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  • 1
    Electronic Resource
    Electronic Resource
    Control of virulence gene expression by plant calcium in the phytopathogen Erwinia carotovora (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 25 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Plant calcium can modulate a particular plant–pathogen interaction and have a decisive role in disease development. Enhanced resistance to the phytopathogenic enterobacterium Erwinia carotovora, the causal agent of bacterial soft rot disease, is observed in high-calcium plants. One of the main virulence determinants of E. carotovora, the PehA endopolygalacturonase, is specifically required in the early stages of the infection. Production of PehA was found to be dependent on the calcium concentration in the bacterial environment. An increase in extracellular calcium to mM concentrations repressed pehA gene expression without reducing or even enhancing expression of other extracellular enzyme-encoding genes of this pathogen. An increase in plant calcium levels could be correlated to enhanced resistance to E. carotovora infection and to an inhibition of in planta production of PehA. Ectopic expression of pehA from a calcium-insensitive promoter allowed E. carotovora to overcome this calcium-induced resistance. The results imply that plant calcium can constitute an important signal molecule in plant–pathogen interaction, which acts by modulating the expression of virulence genes of the pathogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1997.mmi501.x
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  • 2
    Electronic Resource
    Electronic Resource
    The ompS gene of Vibrio cholerae encodes a growth-phase-dependent maltoporin (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 10 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The outer membrane of Vibrio cholerae contains a maltose-inducible major protein, OmpS (43 kDa), that is common to different isolates. Nucleotide sequence analysis of the corresponding structural gene, ompS, revealed an open reading frame encoding a 412-amino-acid polypeptide. The amino acid sequence of OmpS is similar to that of LamB, the Escherichia coli maltoporin, and to ScrY of Klebsilla pneumoniae, although the antigenic determinants of these proteins are different. The cloned ompS gene complemented an ompS mutation of V. cholerae and the corresponding polypeptide could function as a maltoporin in a LamB- mutant of E. coli. The promoter region of ompS is highly homologous to the malK-lamB promoter of E. coli and the ompS gene is controlled by MalT in E. coli. This indicates that the same kind of regulatory mechanism is used to activate the ompS expression in V. cholerae and malK-lamB expression in E. coli. An ompS-lacZ transcriptional fusion was used to demonstrate a dual control in ompS expression; the ompS gene is responsive to the inducers maltose and trehalose but in their absence it is also expressed in response to growth-phase. These different modes of induction might be of importance during different stages of V. cholerae infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb00960.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cold acclimation in silver birch (Betula pendula). Development of freezing tolerance in different tissues and climatic ecotypes (2002)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 116 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A number of environmental cues including short day photoperiod (SD) and low temperature (LT) are known to interact in triggering growth cessation, cold acclimation and other adaptive responses in temperate-zone tree species. Proper timing of these responses is particularly important for survival of trees in the boreal and subarctic regions. Therefore, we used a northern tree species, silver birch (Betula pendula Roth) as an experimental model to investigate the effect of SD and LT on development of freezing tolerance and on levels of endogenous abscisic acid (ABA) in short-term experiments under controlled conditions. We characterized differences in SD and LT-induced cold acclimation between three different climatic ecotypes from southern, central and northern habitats. The results demonstrated that cold acclimation was rapidly triggered by exposing the plants to SD or LT, and that a combination of the different treatments had an additive effect on freezing tolerance. Freezing tolerance induction was not uniform in the different tissues, the buds and leaves developed freezing tolerance more rapidly than the stem, and the young leaves had a higher freezing tolerance than the old leaves. The ability of the leaves to respond to SD and LT and similarity of the bud and leaf responses indicate that birch leaves provide a rapid and convenient system for studies on molecular mechanisms of cold acclimation. Development of freezing tolerance was dependent on the climatic ecotype, the northern ecotype was clearly more responsive to both SD and LT than the two more southern ecotypes. Development of freezing tolerance induced by SD and LT was accompanied by transient changes in ABA levels. These alterations in ABA levels were ecotype-dependent, the northern ecotype reacting more strongly to the environmental cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1160406.x
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  • 4
    Electronic Resource
    Electronic Resource
