Biology subjects

Delmas, C. E. L.

Publications and source records attributed to Delmas, C. E. L..

6 recordsLinked to original sources

bioRxiv2025

Esca Disease triggers local transcriptomic response and systemic DNA methylation changes in grapevine

Woody plants such as grapevine are vulnerable to trunk diseases caused by pathogens that colonize the wood, disrupt vascular function, and induce recurrent leaf symptoms associated with major metabolic disturbances and canopy decline. Over time, these diseases can irreversibly alter plant physiology and phenotype, ultimately reducing vine longevity. One of the most predominant of such diseases is esca, which is a major cause of vineyard dieback, with rising incidence worldwide over the past decade. However, the molecular mechanisms underlying esca symptom development remain unclear. In this study, we leveraged the heterogeneous expression of esca-symptoms within individual grapevines to investigate molecular responses in both symptomatic and asymptomatic leaf tissues. By combining metabolite profiling, RNA-seq and whole genome bisulfite sequencing, we show that metabolic alterations and extensive transcriptomic reprogramming are restricted to symptomatic leaves and are partially associated with local changes in DNA methylation. Asymptomatic leaves display distinct DNA methylation changes, some of which are shared with symptomatic tissues, suggesting a systemic response to the disease at the epigenetic level. Notably, subset of these methylation marks are observable prior to symptom emergence, highlighting the potential of epigenetic biomarkers for the early detection of trunk diseases in perennial plants.

plant biology↗

bioRxiv2025

Stress-dependent responses of grapevine wood and fungal pathogen activity under esca and drought

O_LIBiotic and abiotic stresses alter the physiology of perennial plants, with consequences for fungal endophytes and disease expression. In grapevine, one of the worlds most valuable crops, drought inhibits esca disease expression, but the underlying molecular interactions between plant and fungi are unknown. C_LIO_LIWe combined wood metatranscriptomics, metabolomics, and metabarcoding to investigate these interactions in 30-year-old grapevines and eight wood-pathogenic fungi under conditions of drought or esca leaf symptom expression. C_LIO_LIBoth esca and drought decreased grapevine transpiration, but with different transcriptomic and metabolic signatures. Similar pathways were also activated, including the phenylpropanoid and stilbenoid synthesis pathways. These stress responses could potentially confer cross-tolerance, and elicit different fungal molecular responses. The levels of putative fungal virulence factors increased significantly under both stresses. Under drought, only the relative abundance of Phaeomoniella chlamydospora and gene expression involved in anti-oxidative mechanisms, growth, and reproduction increased. Under esca expression conditions, only the relative abundance of Fomitiporia mediterranea and gene expression involved in wood degradation, competition, detoxification, and growth increased. C_LIO_LIThe grapevine defense mechanisms induced by drought coupled with a low transpiration rate and a low abundance and virulence of F. mediterranea may account for esca leaf symptom inhibition upon water deficit. C_LI

plant biology↗

bioRxiv2024

Nitrogen nutrition impacts grapevine esca leaf symptom incidence, physiology and metabolism.

Nitrogen plays a crucial role in plant growth and defence mechanisms, yet its role in plant-pathogen interactions is complex and remains largely unexplored, especially in perennial crops. This study aimed to investigate the effects of controlled nitrogen nutrition levels on disease incidence, fungal communities, and plant physiology and metabolism. Esca is a widespread grapevine vascular disease affecting physiology, xylem integrity and metabolism. Naturally infected Vitis vinifera L. cv. Sauvignon blanc were subjected to three ammonium nitrate treatments across three seasons, resulting in reduced esca incidence under nitrogen deficiency compared with medium nutrition levels, while excess nitrogen had no significant impact. Nitrogen treatments significantly impacted vine physiology and leaf metabolites but did not affect fungal wood communities. Nitrogen deficiency significantly reduced stem diameter, photosynthesis, and leaf area, likely decreasing whole-plant transpiration, while excess nitrogen increased these factors suggesting a key role of plant transpiration in esca incidence. Additionally, nitrogen deficiency led to significantly higher production of phenylpropanoids, particularly flavonoids, in leaf metabolomes compared to the medium level. These findings highlight the pivotal role of nitrogen in the development of esca through alterations in vine morphology, physiology and metabolism. Fertilization practices may be crucial in the management of plant diseases.

plant biology↗

bioRxiv2024

Exploring the role of cultivar, year and plot age in the incidence of grapevine trunk diseases: insights from 20 years of regional surveys in France

