Interactions between bois noir and the esca disease complex in a Chardonnay vineyard in Italy

Abstract

Grapevine yellows bois noir (BN) and the grapevine trunk disease esca complex (EC) cause serious yield losses in European vineyards and are often widespread in the same vineyard. In a Chardonnay vineyard in north-eastern Italy, evolution of the two diseases from 2007 to 2020 was compared and their possible interaction was investigated. Evolution of symptomatic grapevines over the 16 years was very different between the two diseases, with a substantial linear increase for BN and an exponential increase for EC. The BN increase from one year to another was associated with the abundance of Hyalesthes obsoletus, the BN-phytoplasma vector, whereas the exponential increase in EC was likely due to the amount of inoculum and the increased size of pruning cuts over time. The courses of the two diseases were also very different, with a much greater occurrence of dead grapevines from EC than from BN. Some grapevines showed symptoms of both diseases, but the probability was less that a grapevine symptomatic for BN or EC showed symptoms of the other disease. Examinations of the spatial distribution of the two diseases showed dissociation between them. Data indicated that mechanisms of induced defense were involved in the lower probability that a grapevine affected by one showed symptoms of the other.

Headnote

Summary. Grapevine yellows bois noir (BN) and the grapevine trunk disease esca complex (EC) cause serious yield losses in European vineyards and are often widespread in the same vineyard. In a Chardonnay vineyard in north-eastern Italy, evolution of the two diseases from 2007 to 2020 was compared and their possible interaction was investigated. Evolution of symptomatic grapevines over the 16 years was very different between the two diseases, with a substantial linear increase for BN and an exponential increase for EC. The BN increase from one year to another was associated with the abundance of Hyalesthes obsoletus, the BN-phytoplasma vector, whereas the exponential increase in EC was likely due to the amount of inoculum and the increased size of pruning cuts over time. The courses of the two diseases were also very different, with a much greater occurrence of dead grapevines from EC than from BN. Some grapevines showed symptoms of both diseases, but the probability was less that a grapevine symptomatic for BN or EC showed symptoms of the other disease. Examinations of the spatial distribution of the two diseases showed dissociation between them. Data indicated that mechanisms of induced defense were involved in the lower probability that a grapevine affected by one showed symptoms of the other.

Keywords. Grapevine yellows, phytoplasmas, grapevine trunk diseases, symptom evolution, induced defense.

INTRODUCTION

Grapevine age positively influences yields, rooting depths, plant resilience and wine quality (Riffle et al., 2022), so factors that influence grapevine longevity can compromise the economic sustainability of vineyards. In European vineyards, yield losses, often associated with early grapevine death, are caused by grapevine yellows (GYs) [i.e., flavescence dorèe (FD) and bois noir (BN)] (Garau et al., 2007; Belli et al., 2010; Pavan et al., 2012; Romanazzi et al., 2013), and trunk diseases [esca complex (EC), in particular)] (Larignon and Dubos, 1997; Mugnai et al., 1999; Bertsch et al., 2013; Bruez et al., 2013; De la Fuente et al., 2016).

GYs are associated with phytoplasmas that colonize phloem vessels (Santi et al., 2013; Angelini et al., 2018), and are vectored by auchenorrhyncha phloem-feeding insects (Alma et al., 2019). Bois noir (BN), unlike FD, is widespread in all Euro-Mediterranean grape-growing regions (Angelini et al., 2018). BN is associated with 'Candidatus Phytoplasma (Ca. P.) solani' (subgroup 16SrXII-A) (Quaglino et al., 2013; Angelini et al., 2018), and the most important vector of this pathogen is the planthopper Hyalesthes obsoletus Signoret (Homoptera, Cixiidae) (Maixner, 1994; Alma et al., 2019; Kosovac et al., 2019).

Different susceptibilities and sensitivities of grapevine cultivars to BN have been reported (Bellomo et al., 2007; Garau et al., 2007; Panassiti et al., 2015; Zahavi et al., 2013). After symptom appearance, the course of the disease in BN-symptomatic grapevines during subsequent vegetative seasons can lead to recovery or death of the infected grapevines (Osler et al., 1993, 2002; Garau et al., 2007; Pavan et al., 2012; Zahavi et al., 2013). In general, recovery from GYs involves phytoplasma-induced grapevine response mechanisms (Musetti et al., 2007; Albertazzi et al., 2009; Romanazzi et al., 2009; Landi and Romanazzi, 2011; Margaria and Palmano, 2011; Santi et al., 2013; Paolacci et al., 2017; Bertazzon et al., 2019; Pacifico et al., 2019; Mátai et al., 2020; Pagliarani et al., 2020; Nutricati et al., 2023). Furthermore, fungal and bacterial endophytes have been suggested to affect grapevine recovery from GYs (Martini et al., 2009; Bulgari et al., 2016).

Grapevine trunk diseases (GTDs) are caused by fungi that penetrate host plants through wood wounds and invade the vascular systems (Bertsch et al., 2013; Bruez et al., 2013; Claverie et al., 2020). Esca complex (EC) is the most widespread GTD, and is characterised by inner necrosis in grapevine wood tissues and external plant symptoms ("tiger-striped" leaves or "black measles" on the berries) (Larignon and Dubos, 1997; Mugnai et al., 1999; Graniti et al., 2000; Úrbez-Torres, 2011; Mondello et al., 2018; Fischer and Peighami-Asnaei, 2019; Nerva et al., 2019; Bruez et al., 2020). When grapevines show typical leaf symptoms, the EC is defined as grapevine leaf stripe disease (GLSD), whereas when grapevines dry out and die, the EC shows apoplectic symptoms (Surico et al., 2006; Surico, 2009). Grapevines can produce defensive compounds in response to wood invasion by escaassociated fungi (Ramírez-Suero et al., 2014; Stempien et al., 2018; Goufo et al., 2019). Activity of non-pathogenic fungi (e.g., Epicoccum spp., Pythium oligandrum, Trichoderma spp.) or bacteria [e.g., Bacillus pumilus (S32), Paenibacillus sp. (S19)] in preventing EC fungal infections has been reported, and different mechanisms were considered, including production of inhibitory compounds, competition for nutrients and space, triggering of grapevine resistance, and interference with pathogenicity genes of esca-associated fungi (Haidar et al., 2016; Del Frari et al., 2019; Bigot et al., 2020; Yacoub et al., 2020; Romeo- Oliván et al., 2022). Susceptibility to EC can be influenced by V. vinifera cultivar, rootstock genotype, and cultivar × rootstock combination (Fischer and Peighami-Ashnaei, 2019). Chardonnay was classified as intermediate in EC susceptibility (Borgo et al., 2016).

