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Journal ArticleDOI

Genes controlling expression of defense responses in Arabidopsis — 2001 status

01 Aug 2001-Current Opinion in Plant Biology (Curr Opin Plant Biol)-Vol. 4, Iss: 4, pp 301-308
TL;DR: It is now clear that gene-for-gene resistance can be mediated through at least three genetically distinguishable pathways.
About: This article is published in Current Opinion in Plant Biology.The article was published on 2001-08-01. It has received 763 citations till now. The article focuses on the topics: Arabidopsis & Arabidopsis thaliana.
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Journal ArticleDOI
05 Apr 2002-Science
TL;DR: A draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp.indica, by whole-genome shotgun sequencing is produced, with a large proportion of rice genes with no recognizable homologs due to a gradient in the GC content of rice coding sequences.
Abstract: We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC-content of rice coding sequences.

4,064 citations

Journal ArticleDOI
14 Jun 2001-Nature
TL;DR: The current knowledge of recognition-dependent disease resistance in plants is reviewed, and a few crucial concepts are included to compare and contrast plant innate immunity with that more commonly associated with animals.
Abstract: Plants cannot move to escape environmental challenges. Biotic stresses result from a battery of potential pathogens: fungi, bacteria, nematodes and insects intercept the photosynthate produced by plants, and viruses use replication machinery at the host's expense. Plants, in turn, have evolved sophisticated mechanisms to perceive such attacks, and to translate that perception into an adaptive response. Here, we review the current knowledge of recognition-dependent disease resistance in plants. We include a few crucial concepts to compare and contrast plant innate immunity with that more commonly associated with animals. There are appreciable differences, but also surprising parallels.

3,814 citations


Cites background from "Genes controlling expression of def..."

  • ...Such loci are likely to encode proteins that function either as guardees (described above) or to mediate the series of biochemical events outlined belo...

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Journal ArticleDOI
28 Feb 2002-Nature
TL;DR: An Arabidopsis thaliana leaf cell system based on the induction of early-defence gene transcription by flagellin, a highly conserved component of bacterial flagella that functions as a PAMP in plants and mammals is developed, suggesting that signalling events initiated by diverse pathogens converge into a conserved MAPK cascade.
Abstract: There is remarkable conservation in the recognition of pathogen-associated molecular patterns (PAMPs) by innate immune responses of plants, insects and mammals. We developed an Arabidopsis thaliana leaf cell system based on the induction of early-defence gene transcription by flagellin, a highly conserved component of bacterial flagella that functions as a PAMP in plants and mammals. Here we identify a complete plant MAP kinase cascade (MEKK1, MKK4/MKK5 and MPK3/MPK6) and WRKY22/WRKY29 transcription factors that function downstream of the flagellin receptor FLS2, a leucine-rich-repeat (LRR) receptor kinase. Activation of this MAPK cascade confers resistance to both bacterial and fungal pathogens, suggesting that signalling events initiated by diverse pathogens converge into a conserved MAPK cascade.

2,480 citations

Journal ArticleDOI
TL;DR: The observed diversity of these NBS-LRR proteins indicates the variety of recognition molecules available in an individual genotype to detect diverse biotic challenges.
Abstract: The Arabidopsis genome contains ∼200 genes that encode proteins with similarity to the nucleotide binding site and other domains characteristic of plant resistance proteins. Through a reiterative process of sequence analysis and reannotation, we identified 149 NBS-LRR–encoding genes in the Arabidopsis (ecotype Columbia) genomic sequence. Fifty-six of these genes were corrected from earlier annotations. At least 12 are predicted to be pseudogenes. As described previously, two distinct groups of sequences were identified: those that encoded an N-terminal domain with Toll/Interleukin-1 Receptor homology (TIR-NBS-LRR, or TNL), and those that encoded an N-terminal coiled-coil motif (CC-NBS-LRR, or CNL). The encoded proteins are distinct from the 58 predicted adapter proteins in the previously described TIR-X, TIR-NBS, and CC-NBS groups. Classification based on protein domains, intron positions, sequence conservation, and genome distribution defined four subgroups of CNL proteins, eight subgroups of TNL proteins, and a pair of divergent NL proteins that lack a defined N-terminal motif. CNL proteins generally were encoded in single exons, although two subclasses were identified that contained introns in unique positions. TNL proteins were encoded in modular exons, with conserved intron positions separating distinct protein domains. Conserved motifs were identified in the LRRs of both CNL and TNL proteins. In contrast to CNL proteins, TNL proteins contained large and variable C-terminal domains. The extant distribution and diversity of the NBS-LRR sequences has been generated by extensive duplication and ectopic rearrangements that involved segmental duplications as well as microscale events. The observed diversity of these NBS-LRR proteins indicates the variety of recognition molecules available in an individual genotype to detect diverse biotic challenges.

