The interplay of suppressive soil bacteria and plant root exudates determines germination of microsclerotia of Verticillium longisporum.

Dormant microsclerotia play a vital role in the survival and spread of Verticillium longisporum, as they can stay viable in the soil and maintain their infectivity for many years. In our previous work, we revealed that soil bacterial volatiles are a key inhibitory factor causing microsclerotia dormancy in the soil. In this study, we further demonstrate that root exudates collected from both host and non-host plants can effectively rescue microsclerotia from bacterial suppression and initiate germination. To identify the specific compounds in root exudates responsible for microsclerotia germination, we fractionated the collected root exudates into polar and non-polar compounds. Subsequently, we conducted comprehensive bioassays with each fraction on germination-suppressed microsclerotia. The result revealed a pivotal role of primary metabolites in root exudates, particularly glutamic acid, in triggering microsclerotia germination and overcoming bacterial inhibition. Moreover, our studies revealed a decrease in inhibitory bacterial volatile fatty acids when bacteria were cultured in the presence of root exudates or glutamic acid. This suggests a potential mechanism, by which root exudates set-off bacterial suppression on microsclerotia. Here, we reveal for the first time that plant root exudates, instead of directly inducing the germination of microsclerotia, enact a set-off effect by counteracting the suppressive impact of soil bacteria on the microsclerotia germination process. This nuanced interaction advances our understanding of the multifaceted dynamics governing microsclerotia dormancy and germination in the soil environment. IMPORTANCE: Our research provides first-time insights into the crucial interaction between plant root exudates and soil bacteria in regulating the germination of Verticillium longisporum microsclerotia, a significant structure in the survival and proliferation of this soil-borne pathogen. We describe so far unknown mechanisms, which are key to understand how root infections on oilseed rape can occur. By pinpointing primary metabolites in root exudates as key factors in overcoming bacteria-induced dormancy and promote microsclerotia germination, our study highlights the potential for exploiting plant - as well as soil microbe-derived - compounds to control V. longisporum. This work underscores the importance of elucidating the nuanced interactions within the soil ecosystem to devise innovative strategies for managing root infective plant diseases, thereby contributing to the resilience and health of cropping systems.

Mycoviruses Increase the Attractiveness of Fusarium graminearum for Fungivores and Suppress Production of the Mycotoxin Deoxynivalenol.

RNA viruses of the genera Ambivirus, Mitovirus, Sclerotimonavirus, and Partitivirus were found in a single isolate of Fusarium graminearum. The genomes of the mitovirus, sclerotimonavirus, and partitivirus were assigned to previously described viruses, whereas the ambivirus genome putatively represents a new species, named Fusarium graminearum ambivirus 1 (FgAV1). To investigate the effect of mycoviruses on the fungal phenotype, the spontaneous loss of mycoviruses during meiosis and the transmission of mycoviruses into a new strain via anastomosis were used to obtain isogenic F. graminearum strains both with and without mycoviruses. Notable effects observed in mycovirus-harboring strains were (i) the suppression of the synthesis of trichothecene mycotoxins and their precursor trichodiene, (ii) the suppression of the synthesis of the defense compound aurofusarin, (iii) the stimulation of the emission of 2-methyl-1-butanol and 3-methyl-1-butanol, and (iv) the increased attractiveness of fungal mycelia for fungivorous collembolans. The increased attractiveness of mycovirus-infected filamentous fungi to animal predators opens new perspectives on the ecological implications of the infection of fungi with viruses.

Changes in bioactive compounds and antioxidant activity of three Amaranthus L. genotypes from a model to household processing.

Amaranthus L. leaves are consumed as vegetables and are a rich source of secondary plant metabolites. The phenolic profiles of the three analyzed genotypes by LC-Q-TOF-MS/MS and HPLC-DAD were characterized by high amounts of hydroxycinnamic glucaric and -isocitric acids. 'Gartenfuchsschwanz' (A. hybridus L.) and 'Red Callaloo' (A. tricolor L.) had similar profiles. 'Gemüse-Amaranth' (A. tricolor L.) had a high amount of caffeoylglucaric acid 4, which was isolated, and afterward identified by NMR. Its antioxidant activity, measured by TEAC, DPPH, and TPC, was similar to 5-caffeoylquinic acid, common in many plant species. The antioxidant activity of Amaranthus L. can be explained rather by their different phenolic- and ascorbic acid concentrations than by their species. Household cooking reduces antioxidant activity due to oxidation processes while leaching into cooking water could be neglected. Amaranthus L. baked into a wheat-dough-matrix showed lower phenolic concentrations, presumably due to the formation of phenol-protein-bounds and thermal degradation.