No studies have been reported on comparative evolution of GYs and EC within the same vineyard, or the possible interaction between the GYs and EC. For this purpose, grapevines in a large Chardonnay vineyard in north-eastern Italy were annually monitored from 2007 to 2020. This allowed comparison of the evolution of the two diseases at vineyard level, and determination of whether the two diseases can coexist in individual host plants. This also would give knowledge of the degree of interaction (none, synergistic, or antagonistic) between the two in manifestation of host symptoms.

MATERIALS AND METHODS

Vineyard studied

The study was conducted from 2007 to 2020, in a vineyard in north-eastern Italy (Friuli Venezia Giulia region, Gorizia district, Cormons locality; 45°56'34"N, 13°26'45"E, 44 m a.s.l.). The vineyard was planted in 2000, with approx. 3.5 ha of Chardonnay R8 clone grafted onto SO4. The vineyard had 21 rows of length 370 m (westernmost row) to 408 m (easternmost row). The grapevines were trained to the double-arched Guyot system, and were at spacing of 3.5 m between rows and 1.0 m within rows.

In the vineyard, the only GY detected up to 2022 was BN. All the 128 GY symptomatic samples randomly collected and analysed by qPCR/HRM from 2010 to 2021 tested positive for 'Ca. P. solani' and negative for FD phytoplasma (Mori et al., 2020; Pavan et al., 2024; Martini et al., unpublished data). No symptoms of virus or soil-borne diseases were observed in the vineyard.

During the years of the study, FD had not been reported in the vineyards of the wine-growing area where the vineyard was located, but mandatory insecticide treatments against Scaphoideus titanus were applied each year, at the beginning of July. Since the active ingredients used were not basipetal systemic insecticides (organophosphate in the early years, thiamethoxam more recently), the insecticides would not have affected H. obsoletus nymphs living in the roots of herbaceous plants. Even against H. obsoletus adults, the efficacy of insecticides is not high, as the insects emerge gradually and can colonize vineyards, even from outside. Only mechanical weeding was used in the vineyard. After winter pruning, no fungicide treatments were applied to protect the pruning cuts.

Sampling and data analyses

Mapping of the vineyard

In 2007, the vineyard rows and plants were mapped, by referring each grapevine to a row (numbered 1 to 21, starting from the west), a supporting pole along the row (numbered from the north end of each row), and a position (designated a, b, c, or d) between neighbouring poles. From 2007 to 2020, each grapevine was checked each year in early September, by the same observers every year, to determine which plants showed GY or EC symptoms. Replacement of dead grapevines occurred in only a few rows in 2019, but newly planted grapevines were not considered in this study.

Grapevines with BN symptoms were identified based on their characteristic GY symptoms, including leaf rolling, sectorial leaf blade discolourations, poorly lignified and falling shoots, and shriveled berries. Grapevines with the GLSD form of EC were identified based on tiger-striped leaves or black measles on the berries. Grapevines with the apoplexy form of EC were identified based on necrosis and shoots without leaves. Since these symptoms were visible both in grapevines that had or had not previously manifested GLSD symptoms, death of these plants was attributed to EC, even when the GLSD form of EC had not previously manifested. The grapevines that died from BN could not be confused with those that died from EC, as BN-affected plants had green shoots in the previous year, which only in the following year were necrotic due to frost damage, as they were not lignified.

Symptom evolution in BN and EC symptomatic grapevines

Annual records were made to check whether grapevines were affected by BN, and if the symptoms were noted for the first time. In subsequent sampling years, these grapevines were assigned to three categories: "still symptomatic", "asymptomatic", or "dead". Grapevines that became asymptomatic were recorded as "recovered" only after three consecutive years without symptoms, and taking into account that pollarding can mask GY symptoms for some years (Pavan et al., 1997; Mutton et al., 2002). Grapevines that did not have lignified shoots at the time of sampling, or that did not sprout in the following year, were considered dead. The annual sampling of grapevines affected by BN allowed recording of the evolution of symptoms for individual grapevines, from the year of the first symptom appearance (year = 0) to year n (maximum n = 13 for grapevines that showed symptoms in the first sampling year).

For each grapevine exhibiting EC symptoms, the following details were noted: (i) the year in which symptoms first appeared, and whether they were in the form of GLSD or apoplexy, and (ii) the year in which apoplexy occurred for grapevines that had previously exhibited GLSD symptoms. To determine when the grapevines affected by EC showed apoplexy (0, or more years), only grapevines during the period 2015 to 2020 were considered, which enabled certainty for exclusion of grapevines that could have presented symptoms of GLSD in the years preceding the start of mapping.

