CNRS – Université de Toulouse,Pôle de Biotechnologie végétale,24 chemin de Borde Rouge,BP 42617, 31326 Castanet-Tolosan,France
Mini-biographyChristophe Jacquet is an assistant professor in plant pathology and plant biotechnology at the Toulouse University since 1999. He received his PhD in 1997, studying resistance of transgenic herbaceous and woody plants to viruses. He has now integrated B. Dumas’ group “Plant immunity and microbial effectors”. His main goal is to develop and characterize pathosystems involving the model legume Medicago truncatula and major pathogens of crop and forage legumes. Colletotrichum sp., responsible for anthracnose disease on alfalfa and Phaseolus bean and Aphanomyces euteiches, causing root rot disease on pea are particularly studied. C. Jacquet has developed simultaneous transcriptome, cytological and genetic approaches to gain insight into legume resistance mechanisms and to identify molecular components involved in plant defence. He is also involved in research projects aiming at discovering new natural molecules that could stimulate basal plant defences and help to protect crops against pathogens using environmentally friendly methods.
Development of strategies for the protection of legume crops against fungal diseases using the model plant Medicago truncatulaChristophe Jacquet, Thierry Huguet, Bernard Dumas.
UMR 5546 CNRS-UPS. Pôle de Biotechnologies Végétales, 24, chemin de Borde Rouge. BP42617. 31326 CASTANET-TOLOSAN.
jacquet@scsv.ups-tlse.frMedicago truncatula has emerged since 1999 as a model legume, for which a wealth of genomic and genetic resources has been generated. Biological characteristics of
M. truncatula are well adapted to study mechanisms involved in legume-pathogen interactions. We have developed pathosystems with
M. truncatula and pathogens causing major diseases on legumes:
Colletotrichum trifolii (alfalfa anthracnose) and
Aphanomyces euteiches (pea root rot disease). For each of these pathosystems, resistant and susceptible
M. truncatula lines were identified, opening the way to the characterisation of defence mechanisms and genes involved in resistance through cytological, transcriptomic and genetic analyses. Based on these different approaches we developed two strategies that will provide new ways to increase resistance to biotic stress in legume crops.
To identify molecular components controlling the specific resistance level to
A. euteiches,
C. trifolii and other pathogens (through collaborations with American research teams) a QTL approach was developed using Recombinant Inbred Lines (RIL) populations available for the two parental lines A17 and F83005.5, resistant and susceptible to
C. trifolii and
A. euteiches respectively. As A17
M. truncatula line, whose genome sequencing is almost finished, was one of the parental lines, genetic and physical maps were compared. Search for resistance gene(s) has now focused on 2-3 BAC contigs (about 150 to 400 kb M. truncatula genome regions). Complementation experiments through Agrobacterium genetic transformation of the susceptible line with putative candidate genes will be undertaken in the next months to clone and identify the resistance gene(s).
The second strategy we developed to increase plant resistance was to induce the basal plant defence level through a treatment with molecules that might act as elicitors. In view of a potential use of elicitors as plant protectants, it is important to select extracts that i) trigger a large array of defence responses, ii) do not significantly disturb the primary metabolism, iii) ensure protection against diseases. To find such molecules, we exploited the high diversity of natural biochemical compounds found in algae. Algae extracts were sprayed on susceptible
M. truncatula plants prior to inoculation with
C. trifolii or
A. euteiches. Gene expression profiling of the treated plants was performed in order to get an integrated view of the elicitor effects on the plant’s transcriptome, metabolism, and specific biochemical pathways. These experiments allowed the identification of new compounds able to induce defence reactions and to protect
M. truncatula against
C. trifolii or
A. euteiches. Some of these results will be presented and the use of such molecules to protect crop legume fields will be discussed.
