Durable and effective strategies to fight plant diseases
To better understand the pathogens that affect plants...
Loup Rimbaud was recently hired through a competitive selection process as a research scientist by the Plant Health and Environment Division. He joined the Plant Pathology research unit in 2018 as a member of the virology team at INRA’s Provence-Alpes-Côte d’Azur research centre in Avignon. This unit strives to better understand the pathogens that affect plants (bacteria, fungi, viruses and, more specifically, the species that attack horticultural crops) to develop effective, sustainable and environmentally safe methods to fight these pathogens.
Loup Rimbaud’s research focuses on identifying effective and durable strategies to manage plant diseases, especially viral diseases that impact crops. He uses spatio-temporal simulation models combined with laboratory and greenhouse experiments and statistical analysis of epidemiological field data. These experiments and field data provide valuable biological information on pathogen-host plant interactions, and sometimes even disease vectors. Loup works closely with other researchers in his unit to conduct experiments on viruses, as well as with INRA’s BioSP1and SAVE2 units to create simulation models. He is highly involved in a French National Research Agency (ANR) project (ArchiV) developed to understand the pathogenic potential of viruses and to optimise the deployment of plants’ resistance to these viruses.
A taste for academic research
... to develop farming practices profitable and responsible in terms of ecosystems.
Loup has always wanted to work towards a common cause and for the greater good. It was only natural that public research would appeal to him. Today, he is driven by INRA’s push to improve farming practices and transform them into systems that are both profitable and responsible in terms of local populations and ecosystems.
But the journey to get here was full of twists and turns. After nurturing a long-time passion for biology and maths, Loup first studied agricultural engineering with the hopes of using maths in farming applications. During his various internships, he became more familiar with the scientific approach. He began studying the consequences of forest fires in Oregon (Oregon State University, USA), before moving on to AFSSA (now ANSES3) to research allergy risks. He later joined CIRAD4 in Réunion to investigate the impact of viruses in tomato greenhouses. He then took up the challenge of working for a small company that produces microalgae for dermocosmetics and food supplements. However, after two years, a proposal to do a thesis on managing viral disease epidemics came his way, and he decided to shift towards academic research and his first love: plant viruses.
After successfully combining maths and biology in his research project, this young researcher – who also happens to be an extreme sports enthusiast – now dreams of participating in a scientific expedition…
1 UR0546 BioSP Biostatistics and Spatial Processes Research Unit
2 UMR1065 SAVE Joint Research Unit for Grapevine Health and Wine Quality
3 French Agency for Food, Environmental and Occupational Health & Safety
4 French Agricultural Research Centre for International Development
- Since 2018: Research Scientist at INRA, Plant Pathology Unit, Virology Team, Montfavet, France. Virus evolution in response to the deployment of plant resistance and tolerance.
- 2016-2018: Postdoctoral fellow at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Management of Biotic Threats Team, Canberra, Australia.
- 2012-2015: PhD in Microbiology – Parasitology from Montpellier SupAgro at the Joint Research Unit for Biology and Genetics of Plant-Pathogen Interactions for Integrated Protection (UMR BGPI), Epi2V Team (Plant Epidemiology and Vector Transmission), First-Class Honours. Conception et évaluation assistée par la modélisation de stratégies de gestion d’une épidémie dans un paysage hétérogène (Model-based design and assessment of management strategies for epidemics in a heterogeneous landscape).
- 2006-2010: Master’s Degree in Agricultural Engineering from AgroParisTech (formerly INA P-G). Specialty in Production and Innovation in Technical Plant Systems.
- 2004-2006: BCPST preparatory classes for the grandes écoles, Lycée Thiers (Marseille).
- 2004: High School Diploma, Scientific Stream, Lycée Dumont d’Urville (Toulon), with distinction.
WHAT IS THE OPTIMAL STRATEGY TO EFFECTIVELY AND SUSTAINABLY DEPLOY PLANT RESISTANCE TO VIRUSES?
Growing pathogen-resistant plant varieties is a very effective way to fight epidemics while limiting environmental impact, since lower amounts of plant protection products are used. However, because of their extraordinary capacity to evolve, pathogens can adapt (sometimes quite quickly) and circumvent plant resistance, leading to serious epidemics and the need to undertake the long and costly process of developing new resistant varieties. Several strategies could help improve resistance durability. They are mainly based on the combination of several sources of resistance over time and/or space, via gene pyramiding (several genes in a same variety), crop rotation (several different resistant varieties are grown in succession in a field), mixing (several varieties are planted in a single field), and mosaic cropping (different varieties are grown in different fields of the landscape). These four strategies must be assessed at the agricultural landscape scale and over several years, which considerably limits experimental methods. Mathematical models have proven to be valuable tools for measuring the effectiveness (the ability to limit the impact of an epidemic) and durability (ability to prevent or delay a pathogen overcoming resistance) of chosen strategies.
Loup Rimbaud’s initial research in this field led him to develop the R landsepi package in cooperation with the BioSP Unit and CSIRO. It is a demogenetic, stochastic and spatial simulation model that simulates a pathogen’s propagation and evolution in an agricultural landscape where several sources of resistance are deployed based on one of the four above-mentioned strategies. When early results were applied to cereal rusts (caused by fungi from the Puccinia genus), they appeared to show that no single strategy was best: each has its benefits and drawbacks. Loup’s next goals include combining these strategies into one comprehensive strategy and to calibrate the landsepi model for viruses.