Interactions between BN- and EC-affected grapevines

For comparison of symptom evolution of BN and EC with time, and disease interactions, the grapevines were grouped into those displaying symptoms of only BN or EC, or of both diseases. For both diseases, the following parameters were calculated: (i) Proportions (%) of dead grapevines to total live grapevines in 2007; (ii) Proportions (%) of dead grapevines to total symptomatic grapevines; (iii) Accumulated numbers of dead grapevines; (iv) Accumulated numbers of total symptomatic grapevines (symptomatic live plus dead grapevines). Grapevines with symptoms of both diseases over the sampling years were also divided into three groups: (1) grapevines that showed EC symptoms for the first time in years following their first year of exhibiting BN symptoms; (2) grapevines showing EC symptoms for the first time one or more years after recovering from BN; or (3) grapevines that showed BN symptoms for the first time in the years following their first year of exhibiting EC symptoms.

Fisher's exact test was used to compare two proportions in each dataset, while Rayan's test was used to compare three proportions. Dynamics of BN or EC dead grapevines over the years were determined using polynomial regressions of best fit to the experimental data for the two diseases.

Comparisons of spatial distribution of BN- and ECsymptomatic grapevines

SADIE red-blue analysis (Perry et al., 1999) was used to determine spatial distributions of cumulative BN- and EC-symptomatic grapevines within the vineyard. The sampling units were groups of 16 grapevines (four inter-poles), and the total number of grapevines with symptoms of either or both diseases in each year was determined for each 16 plant unit. This analysis identified areas with high-density counts (disease patches) or low or zero counts (gaps), and calculated indices of clustering (vi; vj) for each unit, which measured local contribution to either patch or gap. The clustering significance (α = 0.05) for each variable was determined by comparing the mean values of vi and vj with their corresponding values under the null hypothesis (Perry et al., 1999).

A two-dimensional map depicting the spatial distribution of local clustering indices (vi; vj) for each variable was generated using linear kriging with SURFER (Golden Software 191 Inc.). The red-blue analysis datasets were then used to assess similarity between spatial patterns of BN-symptomatic grapevines and EC-symptomatic grapevines. An algorithm was used to derive overall indices of spatial association (Xk), and their statistical significance (Px) was determined through a randomisation test (Perry and Dixon, 2002). This test determined if the spatial patterns of two variables were associated (Px < 0.025), unassociated (0.025 ≤ Px ≤ 0.975), or dissociated (Px > 0.975), with association indicating the coincidence of a patch cluster for one variable with a patch cluster for the other, or the coincidence of two gaps, and dissociation indicating that a patch for one variable coincides with a gap for the other (Perry, 1998).

RESULTS

Evolution of grapevines affected by BN

In the first sampling year (2007), 199 grapevines had symptoms of BN, and cumulative numbers of grapevines with these symptoms rose to 831 in the last sampling year (2020). The status of most of the grapevines affected by BN changed to "recovered" or "dead" in the years following the first onset of symptoms (Figure 1). A substantial proportion of the grapevines (11%) showed symptoms for at least 13 years, highlighting that the infection can last for many years. Probability of recovery of a symptomatic grapevine was greater in the first few years than later, as more than half of recovered plants were recorded within the following 3 years. Likelihood of a symptomatic grapevine dying was also greater in the first few years than later, as more than two-thirds of symptomatic plants died within the first 5 years after first symptom observation.

Evolution of grapevines affected by EC

From 2015 to 2020, 1126 grapevines died for apoplexy. Apoplexy was observed in a third of the grapevines without them having previously shown GLSD symptoms (Figure 2). Over 95% of the grapevines with GLSD symptoms exhibited apoplexy within 5 years. Three grapevines died 9 years after first showing GLSD symptoms, and two grapevines did not develop apoplexy more than 9 years (10 and 12, respectively) after the first appearance of GLSD symptoms in 2008, which increased initially very slowly

Comparisons of BN and EC evolution

From 2008 to 2020, 2236 grapevines died (29.2% of the live grapevines in 2007), 1952 of which had EC symptoms, 227 had BN symptoms, and 57 had symptoms of both diseases. The proportion of dead grapevines from EC was eight times greater (P ≤ 0.05) than from BN (Table 1). Approx. 1% of the grapevines died after showing symptoms of both diseases. Grapevine deaths from EC started 1 year after the BN deaths, but accumulated death numbers subsequently increased more rapidly, as the ratios of EC deaths to BN deaths rose from 2.0 in 2009 to 8.6 in 2020 (Figure 3 A). The trend towards increases in dead grapevines over time was sinusoidal for BN (Y = -0.2486X3 + 1502X2 - 3E + 06X + 2E+09; R² = 0.9947), and more than proportional for EC (Y = 13.41X2 – 53854X + 5E + 07; R² = 0.9968).

Considering the total number of symptomatic grapevines (i.e. "symptomatic alive" plus "dead"), the differences between BN and EC were less marked (Figure 3 B). From 2007 to 2020, 2262 grapevines exhibited symptoms of EC, 831 of BN, and 82 of both diseases. The number of accumulated symptomatic grapevines was greater for BN up to 2013 and greater for EC in the subsequent years.

The EC / BN ratio of the total number of affected grapevines (2.74) was three times smaller than that of the dead grapevines (8.60), due to the different mortality rates between the EC and BN. The percentage of "dead" grapevines relative to the total of "symptomatic" grapevines was greater (P ≤ 0.05) for EC than for BN, with EC being three times greater than BN (Table 1). There was also a smaller proportion of grapevines that died with symptoms of both diseases than grapevines dying only with EC symptoms (P ≤ 0.05).

Interactions between BN and EC

The percentage of grapevines displaying EC symptoms was less among grapevines that had exhibited BN symptoms in previous years than among those that had never shown BN symptoms (Figure 4 A). Within the BN-symptomatic grapevines, the recovered grapevines showed greater proportions with EC symptoms than the non-recovered grapevines (Figure 4 B), but were still less likely to show EC symptoms than grapevines that never showed BN symptoms (Figure 4, A and B).

