Impact de la diversité des communautés de nématodes phytoparasites sur la durabilité de systèmes de culture maraîchers visant spécifiquement le contrôle des nématodes à galles : de la pertinence d’une approche « diversité ».

Ce numéro est constitué d’articles issus du colloque «De la connaissance de la biologie des sols et de ses fonctions, à son pilotage » organisé en partenariat avec l’Ademe et l’AFB, le 18 octobre 2018 à Dijon.Experimental field co-design and evaluation of prototype cropping systems (PCS) combining technicaland varietal innovations were implemented within the framework of the INRA project 'GEDUNEM' for thesustainable management of root-knot nematodes (RKN) under Mediterranean sheltered vegetablesystems. A PCS, alternating sorghum green manure and partially resistant crops (tomato and pepper)during the summer period, was tested at two sites differing in the diversity of their nematodecommunities and their richness in organic matter (OM). The PCS allowed a significant decrease in RKNpopulations in both sites (70 and 99%). However, its efficacy was more sustainable on the richest site inOM, where the global soil nematofauna was the most diversified and abundant, and where nonphytoparasitic nematodes multiplied throughout the experiment. The hypothesis is that the diversity ofnematodes in communities plays a regulatory role by competition between phytoparasitic species and through the contribution of non-phytoparasitic species to soil health. This PCS is currently beingrepeated within the framework of the PEI project 'GONem' where ten sites are monitored over four yearsto improve new PCS and confirm these results.La conception et l’évaluation expérimentale in situ de systèmes de culture prototypes (SCP) combinantdes innovations techniques et variétales ont été mises en œuvre dans le cadre du projet INRA‘GEDUNEM’ pour une gestion durable des nématodes à galles (NG) dans les systèmes maraîchersméditerranéens sous abris. Un SCP, alternant un engrais vert sorgho et des cultures partiellementrésistantes (tomate et piment) en période estivale, a été testé sur deux sites différant par la diversité deleurs communautés de nématodes et leur richesse en matière organique (MO). Le SCP a permis unediminution significative des populations de NG dans les deux sites (70 et 99%). Cependant, sonefficacité a été plus durable dans le site le plus riche en MO, où la nématofaune totale était la plusdiversifiée et abondante, et où les nématodes non phytoparasites se sont multipliés tout au long del’expérimentation. L’hypothèse est que la diversité des nématodes en communautés joue un rôlerégulateur par compétition entre espèces phytoparasites et par contribution des espèces nonphytoparasites à la santé des sols. Ce SCP est actuellement répété dans le cadre du projet PEI‘GONem’ où dix sites sont suivis sur quatre ans pour améliorer de nouveaux SCP et confirmer cesrésultats

Tests biologiques pour la détermination du caractère résistant ou sensible de plantes aux nématodes à galles des racines

National audienc

Marqueurs moléculaires pour la détermination du caractère résistant ou sensible de piments/poivrons aux nématodes à galles des racines

National audienc

Nematicidal and nematode-resistant plants

International audienc

Plantes magiques, plantes protectrices : quelques techniques d'horticulture traditionnelle à Vanuatu

As part of our research of new nematicidal substances from flowering plants, we have made an inventory of the plants used to protect crops in the Vanuatu archipelago. The use of these plants is a part of local folk knowledge. In Vanuatu, most phytopathogenic diseases are prevented through careful preparation of garden sites. In this paper we detail the different gardening techniques and plant species used in Vanuatu to fight diseases and protect crops.Notre recherche visant à mettre en évidence de nouvelles substances naturelles nématicides nous a conduit à répertorier les espèces utilisées à Vanuatu comme protectrices des cultures. L'utilisation de ces plantes fait partie d'un savoir traditionnel. A Vanuatu, la plupart des maladies phytopathogènes sont prévenues par une préparation soigneuse du futur jardin. Nous détaillons dans cet article les différentes techniques et les espèces employées dans ce but par les habitants de Vanuatu.Bourdy Geneviève, Cabalion Pierre, Walter Annie, Caporalino-Djian Caroline. Plantes magiques, plantes protectrices : quelques techniques d'horticulture traditionnelle à Vanuatu. In: Journal d'agriculture traditionnelle et de botanique appliquée, 37ᵉ année, bulletin n°2,1995. pp. 51-78

Histological characterization of resistance to different root-knot nematode species related to phenolics accumulation in Capsicum annuum

International audienc

A demo-genetic model of root-knot nematod dynamics with applications to the deployment of plant resistance

