Internship offer: Role of wood traits (anatomy and composition) on grapevine varietal susceptibility to wood fungal pathogens

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

Scientific context:
Secondary xylem (or wood) represents the niche where interactions between perennial plant hosts
and diverse fungal vascular communities take place (Yadeta and Thomma, 2013). Wood characteristics
are thus key drivers of plant interactions with fungal species and disease expression. Yet, the specific
role of anatomical and biochemical wood traits in the development of wood-colonising fungal species
needs to be further explored.
Cultivated grapevine (Vitis vinifera L.) is exposed to a series of threats, and fungal trunk diseases are a
major concern (Bertsch et al. 2013). One of the symptoms often associated with these diseases are
wood necrosis (together or not with external foliar symptoms), usually enriched with fungal
communities belonging to different taxa and ecological categories (Bruez et al., 2020; Galarneau et al.,
2025; Gastou et al. 2026a). The consequent reduction in wood integrity and functionality creates issues
at plant and vineyard levels (Gramaje et al., 2018). Even if no grapevine cultivar has been identified as
being completely resistant to this class of diseases, there is evidence that a gradient of varietal
susceptibility exists (Gastou et al., 2024; Etienne et al., 2024). Phenotypic traits such as stem xylem
anatomy, healthy wood fungal communities and biochemical composition have been characterised in
cultivars of contrasted varietal susceptibility, showing significant variation across cultivars, with
different levels of correlation to diseases susceptibility and wood integrity (Pouzoulet et al., 2020;
Gastou et al., 2026b). Therefore, extend the phenotyping of wood properties to a broad panel of
grapevine diversity with known genetic variability, and phenotyping the development of a range of
fungal species on wood samples of contrasted composition are two complementary steps toward a
better understanding of the underlying mechanisms of grapevine varietal susceptibility to trunk
diseases.
Objectives:
The aim of this internship is to investigate (1) the potential relationships between xylem anatomical
traits of apparently healthy wood collected from trunks and the level of varietal susceptibility to wood
diseases such as esca, and (2) how contrasting healthy wood composition (based on previous wood
characterisation) might influence fungal propagation in different ways.
Methods:
(i) Phenotyping the variability of xylem anatomical traits of the trunk in a selection of 20 grapevine
genotypes (belonging to the INRAE-ResDur program, a source of grapevine genetic variability originally
studied for resistance to downy mildew and powdery mildew; Merdinoglu et al., 2018) of contrasting
susceptibility to trunk diseases (incidence of symptom expression and necrosis proportion per
genotype), using a quantitative wood anatomy approach (cross-sectioning of standardised wood
samples - previously collected in the field - using a microtome, staining techniques, and image analysis
as done by Gastou et al. 2025); (Gärtner et al., 2015);
(ii) Inoculating five fungal species on healthy wood blocks for which the contrasting structural
composition is known at varietal level (Gastou et al., 2026b). Different fungal pathogens isolated from
grapevine wood and part of the UMR SAVE strain collection will be used. Following inoculation, the
development of necrosis will be monitored by image analysis, as well as by the weight loss of the wood.
(iii) Statistical analysis and data interpretation using the literature.
Prerequisites:
• Interest in plant pathology / wood anatomy / image analysis / microscopy
• Seriousness, motivation and patience in conducting experiments
• Good communication skills (in French or in English) and the ability to work well in a team
• Skills in data analysis would be appreciated
Supervisors:
The student will be co-supervised by Chloé DELMAS (DR INRAE) (chloe.delmas@inrae.fr) and Samuele
MORETTI (postdoctoral researcher INRAE) (samuele.moretti@inrae.fr) and will join the research team
“Physiopathology” of UMR SAVE.
Name and address of the laboratory:
UMR 1065 Santé et Agroécologie du Vignoble (SAVE). INRAE Centre Nouvelle-Aquitaine Bordeaux, 71
avenue Edouard Bourlaux, 33882 Villenave d’Ornon.
References
Bertsch, C. et al. 2013. Grapevine trunk diseases: complex and still poorly understood. Plant Pathology,
62(2): 243-265. Bruez, E. et al. 2020. Major changes in grapevine wood microbiota are associated with
the onset of esca, a devastating trunk disease. Environmental Microbiology, 22:5189-5206. Etienne, L.
et al. 2024. Exploring the role of cultivar, year and plot age in the incidence of esca and Eutypa dieback:
Insights from 20 years of regional surveys in France. Plant Pathology, 73 : 2344–2358. Galarneau, E.R.,
et al. 2025. Biochemical characterization of wood decay and metabolization of phenolic compounds
by causal fungi of grapevine trunk diseases. PLOS ONE, 20(4): e0315412. Gärtner, H., et al. 2015. A
new sledge microtome to combine wood anatomy and tree-ring ecology. IAWA Journal, 36(4), 452-
459. Gastou, P., et al. 2024. Large gradient of susceptibility to esca disease revealed by long-term
monitoring of 46 grapevine cultivars in a common garden vineyard. OENO One, 58(2). Gastou P., et
al. 2025. Intraspecific variation in functional strategies underlies susceptibility to a vascular disease in
grapevine. submitted. bioRxiv preprint, 2025. https://doi.org/10.64898/2025.12.15.694483. Gastou,
P., et al. 2026a. Differential impacts of drought and esca expression on Ascomycota fungi in the trunks
and young organs of mature grapevines. Phytobiomes Journal, 10(1), 57-71. Gastou, P., et al. 2026b.
Contrasting wood chemical traits are associated with differences in wood degradation and esca
susceptibility among grapevine cultivars. Journal of Experimental Botany, erag510. Gramaje, D., et al.
2018. Managing grapevine trunk diseases with respect to etiology and epidemiology: Current
strategies and future prospects. Plant Disease 102:12-39. Merdinoglu, D., et al. 2018. Breeding for
durable resistance to downy and powdery mildew in grapevine. OENO One, 52(3): 203-209. Pouzoulet,
J., et al. 2020. Behind the curtain of the compartmentalization process: Exploring how xylem vessel
diameter impacts vascular pathogen resistance. Plant, Cell & Environment 43(11): 2782-2796. Yadeta,
K.A. and J. Thomma, B.P.H., 2013. The xylem as battleground for plant hosts and vascular wilt
pathogens. Frontiers in Plant Science. 4:97.

Training and skills

How to apply

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