The percentage of grapevines succumbing to EC was less in those that had previously exhibited symptoms of BN than in those that had never shown BN symptoms (Figure 4 C). The proportion of dead grapevines among symptomatic ones (86.3%) was greater (P = 0.017; Fisher's exact test) for those without previous BN symptoms than for those with prior BN symptoms (76.0%). Within the BN-symptomatic grapevines, the recovered grapevines died from EC at a greater proportion than the non-recovered grapevines (Figure 4 D), but they still died at lower percentage (P ≤ 0.05) than grapevines that had never exhibited BN symptoms (Figure 4, C and D).

Among grapevines that displayed GLSD symptoms, only seven plants (2.3%) later had symptoms of BN, and this contrasted with grapevines that had never exhibited GLSD symptoms, which had a greater rate (13.8%) of BN symptoms (P < 0.00001; Fisher's exact test).

Spatial distribution of BN- and EC-symptomatic grapevines

The distribution of BN-symptomatic grapevines was aggregated. The most important patches were found in the first 100 m from the northern edge of the vineyard (vi = 6.365, Pvi < 0.001), while gaps occurred in the remaining vineyard area and predominantly in the south-western part of the vineyard (vj = - 5.691; Pvj < 0.001) (Figure 5 A).

The distribution of EC-symptomatic grapevines was aggregated. The most significant patches occurred along the eastern edge of the vineyard, between the central and southern parts (vi = 5.08; Pvi < 0.001), while gaps occurred along the western vineyard edge in the first 100 m from the northern edge (vj = -5.312, Pvj < 0.001) (Figure 5 B).

The distributions of BN- and EC-symptomatic grapevines were dissociated, with the areas of greatest dissociation coinciding with the major patches of BNand EC-symptomatic grapevines (Xk = - 0.25; Px > 0.999) (Figure 8 C).

DISCUSSION

This 14-year-long descriptive epidemiology study was carried out in a large vineyard, and aimed to investigate potential synergistic or antagonistic interactions between two important grapevine diseases. The selected vineyard was in a wine-growing area where the exclusive presence of BN among GY had been reported until the last study year (2020), and also during the monitoring survey conducted in 2021 and 2022 seasons. This made it possible to obtain descriptive results, as discussed below.

Evolution of grapevines affected by BN

In the vineyard studied, 50% of the grapevines died, and 10% still showed BN symptoms 13 years after first detection of these symptoms. This evolution was less favourable than that observed for the same cultivar (Chardonnay) in a multi-year study (1987–2000) conducted in ten vineyards in another wine-growing area of north-eastern Italy (Friuli Venezia Giulia region, Pordenone district: Pavan et al., 2012). In that study: (i) only 10% of the affected grapevines had died after 9 years (45% in the present study), and only 1.1% of grapevines showed symptoms after 13 years (11% after 13 years in the present study). These differences could be due to differing virulence of the phytoplasma strains (Langer and Maixner, 2004; Pierro et al., 2022), or to differing host susceptibility. Differences in grapevine susceptibility could have been due to differences in clone-rootstock combinations and/or grapevine training systems. In the study of Pavan et al. (2012), many clone-rootstock combinations were assessed, including some polyclonal vineyards, and the grapevine training system was Sylvoz. In the present study, the vineyard was monoclonal, and the training system was double-arched Guyot. In the Pavan et al. (2012) study, there were three to five canes originating from points of each permanent horizontal trunk, the canes were distant from each other, and the symptoms only rarely seriously affected all the canes. The affected plants also almost always had some lignified shoots. In the present study, each grapevine had two canes originating from the trunk heads, and the symptoms often affected both canes. As there were no lignified shoots, these were probably killed by winter frosts, so the grapevines did not sprout in the following springs.

Comparisons of BN and EC evolution

The appearance of BN before EC is explained by the different epidemiology of the two diseases. For BN, the likelihood that a healthy grapevine may become infected does not depend on the vineyard age, but depends on the number of infectious vectors that can inoculate grapevines with BN phytoplasmas, regardless of grapevine age. In contrast, the likelihood that grapevines are affected by trunk diseases increases with vineyard age, because the overall numbers of pruning cuts increase with time, favouring fungal infections (Mugnai et al., 1999; Amponsah et al., 2011; Kovacs et al., 2017). With increasing vineyard age and EC progression, pathogen inoculum related to EC also increases with time, increasing infection probability. Although EC appeared after BN in the studied vineyard, the number of grapevines affected by EC at the end of the survey years was three times greater than for BN. This occurred because the increase in BN over study period was substantially linear, with some fluctuations. In contrast, the increase in EC was more than proportional. This difference between the two disease syndromes could be due to BN inoculum not originating from the grapevines, which are the final hosts of the phytoplasma (Maixner, 2010; Alma et al., 2019). For EC, the infected grapevines are the inoculum sources. For BN, primary inoculum arrives from other host plants via H. obsoletus, so the pathogen inoculum is likely to be relatively stable, which may explain the low variability in increase with time. In contrast, EC inoculum derives from infected grapevines whose numbers increase with time. This explains the greater than proportional increase in ECaffected grapevines. However, some annual variation in rate of increase also occurs for BN, because the number of infectious vectors can vary relative to the number of host plants that are sources of BN phytoplasma, and relative to the population density of the vector H. obsoletus (Mori et al., 2008; 2012; 2020; Panassiti et al., 2015).

In the present study, EC was more harmful to the grapevines than BN, as indicated by the greater number of symptomatic grapevines and the greater incidence of dead grapevines among those infected.

Interactions between BN and EC

Grapevines previously affected by BN were less likely to show symptoms of EC and die from EC than grapevines without BN. However, the probability that grapevines exhibited symptoms of EC was greater for BN-recovered grapevines than for those still symptomatic, although the likelihood of EC symptoms was always less than for grapevines that had never shown BN symptoms. These two data sets could suggest that in BNinfected grapevines, there are specific defense mechanisms induced by infections that prevent EC infections or symptom expression, and that these mechanisms are less present in BN-recovered grapevines (therefore no longer symptomatic) than in those that have not recovered (therefore still symptomatic) but have active defense mechanisms.

