Aridity or low temperatures : what affects the diversity of plant-parasitic nematode communities in the Moroccan argan relic forest ?

Farming activities that are likely to induce the development of emerging pests increasingly disturbs the Argan Biosphere in Morocco. Considering that plant-parasitic nematodes strongly contribute to the decrease in plant growth production, a survey was conducted in the Argan Biosphere in order to assess nematode diversity and distribution. It was established that the parasitic nematofauna was rich, with 70 species belonging to 34 genera and 12 families. Species with high plant decay potential belonging to Longidoridae, Heteroderidae, Hoplolaimidae, Meloidogynidae, Paratylenchidae and Pratylenchidae are present in the argan forest. Telotylenchus sp., Paratylenchus microdorus and Paratylenchus veruculatus, Xiphinema italiae and Xiphinema pachtaicum (virus-transmitting nematodes), and Helicotylenchus crassatus are the most dominant species. Populations of root-knot (Meloidogyne spp.) and lesion (Pratylenchus spp.) nematodes are also present. Climate forces have driven the structuration of the argan forest to topoclimatic landscapes that led the diversity of the plant-parasitic nematodes communities. The north-south typology of the arid climate affects the richness and the taxonomic and functional diversity of nematodes, while the west-east temperature typology mainly affects the abundance of nematodes, especially of colonizing species. The emergence of plant-parasitic nematode problems as a consequence of intensive agroforestry or argan orchard development is considered

Enhancing the resistance of the potato to Southern root-knot nematodes by using Solanum sparsipilum germplasm

International audienc

Diversity of plant-parasitic nematode communities associated with olive nurseries in Morocco : origin and environmental impacts

Plant-parasitic nematodes (PPN) are key impediments to efficient global crop production and impair the quality of susceptible plants in nurseries as well. In this context, nematode communities were determined in 305 solid substrate samples collected from 25 olive (Olea. europaea. subsp. europaea) nurseries in Morocco. Taxonomical and functional diversity as well as the structures of PPN communities were described and then compared between regions, cultivars as well as according to biotic and abiotic factors. A high diversity of PPN was observed, with the detection of 63 species and 26 genera. The most dominant taxa detected were spiral nematodes (Helicotylenchus spp. and Rotylenchus spp.), stunt nematodes (Tylenchorhynchus spp.), grazer nematodes (Tylenchus spp.) and root-knot nematodes (Meloidogyne spp.). Hoplolaimidae nematodes (Helicotylenchus spp. and Rotylenchus spp.) and Tylenchus spp. were better adapted to rainy conditions that prevailed in the northern regions of Morocco. Multiblock analyses demonstrated that functional diversity (cp and trophic groups) was more affected by the environment than taxonomical diversity (total number, species richness, locale diversity and evenness). They also indicated that PPN communities were more impacted by climatic variables (rainfall and minimum temperature) and nursery substrate origins than by soil physic-chemical factors. Nevertheless, a co-inertia analysis showed that N, P and K amendments in olive nurseries enhanced the development of harmful PPN, especially root-knot nematodes

Plant-parasitic nematodes associated with olive tree in Southern Morocco

Plant-parasitic nematodes affect significantly the production of susceptible plants, including olive trees. In this context, nematode communities were determined in soil samples collected from 23 olive growing sites in the Haouz and Souss regions (southern Morocco). These sites corresponded to various modalities: wild (Olea europaea L. ssp. sylvestris) or cropped olive (Olea. europaea L. ssp. europaea), traditional or high-density cropping, rainfed or irrigated. Even free-living nematodes prevailed in most of the sites, high population levels of plant-parasitic nematodes were observed in rainfed cropping systems than in irrigated systems. Ten nematode families and 14 genera were identified. The most important plant-parasitic nematodes detected, in order decreasing frequency of infestation (percentage of samples), were spiral nematodes Helicotylenchus spp. (100%) and Rotylenchus spp. (87%), lesion nematodes Pratylenchus spp. (100%) and root-knot nematodes Meloidogyne spp. (40%). Most of the nematode species were assigned to more or less colonizer nematodes, whereas only one family (Longidoridae) was assigned to persistent nematodes. Considering the two producing areas, plant-parasitic nematodes were significantly more abundant in the Souss region than in the Haouz region, but nematode diversity was higher in the second one. The prevalence of Meloidogyne spp. in the Haouz region would be related to the predominance of irrigated cropping systems in this region. Hoplolaimidae nematodes (Helicotylenchus spp. and Rotylenchus spp.) are better adapted to rainfed conditions that prevail in the Souss region. Co-inertia analysis showed the importance of soil physic-chemical characteristics (e.g., pH, texture and nutrients) on the structure of the plant-parasitic nematode community patterns. The high occurrence of Helicotylenchus spp. in olive orchards may be induced by fertilization. Aphelenchoides spp., Gracilacus spp., Pratylenchus spp., Rotylenchidae and Tylenchidae were supported by coarse textures as it was observed in the Souss region

Learning from olive evolution and cultivation to understand the diversity of associated plant-parasitic nematodes communities in Morocco

