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International audience; The cyst nematode Heterodera carotae, which parasitizes carrot roots, has been recorded in many countries in Europe (Italy, The Netherlands, Switzerland, France, Denmark, …), in South Africa and in North America (Canada, USA). To date, there is a lack of knowledge about the genetic structure of the populations of this economically important nematode. The aim of this work was to study the structuration of the genetic diversity of the carrot cyst nematode at the European scale. We have developed a set of thirteen polymorphic microsatellite markers and used it to genotype seventeen European populations of H. carotae coming from France, Switzerland, Italy, Denmark and one non-European population from Canada. As previously showed for other cyst nematode species, the H. carotae populations were characterised by a strong heterozygote deficit. A Bayesian clustering analysis revealed two distinct genetic clusters, with one group located in the north of Europe and a second one located in the south of Europe. Moreover, our results highlighted rather limited gene flow at small spatial scale and some events of long distance migration. This first investigation of the genetic diversity of H. carotae populations would be useful to develop sustainable control strategies.

A homologue of a Ran binding protein to microtubules ( ranbpm ) gene, initially known as IC5, was identified and characterised in second-stage juveniles (J2s) of the potato cyst nematode Globodera pallida. The full-length cDNA (937 bp) was obtained by 5′ and 3′ rapid amplification of cDNA ends (RACE) and specific primers were designed to amplify the genomic sequences of 2396 bp containing six introns. The ORF (798 bp) encodes a putative 265 amino acid sequence with a predicted SPRY domain and a signal peptide of 23 amino acids on the N-terminal part of the protein. In situ hybridisation experiments showed that the transcript is located in the dorsal gland of the J2s, suggesting that the encoded protein has an extracellular function and can be involved in the late stages of parasitism such as feeding site establishment. This gene was specifically over-expressed in the juveniles before and during parasitism, but not in adult developmental stages. As this gene is presumed to be involved in plant–nematode interaction, particularly in the development and maintenance of the feeding structure that allows the nematode to achieve parasitic development, homologous genes were sought in other cyst nematode species. One of them was cloned and sequenced in the closely related species Globodera ‘ mexicana ’.