Pesticides are a major threat to the environment and human health. Citizens today are aware of and confronted with the consequences of the massive use of pesticides over the past 50 years. Within these families of molecules, nematicides, which include the most toxic active chemicals used in agriculture, target microscopic worms known as nematodes. Plant parasitic nematodes are crop pests and pathogenic agents worldwide, capable of infesting all types of field crops (vegetables, fruits, cereals, etc.).
Some of these nematodes, among the most harmful for agriculture, have developed very unique forms of parasitism. Their development in the plant depends on their capacity to induce the transformation of plant cells into giant cells that provide the nutrients to the parasite. These structures considerably modify the normal functioning of the root system and lead to a decrease in crop yield.
In the 1990's, the nematicide market reached over 540 billion euros per year worldwide, and the gradual ban on chemical nematicides has made the control of these plant pests a global issue. The use of the natural resistance in plants is an alternative to be developed because of its effectiveness and sustainability.
Research interests and objectives
Studies focuse on two main projects :
- the Molecular determinants of the compatible interaction ;
- the Evolution of nematode pathogenenicity and the durability of resistance genes.
The aims of these projects is to design new control methods that are specific, sustainable and environmentally friendly.
Biological models studied
- Root-knot nematode: Meloidogyne spp.
- Dagger nematode: Xiphinema index, vector of Grape Fanleaf Virus (GFLV)
- Model plant: Arabidopsis thaliana
- Plants of agronomic interest: annuals: Solanaceae family (tomato, pepper, etc.); perennials: family of the genus Prunus (plum tree, almond tree, peach tree, etc.) or species of the genus Vitis.
A. Gall symptom on tomato root. B. Genomics analysis ofMeloidogyne incognitalife stages. C. Test of the durability of pepper nematode resistanceunder greenhouse conditions. D. Nematode proteins secreted during parasitism and involved in the induction of giant feeding cells. E. Hypertrophied giant cells (*) induced by a root-knot nematode (n). F. Giant cell (*) with multiple nuclei (in blue) and bundles of cortical microtubules (in green).
The multifaceted approach developed on Meloidogyne incognita has positioned the team on the international scene and allowed the development of original studies. The team addresses fundamental questions of science, such as plant developmental biology with the study of the nematode-induced differentiation of giant cells, or invertebrate parasitism effectors with the analysis of nematode secretions. Our research also addresses issues arising from urgent societal needs, such as the development of sustainable and environmentally friendly methods to control nematodes. The team has know-how and experimental facilities specific to nematology, an essential asset to effectively carry out studies at the molecular level within a realistic framework.
In addition, the team is coordinating international efforts on the M. incognita sequencing project, performing at the Genoscope (French center for sequencing). The availability of the complete genome of M. incognita will benefit to the scientific community involved in research on parasitic nematodes of agronomic interest worldwide, particularly in terms of comparative genomics.
The team is also a member of the national INRA network (Bordeaux, Montpellier, Colmar) working on the resistance of grape vines to GFLV (resistance either to the nematode vector and/or to the virus).
What are the mechanisms involved in the plant susceptibility to root-knot nematodes?
What are the mechanisms involved in the pathogenicity of root-knot nematodes?
How do these parthenogenetic nematodes (clonal reproduction) evolve in response to the selection pressure of plant resistance genes?
How can we assess and improve the durability of plant resistance to nematodes?
Scientific partnerships and financing
National partnerships: teams of the Plant Breeding and Genetics (PBG) Division of INRA at Avignon and Bordeaux, private plant breeders (Syngenta, Vilmorin, etc.)
International partnerships: WUR Wageningen (NL), SCRI Dundee (Scotland), CNR Bari (I), Gent University (B), Toledo University (E), BOKU Vienna (A), NCSU Raleigh (USA), ISU Ames (USA), GU Athens (USA), MU Columbia (USA),…
Coordination of an international consortium for the expert annotation of the genome of M. incognita (genome sequencing was done within the framework of Genoscope).
Participation to numerous large partnership networks at the European level (EU contracts of the 4th, 5th and 6th RDFP) and international level ("International Molecular Plant-Nematode Interaction group" that includes several American and European laboratories).
Financial support from national and international agencies (French National Research Agency, Genoplante, etc.).
Background and main results
Over the last few years, the team has focused on the molecular and cellular aspects of the plant/nematode interaction. The team has made a considerable contribution to deciphering the molecular dialogue between the nematode and the plant by characterising key genes that are involved in the virulence of the nematode and the resistance or plant susceptibility. Moreover, the team is also involved in the study of the sustainability of resistance genes, and works closely with teams from INRA PBG Division, plant breeders and growers
Our team has developed strong partnerships with several teams from the Plant Breeding and Genetics Division of INRA to study resistant genes and the ability of nematodes to overcome the plant resistance. This situation allows the development of studies on the durability of plant resistance to nematodes in a particularly favorable context. The analysis of sustainable management of nematode populations in the field is focused on the populational aspects of nematodes, particularly in relation to population structure and evolution in response to the selection pressure of plant resistance genes.