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresPlant-parasitic nematodes (PPN) significantly contribute to economic losses in the top-tenolive producing countries, especially in the Mediterranean basin. Instead of controlling themain pathogenic nematode species as usual, one innovative strategy to control PPN would beto manage diversity in communities in order to lead them to be less pathogenic. Then,knowing assemblage mechanisms in communities due to evolution and environmental forcesis a prerequisite. This study was conducted in Morocco, because (i) information about PPNdiversity is lacking, (ii) different forms of olive occur as wild (including two sub species O.europaea subsp. europaea and subsp. Maroccana), feral and typical cropping systems astraditional and high density and as irrigated or not) are present. Morphobiometric observationsrevealed a very diverse parasite nematofauna (117 species), seven new taxa being recorded forthe first time on olive. Tylenchidae, Hoplolaimidae and Telotylenchidae nematodes weredominant (80% of the samples), whereas root-knot nematodes (Meloidogyne spp.) weredetected in 40% of the samples. Multivariate analyzes showed that the development ofHeteroderidae and Longidoridae nematodes was favored in PPN communities on wild olive,while lesion (Pratylenchidae) and root-knot nematodes multiply in orchards. ThreeMeloidogyne species were identified: M. javanica on feral and cultivated olive in southern andcenter Morocco; M. arenaria and M. hapla on wild olive in the north. Cytochrome oxidase I(COI) and Internal transcribed spacer-2 (ITS2) genes were good markers for speciesdifferentiation, but they were not able to distinguish M. javanica and M. arenaria populationsand were not adapted for intraspecific differentiation. However, a significant morphologicalvariability was observed between the Meloidogyne species, and within and between M.javanica populations. The response of the diversity of PPN communities as well as ofMeloidogyne populations to olive genotype, geo-climatic zones and soil physico-chemicalcharacteristics, and diversity of plants associated with olive trees is discussed

A global database of soil nematode abundance and functional group composition

As the most abundant animals on earth, nematodes are a dominant component of the soil community. They play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns.Peer reviewe

PESTOLIVE: a mediterranean research project for understanding and managing soil-borne parasites on olive using historical and ecological approaches

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresPESTOLIVE (Contribution of olive history for the management of soil-borne parasites inthe Mediterranean Basin) is a project funded by ARIMNet, an ERANET action supported bythe 7th European Framework Programme and by non-European Mediterranean countries.PESTOLIVE aims at producing knowledge and tools for a new and efficient management ofplant-parasitic nematodes (PPN) and plant-pathogenic fungi (PPF) in olive (Olea europaea L.)cropping systems and nurseries, while reducing the use of pesticides. Because of the anthropiccontinuum from Olea post-glacial refuges to Oleasters (domestication) and then to olive-trees(breeding and cropping), the fragmentation of the PPN and PPF communities and of theirnatural enemies could explain the scattered diversity of the control techniques (especiallyresistance rootstocks, biocontrol, cropping strategies) developed and applied all around theMediterranean Basin. The novelty of PESTOLIVE is based on: i) the analysis and themanagement of the parasite diversity (ecology of communities) instead of controllingemblematic species (population approach), and ii) the involvement of knowledge about thehistorical co-adaptation of soil-borne parasite and natural enemies communities to olive-treedomestication (origins and past assemblages) and breeding that follows the history of O.europaea around the Mediterranean Basin

PESTOLIVE: a mediterranean research project for understanding and managing soil-borne parasites on olive using historical and ecological approaches

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitièresPESTOLIVE (Contribution of olive history for the management of soil-borne parasites inthe Mediterranean Basin) is a project funded by ARIMNet, an ERANET action supported bythe 7th European Framework Programme and by non-European Mediterranean countries.PESTOLIVE aims at producing knowledge and tools for a new and efficient management ofplant-parasitic nematodes (PPN) and plant-pathogenic fungi (PPF) in olive (Olea europaea L.)cropping systems and nurseries, while reducing the use of pesticides. Because of the anthropiccontinuum from Olea post-glacial refuges to Oleasters (domestication) and then to olive-trees(breeding and cropping), the fragmentation of the PPN and PPF communities and of theirnatural enemies could explain the scattered diversity of the control techniques (especiallyresistance rootstocks, biocontrol, cropping strategies) developed and applied all around theMediterranean Basin. The novelty of PESTOLIVE is based on: i) the analysis and themanagement of the parasite diversity (ecology of communities) instead of controllingemblematic species (population approach), and ii) the involvement of knowledge about thehistorical co-adaptation of soil-borne parasite and natural enemies communities to olive-treedomestication (origins and past assemblages) and breeding that follows the history of O.europaea around the Mediterranean Basin

A global database of soil nematode abundance and functional group composition [Data paper]

Measurement(s)Abundance center dot Nematoda center dot environmental factorTechnology Type(s)Elutriative Centrifugation center dot computational modeling techniqueFactor Type(s)geographic locationSample Characteristic - OrganismNematodaSample Characteristic - Environmentsoil environment center dot climateSample Characteristic - LocationEarth (planet) Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11925843 As the most abundant animals on earth, nematodes are a dominant component of the soil community. They play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns