished the freezing tolerance in M808; thus the fully acclimated M808 seedlings rapidly lost the acquired freezing tolerance within a day of deacclimation.
|
wlt10 gene expression
A time-course of the expression of wlt10 was studied during cold acclimation. The experimental conditions were the same as for the bioassay for freezing tolerance, except for that 7-d-old seedlings were used. wlt10 mRNA appeared in the above-ground tissues within a day of acclimation in M808, while in CS the appearance of the mRNA was delayed until the 3rd day (Fig. 3A). The time-dependent expression of wlt10 was different between the two cultivars; the mRNA accumulated to reach a maximum level within 3 d of acclimation in M808, while a maximum level reached at the 7th day in CS. The increase in the mRNA level was temporary and the amount of mRNA decreased to a low but steady-state level in M808 during the 7–10 d. In contrast, the amount of mRNA decreased to a much lower level towards the 10th day in CS. Within 1 d of deacclimation under the standard temperature condition, the mRNA disappeared from the 3-d-acclimated seedlings of both cultivars. This rapid disappearance of mRNAs coincided with the rapid loss of freezing tolerance in the deacclimated M808 seedlings.
|
Many of the low temperature responsive genes are known to be regulated by dehydration and ABA (Lång et al., 1989
; Nordin et al., 1991; White et al., 1994). Therefore the effects of dehydration stresses and two plant hormones on the expression of wlt10 in the two cultivars were studied. No homologous transcripts were detected in the non-acclimated control seedlings and the seedlings treated with 400 mM NaCl, 20 µM ABA and GA3, and dehydration under the standard temperature condition (Fig. 3B
). The result clearly showed that the expression of wlt10 was low temperature specific, similar to the barley blt14-Cor gene family (Phillips et al., 1997).
Next, the level of wlt10 expression was studied separately in the cold acclimated seedling leaves and roots under the standard light/dark regime (16 h light and 8 h dark). The mRNA accumulated more in the leaves than in the roots in both cultivars (Fig. 4A). Accumulation of the mRNA was also studied in the seedlings acclimated under continuous dark. A 3 d dark treatment did not change the mRNA level in the leaves, whereas 5 d dark treatment markedly reduced the mRNA level, particularly in M808 (Fig. 4B). No changes were observed in the mRNA level when the 5 d acclimated seedlings under the standard light/dark regime were further acclimated for additional 3 d in dark (compare 5L3D versus 5L in Fig. 4B). A dramatic increase occurred in the seedlings acclimated for an additional 3 d under the standard light/dark regime after 5 d acclimation in the dark (5D3L versus 5D in Fig. 4B). Taken together, these results suggested an enhancing effect of light and suppressive effect of dark on the accumulation of wlt10 mRNA. The dark suppression, however, was effective only after a long enough incubation in darkness. This was apparently not due to some adverse effects on seedling physiology, because such dark/light-treated seedlings accumulated as much wlt10 mRNA as ones grown under the standard light/dark regime.
|
Chromosome assignment of wlt10
The barley blt14, which is homologous to wlt10, locates on chromosome 2 (Dunn et al., 1990). Because of the chromosomal synteny between wheat and barley (Linde-Laursen et al., 1997), it was expected that wlt10 locates on the wheat homologous group 2 chromosomes. To confirm this, a Southern blot analysis was conducted using DNA extracted from M808, tetraploid T. durum and diploid T. monococcum. Southern blot analysis suggested that each of the basic diploid genomes (A, B and D genomes) possessed one copy of the gene (Fig. 5A). In the Southern blot made using the nulli-tetrasomic series of CS, one smallest band disappeared in the line nulli2B-tetra2A, and similarly one largest band disappeared in the lines nulli2D-tetra2A and nulli2D-tetra2B (Fig. 5B). The result showed that the wlt10 homologues located on the homologous group 2 chromosomes. The line nulli2B-tetra2D however appeared to retain the smallest 2B-band. A reason for this discrepancy remained unknown, but it might be due to some unknown structural rearrangements in the nulli-tetrasomic series.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
The level of expression of wlt10, a novel wheat member of the Lt-Cor gene family, was monitored closely and compared with the development of freezing tolerance during cold acclimation in wheat. Two cultivars with the contrasting levels of winter hardiness were used and the gene expression under a range of treatment conditions was monitored. The level of freezing tolerance increased dramatically after cold acclimation in the winter cultivar M808 (Table 1
