Réactions différentielles du tabac à 9 espèces de Phytophthora

Bonnet, Philippe; Rousse, Georges

doi:10.1051/agro:19850905

Cited by 27 publications

(21 citation statements)

References 3 publications

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“…However, necroses also develop on the leaves at a distance from the inoculation court (8). We believe that they are also hypersensitive-like reactions (despite their unusual location) because both the local and the distant necroses occur simultaneously (24-36 h post inoculation) and do not evolve afterward.…”

mentioning

confidence: 91%

“…It also elicits PR protein accumulation and protects tobacco plants against invasion following inoculation with the compatible pathogen Phytophthora parasitica var. nicotianae (8,9). It has been purified and its amino acid sequence determined (25 CRY was purified according to the method of Ricci et al (25) and added to suspension cultures as an aqueous solution.…”

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confidence: 99%

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Responses of Cultured Tobacco Cells to Cryptogein, a Proteinaceous Elicitor from Phytophthora cryptogea

Blein¹,

Milat²,

Ricci³

1991

Plant Physiol.

126

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In culture, the phytopathogenic fungus Phytophthora cryptogea secretes a protein which elicits hypersensitive-like necroses and protects tobacco plants against invasion by the pathogen Phytophthora parasitca var. nicotianae. This protein, named cryptogein, has been purified and its amino acid sequence determined. In this work, we studied the effect of cryptogein on tobacco cell suspension cultures. Cryptogein was lethal at about 0.10 micromolar. When added at sublethal doses, it elicited the production of ethylene and phytoalexins. It also induced a rapid increase in pH and conductivity of the extracellular medium without affecting the integrity of the plasma membrane. Cryptogein reduced the fusicoccin-induced acidification of the extracellular medium. The concentration which inhibited the fusicoccin response by 50% was 0.8 nanomolar, while 1 micromolar erythrosine B, an ATPase inhibitor, was needed to produce the same inhibition. However, cryptogein did not inhibit the activity of a purified plasma membrane ATPase. Results of binding studies with whole cells suggested the presence of elicitor-binding sites with a high affinity for cryptogein. The involvement of the plasma membrane during the initial interaction between elicitor and cells is discussed.

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confidence: 91%

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confidence: 99%

Responses of Cultured Tobacco Cells to Cryptogein, a Proteinaceous Elicitor from Phytophthora cryptogea

Blein¹,

Milat²,

Ricci³

1991

Plant Physiol.

126

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“…The interaction between the phytopathogenic fungus Phytophthora cryptogea and the nonhost plant tobacco (Nicotiana tabacum) leads to an HR2 characterized by plant tissue necrosis and a restricted growth of the fungus (5). An unusual feature of this HR is that necrosis occurs not only at the inoculation court but also on the leaves at a distance from the fungus.…”

mentioning

confidence: 99%

Migration of the Fungal Protein Cryptogein within Tobacco Plants

Devergne¹,

Bonnet²,

Panabieres³

et al. 1992

Plant Physiol.

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Cryptogein (CRY), a protein secreted by Phytophthora cryptogea, causes necrosis on tobacco (Nicotiana tabacum) plants at the site of application (the stem or the roots) and also on distant leaves. Autoradiography of plantlets after root absorption of radioiodinated CRY demonstrated a rapid migration of the label to the leaf lamina via the veins. Using an anti-CRY antiserum, a CRY-related antigen was detected in the stem and leaves of CRY-treated plants at a distance from the site of application. This antigen had the same molecular weight as CRY and was detected in the leaves as early as 1 hour after stem treatment, i.e. long before necrosis was detectable. The antigen was also detected in plants inoculated with P. cryptogea. The distant location of the necrosis induced by the fungus or by CRY can be ascribed to the migration of this protein, which is toxic to tobacco cells. It is proposed that CRY, which also elicits defense reactions in tobacco, might contribute to the hypersensitive response of tobacco to P. cryptogea.The interaction between the phytopathogenic fungus Phytophthora cryptogea and the nonhost plant tobacco (Nicotiana tabacum) leads to an HR2 characterized by plant tissue necrosis and a restricted growth of the fungus (5). An unusual feature of this HR is that necrosis occurs not only at the inoculation court but also on the leaves at a distance from the fungus. In culture, P. cryptogea secretes a protein, CRY (mol wt 10,323), which causes the rapid death of tobacco cells and is an elicitor of phytoalexin accumulation (4,6,11,12). When applied to the wounded stem or roots of a tobacco plant, CRY induces necrosis within 24 h at the point of application and also on distant leaves (14). This raises two questions: (a) does this elicitor actually move within the plant; and (b) interaction, then it should be possible to detect this proteinaceous elicitor in noninfected tissues from inoculated plants.We have investigated the possibility that CRY migrates in tobacco by two approaches: (a) autoradiography of plantlets after absorption of radioiodinated CRY by the roots; and (b) immunodetection of the protein in the stem and the leaves after application of exogenous CRY to the stem or to the roots, or after stem-inoculation with P. cryptogea. In addition, the behavior of CRY was compared with that of CAP, a related protein produced by Phytophthora capsici, which has slightly different biological effects on tobacco (14). MATERIALS AND METHODSTobacco plants (Nicotiana tabacum cv Xanthi nc) grown in a greenhouse for 30 d were transferred into a growth chamber (240C, 16 h daylength), and CRY was applied 10 d later to the stem or to the roots. Stem treatments were as previously described (14): the plant was decapitated above the third highest fully expanded leaf, and the wounded stem received 2.5 ,ug of elicitor as a 20-,uL drop of aqueous solution or a plug taken from a malt-agar culture of Phytophthora cryptogea; only the two upper remaining leaves (Li and L2) were left attached. In root treatments, t...