1,503 citations


Cites background from "Genes controlling expression of def..."

  • ...CNL and TNL proteins may activate different but overlapping downstream signaling pathways (reviewed by Glazebrook, 2001)....

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  • ...Mutations in EDS1 and NDR1 differentially affect some but not all CNL and TNL proteins (McDowell et al., 2000; Glazebrook, 2001)....

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Journal ArticleDOI
TL;DR: Large-scale transcriptional changes accompany insect-induced resistance, which is organized into specific temporal and spatial patterns and points to the existence of herbivore-specific trans-activating elements orchestrating the responses.
Abstract: ▪ Abstract Plants respond to herbivore attack with a bewildering array of responses, broadly categorized as direct and indirect defenses, and tolerance. Plant-herbivore interactions are played out on spatial scales that include the cellular responses, well-studied in plant-pathogen interactions, as well as responses that function at whole-plant and community levels. The plant's wound response plays a central role but is frequently altered by insect-specific elicitors, giving plants the potential to optimize their defenses. In this review, we emphasize studies that advance the molecular understanding of elicited direct and indirect defenses and include verifications with insect bioassays. Large-scale transcriptional changes accompany insect-induced resistance, which is organized into specific temporal and spatial patterns and points to the existence of herbivore-specific trans-activating elements orchestrating the responses. Such organizational elements could help elucidate the molecular control over the d...

1,423 citations

References
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Journal ArticleDOI
TL;DR: The identification of a new locus, FLS2, is described, which is ubiquitously expressed and encodes a putative receptor kinase and shares structural and functional homologies with known plant resistance genes and with components involved in the innate immune system of mammals and insects.

2,056 citations

Journal ArticleDOI
15 May 1998-Science
TL;DR: The coi1 mutation defines an Arabidopsis gene required for response to jasmonates, which regulate defense against insects and pathogens, wound healing, and pollen fertility as mentioned in this paper.
Abstract: The coi1 mutation defines an Arabidopsis gene required for response to jasmonates, which regulate defense against insects and pathogens, wound healing, and pollen fertility. The wild-type allele, COI1, was mapped to a 90-kilobase genomic fragment and located by complementation of coi1-1 mutants. The predicted amino acid sequence of the COI1 protein contains 16 leucine-rich repeats and an F-box motif. It has similarity to the F-box proteins Arabidopsis TIR1, human Skp2, and yeast Grr1, which appear to function by targeting repressor proteins for removal by ubiquitination.

