This project aims at identifying the pathogenicity effectors of the obligate biotrophic oomycete Plasmopara halstedii, the agent of sunflower downy mildew, and exploiting them in the search for durable resistance to the disease in the cultivated sunflower, Helianthus annuus.
Our objectives are: (i) to define the repertoire of secreted and in planta translocated effectors (RXLR and CRN) of P.halstedii pathotypes, to exploit (ii) the effector variability between pathotypes in order to characterize avirulence genes or (iii) the conservation of effectors between pathotypes to identify more sustainable resistance sources to sunflower mildew, a major agricultural issue.
Dr. Laurence Godiard, CR1 INRA, HDR (PI)
Past research projects Laurence Godiard obtained his PhD in 1992 at the University Paul Sabatier of Toulouse, on the characterization of tobacco genes induced during the Hypersensitive Reaction (HR) caused by the phytopathogenic bacterium Ralstonia solanacearum. She then joined the group of Dr Jeffery Dangl at the Max Planck Institute in Cologne, Germany, where she cloned with Dr Murray Grant the RPM1 gene of Arabidopsis thaliana, one of the first plant resistance genes with NBS-LRR domains. She was recruited as a researcher at INRA in 1995 at the Laboratory of Plant-Microbe Interactions (LIPM). Her research initially focused on the characterization of quantitative resistance in A. thaliana, to a race of R. solanacearum isolated in France. In 2000, she developed the transcriptomics of the legume model Medicago truncatula during rhizobial symbiosis, constructed and analyzed SSH (subtractive hybridization) libraries in order to find new plant genes regulating nodulation. She studied one of these genes encoding a putative basic-helix-loop-helix (bHLH) transcription factor expressed early and in some cells of the mature nodule of M. truncatula. This gene may be involved in the structuring of the nodule vascularization and in the metabolic exchanges between the nodule and the rest of the plant, key steps in nodular functioning that are still poorly documented.
Current research project Since 2008, she runs a brand new project set up at the LIPM on the downy mildew of a field crop, sunflower. Sunflower downy mildew is caused by the obligate biotrophic oomycete, Plasmopara halstedii, close to grape downy mildew, Plasmopara viticola. The sunflower downy mildew project is based on two main axes: the identification of the effectors of the pathogen and their use in the characterization of broad-spectrum resistances in sunflower, potentially more durable in the field. This project benefited from ANR funding (EFFECTOORES 2014-2017) and resulted in the sequencing of 10 pathotypes of P. halstedii, and to the first RNAseq expression data on sunflower downy mildew, in collaboration with LIPM bioinformatic team and Get-Plage facilities. In 2012, Laurence obtained her HDR at Toulouse III University. In 2015, a three-year PROMOSOL funding was awarded to establish a collection of isolates of P. halstedii, to define molecular markers of P. halstedii pathotypes, and to map new resistances to downy mildew in sunflower. A recent Tulip-FR Inter units funding obtained in collaboration with a CNRS researcher from the EDB (Evolution and Biological Diversity) laboratory will lead to the sequencing of P. halstedii genomes with the PacBio technology. This project aims to evaluate the importance of genomic rearrangements in the diversification of P. halstedii. In 2017, she was elected as a board member of the French Society of Phytopathology.
Charlotte Penouilh,assistant engineer, PROMOSOL contract
Charlotte Penouilh was recruited in November 2015 on the MILVARSUNRES contract with a PROMOSOL funding. Her project is to participate in maintaining the variability of Plasmopara halstedii isolates, to identify molecular markers of pathotypes and to map new Resistance genes to Downy Mildew in Sunflower.
Dr Yann Pecrix, post-doctoral fellow, ANR EFFECTORES contract (2015-2017)
Luis Buendia, Master student 2 (2014-2015)
Dr Quentin Gascuel, Master 2 (2010-2011) et doctorant (2011-2014)
- PROMOSOL MilVarSunRes project : 2015-2018. MilVarSunRes: Maintaining the Variability of isolates of Plasmopara halstedii, identification of molecular markers of P. halstedii pathotypes and mapping of new Sunflower Resistances to downy Mildew.The PROMOSOL association (Association for the Promotion of selecting oilseeds) brings together representatives of the oilseeds sector, Terres Innovia (formerly CETIOM), seed companies and provides research contract with INRA. The MilVarSunRes project coordinated by L. Godiard includes three complementary axes aiming at: (i) the maintaining of the variability of Plasmopara halstedii isolates, (ii) the characterization of a complete set of effector genes as markers of pathotypes and (iii) the mapping of new broad spectrum sunflower resistances to downy mildew, previously identified by the sunflower geneticist Dr Felicity Vear (INRA Clermont-Ferrand).
- ANR EFFECTOORES project, 2014-2017:Exploitation of the knowledge on Oomycete effectors to drive the discovery of durable disease resistance in cultivated plants. This project proposes to use the most conserved genes of effector repertoires of three oomycetes Phytophthora infestans, Plasmopara viticola et Plasmopara halstedii causing disease in crops (tomato, grapevine and sunflower respectively) to accelerate the identification, the functional characterization and the cloning of broad spectrum disease resistance genes, potentially more sustainable. It includes 5 INRA laboratories and a Scottish team; L. Godiard is the scientific leader for the LIPM.
- TULIP – FR inter units project (2016- 2017) : Does genome reshuffling of the sunflower downy mildew (Plasmopara halstedii) drive its recent virulence diversification? PIs : L. Godiard (LIPM) and G. Besnard (Evolution and Biological Diversity, EDB laboratory). This project aims to evaluate the importance of genomic rearrangements in the diversification of P. halstedii, based on PacBio genome assemblies.