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   Faced with certain types of pests (most insect pests, some bacteria and some fungal pathogens including necrotrophs), plants develop so-called quantitative resistance, as opposed to qualitative resistance - all or nothing - mediated by genes that in most cases code for receptors triggering the hypersensitive response. In cases of quantitative resistance, the link between defence processes and resistance is complex, difficult to understand and to quantify insofar as (i) the defence response is quantified by the observed symptoms (ii) the defence response involves transcriptional reprogramming of the majority of the genome and adaptation of almost all primary and secondary metabolic pathways, (iii) the intensity of this response depends on the virulence of the aggressor and (iv) these physiological processes are modulated by the abiotic environment before and during the host-bioaggressor interaction.

   On the main pest model studied, Botrytis cinerea, we are looking for metabolic markers of resistance and their variations in relation to the abiotic environment (water, nitrogen) using a metabolomic and transcriptomic approach (Lecompte et al. 2017, Lacrampe et al., 2021, 2022). We have in the past studied host genetic variability for resistance markers and plan to reinforce these aspects with GWAS approaches to study the link between marker expression and identified resistance QTLs, and to study the robustness of resistance QTLs in contrasting abiotic environments (activities planned on Botrytis cinerea - tomato and possibly after feasibility tests Phytophthora capsici - pepper in the PPR CapZeroPhyto project). The arrival in the unit in 2023 of a guest lecturer will make it possible to deepen, with coupled metabolomics and transcriptomics approaches, previous observations on a potential role of galactose metabolism in the defence against B. cinerea. In a complementary manner, hormonal signalling probably also plays a role in biotic x abiotic integration, a role that will be studied via the links between hormonal profiles and plant susceptibility on a range of host species and organs and under various environmental conditions (Project "HorNorm" submitted to the ANR 2023 generic AAP). Finally, using a fluxomic modelling approach, we are studying the variations in fluxes in the various primary and secondary metabolic pathways in order to identify the equilibria of pathways favourable to resistance.

   We are also exploring the effects of abiotic factors on the harmfulness of pathogens in the above-mentioned models and others (oidium on tomato and strawberry). The aim is to manipulate, under conditions consistent with those of vegetable production, irrigation and mineral nutrition during the crop cycle in order to minimise pest damage (Abro et al., 2013, 2014, work continued in the framework of the PPR Capzerophyto project). Other questions of a similar nature, more focused on plant-pest interactions and modelling, will be studied in the MESH axis.

Publications :

Abro M. A., Lecompte F., Bryone F., Nicot P. C. (2013). Nitrogen fertilization of the host plant influences production and pathogenicity of Botrytis cinerea secondary inoculum. Phytopathology, 103 (3), 261-267, https://dx.doi.org/10.1094/PHYTO-08-12-0189-R

Abro M. A., Lecompte F., Bardin M., Nicot P. C. (2014). Nitrogen fertilization impacts biocontrol of tomato gray mold. Agronomy for Sustainable Development, 34 (3), 641-648, https://dx.doi.org/10.1007/s13593-013-0168-3

Lacrampe N., Lopez-Lauri F., Lugan R., Colombié S., Olivares J., Nicot P. C., Lecompte F. (2021). Regulation of sugar metabolism genes in the N-dependent susceptibility of tomato stems to Botrytis cinerea. Annals of Botany, 127, 143-154, https://dx.doi.org/10.1093/aob/mcaa155

Lecompte F., Nicot P. C., Ripoll J., Abro M. A., Raimbault A. K., Lopez-Lauri F., Bertin N. (2017). Reduced susceptibility of tomato stem to the necrotrophic fungus Botrytis cinerea is associated with a specific adjustment of fructose content in the host sugar pool. Annals of Botany, 119 (5), 931-943, https://dx.doi.org/10.1093/aob/mcw240

Resources and Partnership :

Projects : CapZeroPhyto (PPR 2020-2026), projet HorNorm soumis ANR AAP générique 2023 (PRME mono équipe)

Thesis : N. Lacrampe (2018-2021), demande de bourse 2023

Collaborations : Université Avignon, INRAE UMR BFP, INRAE UR GAFL, INRAE UR Pathologie Végétale, INRAE UMR ISA