). The increase occurred in a time-dependent manner, i.e. the longer the acclimation period, the higher the level of freezing tolerance, under these experimental conditions. M808 developed freezing tolerance more rapidly than the spring cultivar CS. A good correlation was observed between the time-course of the development of freezing tolerance and the level of wlt10 gene expression (Fig. 3). The expression of wlt10 was induced within 1 d of cold acclimation in M808, when M808 already developed a low level of freezing tolerance. The mRNA level then increased to reach a maximum at day 3, when M808 developed a nearly full level of freezing tolerance. In contrast, the expression of wlt10 delayed in CS until the 3rd day of cold acclimation and the mRNA level reached a maximum at the 7th day. The amount of mRNA increased temporarily in both cultivars, however, M808 retained a low but steady-state level of mRNA for a longer period than CS. Under this steady-state condition, M808 retained a high level of freezing tolerance. It was further noted that wlt10 mRNA rapidly disappeared within 1 d of deacclimation, which was associated with the rapid loss of acquired freezing tolerance in M808 (Fig. 3A; Table 1). These results suggest that WLT10 protein is more stable under the low temperature condition than under the normal temperature condition. A post-transcriptional regulation of the barley blt14 mRNA has been reported and it was suggested that the mRNA is stabilized by a low-temperature-dependent protein factor(s) (Phillips et al., 1997).
In the bioassay for freezing tolerance a simple and rapid method was adopted, in which a single freezing temperature (-20 °C) was applied for periods of 3, 6 or 9 h after different periods (0 to 7 d) of cold acclimation (4 °C). In the standard freezing test, exposure to a series of subzero temperatures is used to determine LT50 (the temperature giving 50% of plants regrowing) after each acclimation or other treatments (Pearce, 1980). This simple method proved to be adequate for cultivars with a great enough difference in winter hardiness. However, these experimental conditions, including those for gene expression, do not necessarily represent normal physiological conditions for wheat in the field. The gene expression observed, therefore, may not necessarily be of direct relevance to freezing tolerance under field conditions. In particular, young seedlings were used, which presumably were not photosynthetically active enough but were still deriving many nutrients from seeds. Despite these problems, it was possible at least to show that wlt10 gene expression served as a useful marker for monitoring the development of freezing tolerance in wheat. Several wheat Cor genes including wcor14 (Tsvetanov et al., 2000) and wcor15 (unpublished data) show quite a similar pattern of expression to that of wlt10 during cold acclimation/deacclimation in wheat.
Tissue-dependent expression is characteristically observed in the Lt-Cor gene members. The barley pao86, a cognate of wlt10, and blt14 are expressed in both leaves and roots (Cattivelli and Bartel, 1990; Grossi et al., 1998; Pearce et al., 1998). Expression of the barley blt14.1 and rye rlt1412 is root-preferential, thus more abundant mRNAs are accumulated in roots than in leaves and shoot meristems (Phillips et al., 1997). On the other hand, the barley blt14.2 and rye rlt1421 are leaf-specific. Apparently, different members of the Lt-Cor gene family show different tissue-dependent expression. It was shown that wlt10 was expressed at a higher level in the leaves than in the roots under cold acclimation (Fig. 4A). The result obtained suggests that different light/dark regimes modulated the accumulation of wlt10 mRNA; light was stimulatory and dark was suppressive (Fig. 4B). Since low light intensity was used (55–65 µE m-2 s-1) for growth, both under normal temperature and cold acclimation, a stimulatory effect of light could have been masked to some extent. Light regulation of the mRNA accumulation was reported for the barley blt14-Cor gene family using albino mutant seedlings and etiolated wild-type seedlings (Grossi et al., 1998). They showed that a short-time exposure (30 min and 2 h) to light reduced the accumulation of blt14 mRNA. The light responses of the barley blt14 and the wheat wlt10 are thus apparently different. These two genes show limited homology as compared with other Lt-Cor gene members (Fig. 1). A mechanism responsible for such a difference in the mode of light/dark regulation must be studied further.
