Biology subjects

Poullet, M.

Publications and source records attributed to Poullet, M..

3 recordsLinked to original sources

bioRxiv2024

Unveiling the genome assembly of the polyploid and quarantine root-knot nematode, Meloidogyne enterolobii

Root-knot nematodes of the genus Meloidogyne are obligatory plant endoparasites that cause substantial economic losses to the agricultural production and impact the global food supply. These plant parasitic nematodes belong to the most widespread and devastating genus worldwide, yet few measures of control are available. The most efficient way to control root-knot nematodes (RKN) is deployment of resistance genes in plants. However, current resistance genes that control other Meloidogyne species are mostly inefficient on M. enterolobii. Consequently, M. enterolobii was listed as a European Union quarantine pest implementing regulation. To gain insight into the molecular characteristics underlying its parasitic success, exploring the genome of M. enterolobii is essential. Here, we report a high-quality genome assembly of Meloidogyne enterolobii using the high-fidelity long-read sequencing technology developed by Pacific Biosciences, combined with a gap-aware sequence transformer, DeepConsensus. The resulting genome assembly spans 273 Mbp with 556 contigs, a GC% of 30 {+/-} 0.042 and an N50 value of 2.11Mb, constituting a useful platform for comparative, population and functional genomics.

genomics↗

bioRxiv2023

Convergent origin and accelerated evolution of vesicle-associated RhoGAP proteins in two unrelated parasitoid wasps

Animal venoms and other protein-based secretions that perform a variety of functions, from predation to defense, are highly complex cocktails of bioactive compounds. Gene duplication, accompanied by modification of the expression and/or function of one of the duplicates under the action of positive selection, followed by further duplication to produce multigene families of toxins is a well-documented process in venomous animals. This evolutionary model has been less described in parasitoid wasps, which use maternal fluids, including venom, to protect their eggs from encapsulation by the host immune system. Here, we evidence the convergent recruitment and accelerated evolution of two multigene families of RhoGAPs presumably involved in virulence in two unrelated parasitoid wasp species, Leptopilina boulardi (Figitidae) and Venturia canescens (Icheumonidae). In both species, these RhoGAPs are associated with vesicles that act as transport systems to deliver virulence factors, but are produced in different tissues: the venom gland in Leptopilina sp. and the ovarian calyx in V. canescens. We show that the gene encoding the cellular RacGAP1 is at the origin of the virulent RhoGAP families found in Leptopilina sp. and V. canescens. We also show that both RhoGAP families have undergone evolution under positive selection and that almost all of these RhoGAPs lost their GAP activity and GTPase binding ability due to substitutions in key amino acids. These results suggest an accelerated evolution and functional diversification of these vesicle-associated RhoGAPs in the two phylogenetically distant parasitoid species. The potential new function(s) and the exact mechanism of action of these proteins in host cells remain to be elucidated.

evolutionary biology↗

bioRxiv2019

The polyploid genome of the mitotic parthenogenetic root knot nematode Meloidogyne enterolobii

Root-knot nematodes (genus Meloidogyne) are plant parasitic species that cause huge economic loss in the agricultural industry and affect the prosperity of communities in developing countries. Control methods against these plant pests are sparse and the current preferred method is deployment of plant cultivars bearing resistance genes against Meloidogyne species. However, some species such as M. enterolobii are not controlled by the resistance genes deployed in the most important crop plants cultivated in Europe. The recent identification of this species in Europe is thus a major concern. Like the other most damaging Meloidogyne species (e.g. M. incognita, M. arenaria and M. javanica), M. enterolobii reproduces by obligatory mitotic parthenogenesis. Genomic singularities such as a duplicated genome structure and a relatively high proportion of transposable elements have previously been described in the above mentioned mitotic parthenogenetic Meloidogyne.\n\nTo gain a better understanding of the genomic and evolutionary background we sequenced the genome of M. enterolobii using high coverage short and long read technologies. The information contained in the long reads helped produce a highly contiguous genome assembly of M. enterolobii, thus enabling us to perform high quality annotations of coding and non-coding genes, and transposable elements.\n\nThe genome assembly and annotation reveals a genome structure similar to the ones described in the other mitotic parthenogenetic Meloidogyne, described as recent hybrids. Most of the genome is present in 3 different copies that show high divergence. Because most of the genes belong to these duplicated regions only few gene losses took place, which suggest a recent polyploidization. The most likely hypothesis to reconcile high divergence between genome copies despite few gene losses and translocations is also a recent hybrid origin. Consistent with this hypothesis, we found an abundance of transposable elements at least as high as the one observed in the mitotic parthenogenetic nematodes M. incognita and M. javanica.

genomics↗