Grapevine trunk diseases cause yield losses and vine mortality in vineyards worldwide. However, there have been few quantitative studies evaluating grapevine dieback on a large spatial and temporal scale. Here, we consolidated and standardized databases from the 13 main wine regions of France, compiling records of leaf symptoms associated with esca and Eutypa dieback from 2082 plots and 36 cultivars over a 20-year period. This large dataset was used (a) for quantitative analysis of the prevalence (number of plots with at least one symptomatic plant) and incidence (percentage of symptomatic plants) of esca and Eutypa dieback; and (b) to decipher the effects of cultivar, year and plot age on both the prevalence and incidence of esca leaf symptoms by temporal Bayesian modelling. Esca was present on a mean of 74 {+/-} 2% plots annually, with an incidence of 3.1 {+/-} 0.1%. Eutypa dieback occurred in 41 {+/-} 3% of the plots, with an incidence of 1.4 {+/-} 0.1%. Our modelling approach revealed that the cultivar had a significant impact on the prevalence of esca, but not on its incidence when prevalence is greater than zero. Esca prevalence remained stable, whereas esca incidence was higher than the mean value in six of the years after 2012. We also found a significant non-linear effect of plot age, with 10- to 30-year-old plots significantly more susceptible, depending on the cultivar. This study clearly illustrates the importance of considering extensive and continuous monitoring to improve our understanding of the impact and evolution of crop diseases.

plant biology↗

bioRxiv2024

Large gradient of susceptibility to esca disease revealed by long-term monitoring of 46 grapevine cultivars in a common garden vineyard

Grapevine (Vitis vinifera L.) is prone to many fungal diseases, including esca, a severe vascular disease threatening the wine sector and for which there is no cost-effective cure. Susceptibility to esca varies between cultivars in different infection conditions. It may therefore be possible to use the genetic diversity of grapevine cultivars to mitigate disease impact. However, the genetic component of esca susceptibility has rarely been investigated in the vineyard, and the specific mechanisms and varietal traits underlying esca susceptibility remain unknown. In this study, we monitored the incidence and severity of esca foliar symptoms and plant dieback (apoplexy and mortality) at plant level for seven years, on 46 cultivars planted in an experimental common garden, to separate the genetic component of esca susceptibility from the effects of environment and cropping practices. We observed a broad gradient of varietal susceptibility, with a mean incidence of 0 to 26% of vines expressing esca foliar symptoms depending on the variety. This gradient remained similar across years and, unlike the severity of foliar symptoms, the incidence of grapevine dieback was significantly correlated with that of foliar symptoms. We detected a significant but weak and very localised phylogenetic signal for the incidence of esca foliar symptoms in this panel of cultivars. We then explored the relationships between epidemiological metrics and ecophysiological and phenological traits phenotyped on the same plot. Esca disease incidence was negatively correlated with {delta}13C across cultivars, suggesting that varieties with higher water use efficiency are less prone to the expression of esca symptoms on leaves. Moreover, the least vigorous cultivars were among the least susceptible, although this relationship was not significant. By contrast, neither phenological stages nor nitrogen status were significantly predictive of cultivar susceptibility to the disease. Together, these results provide new insight into the potential of genetic resources for use in the sustainable management of grapevine trunk diseases and open up new perspectives for studying the pathological and physiological determinants of their incidence.

plant biology↗

bioRxiv2020

Seasonal and long-term consequences of esca on grapevine stem xylem integrity

Hydraulic failure has been extensively studied during drought-induced plant dieback, but its role in plant-pathogen interactions is under debate. During esca, a grapevine (Vitis vinifera) disease, symptomatic leaves are prone to irreversible hydraulic dysfunctions but little is known about the hydraulic integrity of perennial organs over the short- and long-term. We investigated the effects of esca on stem hydraulic integrity in naturally infected plants within a single season and across season(s). We coupled direct (ks) and indirect (kth) hydraulic conductivity measurements, and tylose and vascular pathogen detection with in vivo X-ray microtomography visualizations. We found xylem occlusions (tyloses), and subsequent loss of stem ks, in all of the shoots with severe symptoms (apoplexy) and in more than 60% of the shoots with moderate symptoms (tiger-stripe), and no tyloses in shoots that were currently asymptomatic. In vivo stem observations demonstrated that tyloses were observed only when leaf symptoms appeared, and resulted in more than 50% PLC in 40% of symptomatic stems, unrelated to symptom age. The impact of esca on xylem integrity was only seasonal and no long-term impact of disease history was recorded. Our study demonstrated how and to what extent a vascular disease such as esca, affecting xylem integrity, could amplify plant mortality by hydraulic failure. HighlightOur study reveals that esca can critically affect xylem water movement in grapevine perennial organs, by the presence of plant-derived tyloses.

plant biology↗