Disentangling the effects of terroir, season, and vintage on the grapevine fungal pathobiome

The composition, diversity and dynamics of microbial communities associated with grapevines may be influenced by various environmental factors, including terroir, vintage, and season. Among these factors, terroir stands out as a unique possible determinant of the pathobiome, the community of plant-associated pathogens. This study employed high-throughput molecular techniques, including metabarcoding and network analysis, to investigate the compositional dynamics of grapevine fungal pathobiome across three microhabitats (soil, woody tissue, and bark) using the Furmint cultivar. Samples were collected during late winter and late summer in 2020 and 2021, across three distinct terroirs in Hungary’s Tokaj wine region. Of the 123 plant pathogenic genera found, Diplodia, Phaeomoniella, and Fusarium displayed the highest richness in bark, wood, and soil, respectively. Both richness and abundance exhibited significant disparities across microhabitats, with plant pathogenic fungi known to cause grapevine trunk diseases (GTDs) demonstrating highest richness and abundance in wood and bark samples, and non-GTD pathogens prevailed soil. Abundance and richness, however, followed distinct patterns Terroir accounted for a substantial portion of the variance in fungal community composition, ranging from 14.46 to 24.67%. Season and vintage also contributed to the variation, explaining 1.84 to 2.98% and 3.67 to 6.39% of the variance, respectively. Notably, significant compositional differences in fungi between healthy and diseased grapevines were only identified in wood and bark samples. Cooccurrence networks analysis, using both unweighted and weighted metrics, revealed intricate relationships among pathogenic fungal genera. This involved mostly positive associations, potentially suggesting synergism, and a few negative relationships, potentially suggesting antagonistic interactions. In essence, the observed differences among terroirs may stem from environmental filtering due to varied edaphic and mesoclimatic conditions. Temporal weather and vine management practices could explain seasonal and vintage fungal dynamics. This study provides insights into the compositional dynamics of grapevine fungal pathobiome across different microhabitats, terroirs, seasons, and health statuses. The findings emphasize the importance of considering network-based approaches in studying microbial communities and have implications for developing improved viticultural plant health strategies

Mycoparasitism capability and growth inhibition activity of Clonostachys rosea isolates against fungal pathogens of grapevine trunk diseases suggest potential for biocontrol

The present study aimed to examine the capability of Clonostachys rosea isolates as a biological control agent against grapevine trunk diseases pathogens. Five C. rosea and 174 pathogenic fungal strains were isolated from grafted grapevines and subjected to in vitro confrontation tests. Efficient antagonism was observed against Eutypa lata and Phaeomoniella chlamydospora while mycoparasitism was observed to the pathogens of Botryosphaeria dothidea and Diaporthe spp. pathogens in in vitro dual culture assays. The conidia production of the C. rosea isolates were also measured on PDA plates. One isolate (19B/1) with high antagonistic capabilities and efficient conidia production was selected for in planta confrontation tests by mixing its conidia with the soil of Cabernet sauvignon grapevine cuttings artificially infected with B. dothidea, E. lata and P. chlamydospora. The length and/or the incidence of necrotic lesions caused by E. lata and P. chlamydospora at the inoculation point were significantly decreased after a three months incubation in the greenhouse on cuttings planted in soils inoculated with the conidia of strain 19B/1, while symptom incidence and severity were unaffected in the case of the pathogen B. dothidea. Based on the above results, we consider C. rosea a promising biological control agent against some grapevine trunk diseases

The origin of the particular aroma of noble rot wines: various fungi contribute to the development of the aroma profile of botrytised grape berries

During noble rot (NR), B. cinerea, together with other filamentous fungi and yeasts, play a role in developing the unique aromatic profile of botrytised wines. To gain more insight into the latter, we generated metatranscriptomic data representing the four NR stages (I-IV) from the Tokaj wine region of Hungary over three months. Since previous research has indicated that the most prevalent filamentous fungi and yeast include Alternaria alternata, Botrytis cinerea, Epicoccum nigrum, Aureobasidium pullulans and Rhodotorula graminis, RNAseq reads were aligned to the latter species. A weighted gene co-expression network analysis (WGCNA) followed by a non-metric multidimensional scaling (NMDS), eigengene ANOVA and enrichment analyses were performed. Amongst the ten generated gene module clusters, enriched pathways involved in synthesising aromatic compounds such as amino acid-, carbohydrate- and lipid metabolism co-jointly expressed by all filamentous fungi and yeast were identified within the turquoise module. Furthermore, it was found that the enzymes involved in the synthesis of aromatic compounds are expressed and up-regulated during the later stages (III-IV) of the NR process. This study has indicated that the unique aromatic profile of botrytised wines is due to the contributions of filamentous fungi and yeasts belonging to the NR grape microbiome, with the main aromatic contributions occurring during the later NR stages

A Clonostachys rosea biokontroll ágensként történő jellemzése a szőlő korai elhalását okozó gombás betegségek ellen

Diplomadolgozatomban szőlőoltványok mikobiótája került megvizsgálásra, fokuszálva a korai tőkeelhalás (grapevine trunk diseases - GTD) kórokozóira és az ellenük használható biokontroll ágensekre. Száz oltványról összesen 271 gomba került izolálásra és meghatározásra. Ezek közül 163 bizonyult GTD kórokozónak melyek az oltványok több mint feléről voltak izolálhatók.További vizsgálataim tárgya volt az ugyancsak szőlőoltványról izolált Clonostachys rosea biokontroll képességeinek felmérése a szőlő korai elhalását okozó patogén gombafajok ellen. In vitro tesztek segítségével a C. rosea izolátumok antagonista (gátló) képességeit, mikoparazita képességeit mértem fel a GTD kórokozókkal szemben. Ezenkívül sor került került a C. rosea izolátumok összehasonlító vizsgálatára. Az in vitro tesztek eredményei alapján a GTD kórokozók ellen eredményes lehet a C. rosea, azonban a megfelelő törzsek és technológiák kiválasztásához további kísérletek elvégzése szükséges.MSc/MAÉlelmiszerbiztonsági és -minőségi mérnökV

In vitro characterization of a Bacillus velezensis isolate as an antagonist of grapevine trunk disease pathogens

One of the major and yet unsolved threats for viticulture is the group of vascular fungal infections, the so-called grapevine trunk diseases. Besides their latent nature and the enormous number of associated pathogens, their control is also hampered by the lack of effective fungicides, directing growing attention toward the use of biocontrol agents. In the present study the isolation, identification, and characterization of a bacterial strain are presented, showing biocontrol potential against some main causal agents of grapevine trunk diseases. The strain was isolated from the wood of an asymptomatic grapevine and selected for the fungicidal activity against the pathogen Phaeomoniella chlamydospora . According to 16S rDNA, gyrA, and gyrB sequences, the isolate belongs to Bacillus velezensis species. Confrontation tests with the bacterium or with its fermentation broth further revealed growth inhibition and fungicide activity against Botryosphaeria dothidea , Eutypa lata and Diaporthe ampelina pathogens. Fractionation of the bacterial culture filtrate suggests that the antifungal agents secreted by the B. velezenzis isolate are mainly lipoproteins. Phytotoxicity tests were also carried out with the isolate, showing no harmful effects on grapevine foliar disks