The Genetics and Biology ofPhytophthora infestans:Modern Approaches to a Historical Challenge

Judelson, Howard S.

doi:10.1006/fgbi.1997.1006

Cited by 91 publications

(67 citation statements)

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“…Despite the importance of Phytophthora species as devastating plant pathogens, little is known about the molecular mechanisms that determine the outcome of interactions between Phytophthora and plants (Judelson, 1996(Judelson, , 1997. Elicitins, a family of host-specific elicitor proteins of Phytophthora, induce the HR on particular plant species, most notably tobacco and other Nicotiana species in the Solanaceae family.…”

Section: Discussionmentioning

confidence: 99%

“…The life cycle and infection process of P. infestans are well known (Pristou and Gallegly, 1954; Hohl and Suter, 1976; Coffey and Wilson, 1983;Judelson, 1997). Infection generally starts when motile zoospores that swim on the leaf surface encyst and germinate.…”

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confidence: 99%

“…Only sporadic reports of natural infection of plants outside of the genera Solanum and Lycopersicon have been provided (Erwin and Ribeiro, 1996). The molecular basis of host specificity of P. infestans is poorly understood (Judelson, 1996(Judelson, , 1997. To date, no late blight resistance gene of Solanum spp or race-specific avirulence gene of P. infestans has been isolated.…”

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confidence: 99%

“…Molecular manipulations and stable DNA transformation of P. infestans are well-established techniques Judelson, 1996Judelson, , 1997van West et al, 1998). Because DNA transformation is a prerequisite for an unequivocal demonstration of the role of elicitins in Phytophthora -plant interactions, we decided to exploit P. infestans for functional analysis of elicitins.…”

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“…This recognition is thought to be determined by the interaction of elicitins with a high-affinity binding site in the tobacco plasma membrane (Wendehenne et al, 1995; Yu, 1995). However, no direct assessment of the role of elicitins as avirulence factors through genetic manipulation of elicitin production has been reported to date.Molecular manipulations and stable DNA transformation of P. infestans are well-established techniques Judelson, 1996Judelson, , 1997van West et al, 1998). Because DNA transformation is a prerequisite for an unequivocal demonstration of the role of elicitins in Phytophthora -plant interactions, we decided to exploit P. infestans for functional analysis of elicitins.…”

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Resistance of Nicotiana benthamiana to Phytophthora infestans Is Mediated by the Recognition of the Elicitor Protein INF1

et al. 1998

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Phytophthora infestans , the agent of potato and tomato late blight disease, produces a 10-kD extracellular protein, INF1 elicitin. INF1 induces a hypersensitive response in a restricted number of plants, particularly those of the genus Nicotiana. In virulence assays with different P. infestans isolates, five Nicotiana species displayed resistance responses. In all of the interactions, after inoculation with P. infestans zoospores, penetration of an epidermal cell was observed, followed by localized necrosis typical of a hypersensitive response. To determine whether INF1 functions as an avirulence factor in these interactions, we adopted a gene-silencing strategy to inhibit INF1 production. Several transformants deficient in inf1 mRNA and INF1 protein were obtained. These strains remained pathogenic on host plants. However, in contrast to the wild-type and control transformant strains, INF1-deficient strains induced disease lesions when inoculated on N. benthamiana . These results demonstrate that the elicitin INF1 functions as an avirulence factor in the interaction between N. benthamiana and P. infestans . INTRODUCTIONMicrobial plant pathogens often exhibit high degrees of specialization and can only infect a limited number of plant species (Agrios, 1988). Pathogen specialization results when a complex set of preformed and induced mechanisms is put into motion to defend a plant against invading pathogens. In some interactions, preformed physical barriers and antimicrobial compounds in the plant help to ward off pathogens (Osbourn, 1996a(Osbourn, , 1996b. In other interactions, perception by the plant of signal molecules, namely, elicitors, produced by the avirulent pathogen leads to the induction of effective defense responses, including a programmed cell death response termed the hypersensitive response (HR) (Lamb et al., 1989; Dixon and Harrison, 1990; Ebel and Scheel, 1992; Baker et al., 1997;Morel and Dangl, 1997). This model has been genetically defined by Flor's gene-for-gene hypothesis (Flor, 1956(Flor, , 1971. According to this hypothesis, a resistance reaction is determined by the simultaneous expression of a pathogen avirulence ( Avr ) gene with the corresponding plant resistance ( R ) gene (Staskawicz et al., 1995).In recent years, the gene-for-gene hypothesis has received tremendous experimental support through the identification and functional characterization of both Avr and R genes. A number of Avr genes from fungi, bacteria, and viruses were shown to encode specific elicitor proteins. This was demonstrated directly by infiltration of Avr proteins into plant leaves or indirectly by expression of Avr genes in plant cells containing the corresponding R gene (Culver and Dawson, 1991; de Wit, 1995; Alfano and Collmer, 1996;Knogge, 1996; Bonas and van den Ackerveken, 1997; van den Ackerveken and Bonas, 1997). Elicitor treatment or Avr gene expression triggers the HR and related defense responses in plants that mimic the response induced by avirulent pathogens (Hahlbrock et al., 1995; Hammond-Kosa...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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