Carbohydrates in plant immunity and plant protection: roles and potential application as foliar sprays

Increasing interest is devoted to carbohydrates for their roles in plant immunity. Some of them are elicitors of plant defenses whereas other ones act as signaling molecules in a manner similar to phytohormones. This review first describes the main classes of carbohydrates associated to plant immunity, their role and mode of action. More precisely, the state of the art about perception of “PAMP, MAMP and DAMP type” oligosaccharides is presented and examples of induced defense events are provided. A particular attention is paid to the structure / activity relationships of these compounds. The role of sugars as signaling molecules, especially in plant microbe interactions, is also presented. Secondly, the potentialities and limits of foliar sprays of carbohydrates to stimulate plant immunity for crop protection against diseases are discussed, with focus on the roles of the leaf cuticle and phyllosphere microflora.Peer reviewe

Étude des effecteurs de type RXLR de Plasmopara viticola pour la recherche de résistances durables au mildiou de la vigne

Grapevine downy mildew is caused by the oomycete Plasmopara viticola, which attacks the aerial non-lignified tissues affecting wine production. An alternative to the use of pesticides is the use of vine varieties with sustainable resistances. A programme aiming to create such varieties by crossing resistant species with the cultivated grapevine, Vitis vinifera, is ongoing. Within this program requiring the indentification of new resistance genes, which the project aims to do by (1) screening resistant vines with effectors stored in P. viticola, (2) performing a functional study of candidate effectors. The screening of resistant plants did not lead to the identification of any new major resistance factors. The functional study of effectors revealed a new family of effectors in P. viticola and led to the identification of two effectors Pv33, nuclear, and Pv47, associated with the endoplasmic reticulum, which induce plant defences.Le mildiou de la vigne est causé par l’oomycète Plasmopara viticola, qui s’attaque aux parties aériennes non-lignifiées affectant la production viticole. Une alternative à l’utilisation de pesticides est l’utilisation de variétés de vigne à la résistance durable, et un programme pour leur création par croisement entre espèces résistantes et la vigne cultivée, Vitis vinifera, est en cours. Ce programme nécessite l’identification de nouveaux gènes de résistance, ce que le projet vise à faire par (1) le criblage de vignes résistantes avec des effecteurs conservés chez P. viticola, (2) l’étude fonctionnelle d’effecteurs candidats. Le criblage de plantes résistantes n’a conduit à l’identification d’aucun nouveau facteur de résistance majeur. L’étude fonctionnelle d’effecteurs a permis la mise en évidence d’une nouvelle famille d’effecteurs chez P. viticola et a conduit à l’identification de deux effecteurs Pv33, nucléaire, et Pv47, associé au réticulum endoplasmique, qui induisent des défenses végétales

Study of Plasmopara viticola RXLR effectors for the search for durable resistance to downy mildew

Le mildiou de la vigne est causé par l’oomycète Plasmopara viticola, qui s’attaque aux parties aériennes non-lignifiées affectant la production viticole. Une alternative à l’utilisation de pesticides est l’utilisation de variétés de vigne à la résistance durable, et un programme pour leur création par croisement entre espèces résistantes et la vigne cultivée, Vitis vinifera, est en cours. Ce programme nécessite l’identification de nouveaux gènes de résistance, ce que le projet vise à faire par (1) le criblage de vignes résistantes avec des effecteurs conservés chez P. viticola, (2) l’étude fonctionnelle d’effecteurs candidats. Le criblage de plantes résistantes n’a conduit à l’identification d’aucun nouveau facteur de résistance majeur. L’étude fonctionnelle d’effecteurs a permis la mise en évidence d’une nouvelle famille d’effecteurs chez P. viticola et a conduit à l’identification de deux effecteurs Pv33, nucléaire, et Pv47, associé au réticulum endoplasmique, qui induisent des défenses végétales.Grapevine downy mildew is caused by the oomycete Plasmopara viticola, which attacks the aerial non-lignified tissues affecting wine production. An alternative to the use of pesticides is the use of vine varieties with sustainable resistances. A programme aiming to create such varieties by crossing resistant species with the cultivated grapevine, Vitis vinifera, is ongoing. Within this program requiring the indentification of new resistance genes, which the project aims to do by (1) screening resistant vines with effectors stored in P. viticola, (2) performing a functional study of candidate effectors. The screening of resistant plants did not lead to the identification of any new major resistance factors. The functional study of effectors revealed a new family of effectors in P. viticola and led to the identification of two effectors Pv33, nuclear, and Pv47, associated with the endoplasmic reticulum, which induce plant defences

