Purification de divers filtrats de culture de Phytophthora et activités biologiques sur le tabac des différentes fractions

Bonnet, Philippe; Rousse, Georges

doi:10.1051/agro:19880410

Cited by 9 publications

(6 citation statements)

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“…From culture filtrates of P. cryptogea and of P. capsici, proteinaceous elicitors named elicitins (cryptogein and capsicein, respectively) were subsequently isolated [14]. These proteins stimulate natural defenses of tobacco against many pathogens, accompanied by restricted leaf necrosis [15][16][17]. About 40 Phytophthora species were screened for the production of elicitins, and different modes of treatment were assayed for plant responses [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Are elicitins cryptograms in plant-Oomycete communications?

Ponchet

Panabières

Milat³

et al. 1999

Cellular and Molecular Life Sciences (CMLS)

178

146

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Stimulation of plant natural defenses is an important challenge in phytoprotection prospects. In that context, elicitins, which are small proteins secreted by Phytophthora and Pythium species, have been shown to induce a hypersensitive-like reaction in tobacco plants. Moreover, these plants become resistant to their pathogens, and thus this interaction constitutes an excellent model to investigate the signaling pathways leading to plant resistance. However, most plants are not reactive to elicitins, although they possess the functional signaling pathways involved in tobacco responses to elicitin. The understanding of factors involved in this reactivity is needed to develop agronomic applications. In this review, it is proposed that elicitins could interact with regulating cell wall proteins before they reach the plasma membrane. Consequently, the plant reactivity or nonreactivity status could result from the equilibrium reached during this interaction. The possibility of overexpressing the elicitins directly from genomic DNA in Pichia pastoris allows site-directed mutagenesis experiments and structure/function studies. The recent discovery of the sterol carrier activity of elicitins brings a new insight on their molecular activity. This constitutes a crucial property, since the formation of a sterol-elicitin complex is required to trigger the biological responses of tobacco cells and plants. Only the elicitins loaded with a sterol are able to bind to their plasmalemma receptor, which is assumed to be an allosteric calcium channel. Moreover, Phytophthora and Pythium do not synthesize the sterols required for their growth and their fructification, and elicitins may act as shuttles trapping the sterols from the host plants. Sequence analysis of elicitin genes from several Phytophthora species sheds unexpected light on the phylogenetic relationships among the genus, and suggests that the expression of elicitins is under tight regulatory control. Finally, general involvement of these lipid transfer proteins in the biology of Pythiaceae, and in plant defense responses, is discussed. A possible scheme for the coevolution between Phytophthora and tobacco plants is approached.

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Section: Introductionmentioning

confidence: 99%

Are elicitins cryptograms in plant-Oomycete communications?

Ponchet

Panabières

Milat³

et al. 1999

Cellular and Molecular Life Sciences (CMLS)

178

146

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“…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).…”

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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Purification de divers filtrats de culture de Phytophthora et activités biologiques sur le tabac des différentes fractions

Abstract: RÉSUMÉ

Cited by 9 publications

References 2 publications

Are elicitins cryptograms in plant-Oomycete communications?

Are elicitins cryptograms in plant-Oomycete communications?

Migration of the Fungal Protein Cryptogein within Tobacco Plants

Involvement of lipid-protein complexes in plant-microorganism interactions

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