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Membrane voltage initiates Ca2+ waves and potentiates Ca2+ increases with abscisic acid in stomatal guard cells
279
Paper alert
. Significance: CPR6 is a newly discovered regulator which helps to control multiple defense pathways and is an important tool for the study of signal pathway cross-talk. Findings: cpr6-7 is a dominant Arabidopsis mutant which has elevated salicylic acid levels and has enhanced resistance to Pseudomonas syringae and Peronspora parasitica. The cpr6- 1 plants have elevated expression of both NPR-l-dependent and NPR-1 -independent defense genes. CO/l: An Arabidopsis gene required for jasmonate-regulated defense and fertility. Xie D-X, Feys BF, James S, Nieto094. Rostro M, Turner JG: Science 1998, 280:1091-l ?? Significance: One of the first genes of jasmonate defense and developmental signalling to be characterised. Having the CO/l gene may facilitate the isolation of other components of the jasmonate signal network. Findings: The CO/l gene is necessary for jasmonate sensitivity and the coil mutant is a useful tool with which to study the biological functions of JA. The CO/l gene was isolated and sequenced. It encodes a leucine-rich repeat protein with homology to F-box proteins which function by targetting transcriptional repressor proteins for proteolysis. Endogenous cellulases in animals: isolation of B-1,4-endoglucanase genes from two species of plant-parasitic cyst nematodes. Smant G, Stockermans JPWG, Yan Y, de Boer JM, Baum TJ, Wang X, Hussey RS, Gommers FJ, Henrissat B, Davis EL et al.: Proc Nat/ Acad Sci USA 1998, 954906-4911. ?? Significance: The first report of cellulase genes in animals. Suggests that such genes may be widespread in phylum Nematoda and may be important pathogenicity factors involved in penetration of the plant cell wall. Findings: Two plant parasitic nematode species encode and secrete p-1,4-endoglucanases. Magnaportha grisea pathogenicity genes obtained through insertional mutagenesis. Sweigard JA, Carroll AM, Farrall L, Chumley FG, Valent B: MO/ P/ant-Microbe Int 1998, 11:40441 2. ?? Significance: This work reports new pathogenicity genes for a filamentous fungus, the causal agent of the economically important rice blast disease. Findings: Restriction enzyme-mediated integration was used Seven to generate pathogenicity mutants in Magnaportha. pathogenicity genes were cloned and found to encode metabolic enzymes, a protein kinase subunit and two proteins of unknown function.
tathione S transferase mRNA transcripts and appearance of micro-hypersensitive responses in leaves distant to the site of primary challenge. The authors conclude that a mobile signal, generated by the oxidative burst at the site of the local challenge, is responsible for initiating secondary oxidative bursts in the discrete cells and this lead to the micro-hypersensitive responses.
Membrane voltage initiates Ca2+ waves and potentiates Ca2+ increases with abscisic acid in stomata1 guard cells. Grabov A, Blatt MR: Proc Nat/ Acad Sci USA 1998, 95:47784783. ?? Significance: The work reported in this paper highlights the importance of membrane voltage in cell signalling. Findings: The authors measured cytosolic Ca2+ and membrane voltage concurrently in guard cells and showed that hyperpolarization triggers increases in Ca2+. They also showed that abscisic acid was able to influence these voltage induced Ca2+ increases. These results point to the importance of membrane voltage in determining the outcome of challenging a guerd cell with ABA.
The indeterminate gene encodes a zinc finger protein and regulates a leaf-generated signal required for the transition to flowering in maize. Colasanti J, Yuan Z, Sundaresan V: Cell 1998, 93:593-603. ?? * Significance: The data in this paper strongly support the hy pothesis that a signal originating from the leaves is responsible for the induction of flowering. Findings: The authors show that the maize indeterminate7 gene (idl) encodes a transcriptional regulator which, although it controls floral transition, is only expressed in immature leaves. They also showed that plants chimeric for ID1 function flowered earlier than fully mutant plants. It is possible that ID1 or its mRNA may be the mobile factor: alternatively, the gene product could be involved in the activation of other genes involved the production of the signal.
Role of calcium in signal transduction during the hypersensitive response caused by basidiospore-derived infection of the cowpea rust fungus. Xu H, Heath MC: Plant Cell 1998, 10:585-597. ??Significance: This paper shows that, in intact plant tissue, an elevation in cytosolic calcium is a very early step in the signal
transduction Findings:
pathway responsible
cells from cowpea basidiospores.
plants inoculated
The authors
free calcium occurred
Cell signalling Al&air M Hetherington Lancaster University, Lancaster, UK Reactive oxygen intermediates mediate a systemic signal network in the establishment of plant immunity. Alvarez ME, Pennell RI, Meijer P-J, lshikawa A, Dixon RA, Lamb C: Cell 1998, 92:773-784. ?? Significance: This paper adds to our understanding of the cellular processes which underlie plant disease resistance. Findings: The authors showed that local challenge of Arabidopsis with Pseudomonas syringae results in a local primary oxidative burst. They also observed the rapid accumulation of glu-
for plant disease
Cytosolic calcium levels were measured with cowpea
rust fungus
found that increases
in cytosolic
in resistant plants during the fungal pen-
etration of the plant epidermal finding is indicated
resistance. in epidermal
because
cellular changes associated
cell wall. The importance it was observed
of this
before any other
with the hypersensitive
response.