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“…Then, from culture filtrates of P. cryptogea and of P. capsici proteinaceous elicitors named elicitins (cryptogein and capsicein, respectively) were isolated [8]. These proteins stimulate natural defenses of tobacco against many pathogens, and this phenomenon is accompanied by the formation of restricted leaf necroses [9][10][11]. The development of this hypersensitive cell death involves the lipoxygenase-dependent production of fatty acid hydroperoxides [12].…”

Section: Tobacco-phytophthora Interaction Elicitins Induce Plant Defmentioning

confidence: 99%

Involvement of lipid-protein complexes in plant-microorganism interactions

Blein¹

2002

OCL

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Summary : Increasing concerns about the environmental impact of modern agricultural have prompted research for alternate practices to pesticide treatments, notably using plant defense mechanisms. Thus, isolation and characterization of plant defense elicitors have been the main step of studies in many groups. Moreover, in the global concept of interactions between organisms and their environment, a major concern is to discriminate recognition between exogenous and endogenous signals, notably during pathogenic or allergenic interactions involving small proteins, such as elicitins or lipid transfer proteins (LTPs). Elicitins and lipid transfer proteins (LTP) are both able to load and transfer lipidic molecules and share some structural and functional properties. While elicitins are known as elicitors of plant defense mechanisms, the biological function of LTPs is still an enigma. They are ubiquitous plant proteins able to load and transfer hydrophobic molecules such as fatty acids or phospholipids. Among them, LTPs1 (type 1 lipid transfer proteins) constitute a multigenic family of secreted plant lipid binding proteins that are constitutively expressed in specific tissues and/or induced in response to biotic and abiotic stress (for reviews [1][2][3][4]). Their biological function is still unknown, even if some data provide arguments for a role of these proteins in the assembly of extracellular hydrophobic polymers (i.e., cutin and suberin) [2,4] and/or in plant defense against fungal pathogens [1,3]. Beside their involvement in plant defense, LTPs1 are also known to be pan-allergens of plant-derived foods [5]. Finally, the discovery of the sterol carrier-properties of elicitins has opened new perspectives dealing with the relationship between this function and the elicitor activity of these small cystein-rich proteins. Nevertheless, this elicitor activity is restrained to few plant species, and thus does not appear in accordance with a universal lipid transfer function. These considerations required a reassessment of the precise role of elicitins for both fungi and plants [6].Résumé : La stimulation des mécanismes naturels de défense des plantes représente une stratégie alternative à l'utilisation de la lutte chimique en phytoprotection. Dans ce contexte, les élicitines, qui sont de petites protéines sécrétées par des Phytophthora et des Pythium, induisent une réaction de type hypersensible chez des plantes comme le tabac. Ces plantes deviennent résistantes à l'agression de leurs agents pathogènes. La récente découverte que les élicitines sont des protéines de transfert de stérols a apporté une vue nouvelle sur l'activité moléculaire des élicitines. Élicitines et protéines de transfert de lipides (LTP) sont capables de charger et de transporter des molécules lipidiques et partagent des caractères communs tant au plan structural que fonctionnel mais, tandis que les élicitines sont connues pour leur activité élicitrice de réaction de défense chez les plantes, l'activité biologique des LTP reste inconnue. Cependant, ...

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Réactions différentielles du tabac à 9 espèces de Phytophthora

Cited by 27 publications

References 3 publications

Responses of Cultured Tobacco Cells to Cryptogein, a Proteinaceous Elicitor from Phytophthora cryptogea

Responses of Cultured Tobacco Cells to Cryptogein, a Proteinaceous Elicitor from Phytophthora cryptogea

Migration of the Fungal Protein Cryptogein within Tobacco Plants

Involvement of lipid-protein complexes in plant-microorganism interactions

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