It is known that induced defense in host plants confers resistance, not only towards the pathogen that activated the resistance mechanisms, but also against other pathogens (Sticher et al., 1997; Durrant and Dong, 2004; Vlot et al., 2021; Cooper and Ton, 2022). Activation of defense mechanisms is well documented for GYs. Recent studies have shown that concentrations of defense compounds (phenolic substances), including stilbenoids, flavonols and flavanols, are increased in the presence of BN or FD infections (Rusjan et al., 2015; Pagliarani et al., 2020; Casarin et al., 2023). Other studies have reported that after infection of grapevines with 'Ca. P. solani', most jasmonic acid (JA) and salicylic acid (SA) biosynthetic genes are up-regulated, as compared to uninfected plants (Paolacci et al., 2017; Rotter et al., 2018; Dermastia, 2019). In stably recovered plants, increased levels of endogenous H2O2 and increased concentrations of specific stilbenoids, including viniferin, have been demonstrated (Musetti et al., 2007; Gambino et al., 2013; Pagliarani et al., 2020). Activation of defense genes is also linked to JA-dependent signalling, and suppression of SA-dependent signalling is important for establishment and maintenance of host recovery (Paolacci et al., 2017; Pagliarani et al., 2020). The role of mechanisms of induced resistance in recovered grapevines has been indirectly confirmed by the efficacy of resistance inducers in improving the recovery of BN-affected grapevines (Romanazzi et al., 2009).

EC infections also significantly reduce the likelihood of BN infections. In this case, it would be the EC infections that induce traits in grapevines that act as resistance factors against phytoplasmas. Several reports have indicated involvement of upregulations of the phenylalanine ammonia-lyase (PAL) gene, which encodes the first enzyme of the phenylpropanoid pathway, along with the chalcone synthase (CHS) and stilbene synthase (STS) genes, coding for enzymes of the flavonoid and stilbenoid pathways (Kenfaoui et al., 2022; Garcia et al., 2022). Recent data also suggested a JA-dependent signalling mechanism activated after invasion of wood by EC-associated fungi, that induces accumulation of secondary metabolites such as phytoalexins and pathogenesis-related proteins (PRs) (Goufo et al., 2020). EC-symptomatic plants are also unattractive for the vector H. obsoletus, as happened in grapevines treated with a chemical elicitor emitting volatiles that repelled adult planthoppers (Minuz et al., 2020).

Grapevines previously symptomatic for BN were less likely to show EC symptoms, and non-BN symptomatic plants were more likely than BN symptomatic plants to develop EC symptoms, probably influenced the spatial distribution of grapevines with symptoms of each disease. This might explain why where there are patches of one disease there are gaps of the other, and vice versa. The present study has therefore highlighted that spatial distribution of a disease within a crop can be influenced by the presence of a separate pathogen.

Sidebar

Citation: Pavan, F., Cargnus, E., Frizzera, D., Martini, M., & Ermacora, P. (2024). Interactions between bois noir and the esca disease complex in a Chardonnay vineyard in Italy. Phytopathologia Mediterranea 63(2): 303-314.

Accepted: August 10, 2024

Published: September 15, 2024

Data Availability Statement: All relevant data are within the paper and its Supporting Information files.

Competing Interests: The Author(s) declare(s) no conflict of interest.

Editor: Josep Armengol Forti, Polytechnical University of Valencia, Spain.

ORCID:

FP: 0000-0001-9111-2144

EC: 0000-0002-2107-6245

DF : 0000-0002-8809-2768

MM: 0000-0002-7271-5297

PE: 0000-0003-0757-7956

*Corresponding author. E-mail: [email protected]

References

LITERATURE CITED

Albertazzi G., Milc J., Caffagni A., Francia E., Roncaglia E., ... Pecchioni N., 2009. Gene expression in grapevine cultivars in response to Bois Noir phytoplasma infection. Plant Science 176: 792–804.

Alma A., Lessio F., Nickel H., 2019. Insects as phytoplasma vectors: Ecological and epidemiological aspects. In: Phytoplasmas: Plant Pathogenic Bacteria-II, Transmission and Management of PhytoplasmaAssociated Diseases (A. Bertaccini, P.G. Weintraub, G.P. Rao, N. Mori, ed.) Springer, Singapore, 1–25.

Amponsah N.T., Jones E.F., Ridgway H.J., Jaspers M.V., 2011. Identification, potential inoculum sources and pathogenicity of botryosphaeriaceous species associated with grapevine dieback disease in New Zealand. European Journal of Plant Pathology 131: 467–482.

Angelini E., Constable F., Duduk B., Fiore N., Quaglino F., Bertaccini A., 2018. Grapevine phytoplasmas. In: Phytoplasmas: Plant Pathogenic Bacteria-I, Characterisation and Epidemiology of Phytoplasma-Associated Diseases (G.P. Rao, A. Bertaccini, N. Fiore, L.W. Liefting, ed.) Springer, Singapore, 123–152.

Belli G., Bianco P.A., Conti M., 2010. Grapevine yellows in Italy: past, present and future. Journal of Plant Pathology 92: 303–326.

Bellomo C., Carraro L., Ermacora P. Pavan F., Osler R., ... Governatori G., 2007. Recovery phenomena in grapevines affected by grapevine yellows in Friuli Venezia Giulia. Bulletin of Insectology 60: 235‒236.

Bertazzon N., Bagnaresi P., Forte V., Mazzucotelli E., Filippin L., ... Angelini E., 2019. Grapevine comparative early transcriptomic profiling suggests that Flavescence dorée phytoplasma represses plant responses induced by vector feeding in susceptible varieties. BMC Genomics 20: 526.