Several LT-COR proteins including WLT10 commonly possess a hydrophobic N-terminal 20 amino acid sequence that shows consensus features for signal peptides (von Heijne, 1991) (Fig. 1). This putative N-terminal signal peptide can be found in a number of extracellular proteins that are secreted through the ER and Golgi apparatus (Chrispeels, 1991). In the bioassay for freezing tolerance, a higher tolerance was observed in the meristems than in the developed leaves (Fig. 2B). It has long been known that the survival of crowns containing shoot and apical meristems are essential for the survival of cereals against freezing temperature (Olien, 1964; Peacock, 1975; Gusta and Fowler, 1979). Freezing tolerance therefore is clearly achieved by safeguarding meristems for subsequent regrowth, not by protecting existing leaves. The barley blt14 with the putative signal peptide is strongly expressed in the crown cortex, particularly in cell layers surrounding vascular bundles in the vascular-transition zone (Pearce et al., 1998). This observation indicates that the protein is secreted into the vascular tissues within the crowns and plays a role to confer high freezing tolerance on these tissues. The transport and tissue-dependent accumulation of WLT10 protein, particularly in the crown tissues, is now being studied using specific antibodies.
|
Acknowledgments |
|---|
The work was supported in parts by grant-in-aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan (Nos 10460006 and 10044207 to CN). We thank L Cattivelli for kindly providing us with the barley cDNA clone pAO86. The sequence of wlt10 has been deposited in the GenBank database (accession no. AF271260). Contribution no. 138 from the Laboratory of Plant Genetics, Kobe University.
|
Notes |
|---|
1 To whom correspondence should be addressed. Fax: +81 78 803 5858. E-mail: nakamura{at}kobe\|[hyphen]\|u.ac.jp
|
References |
|---|
|
TopAbstractIntroductionMaterials and methodsResultsDiscussionReferences |
|---|
Bray EA. 1997. Plant responses to water deficit. Trends in Plant Science 2, 48–54.
Cattivelli L, Bartel D. 1990. Molecular cloning and characterization of cold-regulated genes in barley. Plant Physiology 93, 1504–1510.
Chrispeels MJ. 1991. Sorting of proteins in the secretary system. Annual Review of Plant Physiology and Plant Molecular Biology 42, 21–53.[Web of Science]
Dunn MA, Hughes MA, Pearce RS, Jack PL. 1990. Molecular characterization of a barley gene induced by cold treatment. Journal of Experimental Botany 41, 1405–1413.
Grossi M, Giorni E, Rizza F, Stanca AM, Cattivelli L. 1998. Wild and cultivated barleys show differences in the expression pattern of a cold-regulated gene family under different light and temperature conditions. Plant Molecular Biology 38, 1061–1069.[Web of Science][Medline]
Gusta LV, Fowler DB. 1979. Cold resistance and injury in winter cereals. In: Mussel H, Staples RC, eds. Stress physiology of crop plants. New York: Wiley-Interscience, 159–178.
Guy CL. 1990. Cold acclimation and freezing stress tolerance: role of protein metabolism. Annual Review of Plant Physiology and Plant Molecular Biology 41, 187–223.[Web of Science]
Guy CL, Niemi KL, Brambl R. 1985. Altered gene expression during cold acclimation of spinach. Proceedings of the National Academy of Sciences, USA 82, 3673–3677.
Hughes MA, Dunn MA. 1990. The effect of temperature on plant growth and development. Biotechnology and Genetic Engineering Review 8, 161–188.
Hughes MA, Dunn MA. 1996. The molecular biology of plant acclimation to low temperature. Journal of Experimental Botany 47, 291–305.
Lång V, Heino P, Palva ET. 1989. Low temperature acclimation and treatment with exogenous abscisic acid induce common polypeptides in Arabidopsis thaliana (L.) Heynh. Theoretical and Applied Genetics 77, 729–734.
Levitt J. 1980. Responses of plants to environmental stresses, Vol. 1, 2nd edn. New York: Academic Press, 166–222.
Linde-Laursen I, Heslop-Harrison JS, Shepherd KW, Taketa S. 1997. The barley genome and its relationship with the wheat genomes. A survey with an internationally agreed recommendation for barley chromosome nomenclature. Hereditas 126, 1–16.