A Pilot Study on Monomer and Bisphenol A (BPA) Release from UDMA-Based and Conventional Indirect Veneering Composites.

This study aimed to investigate the release of common monomers from conventional (Dialog Vario, Enamel Plus HFO) and UDMA-based indirect veneering composites (VITA VM LC, GC Gradia). Ten cylindrical samples of each material were prepared (n = 40), immersed in HPLC grade water, and incubated for 24 h in an incubation shaker at 37 °C and 112 rpm. Extraction was performed following ISO 10993-12 and monomers were detected and quantified by HPLC-MS/MS. In all the samples, urethane dimethacrylate (UDMA) and bisphenol A (BPA) were quantifiable. Compared to water blanks, BPA levels were only elevated in the eluates from conventional composites. In all other samples, concentrations were in the range of extraneous BPA and were therefore clinically irrelevant. Low concentrations of Bisphenol A-glycidyl methacrylate (BisGMA) were found in one BPA-free composite and in both conventional materials. Statistical analyses showed that BPA-free materials released significantly less BisGMA and no BPA, while UDMA elution was comparable to elution from conventional materials. All measured concentrations were below reported effective cytotoxic concentrations. Considering these results, the substitution of BPA-derivatives with UDMA might be beneficial since BPA-associated adverse effects are ruled out. Further studies should be enrolled to test the biocompatibility of UDMA on cells of the oral environment.

Root Colonization by Fungal Entomopathogen Systemically Primes Belowground Plant Defense against Cabbage Root Fly.

Entomopathogenic fungi infect insects via spores but also live inside plant tissues as endophytes. Frequently, colonization by entomopathogens provides plants with increased resistance against insects, but the mechanisms are little understood. This study investigated direct, local, and systemic root-mediated interactions between isolates of the fungus Metarhizium brunneum and larvae of the cabbage root fly (CRF) Delia radicum attacking Brassica napus plants. All fungal isolates infected CRF when conidia were present in the soil, leading to 43-93% mortality. Locally, root-associated M. brunneum isolates reduced herbivore damage by 10-20% and in three out of five isolates caused significant insect mortality due to plant-mediated and/or direct effects. A split-root experiment with isolate Gd12 also demonstrated systemic plant resistance with significantly reduced root collar damage by CRF. LC-MS analyses showed that fungal root colonization did not induce changes in phytohormones, while herbivory increased jasmonic acid (JA) and glucosinolate concentrations. Proteinase inhibitor gene expression was also increased. Fungal colonization, however, primed herbivore-induced JA and the expression of the JA-responsive plant defensin 1.2 (PDF1.2) gene. We conclude that root-associated M. brunneum benefits plant health through multiple mechanisms, such as the direct infection of insects, as well as the local and systemic priming of the JA pathway.

Fusarium culmorum Produces NX-2 Toxin Simultaneously with Deoxynivalenol and 3-Acetyl-Deoxynivalenol or Nivalenol

Fusarium culmorum is a major pathogen of grain crops. Infected plants accumulate deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ADON), or nivalenol (NIV), which are mycotoxins of the trichothecene B group. These toxins are also produced by F. graminearum species complex. New trichothecenes structurally similar to trichothecenes B but lacking the carbonyl group on C-8, designated NX toxins, were recently discovered in atypical isolates of F. graminearum from North America. Only these isolates and a few strains of a yet to be characterized Fusarium species from South Africa are known to produce NX-2 and other NX toxins. Here, we report that among 20 F. culmorum strains isolated from maize, wheat, and oat in Europe and Asia over a period of 70 years, 18 strains produced NX-2 simultaneously with 3-ADON and DON or NIV. Rice cultures of strains producing 3-ADON accumulated NX-2 in amounts corresponding to 2−8% of 3-ADON (1.2−36 mg/kg). A strain producing NIV accumulated NX-2 and NIV at comparable amounts (13.6 and 10.3 mg/kg, respectively). In F. graminearum, producers of NX-2 possess a special variant of cytochrome P450 monooxygenase encoded by TRI1 that is unable to oxidize C-8. In F. culmorum, producers and nonproducers of NX-2 possess identical TRI1; the reason for the production of NX-2 is unknown. Our results indicate that the production of NX-2 simultaneously with trichothecenes B is a common feature of F. culmorum.