Selected by Klaus Palme Max-Delbrueck-Laboratorium in der Max-Planck-Gesellschaft, Koeln, Germany of single RNA transcripts in situ. Femino AM, Fay, FS, Fogarty K, Singer RH: Science 1998, 280:585-590. ?? Significance: Using fluorescence in situ hybridization (FISH)
Visualization
and digital imaging microscopy, allow detection
a method
of single RNA molecules.
was developed
to
Paper alert
. Significance: CPR6 is a newly discovered regulator which helps to control multiple defense pathways and is an important tool for the study of signal pathway cross-talk. Findings: cpr6-7 is a dominant Arabidopsis mutant which has elevated salicylic acid levels and has enhanced resistance to Pseudomonas syringae and Peronspora parasitica. The cpr6- 1 plants have elevated expression of both NPR-l-dependent and NPR-1 -independent defense genes. CO/l: An Arabidopsis gene required for jasmonate-regulated defense and fertility. Xie D-X, Feys BF, James S, Nieto094. Rostro M, Turner JG: Science 1998, 280:1091-l ?? Significance: One of the first genes of jasmonate defense and developmental signalling to be characterised. Having the CO/l gene may facilitate the isolation of other components of the jasmonate signal network. Findings: The CO/l gene is necessary for jasmonate sensitivity and the coil mutant is a useful tool with which to study the biological functions of JA. The CO/l gene was isolated and sequenced. It encodes a leucine-rich repeat protein with homology to F-box proteins which function by targetting transcriptional repressor proteins for proteolysis. Endogenous cellulases in animals: isolation of B-1,4-endoglucanase genes from two species of plant-parasitic cyst nematodes. Smant G, Stockermans JPWG, Yan Y, de Boer JM, Baum TJ, Wang X, Hussey RS, Gommers FJ, Henrissat B, Davis EL et al.: Proc Nat/ Acad Sci USA 1998, 954906-4911. ?? Significance: The first report of cellulase genes in animals. Suggests that such genes may be widespread in phylum Nematoda and may be important pathogenicity factors involved in penetration of the plant cell wall. Findings: Two plant parasitic nematode species encode and secrete p-1,4-endoglucanases. Magnaportha grisea pathogenicity genes obtained through insertional mutagenesis. Sweigard JA, Carroll AM, Farrall L, Chumley FG, Valent B: MO/ P/ant-Microbe Int 1998, 11:40441 2. ?? Significance: This work reports new pathogenicity genes for a filamentous fungus, the causal agent of the economically important rice blast disease. Findings: Restriction enzyme-mediated integration was used Seven to generate pathogenicity mutants in Magnaportha. pathogenicity genes were cloned and found to encode metabolic enzymes, a protein kinase subunit and two proteins of unknown function.
tathione S transferase mRNA transcripts and appearance of micro-hypersensitive responses in leaves distant to the site of primary challenge. The authors conclude that a mobile signal, generated by the oxidative burst at the site of the local challenge, is responsible for initiating secondary oxidative bursts in the discrete cells and this lead to the micro-hypersensitive responses.
Membrane voltage initiates Ca2+ waves and potentiates Ca2+ increases with abscisic acid in stomata1 guard cells. Grabov A, Blatt MR: Proc Nat/ Acad Sci USA 1998, 95:47784783. ?? Significance: The work reported in this paper highlights the importance of membrane voltage in cell signalling. Findings: The authors measured cytosolic Ca2+ and membrane voltage concurrently in guard cells and showed that hyperpolarization triggers increases in Ca2+. They also showed that abscisic acid was able to influence these voltage induced Ca2+ increases. These results point to the importance of membrane voltage in determining the outcome of challenging a guerd cell with ABA.
The indeterminate gene encodes a zinc finger protein and regulates a leaf-generated signal required for the transition to flowering in maize. Colasanti J, Yuan Z, Sundaresan V: Cell 1998, 93:593-603. ?? * Significance: The data in this paper strongly support the hy pothesis that a signal originating from the leaves is responsible for the induction of flowering. Findings: The authors show that the maize indeterminate7 gene (idl) encodes a transcriptional regulator which, although it controls floral transition, is only expressed in immature leaves. They also showed that plants chimeric for ID1 function flowered earlier than fully mutant plants. It is possible that ID1 or its mRNA may be the mobile factor: alternatively, the gene product could be involved in the activation of other genes involved the production of the signal.
Role of calcium in signal transduction during the hypersensitive response caused by basidiospore-derived infection of the cowpea rust fungus. Xu H, Heath MC: Plant Cell 1998, 10:585-597. ??Significance: This paper shows that, in intact plant tissue, an elevation in cytosolic calcium is a very early step in the signal
transduction Findings:
pathway responsible
cells from cowpea basidiospores.
plants inoculated
The authors
free calcium occurred
Cell signalling Al&air M Hetherington Lancaster University, Lancaster, UK Reactive oxygen intermediates mediate a systemic signal network in the establishment of plant immunity. Alvarez ME, Pennell RI, Meijer P-J, lshikawa A, Dixon RA, Lamb C: Cell 1998, 92:773-784. ?? Significance: This paper adds to our understanding of the cellular processes which underlie plant disease resistance. Findings: The authors showed that local challenge of Arabidopsis with Pseudomonas syringae results in a local primary oxidative burst. They also observed the rapid accumulation of glu-
for plant disease
Cytosolic calcium levels were measured with cowpea
rust fungus
found that increases
in cytosolic
in resistant plants during the fungal pen-
etration of the plant epidermal finding is indicated
resistance. in epidermal
because
cellular changes associated
cell wall. The importance it was observed
of this
before any other
with the hypersensitive
response.
Selected by Klaus Palme Max-Delbrueck-Laboratorium in der Max-Planck-Gesellschaft, Koeln, Germany of single RNA transcripts in situ. Femino AM, Fay, FS, Fogarty K, Singer RH: Science 1998, 280:585-590. ?? Significance: Using fluorescence in situ hybridization (FISH)
Visualization
and digital imaging microscopy, allow detection
a method
of single RNA molecules.
was developed
to