Study of Plasmopara viticola RXLR effectors for the search for durable resistance to downy mildew

Le mildiou de la vigne est causé par l’oomycète Plasmopara viticola, qui s’attaque aux parties aériennes non-lignifiées affectant la production viticole. Une alternative à l’utilisation de pesticides est l’utilisation de variétés de vigne à la résistance durable, et un programme pour leur création par croisement entre espèces résistantes et la vigne cultivée, Vitis vinifera, est en cours. Ce programme nécessite l’identification de nouveaux gènes de résistance, ce que le projet vise à faire par (1) le criblage de vignes résistantes avec des effecteurs conservés chez P. viticola, (2) l’étude fonctionnelle d’effecteurs candidats. Le criblage de plantes résistantes n’a conduit à l’identification d’aucun nouveau facteur de résistance majeur. L’étude fonctionnelle d’effecteurs a permis la mise en évidence d’une nouvelle famille d’effecteurs chez P. viticola et a conduit à l’identification de deux effecteurs Pv33, nucléaire, et Pv47, associé au réticulum endoplasmique, qui induisent des défenses végétales.Grapevine downy mildew is caused by the oomycete Plasmopara viticola, which attacks the aerial non-lignified tissues affecting wine production. An alternative to the use of pesticides is the use of vine varieties with sustainable resistances. A programme aiming to create such varieties by crossing resistant species with the cultivated grapevine, Vitis vinifera, is ongoing. Within this program requiring the indentification of new resistance genes, which the project aims to do by (1) screening resistant vines with effectors stored in P. viticola, (2) performing a functional study of candidate effectors. The screening of resistant plants did not lead to the identification of any new major resistance factors. The functional study of effectors revealed a new family of effectors in P. viticola and led to the identification of two effectors Pv33, nuclear, and Pv47, associated with the endoplasmic reticulum, which induce plant defences

Candidate effector proteins from the oomycetes Plasmopara viticola and Phytophthora parasitica share similar predicted structures and induce cell death in Nicotiana species.

Acknowledgements: We thank Eric Galiana at Institut Sophia Agobiotech for P. parasitica strain 329, Olivier Lamotte at INRAE Dijon for B. cinerea strain BMM, Muriel Viaud at INRAE Versailles for B. cinerea strain B05-10-GFP and Jérôme Mutterer at IBMP Strasbourg for assistance with confocal microscopy. We are grateful to the UEAV at INRAE Colmar for technical support in the production of plants.Funder: INRA BAP DepartmentFunder: Region AlsaceFunder: Gatsby Charitable Foundation; funder-id: http://dx.doi.org/10.13039/501100000324Effector proteins secreted by plant pathogens are essential for infection. Cytoplasmic RXLR effectors from oomycetes are characterized by the presence of RXLR and EER motifs that are frequently linked to WY- and/or LWY-domains, folds that are exclusive to this effector family. A related family of secreted candidate effector proteins, carrying WY-domains and the EER motif but lacking the canonical RXLR motif, has recently been described in oomycetes and is mainly found in downy mildew pathogens. Plasmopara viticola is an obligate biotrophic oomycete causing grapevine downy mildew. Here we describe a conserved Pl. viticola secreted candidate non-RXLR effector protein with cell death-inducing activity in Nicotiana species. A similar RXLR effector candidate from the broad host range oomycete pathogen Phytophthora parasitica also induces cell death in Nicotiana. Through comparative tertiary structure modelling, we reveal that both proteins are predicted to carry WY- and LWY-domains. Our work supports the presence of LWY-domains in non-RXLR effectors and suggests that effector candidates with similar domain architecture may exert similar activities

Carbohydrates in plant immunity and plant protection: roles and potential application as foliar sprays