Liu YG, Mori N, Tsunewaki K. 1990. Restriction fragment length polymorphism (RFLP) analysis in wheat. I. Genomic DNA library construction and RFLP analysis in common wheat. Japanese Journal of Genetics 65, 367–380.[Medline]
Nordin K, Vahala T, Palva ET. 1991. Differential expresion of two related, low-temeprature-induced genes in Arabidopsis thaliana (L.) Heynh. Plant Molecular Biology 21, 641–653.
Olien CR. 1964. Freezing processes in the crown of ‘Hudson’ barley (Hordeum vulgare L.). Crop Sciences 4, 91–95.
Palva ET. 1994. Gene expression under low temperature stress. In: Basra AS, ed. Stress-induced gene expression in plants. New York: Harwood Academic Publishers, 103–130.
Peacock JM. 1975. Temperature and leaf growth of Lolium perenne. II. The site of temperature perception. Annals of Applied Ecology 12, 115–123.
Pearce RS. 1980. Relative hardiness to freezing of laminae, roots and tillers of tall fescue. New Phytologist 84, 449–463.
Pearce RS, Houlston CE, Atherton KM, Rixon JE, Harrison P, Hughes MA, Dunn MA. 1998. Localization of expression of three cold-induced genes, blt101, blt4.9, and blt14, in different tissues of the crown and developing leaves of cold-acclimated cultivated barley. Plant Physiology 117, 787–795.
Phillips JR, Dunn MA, Hughes MA. 1997. mRNA stability and localization of the low-temperature-responsive barley gene family blt14. Plant Molecular Biology 33, 1013–1023.[Web of Science][Medline]
Sears ER. 1966. Nullisomic-tetrasomic combinations in hexaploid wheat. In: Riley R, Lewis KR, eds. Chromosome manipulation and plant genetics. Edinburgh: Oliver and Boyd, 29–45.
Thomashow MF. 1998. Role of cold-responsive genes in plant freezing tolerance. Plant Physiology 118, 1–8.
Tsvetanov S, Ohno R, Tsuda K, Takumi S, Mori N, Atanassov A, Nakamura C. 2000. A cold-responsive wheat (Triticum aestivum L.) gene wcor14 identified in a winter-hardy cultivar ‘Mironovska 808’. Genes and Genetic Systems 75, 49–57.
Von Heijne G. 1991. Signals for protein import into organelles. In: Hermann RG, Larkings B, eds. Plant molecular biology. New York: Plenum Press, 583–593.
Veisz O, Stuka J. 1990. Frost resistance studies with wheat in natural and artificial conditions. In: Panayotov I, Pavlova S, eds. Proceedings of the International Symposium on Cereal Adaptation to Low Temperature Stress. Albena, Bulgaria, 12–17.
White AJ, Dunn MA, Brown K, Hughes MA. 1994. Comparative analysis of genomic sequence and expression of a lipid transfer protein gene family in winter barley. Journal of Experimental Botany 45, 917–928.
Zhang L, Dunn MA, Pearce RS, Hughes MA. 1993. Analaysis of organ specificity of a low temperature responsive gene family in rye (Secale cereale L.). Journal of Experimental Botany 44, 1787–1793.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  S. Ganeshan, P. Vitamvas, D. B. Fowler, and R. N. Chibbar Quantitative expression analysis of selected COR genes reveals their differential expression in leaf and crown tissues of wheat (Triticum aestivum L.) during an extended low temperature acclimation regimen J. Exp. Bot., June 1, 2008; 59(9): 2393 - 2402. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Kobayashi, E. Maeta, A. Terashima, K. Kawaura, Y. Ogihara, and S. Takumi Development of abiotic stress tolerance via bZIP-type transcription factor LIP19 in common wheat J. Exp. Bot., March 7, 2008; (2008) ern014v1. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Kobayashi, S. Takumi, S. Kume, M. Ishibashi, R. Ohno, K. Murai, and C. Nakamura Regulation by Vrn-1/Fr-1 chromosomal intervals of CBF-mediated Cor/Lea gene expression and freezing tolerance in common wheat J. Exp. Bot., March 1, 2005; 56(413): 887 - 895. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Takumi, A. Koike, M. Nakata, S. Kume, R. Ohno, and C. Nakamura Cold-specific and light-stimulated expression of a wheat (Triticum aestivum L.) Cor gene Wcor15 encoding a chloroplast-targeted protein J. Exp. Bot., October 1, 2003; 54(391): 2265 - 2274. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||