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The root-knot nematodes (RKNs) Meloidogyne spp., represent a global threat for annual and perennial crops causing huge crop losses worldwide. Several genes encoding nucleotide-binding (NB) and leucine-rich repeat (LRR)-containing receptor (NLRs) have been isolated for their ability to provide resistance to RKNs. NLRs are intracellular receptors able to detect secreted pathogenic proteins known as effectors, through direct or indirect interaction. Various studies describe the roles of NLRs’ protein domains and how they act at intra- and intermolecular levels for receptor activation and downstream signalling. However, their function for up- and downstream signalling is poorly known and particularly in regards to the large number of NLRs identified in plants, the additional domains they often possess, as well as the diversity of NLRs architecture. The gene Ma, from the Toll/Interleukin 1 receptor (TIR)-NB-LRR (TNL) family, has been cloned from the plum Prunus cerasifera where it confers a high resistance against numerous RKN species. In addition to the core TNL structure, Ma has a large extension in C-terminal encoded by five repeated exons. Interestingly, a single post-LRR (PL) exon, encoding a domain with conserved motifs, is frequently present in plants TNLs. We are investigating how this repeated PL domain in Ma participates to RKNs resistance in Prunus. Using the modular Golden Gate cloning method, I will test Ma truncated versions and chimeras for their ability to provide RKNs resistance in transgenic Prunus roots. Characterization of Ma’s PL domains at intra and intermolecular levels will enable us to reveal the function of this conserved immune region and, ultimately, to contribute to the development of methods to control RKNs infection in crops.
I am fascinated by the ability of plants to recognize non-self and activate immune responses. I performed my Master degree internship at The Sainsbury Laboratory (TSL) in England under the supervision of Jonathan Jones. I identified a bacterial secreted protein (effector) which is recognized and triggers immunity in Arabidopsis thaliana. Strongly motivated from this laboratory experience, I stayed at the TSL for my PhD and I focused on effector- triggered immunity mediated by TIR-NBLRR (TNL) receptors. I then, moved back to France at Sophia Agrobiotech Institute (ISA) to work as a post-doc on TNLs which have been identified in plum and peach trees for resistance against root-knot nematodes. I obtained a JSPS fellowship to go to Japan and work in Ken Shirasu’s laboratory at RIKEN. I focused on the molecular factors enabling a parasitic plant to penetrate the roots of its host plant while avoiding parasitizing its own roots. By being awarded of an AgreenSkills+ postdoctoral fellowship, I could come back in France in Daniel Esmenjaud’s laboratory at ISA and carry out my project to decipher the function of the post-LRR domain which is present in about half of plants’ TNL, such as Ma.
S. Cui, S. Wada, Y. Tobimatsu, Y. Takeda, S. B. Saucet, T. Takano, T. Umezawa, K. Shirasu & S. Yoshida, 2018. Host lignin composition affects haustorium induction in the parasitic plants Phtheirospermum japonicum and Striga hermonthica. New Phytologist. Doi: 10.1111/nph.15033.
S. B. Saucet & K. Shirasu, 2016. Molecular parasitic plant-host interactions. PLOS pathogens 12(12): e1005978. Doi: 10.1371/journal.ppat.1005978.
S. B. Saucet, C. Van Ghelder, P. Abad, H. Duval & D. Esmenjaud, 2016. Resistance to root-knot nematodes Meloidogyne spp. in woody plants. New Phytologist 211:41-56. Doi: 10.1111/nph.13933.
Cui S., Wakatake T., Hashimoto K., Saucet SB., Toyooka K., Yoshida S., Shirasu K., 2015. Haustorial hairs are specialized root hairs that support parasitism in the facultative parasitic plant, Phtheirospermum japonicum. Plant Physiol., pp.01786.2015. Doi: 10.1104/ pp.15.01786.
P. F. Sarris, Z. Duxbury, S. U. Huh, Y. Ma, C. Segonzac, J. Sklenar, P. Derbyshire, V. Cevik, G. Rallapalli, S. B. Saucet, L. Wirthmueller, F. L. H. Menke, K. H. Sohn & J. D. G. Jones, 2015. A plant immune receptor complex is activated by bacterial effectors that target WRKY transcription factors.Cell 161:1089-1100.
S. B. Saucet, Y. Ma, P. F. Sarris, O.J. Furzer, K. H. Sohn & J. D. G. Jones, 2015. Two linked pairs of Arabidopsis TNL resistance genes independently confer recognition of bacterial effector AvrRps4. Nature Communications 6:6338. Doi: 10.1038/ncomms7338.