International audienceIncreasing interest is devoted to carbohydrates for their roles in plant immunity. Some of them are elicitors of plant defenses whereas other ones act as signaling molecules in a manner similar to phytohormones. This review first describes the main classes of carbohydrates associated to plant immunity, their role and mode of action. More precisely, the state of the art about perception of "PAMP, MAMP, and DAMP (Pathogen-, Microbe-, Damage-Associated Molecular Patterns) type" oligosaccharides is presented and examples of induced defense events are provided. A particular attention is paid to the structure/activity relationships of these compounds. The role of sugars as signaling molecules, especially in plant microbe interactions, is also presented. Secondly, the potentialities and limits of foliar sprays of carbohydrates to stimulate plant immunity for crop protection against diseases are discussed, with focus on the roles of the leaf cuticle and phyllosphere microflora

COMPOSES POLYSACCHARIDIQUES, ET LEUR UTILISATION POUR STIMULER DES REPONSES DE DEFENSE DES PLANTES CONTRE LES MICROORGANISMES PATHOGENES

The present invention relates to novel oligogalacturonans having a degree of methylation of 0 and a degree of polymerisation of 1 to 10, and to use there of for stimulating defence responses of plants against pathogenic microorganisms.La présente invention concerne de nouveaux oligogalacturonanes possédant un degré de méthylation de 0 et un degré de polymérisation de 1 à 10, et leur utilisation pour stimuler des réponses de défense des plantes contre des microorganismes pathogènes

Candidate effector Pvit47 induces cell death in <i>Nicotiana</i> species.

(A) Cell death induction following Agrobacterium-mediated transient expression of Pvit47ΔSP (47ΔSP) in N. benthamiana leaves. Cell death responses were assigned to one of five classes based on strength, from no response to uniform tissue collapse. Images are representative of the five classes and numbers indicate the number of responses falling inside each class. Results correspond to five independent experiments. Details of class definition and results for independent experiments are presented in S1 Table. Orange arrow indicates weak cell death and red arrows indicate patches of collapsing tissue. (B) Cell death induction following Agrobacterium-mediated transient expression of 47ΔSP in plants belonging to the same batch. Agrobacterium-mediated transient expression of ß-glucuronidase (GUS) was used as negative control. Arrows indicate patches of collapsing tissue. (C) Cell death induction following Agrobacterium-mediated transient expression of 47ΔSP in Nicotiana species. Top: daylight, bottom: blue light. Agrobacterium-mediated transient expression of candidate effector protein 31ΔSP, reported not to induce cell death in Nicotiana spp. [16], is shown for comparison. (D) Cell death induction following Agrobacterium-mediated transient expression of 47ΔSP in grapevine leaf discs. Cell death was assessed visually and as expression of the cell death marker VvHSR1 by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Leaf discs transiently expressing the green fluorescent protein (GFP) or infiltrated with agroinfiltration buffer are used as negative controls, while leaf discs infiltrated with Agrobacterium carrying the 33ΔSP construct are used as positive control. Arrows indicate cell death spots in leaf discs infiltrated with 33ΔSP. Actin (VvACT) is used as standard for RT-PCRs. Nicotiana pictures were taken at 5 days post-agroinfiltration (dpa). Grapevine pictures and sampling for RT-PCR experiments were done at 5 dpa. Each RT-PCR sample corresponds to four pooled leaf discs. Experiments were repeated two more times with the same results.</p

Alignment of Pvit47 and cell death-inducing candidate RXLR effectors from other oomycetes.

(A) Alignment of Pvit47, Ppar47, PlAvh23 from Pe. litchi and PaRXLR54 from P. agathidicida. Red box: signal peptide, blue box: RXLR, green box: EER motif; orange box: WY domain, purple boxes: LWY-domain. Black background shows identity, grey background shows similarity (70% cutoff). (B) Alignment of LWY-domains from Pvit47, Ppar47 and PaRXLR54. Conserved residues defining the LWY-domain are show in red letters. (C) Superimposition of the predicted structures of Pvit47 (brown), Pa RXLR54 (green). Superimposition done using Pvit47 as reference. (D) Superimposition of the predicted structures of Ppar47 (blue) and PaRXLR54 (green). Superimposition done using Ppar47 as reference. (TIF)</p