Bertsch C., Ramirez-Suero M., Magnin-Robert M., Larignon P., Chong J., ... Fontaine F., 2013. Grapevine trunk diseases: complex and still poorly understood. Plant Pathology 62: 243–265.

Bigot G., Sivilotti P., Stecchina M., Lujan C., Freccero A. Mosetti, D., 2020. Long-term effects of Trichoderma asperellum and Trichoderma gamsii on the prevention of esca in different vineyards of Northeastern Italy. Crop Protection 137: 105264.

Borgo M., Pegoraro G., Sartori E., 2016. Susceptibility of grape varieties to esca disease. In: 39th World Congress of Vine and Wine, BIO Web of Conferences, 7: 01041. DOI: 10.1051/bioconf/20160701041.

Bruez E., Lecomte P., Grosman J., Doublet B., Bertsch C., ... Gu.rin-Dubrana L., 2013. Overview of grapevine trunk diseases in France in the 2000s. Phytopathologia Mediterranea 52: 262–275.

Bruez E., Vallance J., Gautier A., Laval V., Compant, ... Rey P., 2020. Major changes in grapevine wood microbiota are associated with the onset of esca, a devastating trunk disease. Environmental Microbiology 22: 5189–5206.

Bulgari D., Casati P., Quaglino F., Bianco P. A., Compant S., Mathieu F., 2016. Endophytic bacteria associated with grapevine plants: putative candidates for phytoplasma containment. In: Biocontrol of Major Grapevine Diseases: Leading Research, CABI, Wallingford, UK, 215–230.

Casarin S., Vincenzi S., Esposito A., Filippin L., Forte V., Bertazzon N., 2023. A successful defence strategy in grapevine cultivar 'Tocai friulano' provides compartmentation of grapevine Flavescence dorée phytoplasma. BMC Plant Biology 23(1): 161.

Claverie M., Notaro M., Fontaine F., Wery J., 2020. Current knowledge on Grapevine Trunk Diseases with complex etiology: a systemic approach. Phytopathologia Mediterranea 59(1): 29–53.

Cooper A., Ton J. 2022. Immune priming in plants: from the onset to transgenerational maintenance. Essays Biochemistry 66: 635–646. https://doi.org/10.1042/ ebc20210082.

De la Fuente M., Fontaine F., Gramaje D., Armengol J., Smart R., ... Corio-Costet M.F., 2016. Grapevine Trunk Diseases. A Review. In: International Organisation of Vine and Wine , OIV. (Ed.), 1st edition, Paris, France, 24 p. ISBN : 979-10-91799-60-7.

Dermastia M., 2019. Plant Hormones in Phytoplasma Infected Plants. Frontiers in Plant Science 10: 477.

Durrant W.E., Dong X., 2004. Systemic acquired resistance. Annual Review of Phytopathology 42: 185–209.

Del Frari G., Cabral A., Nascimento T., Ferreira R. B., Oliveira H., 2019. Epicoccum layuense a potential biological control agent of esca-associated fungi in grapevine. PloS ONE 14, e0213273.

Fischer M., Peighami-Ashnaei S., 2019. Grapevine, esca complex, and environment: the disease triangle. Phytopathologia Mediterranea 58: 17–37.

Gambino G., Boccacci P., Margaria P., Palmano S., Gribaudo I., 2013. Hydrogen peroxide accumulation and transcriptional changes in grapevines recovered from Flavescence dorée disease. Phytopathology 103: 776784. https://doi.org/ 10.1094/PHYTO-11-12-0309-R

Garau R., Sechi A., Prota V.A., Moro G., 2007. Productive parameters in Chardonnay and Vermentino grapevines infected with "bois noir" and recovered in Sardinia. Bulletin of Insectology, 60(2) 233–234.

García J.A., Garrido I., Ortega A., del Moral J., Llerena, J.L., Espinosa F., 2022. Physiological and Molecular Responses of Vitis vinifera cv. Tempranillo Affected by Esca Disease. Antioxidants 11: 1720. https://doi. org/10.3390/ antiox11091720.

Goufo P., Cortez I., 2020. A lipidomic analysis of leaves of esca-affected grapevine suggests a role for galactolipids in the defense response and appearance of foliar symptoms. Biology 9(9): 268.

Goufo P., Marques A.C., Cortez I., 2019. Exhibition of local but not systemic induced phenolic defenses in Vitis vinifera L. affected by brown wood streaking, grapevine leaf stripe, and apoplexy (escacomplex). Plants 8 (10): 412.

Graniti A., Surico G., Mugnai L., 2000. Esca of grapevine: a disease complex or a complex of diseases? Phytopathologia Mediterranea 39: 16–20.

Haidar R., Roudet J., Bonnard O., Dufour M. C., CorioCostet M. F., ... Fermaud M., 2016. Screening and modes of action of antagonistic bacteria to control the fungal pathogen Phaeomoniella chlamydospora involved in grapevine trunk diseases. Microbiological Research 192: 172–184.

Kenfaoui J., Radouane N., Mennani M., Tahiri A., El Ghadraoui L., ... Barka, E. A., 2022. A panoramic view on Grapevine Trunk Diseases threats: Case of Eutypa dieback, Botryosphaeria dieback, and Esca disease. Journal of Fungi 8(6): 595.

Kosovac A., Jakovljević M., Krstić O., Cvrković T., Mitrović M., ... Jović J., 2019. Role of plant-specialized Hyalesthes obsoletus associated with Convolvulus arvensis and Crepis foetida in the transmission of 'Candidatus Phytoplasma solani'-inflicted bois noir disease of grapevine in Serbia. European Journal of Plant Pathology 153: 183–195.

