Fungal Endophytes of Vitis vinifera-Plant Growth Promoters or Potentially Toxinogenic Agents?

Fungal endophytes occurring in grapevine (Vitis vinifera L.) are usually important sources of various compounds with biological activities with great potential for use in agriculture. Nevertheless, many species isolated from this plant belong to the genera Fusarium, Alternaria, or Aspergillus, all of which are well-known to produce mycotoxins. Our study is focused on the assessment of the toxinogenic potential of fungal endophytes isolated from vineyards in the Czech Republic. In total, 20 endophytic fungal species were cultivated in wine must, and 57 mycotoxins of different classes were analysed by liquid chromatography coupled with mass spectrometry. As a result, alternariol, tentoxin, meleagrin, roquefortine C, gliotoxin, and verruculogen were detected in the culture medium, of which verruculogen followed by gliotoxin were the most frequent (present in 90 and 40% of samples, respectively) and most concentrated (up to thousands ng/mL). The alternaria mycotoxins alternariol and tentoxin were detected not only in Alternaria sp. cultures, but traces of these mycotoxins were also quantified in the Diatripe and Epicoccum cultures. Meleagrin and roquefortine C were detected in Didymella sancta and Penicillium crustosum, gliotoxin was detected in Alternaria sp., Didymella sp., Aureobasidium pullulans, Cladosporium herbarum, Penicillium crustosum and Pleurophoma ossicola, and verruculogen was quantified in 99% of endophytic isolates investigated. The potential of endophytes to produce mycotoxins should be carefully checked, specifically in cases where they are intended for the purpose of V. vinifera growing.

Bacterial Endophytes from Vitis vinifera L. - Metabolomics Characterization of Plant-Endophyte Crosstalk.

Bacterial endophytes are known to protect Vitis vinifera L. against various harmful effects of the environment and support its growth. However, for the most part, biochemical responses of such co-existence have not yet been fully elucidated. In this work, we aimed to characterize the activities of endophytic consortia in a plant-endophyte extract by measuring five indicators of colonization (overall endophyte metabolic activity, microbial ACC deaminase activity, ability to solubilize phosphorus, ability to convert atmospheric nitrogen to ammonia ions, and ability to produce growth promoting indole acetic acid), and find relationships between these activities and metabolome. The V. vinifera canes for the metabolomics fingerprinting were extracted successively with water and methanol, and analysed by ultra-high performance liquid chromatography coupled with high resolution mass spectrometry. For data processing, the MS-DIAL - MS-CleanR - MS-FINDER software platform was used, and the data matrix was processed by PCA and PLS-DA multivariate statistical methods. The metabolites that were upregulated with the heavy endophyte colonization were mainly chlorins, phenolics, flavonoid and terpenoid glycosides, tannins, dihydropyranones, sesquiterpene lactones, and long-chain unsaturated fatty acids.

Metabolomic fingerprinting as a tool for authentication of grapevine (Vitis vinifera L.) biomass used in food production.

Use of 'green biomass' of the grapevine is gradually extending into the food industry. The aim of our study was to demonstrate the potential of metabolomic fingerprinting for characterization of grapevine leaves and canes. Our method comprises successive aqueous-methanolic extractions, followed by U-HPLC-HRMS/MS. For data processing, PCA and (O)PLS-DA methods were utilized, and mathematical models were validated. We showed that from all factors investigated, harvesting season explained most of the variability between samples, followed by locality combined with farming system. The identified statistically significant metabolites for harvesting season models mostly represented the groups of fatty acids, fatty phenols, (lyso)phospholipids, flavonoids and organic acids. For models of localities with different farming systems, majority of identified metabolites significant for organic farming belonged to groups of fatty acids and their derivatives, terpenoids, sterols, and fat soluble vitamins, whereas for conventional farming, the only identified significant metabolites were the pesticide residues.