    Photoperiodic control of growth, cold acclimation and dormancy development in silver birch (Betula pendula) ecotypes (2003)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 117 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Survival and growth of temperate zone woody plants under changing seasonal conditions is dependent on proper timing of cold acclimation and development of vegetative dormancy, shortening photoperiod being an important primary signal to induce these adaptive responses. To elucidate the physiological basis for climatic adaptation in trees, we have characterized photoperiodic responses in the latitudinal ecotypes of silver birch (Betula pendula Roth) exposed to gradually shortening photoperiod under controlled conditions. In all ecotypes, shortening photoperiod triggered growth cessation, cold acclimation and dormancy development, that was accompanied by increases in endogenous abscisic acid (ABA) and decreases in indole-3-acetic acid (IAA). There were distinct differences between the ecotypes in the rates and degrees of these responses. The critical photoperiod and the photoperiodic sensitivity for growth cessation varied with latitudinal origin of the ecotype. The northern ecotype had a longer critical photoperiod and a greater photoperiodic sensitivity than the southern ecotype. Compared with the southern ecotypes, the northern ecotype was more responsive to shortening photoperiod, resulting in earlier cold acclimation, dormancy development, increase in ABA content and decrease in IAA content. However, at the termination of the experiment, all the ecotypes had reached approximately the same level of cold hardiness (−12 to −14°C), ABA content (2.1–2.3 µg g−1 FW) and IAA content (17.2–20.3 ng g−1 FW). In all ecotypes, increase in ABA levels preceded development of bud dormancy and maximum cold hardiness. IAA levels decreased more or less parallel with increasing cold hardiness and dormancy, suggesting a role of IAA in the photoperiodic control of growth, cold acclimation and dormancy development in birch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00002.x
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  • 5
    Electronic Resource
    Electronic Resource
    Drought tolerance in tobacco (1996)
    [s.l.] : Nature Publishing Group
    Nature 379 (1996), S. 683-684 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Water stress due to drought, salinity or freezing is the main limiting factor for plant growth and distribution1'2. A common response to water deficit is the accumulation of osmoprotectants such as sugars and amino acids2'3. High concentrations of the osmoprotectant trehalose occur in many ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/379683a0
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  • 6
    Electronic Resource
    Electronic Resource
    Cold induced gene expression in Arabidopsis thaliana L. (1988)
    Springer
    Plant cell reports 7 (1988), S. 495-498 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of Arabidopsis thaliana L. to an acclimation temperature (+4°C) results in a rapid increase of frost tolerance from −3°C to −7°C. This increase could be correlated to changes in soluble protein pattern. Analysis of in vitro translation products from isolated mRNA suggests that induction acts at the transcriptional level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272740
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  • 7
    Electronic Resource
    Electronic Resource
    The expression of a rab-related gene, rab18, is induced by abscisic acid during the cold acclimation process of Arabidopsis thaliana (L.) Heynh (1992)
    Springer
    Plant molecular biology 20 (1992), S. 951-962 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; cold acclimation ; freezing tolerance ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated a rab-related (responsive to ABA) gene, rab18 from Arabidopsis thaliana. The gene encodes a hydrophilic, glycine-rich protein (18.5 kDa), which contains the conserved serine- and lysine-rich domains characteristic of similar RAB proteins in other plant species. The rab18 mRNA accumulates in plants exposed to low temperature, water stress or exogenous ABA but not in plants subjected to heat shock. This stress-related accumulation of the rab18 mRNA is markedly decreased in the ABA-synthesis mutant aba-1, the ABA-response mutant abi-1 or in wild-type plants treated with the carotenoid synthesis inhibitor, fluridone. Exogenous ABA treatment can induce the rab18 mRNA in the aba-1 mutant but not in the abi-1 mutant. These results provide direct genetic evidence for the ABA-dependent regulation of the rab18 gene in A. thaliana.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027165
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  • 8
    Electronic Resource
    Electronic Resource
    Separate signal pathways regulate the expression of a low-temperature-induced gene in Arabidopsis thaliana (L.) Heynh. (1991)
    Springer