Kovacs C., Balling P., Bihari Z., Nagy A., Sandor E., 2017. Incidence of grapevine trunk diseases is influenced by soil, topology and vineyard age, but not by Diplodia seriata infection rate in the Tokaj Wine Region, Hungary. Phytoparasitica 45: 21–32.

Landi L., Romanazzi G., 2011. Seasonal variation of defense-related gene expression in leaves from bois noiraffected and recovered grapevines. Journal of Agricultural and Food Chemistry 59: 6628–6637.

Langer M., Maixner M., 2004. Molecular characterisation of grapevine yellows associated phytoplasmas of the stolbur-group based on RFLP-analysis of non-ribosomal DNA. Vitis 43, 191–199.

Larignon P., Dubos B., 1997. Fungi associated with esca disease in grapevine. European Journal of Plant Pathology 103: 147–157.

Maixner M., 1994. Transmission of German grapevine yellows (Vergilbungskrankheit) by the planthopper Hyalesthes obsoletus (Auchenorrhyncha: Cixiidae). Vitis 33: 103–104.

Maixner M., 2010. Phytoplasmas epidemiological systems with multiple plant hosts. In Phytoplasmas: Genomes, Plant Hosts and Vectors; (P.G. Weintraub, P. Jones, ed.), CABI Publishing: Wallingford, UK, 213–232.

Margaria P., Palmano S., 2011. Response of the Vitis vinifera L. cv. 'Nebbiolo' proteome to Flavescence dorée phytoplasma infection. Proteomics 11: 212–224.

Martini M., Musetti R., Grisan S., Polizzotto R., Borselli S., Pavan F., Osler R., 2009. DNA-dependent detection of the grapevine fungal endophytes Aureobasidium pullulans and Epicoccum nigrum. Plant Disease 93: 993–998.

Mátai A., Teszlák P., Jakab G., 2020. Recovery of Vitis vinifera L. cv. 'Kékfrankos' from 'bois noir' disease. European Journal of Plant Pathology 156(3): 987–991.

Minuz R.L., Mancini V., Ruschioni S., Mozzon M., Foligni R., ... Riolo P., 2020. Volatiles emitted by resistance inducer-treated grapevines affect Hyalesthes obsoletus behavioural responses. Bulletin of Insectology 73: 117–123.

Mondello V., Larignon P., Armengol J., Kortekamp A., Vaczy K., ... Fontaine F. 2018. Management of grapevine trunk diseases: knowledge transfer, current strategies and innovative strategies adopted in Europe. Phytopathologia Mediterranea 57: 369–383.

Mori N., Pavan F., Bondavalli R., Reggiani N., Paltrinieri S., Bertaccini A., 2008. Factors affecting the spread of "Bois Noir" disease in north Italy vineyards. Vitis 47(1): 65–72.

Mori N., Pavan F., Reggiani N., Bacchiavini M., Mazzon L., ... Bertaccini A., 2012. Correlation of bois noir disease with nettle and vector abundance in northern Italy vineyards. Journal of Pest Science 85(1): 23–28.

Mori N., Cargnus E., Martini M., Pavan F., 2020. Relationships between Hyalesthes obsoletus, its herbaceous hosts and Bois noir epidemiology in northern Italian vineyards. Insects 11: 606.

Mugnai L., Graniti A., Surico G., 1999. Esca (Black Measles) and brown wood-streaking: two old and elusive diseases of grapevines. Plant Disease 83: 404–418.

Musetti R., Marabottini R., Badiani M., Martini M., Toppi L.S., ... Osler R., 2007. On the role of H2O2 in the recovery of grapevine (Vitis vinifera cv. Prosecco) from Flavescence dorée disease. Functional Plant Biology 34(8): 750–758.

Mutton P., Boccalon W., Bressan S., Coassin C., Colautti M., ... Villani A., 2002. Legno nero della vite in vigneti di Chardonnay del Friuli-Venezia Giulia. Informatore Fitopatologico 52(1): 52-59.

Nerva L., Turina M., Zanzotto A., Gardiman M., Gaiotti F., ... Chitarra W., 2019. Isolation, molecular characterization and virome analysis of culturable wood fungal endophytes in esca symptomatic and asymptomatic grapevine plants. Environmental Microbiology 21: 2886–2904.

Nutricati E., Pascali M., de Negro C., Bianco P.A., Quaglino F., ... Luvisi A., 2023. Signalling cross-talk between salicylic and gentisic acid in the 'Candidatus Phytoplasma solani' interaction with Sangiovese grapevines. Plants 12: 14.

Osler R., Carraro L., Loi N., Refatti E., 1993. Symptom expression and disease occurrence of a yellow disease of grapevine in northeastern Italy. Plant Disease 77: 496‒498.

Osler R., Zucchetto C., Carraro L., Frausin C., Mori N., Pavan F., Vettorello G., Girolami V., 2002. Trasmissione di flavescenza dorata e legno nero e comportamento delle viti infette. L'Informatore Agrario 58 (19): 61‒65.

Pacifico D., Margaria P., Galetto L., Legovich M., Abbà S., ... Palmano S., 2019. Differential gene expression in two grapevine cultivars recovered from "flavescence dorée". Microbiological Research 220: 72–82.

Pagliarani C., Gambino G., Ferrandino A., Chitarra W., Vrhovsek U., ... Schubert, A. 2020. Molecular memory of Flavescence dorée phytoplasma in recovering grapevines. Horticulture Research 7: 126.

Panassiti B., Hartig F., Breuer M., Biedermann R., 2015. Bayesian inference of environmental and biotic factors determining the occurrence of the grapevine disease 'bois noir'. Ecosphere 6: 143.