1,551 citations

Journal ArticleDOI
TL;DR: The results indicated the existence of a substantial network of regulatory interactions and coordination occurring during plant defense among the different defense signaling pathways, notably between the salicylate and jasmonate pathways that were previously thought to act in an antagonistic fashion.
Abstract: Disease resistance is associated with a plant defense response that involves an integrated set of signal transduction pathways. Changes in the expression patterns of 2,375 selected genes were examined simultaneously by cDNA microarray analysis in Arabidopsis thaliana after inoculation with an incompatible fungal pathogen Alternaria brassicicola or treatment with the defense-related signaling molecules salicylic acid (SA), methyl jasmonate (MJ), or ethylene. Substantial changes (up- and down-regulation) in the steady-state abundance of 705 mRNAs were observed in response to one or more of the treatments, including known and putative defense-related genes and 106 genes with no previously described function or homology. In leaf tissue inoculated with A. brassicicola, the abundance of 168 mRNAs was increased more than 2.5-fold, whereas that of 39 mRNAs was reduced. Similarly, the abundance of 192, 221, and 55 mRNAs was highly (>2.5-fold) increased after treatment with SA, MJ, and ethylene, respectively. Data analysis revealed a surprising level of coordinated defense responses, including 169 mRNAs regulated by multiple treatments/defense pathways. The largest number of genes coinduced (one of four induced genes) and corepressed was found after treatments with SA and MJ. In addition, 50% of the genes induced by ethylene treatment were also induced by MJ treatment. These results indicated the existence of a substantial network of regulatory interactions and coordination occurring during plant defense among the different defense signaling pathways, notably between the salicylate and jasmonate pathways that were previously thought to act in an antagonistic fashion.

1,472 citations

Journal ArticleDOI
TL;DR: Data point to the existence of at least two separate hormone-dependent defense pathways in Arabidopsis that contribute to resistance against distinct microbial pathogens.
Abstract: The endogenous plant hormones salicylic acid (SA) and jasmonic acid (JA), whose levels increase on pathogen infection, activate separate sets of genes encoding antimicrobial proteins in Arabidopsis thaliana. The pathogen-inducible genes PR-1, PR-2, and PR-5 require SA signaling for activation, whereas the plant defensin gene PDF1.2, along with a PR-3 and PR-4 gene, are induced by pathogens via an SA-independent and JA-dependent pathway. An Arabidopsis mutant, coi1, that is affected in the JA-response pathway shows enhanced susceptibility to infection by the fungal pathogens Alternaria brassicicola and Botrytis cinerea but not to Peronospora parasitica, and vice versa for two Arabidopsis genotypes (npr1 and NahG) with a defect in their SA response. Resistance to P. parasitica was boosted by external application of the SA-mimicking compound 2,6-dichloroisonicotinic acid [Delaney, T., et al. (1994) Science 266, 1247–1250] but not by methyl jasmonate (MeJA), whereas treatment with MeJA but not 2,6-dichloroisonicotinic acid elevated resistance to Alternaria brassicicola. The protective effect of MeJA against A. brassicicola was the result of an endogenous defense response activated in planta and not a direct effect of MeJA on the pathogen, as no protection to A. brassicicola was observed in the coi1 mutant treated with MeJA. These data point to the existence of at least two separate hormone-dependent defense pathways in Arabidopsis that contribute to resistance against distinct microbial pathogens.

1,468 citations

Journal ArticleDOI
TL;DR: It is concluded that both the ethylene and jasmonate signaling pathways need to be triggered concomitantly, and not sequentially, to activate PDF1.2 upon pathogen infection.
Abstract: Activation of the plant defensin gene PDF1.2 in Arabidopsis by pathogens has been shown previously to be blocked in the ethylene response mutant ein2-1 and the jasmonate response mutant coi1-1. In this work, we have further investigated the interactions between the ethylene and jasmonate signal pathways for the induction of this defense response. Inoculation of wild-type Arabidopsis plants with the fungus Alternaria brassicicola led to a marked increase in production of jasmonic acid, and this response was not blocked in the ein2-1 mutant. Likewise, A. brassicicola infection caused stimulated emission of ethylene both in wild-type plants and in coi1-1 mutants. However, treatment of either ein2-1 or coi1-1 mutants with methyl jasmonate or ethylene did not induce PDF1.2, as it did in wild-type plants. We conclude from these experiments that both the ethylene and jasmonate signaling pathways need to be triggered concomitantly, and not sequentially, to activate PDF1.2 upon pathogen infection. In support of this idea, we observed a marked synergy between ethylene and methyl jasmonate for the induction of PDF1.2 in plants grown under sterile conditions. In contrast to the clear interdependence of the ethylene and jasmonate pathways for pathogen-induced activation of PDF1.2, functional ethylene and jasmonate signaling pathways are not required for growth responses induced by jasmonate and ethylene, respectively.

1,031 citations