International audienceRoot-knot nematodes (RKN) are soil-borne, little mobile, polyphagous pests which threaten important sheltered crops such as vegetables or small fruits. They attack plant roots to feed and reproduce and have a major impact on crop yield. Most modern eco-friendly plant protection strategies against RKN are based on the use of resistant crops. The emergence of virulent RKN variants, which are adapted to crop resistance, challenges the durability of such methods. Because virulent RKN exhibit reduced fitness on non-resistant crops, combining both resistant and non-resistant plants can help increase the efficacy and sustainability of resistance-based nematode control. Indeed, if resistant crops select virulent nematodes, non-resistant crops counter-select these less fit nematodes. Furthermore, since nematodes have poor intrinsic dispersal ability, the association between resistant and non-resistant plants should rely on crop rotation over cropping seasons, rather than on spatial arrangements. We proposed a semi-discrete model describing the population dynamics of plant roots infection by nematodes within and over cropping seasons. This model, rooted in epidemiological concepts, was fitted to literature data on within-season dynamics of non-resistant plants and avirulent nematodes, and further extended to account for resistant plants and virulent parasites. The model was used to compute optimal crop rotation strategies with respect to a proxy of crop yield over several cropping seasons, for different epidemiological scenarios. In many instances, crop rotation remarkably enhanced crop yield. Robustness of the results to parameter uncertainty was also assessed

A demo-genetic model of root-knot nematod dynamics with applications to the deployment of plant resistance

International audienc

Sustainable management of root-knot nematodes in horticultural crops by modeling and optimizing resistance gene deployment

International audienceRoot-knot nematodes (RKNs) of the genus Meloidogyne are soil-borne, little mobile, polyphagous pests which threaten important sheltered crops such as vegetables or small fruits. They attack plant roots to feed and reproduce and have a major impact on crop yield. Most eco-friendly plant protection strategies are based on the use of resistant crops. Resistance is usually associated with a hypersensitivity reaction (HR), a rapid and localized cell death in the infected plant in response to a pathogenic attack. In the family Solanaceae, there are two major resistance genes (R genes) with different modes of action : an early HR when the nematode enters in the root system and a late HR when the nematode creates its feeding site. The emergence of virulent nematode variants, which are adapted to the resistance, challenges the durability of such methods. Because virulent root-knot nematodes exhibit a reduced fitness on susceptible crops, combining both resistant and susceptible plants can help increase the efficacy and sustainability of resistance-based nematode control. We carried out a preliminary study to investigate the best rotations of susceptible and resistant cultivars over cropping seasons in terms of yield and resistance durability. The resistance considered was associated with early HR. For this purpose, we developed a semi discrete model describing the plant root growth and nematode population dynamics within and between cropping season, including the plant nematode interactions. Our aim in this study is to implement and compare the action of both R genes. We will first compare the optimal deployment strategies of resistant crops for both R genes. Then we will determine the best rotations based on both resistant cultivars

Sustainable management of root-knot nematodes in horticultural crops by modeling and optimizing resistance gene deployment

International audienceRoot-knot nematodes (RKNs) of the genus Meloidogyne are soil-borne, little mobile, polyphagous pests which threaten important sheltered crops such as vegetables or small fruits. They attack plant roots to feed and reproduce and have a major impact on crop yield. Most eco-friendly plant protection strategies are based on the use of resistant crops. Resistance is usually associated with a hypersensitivity reaction (HR), a rapid and localized cell death in the infected plant in response to a pathogenic attack. In the family Solanaceae, there are two major resistance genes (R genes) with different modes of action : an early HR when the nematode enters in the root system and a late HR when the nematode creates its feeding site. The emergence of virulent nematode variants, which are adapted to the resistance, challenges the durability of such methods. Because virulent root-knot nematodes exhibit a reduced fitness on susceptible crops, combining both resistant and susceptible plants can help increase the efficacy and sustainability of resistance-based nematode control. We carried out a preliminary study to investigate the best rotations of susceptible and resistant cultivars over cropping seasons in terms of yield and resistance durability. The resistance considered was associated with early HR. For this purpose, we developed a semi discrete model describing the plant root growth and nematode population dynamics within and between cropping season, including the plant nematode interactions. Our aim in this study is to implement and compare the action of both R genes. We will first compare the optimal deployment strategies of resistant crops for both R genes. Then we will determine the best rotations based on both resistant cultivars