Paolacci A.R., Catarcione G., Ederli L., Zadra C., Pasqualini S., ... Ciaffi M., 2017. Jasmonate-mediated defence responses, unlike salicylate-mediated responses, are involved in the recovery of grapevine from bois noir disease. BMC PlantBiology 17: 118.

Pavan F., Carraro L., Vettorello G., Pavanetto E., Girolami V., Osler R., 1997. Flavescenza dorata nei vigneti delle colline trevigiane. L'Informatore Agrario 53(10): 73–78.

Pavan F., Mori N., Bressan S., Mutton P., 2012. Control strategies for grapevine phytoplasma diseases: Factors influencing the profitability of replacing symptomatic plants. Phytopathologia Mediterranea 51: 11–22.

Pavan F., Frizzera D., Martini M., Lujan C., Cargnus E., 2024. Is the removal of nettles along ditches effective in controlling Bois noir in vineyards? Agronomy 14: 643.

Perry J. N., 1998. Measures of spatial pattern for counts. Ecology 79: 1008–1017.

Perry J.N., Dixon P.M., 2002. A new method to measure spatial association for ecological count data. Écoscience 9(2): 133–141.

Perry J. N., Winder L., Holland J.M., 1999. Red-blue plots for detecting clusters in count data. Ecology Letters 2: 106–113.

Pierro R., de Pascali M., Panattoni A., Passera A., Materazzi A., ... Quaglino F., 2022. In silico three-dimensional (3D) modeling of the SecY protein of 'Candidatus Phytoplasma solani' strains associated with grapevine "bois noir" and its possible relationship with strain virulence. International Journal of Plant Biology 13(2): 15–30.

Quaglino F., Zhao Y., Casati P., Bulgari D., Bianco P.A., ... Davis R.E., 2013. 'Candidatus Phytoplasma solani', a novel taxon associated with stolbur-and bois noirrelated diseases of plants. International Journal of Systematic and Evolutional Microbiology 63: 2879–2894.

Ramírez-Suero M., Bénard-Gellon M., Chong J., Laloue H., Stempien E., ... Bertsch C., 2014. Extracellular compounds produced by fungi associated with Botryosphaeria diebackinduce differential defence gene expression patterns and necrosis in Vitis vinifera cv. Chardonnay cells. Protoplasma 251(6): 1417–1426.

Riffle V.L., Alvarez Arredondo J., Lomonaco I., Appel C., Catania A.A., ... Casassa L.F., 2022. Vine age affects grapevine performance, grape and wine chemical and sensory composition of cv. Zinfandel from California. American Journal of Enology and Viticulture 73: 277–293. https://doi.org/10.5344/ajev.2022.22014

Romanazzi G., D'Ascenzo D., Murolo S., 2009. Field treatment with resistance inducers for the control of grapevine Bois noir. Journal of Plant Pathology 91(3): 677–682.

Romanazzi G., Murolo S., Feliziani E., 2013. Effects of an innovative strategy to contain grapevine Bois noir: field treatment with resistance inducers. Phytopathology 103(8): 785–791.

Romeo-Oliván A., Chervin J., Breton C., Lagravère T., Daydé J., ... Gaur R.K., 2022. Comparative transcriptomics suggests early modifications by vintec® in grapevinetrunk of hormonal signaling and secondary metabolism biosynthesis in response to Phaeomoniella chlamydospora and Phaeoacremonium minimum. Frontiers in Microbiology 13: 898356.

Rotter A., Nikolić P., Turnšek N., Kogovšek P., Blejec A., Gruden K., Dermastia M., 2018.

Statistical modeling of long-term grapevine response to 'Candidatus Phytoplasma solani' infection in the field. European Journal of Plant Pathology 150: 653–668.

Rusjan D., Mikulic-Petkovsek M., 2015. Phenolic responses in 1-year-old canes of Vitis vinifera cv. Chardonnay induced by grapevine yellows (Bois noir). Australian Journal of Grape and Wine Research 21(1): 123–34.

Santi S., Grisan S., Pierasco A., De Marco F., Musetti R., 2013. Laser microdissection of grapevine leaf phloem infected by stolbur reveals site-specific gene responses associated to sucrose transport and metabolism. Plant, Cell and Environment 36(2): 343–355.

Stempien E., Goddard M.L., Leva Y., Bénard-Gellon M., Laloue H., ... Chong J., 2018. Secreted proteins produced by fungi associated with Botryosphaeria dieback trigger distinct defense responses in Vitis vinifera and Vitis rupestris cells. Protoplasma 255(2): 613–628.

Sticher L., Mauch-Mani B., Métraux J. P., 1997. Systemic acquired resistance. Annual Review of Phytopathology 35: 235–270.

Surico G., 2009. Towards a redefinition of the diseases within the esca complex of grapevine. Phytopathologia Mediterranea 48: 5–10.

Surico G., Mugnai L., Marchi G., 2006. Older and more recent observations on esca: a critical overview. Phytopathologia Mediterranea 45: 68–86.

Úrbez-Torres J.R., 2011. The status of Botryosphaeriaceae species infecting grapevines. Phytopathologia Mediterranea 50: S5−S45

Vlot A., Sales C.J.H., Lenk M., Bauer K., Brambilla A., ... Nayem S., 2021. Systemic propagation of immunity in plants. New Phytologist 229(3): 1234–1250.

Yacoub A., Magnin N., Gerbore J., Haidar R., Bruez E., ... Rey P., 2020. The biocontrol root-oomycete, Pythium oligandrum, triggers grapevine resistance and shifts in the transcriptome of the trunk pathogenic fungus, Phaeomoniella chlamydospora. International Journal of Molecular Sciences 21: 18.

Zahavi T., Sharon R., Sapir G., Mawassi M., Dafny-Yelin M., Naor V., 2013. The long-term effect of Stolbur phytoplasma on grapevines in the Golan Heights. Australian Journal of Grape and Wine Research 19(2): 277–284.