Monomer Release from Dental Resins: The Current Status on Study Setup, Detection and Quantification for In Vitro Testing.

Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However, dental resins are not inert in the oral environment and may release monomers and other substances such as Bisphenol-A (BPA) due to incomplete polymerization and intraoral degradation. Current research shows that various monomers present cytotoxic, genotoxic, proinflammatory, and even mutagenic effects. Of these eluting substances, the elution of BPA in the oral environment is of particular interest due to its role as an endocrine disruptor. For this reason, the release of residual monomers and especially BPA from dental resins has been a cause for public concern. The assessment of patient exposure and potential health risks of dental monomers require a reliable experimental and analytical setup. However, the heterogeneous study design applied in current research hinders biocompatibility testing by impeding comparative analysis of different studies and transfer to the clinical situation. Therefore, this review aims to provide information on each step of a robust experimental and analytical in vitro setup that allows the collection of clinically relevant data and future meta-analytical evaluations.

A comparative in vitro study on monomer release from bisphenol A-free and conventional temporary crown and bridge materials.

This study aimed to investigate the release of common monomers from two conventional and two bisphenol A (BPA)-free temporary crown and bridge materials. Cylindrical samples of all materials were prepared (N = 90; five samples for each material and cycle of analysis). All samples were immersed in high-performance liquid chromatography (HPLC)-grade water and incubated for 1 h, 12 h, 24 h, and 7 days in an incubation shaker at 37°C and 112 rpm. Extraction was performed in accordance with ISO 10993-12. Eluted monomers were detected and quantified by HPLC coupled with ultraviolet-visible spectroscopy and mass spectrometry (HPLC-UV/Vis-MS). Analysis of BPA was performed by HPLC coupled with ultraviolet-visible spectroscopy (HPLC-UV/Vis) and positive results were verified by HPLC-tandem mass spectrometry (HPLC-MS/MS). Neither bisphenol A-glycidyl methacrylate (Bis-GMA) nor BPA was quantifiable in any of the crown and bridge samples investigated in the present study. However, all samples contained triethylene glycol dimethacrylate (TEGDMA) and/or urethane dimethacrylate (UDMA) after 24 h of incubation. Statistical analysis showed that significantly more UDMA was released from the BPA-free materials than from the conventional materials. All concentrations of UDMA measured were below the effective cytotoxic concentrations previously reported. However, for a few materials, especially BPA-free temporary crown and bridge materials, the levels of UDMA were above previously reported potentially harmful concentrations for local cells. As BPA-free materials were introduced as being more biocompatible than materials containing BPA, substitution of Bis-GMA with UDMA should be further investigated.

Protection of Citrus Fruits from Postharvest Infection with Penicillium digitatum and Degradation of Patulin by Biocontrol Yeast Clavispora lusitaniae 146.

Fungal rots are one of the main causes of large economic losses and deterioration in the quality and nutrient composition of fruits during the postharvest stage. The yeast Clavispora lusitaniae 146 has previously been shown to efficiently protect lemons from green mold caused by Penicillium digitatum. In this work, the effect of yeast concentration and exposure time on biocontrol efficiency was assessed; the protection of various citrus fruits against P. digitatum by C. lusitaniae 146 was evaluated; the ability of strain 146 to degrade mycotoxin patulin was tested; and the effect of the treatment on the sensory properties of fruits was determined. An efficient protection of lemons was achieved after minimum exposure to a relatively low yeast cell concentration. Apart from lemons, the yeast prevented green mold in grapefruits, mandarins, oranges, and tangerines, implying that it can be used as a broad-range biocontrol agent in citrus. The ability to degrade patulin indicated that strain 146 may be suitable for the control of further Penicillium species. Yeast treatment did not alter the sensory perception of the aroma of fruits. These results corroborate the potential of C. lusitaniae 146 for the control of postharvest diseases of citrus fruits and indicate its suitability for industrial-scale fruit processing.