Pathogenesis-related Proteins

Cutt, J R; Klessig, Daniel F.

doi:10.1007/978-3-7091-6684-0_9

Cited by 75 publications

(41 citation statements)

References 182 publications

(200 reference statements)

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“…The fact that ToRSV induces a necrotic phenotype that recapitulates the HR suggests that ToRSV RNAs or proteins are perceived by the plant cell as elicitors of the HR. Increased transcription of the PR1a gene, which belongs to a cluster of salicylic acid (SA)-induced defense genes (19), was found in inoculated and distal leaves and seemed to accumulate with or ahead of the virus infection front.…”

Section: Discussionmentioning

confidence: 99%

Recovery of Nicotiana benthamiana Plants from a Necrotic Response Induced by a Nepovirus Is Associated with RNA Silencing but Not with Reduced Virus Titer

Jovel

Walker

Sanfaçon

2007

J Virol

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Recovery of plants from virus-induced symptoms is often described as a consequence of RNA silencing, an antiviral defense mechanism. For example, recovery of Nicotiana clevelandii from a nepovirus (tomato black ring virus) is associated with a decreased viral RNA concentration and sequence-specific resistance to further virus infection. In this study, we have characterized the interaction of another nepovirus, tomato ringspot virus (ToRSV), with host defense responses during symptom induction and subsequent recovery. Early in infection, ToRSV induced a necrotic phenotype in Nicotiana benthamiana that showed characteristics typical of a hypersensitive response. RNA silencing was also activated during ToRSV infection, as evidenced by the presence of ToRSV-derived small interfering RNAs (siRNAs) that could direct degradation of ToRSV sequences introduced into sensor constructs. Surprisingly, disappearance of symptoms was not accompanied by a commensurate reduction in viral RNA levels. The stability of ToRSV RNA after recovery was also observed in N. clevelandii and Cucumis sativus and in N. benthamiana plants carrying a functional RNA-dependent RNA polymerase 1 ortholog from Medicago truncatula. In experiments with a reporter transgene (green fluorescent protein), ToRSV did not suppress the initiation or maintenance of transgene silencing, although the movement of the silencing signal was partially hindered. Our results demonstrate that although RNA silencing is active during recovery, reduction of virus titer is not required for the initiation of this phenotype. This scenario adds an unforeseen layer of complexity to the interaction of nepoviruses with the host RNA silencing machinery. The possibility that viral proteins, viral RNAs, and/or virusderived siRNAs inactivate host defense responses is discussed.RNA silencing is an innate and ubiquitous defense mechanism that is activated by double-stranded RNAs (dsRNAs) and has been implicated in antiviral defense (6,7,60,61). The vast majority of plant viruses possess a positive-sense singlestranded RNA genome that is replicated through dsRNA intermediates (31). In addition, folding of self-complementary stretches within the single-stranded RNA genome allows the formation of stem-loop structures, which provide local regions of dsRNA (66). Once detected by the surveillance machinery of the plant cell, viral dsRNAs are cleaved by dicer-like (DCL) RNase III enzymes into 21-to 24-nucleotide (nt) small interfering RNAs (siRNAs) (20,23,59). The siRNAs guide RNAinduced silencing complexes (RISCs) to the target RNA in a sequence-specific manner (61). The target RNA is then cleaved by argonaute (AGO) proteins, which are RNase H-like enzymes and are associated with the RISC (9, 74). In addition, host RNA-dependent RNA polymerases (RDRs) have been proposed to play a crucial role in amplifying the RNA silencing signal (5,8,60,65). They bind the cleaved fragment released by RISC and produce a new generation of dsRNAs. This is probably followed by a new round of dicer cleavage to p...

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Section: Discussionmentioning

confidence: 99%

Recovery of Nicotiana benthamiana Plants from a Necrotic Response Induced by a Nepovirus Is Associated with RNA Silencing but Not with Reduced Virus Titer

Jovel

Walker

Sanfaçon

2007

J Virol

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“…Many of the hitherto characterized proteins belong to the group of so-called pathogenesis-related proteins, a heterogeneous group separable into at least five different families and induced in many plants during infection with viral, bacterial, or fungal pathogens (Cutt and Klessig, 1992). A prominent and extensively studied family of pathogenesis-related proteins are the chitinases (EC 3.2.1.14), which have becn shown to be capable of inhibiting fungal growth by the degradation of chitin in growing fungal hyphae (for a review, see Collinge et al, 1993).…”

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confidence: 99%

Characterization of a New Antifungal Chitin-Binding Peptide from Sugar Beet Leaves

Nielsen¹,

Nielsen²,

Madrid³

et al. 1997

Plant Physiology

116

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The intercellular washing fluid (IWF) from leaves of sugar beet (Befa vulgaris L.) contains a number of proteins exhibiting in vitro antifungal activity against the devastating leaf pathogen Cercospora beticola (Sacc.). Among these, a potent antifungal peptide, designated IWF4, was identified. The 30-amino-acid residue sequence of IWF4 is rich in cysteines (6) and glycines (7) and has a highly basic isoelectric point. IWF4 shows homology to the chitin-binding (hevein) domain of chitin-binding proteins, e.g. class I and IV chitinases. Accordingly, IWF4 has a strong affinity to chitin. Notably, it binds chitin more strongly than the chitin-binding chitinases. A full-length IWF4 cDNA clone was obtained that codes for a preproprotein of 76 amino acids containing an N-terminal putative signal peptide of 21 residues, followed by the mature IWF4 peptide of 30 residues, and an acidic C-terminal extension of 25 residues. IWF4 mRNA is expressed in the aerial parts of the plant only, with a constitutive expression in young and mature leaves and in young flowers. No induced expression of IWF4 protein or mRNA was detected during infection with C. beficola or after treatment with 2,6-dichloroisonicotinic acid, a well-known inducer of resistance in plants.

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“…The plant hydrolases β-glucanase and Chitinase have attracted considerable interest as defence related genes in a wide variety of plants (Cutt and Klessig, 1992;Chun et al, 2001;. In this study the ability of defence related genes in chickpea was studied.…”

Section: Discussionmentioning

confidence: 97%

Detection of anti-fungal genes in chickpea (Cicer arietinum L.) and their effects on fungal growth

Shahid

Chaudhry²,

Rahman³

et al. 2009

Emir. J. Food Agric

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Anti-fungal genes chitinase, beta-glucanase and ribosomal inactivating proteins (RIP) were detected in chickpea plants when they were artificially exposed to Ascochyta rabei spores. Immunological studies provided evidence for the presence of a chitinase-like proteins in blightinfected chickpea leaves using a poplar chitinase antibody. No activity was detected when a barley chitinase antibody was used, indicating that antifungal proteins in chickpea recognize different antigenic determinants. Purified barley ribosomal inactivating protein (RIP 30) and chitinase (Chi 26) were shown to inhibit the growth of Ascochyta rabiei in vitro. The role of antifungal proteins in the protection of chickpea against pathogen is discussed.

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Pathogenesis-related Proteins

Cited by 75 publications

References 182 publications

Recovery of Nicotiana benthamiana Plants from a Necrotic Response Induced by a Nepovirus Is Associated with RNA Silencing but Not with Reduced Virus Titer

Recovery of Nicotiana benthamiana Plants from a Necrotic Response Induced by a Nepovirus Is Associated with RNA Silencing but Not with Reduced Virus Titer

Characterization of a New Antifungal Chitin-Binding Peptide from Sugar Beet Leaves

Detection of anti-fungal genes in chickpea (Cicer arietinum L.) and their effects on fungal growth

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