    Plant molecular biology 16 (1991), S. 1061-1071 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; freezing tolerance ; cold acclimation ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone corresponding to a novel low-temperature-induced Arabidopsis thaliana gene, named lti140, was employed for studies of the environmental signals and the signal pathways involved in cold-induced gene expression. The single-copy lti140 gene encodes a 140 kDa cold acclimation-related polypeptide. The lti140 mRNA accumulates rapidly in both leaves and roots when plants are subject to low temperature or water stress or are treated with the plant hormone abscisic acid (ABA), but not by heat-shock treatment. The low-temperature induction of lti140 is not mediated by ABA, as shown by normal induction of the lti140 mRNA in both ABA-deficient and ABA-insensitive mutants and after treatment with the ABA biosynthesis inhibitor fluridone. The effects of low temperature and exogenously added ABA are not cumulative suggesting that these two pathways converge. The induction by ABA is abolished in the ABA-insensitive mutant abi-1 indicating that the abi-1 mutation defines a component in the ABA response pathway. Accumulation of the lti140 mRNA in plants exposed to water stress was somewhat reduced by treatment with fluridone and in the ABA-insensitive mutant abi-1 suggesting that the water stress induction of lti140 could be partly mediated by ABA. It is concluded that three separate but converging signal pathways regulate the expression of the lti140 gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016077
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  • 9
    Electronic Resource
    Electronic Resource
    Differential expression of two related, low-temperature-induced genes in Arabidopsis thaliana (L.) Heynh (1993)
    Springer
    Plant molecular biology 21 (1993), S. 641-653 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; Arabidopsis thaliana ; cold acclimation ; drought stress ; signal transduction ; stress response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant cold acclimation is correlated to expression of low-temperature-induced (lti) genes. By using a previously characterized lti cDNA clone as a probe we isolated a genomic fragment that carried two closely located lti genes of Arabidopsis thaliana. The genes were structurally related with the coding regions interrupted by three similarly located short introns and were transcribed in the same direction. The nucleotide sequences of the two genes, lti78 and lti65, predict novel hydrophilic polypeptides with molecular weights of 77856 and 64510, respectively, lti78 corresponding to the cDNA probe. Of the 710 amino acids of LTI78 and 600 amino acids of LTI65, 346 amino acids were identical between the polypeptides, which suggests that the genes may have a common origin. Both lti78 and lti65 were induced by low temperature, exogenous abscisic acid (ABA) and drought, but the responsiveness of the genes to these stimuli was markedly different. Both the levels and the temporal pattern of expression differed between the genes. Expression of lti78 was mainly responsive to low temperature, that of lti65 to drought and ABA. In contrast to the induction of lti78, which follows separate signal pathways during low-temperature, ABA and drought treatment, the drought induction of lti65 is ABA-dependent and the low-temperature induction appears to be coupled to the ABA biosynthetic pathway. This differential expression of two related genes may indicate that they have some-what different roles in the stress response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014547
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization and differential expression of dhn/lea/rab-like genes during cold acclimation and drought stress in Arabidopsis thaliana (1994)
    Springer
    Plant molecular biology 26 (1994), S. 131-144 
    Details
    ISSN: 1573-5028
    Keywords: abscisic acid ; Arabidopsis thaliana ; cold acclimation ; LEA ; RAB ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have characterized cDNAs for two new dhn/lea/rab (dehydrin, late embryogenesis-abundant, responsive to ABA)-related genes from Arabidopsis thaliana. The two genes were strongly induced in plants exposed to low temperature (4 °C) and were accordingly designated lti45 and lti30 (low temperature-induced). The lti45 gene product contains the conserved serine stretch and three lysine-rich repeats characteristic of DHN/LEA/RAB proteins and is very similar to another low temperature-responsive protein of A. thaliana, COR47 [17]. Both proteins have the same repeat structure and an overall amino acid identity of 64%. This structural similarity of the proteins and the tandem array of the genes suggest that this gene pair arose through a duplication. The other polypeptide, LTI30, consists of several lysine-rich repeats, a structure found in CAP85, a low temperature-and water stress-responsive protein in spinach [41] and similar proteins found in wheat [20]. The expression pattern of the five dhn/lea/rab-related genes (cor47, dhnX, lti30, lti45 and rab18) identified so far in A. thaliana, was characterized in plants exposed to low temperature, drought and abscisic acid (ABA). Expression of both lti30 and lti45 was mainly responsive to low temperature similar to cor47. The lti45 and lti30 genes show only a weak response to ABA in contrast to cor47, which is moderately induced by this hormone. The three genes were also induced in severely water-stressed plants although the expression of lti30 and lti45 was rather low. In contrast to these mainly low temperature-induced genes, the expression of rab18 was strongly induced both in water-stressed and ABA-treated plants but was only slightly responsive to cold. The dhnX gene showed a very different expression pattern. It was not induced with any of the treatments tested but exhibited a significant constitutive expression. The low-temperature induction of the genes in the first group, lti30 and lti45, is ABA-independent, deduced from experiments with the ABA-deficient (aba-1) and ABA-insensitive (abi1) mutants of A. thaliana, whereas the induction of rab18 is ABA-mediated. The expression of dhnX was not significantly affected in the ABA mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039526
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