Abstract :
[en] Plant root-knot nematode interaction studies are performed on several host plant models. However, even though root-knot nematodes interact with trees, no perennial woody model has been explored so far. We show here that poplar (Populus tremula x Populus alba) grown in vitro is susceptible to Meloidogyne incognita as this nematode is able to penetrate, to induce feeding sites and to reproduce in poplar roots. As analyzed by Raman spectromicroscopy, the cell walls of the giant cells, with typical characteristics of transfer cell walls, were not lignified and were composed mainly of pectin and cellulose. To better depict the poplar-nematode interaction at the molecular level, a quantitative RT-PCR analysis was performed to study changes in poplar gene expression in galls compared to non-infected roots. Three marker genes, reported for other plant hosts, including expansin A, histone 3.1 and asparagine synthase, were conserved for poplar-nematode interaction. In addition, the down-regulation of four genes coding for enzymes of the lignin biosynthesis pathway was evidenced in galls, suggesting a modification in lignin composition within galls developed in poplar roots. Together, this study shows that poplar is a suitable model host for specific traits of tree-nematode interaction.
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