Fungi of the genus Geosmithia are frequently associated with bark beetles that feed on phloem on various woody hosts. Most studies on Geosmithia were carried out in North and South America and Europe, with only two species being reported from Taiwan, China. This study aimed to investigate the diversity of Geosmithia species in China. Field surveys in Fujian, Guangdong, Guangxi, Hunan, Jiangsu, Jiangxi, Shandong, Shanghai, and Yunnan yielded a total of 178 Geosmithia isolates from 12 beetle species. The isolates were grouped based on morphology. The internal transcribed spacer, β-tubulin, and elongation factor 1-α gene regions of the representatives of each group were sequenced. Phylogenetic trees were constructed based on those sequences. In total, 12 species were identified, with three previously described species (Geosmithia xerotolerans, G. putterillii, and G. pallida) and nine new species which are described in this paper as G. luteobrunnea, G. radiata, G. brevistipitata, G. bombycina, G. granulata (Geosmithia sp. 20), G. subfulva, G. pulverea (G. sp. 3 and Geosmithia sp. 23), G. fusca, and G. pumila sp. nov. The dominant species obtained in this study were G. luteobrunnea and G. pulverea. This study systematically studied the Geosmithia species in China and made an important contribution to filling in the gaps in our understanding of global Geosmithia species diversity.

• Klíčová slova
• 9 new taxa, Geosmithia, bark beetles, fungal community, symbiosis,
• Publikační typ
• časopisecké články MeSH

Degradation of anthocyanins involves scission of the flavonoid skeleton yielding 2,4,6-trihydroxybenzaldehyde (phloroglucinaldehyde, PGA) and a phenolic acid. However, the process is not finished with the formation of PGA, as the consequent condensation of two PGA molecules providing colored hydroxylated anthraquinones was observed for the first time. This process was studied using a combination of preparative column chromatography, nuclear magnetic resonance, liquid chromatography/high resolution tandem mass spectrometry (LC/HRMS2), and quantum calculations using density functional theory. 1,3,5,7-tetrahydroxyanthraquinone (anthrachrysone) and its isomers were found to rise during heating (95 °C) in a buffered PGA model solution (phosphate buffer, pH 7). These compounds were detected in heated red wine after an increase of its pH value. The concentration of the identified anthrachrysone in the red wine reached 0.01 mg·L-1. Presence of those compounds could therefore indicate involvement of certain steps in the processing of plant materials rich in anthocyanins (e.g., utilization of a higher temperature and/or reduction of acidity) or long-term transformation of anthocyanins (potentially, for instance, in archaeological findings such as wine or fruit residues). Additionally, measurement of wine-soil suspensions proved an increase of their pH to the values suitable for anthocyanin cleavage (neutral to slightly alkaline; reached using soil from archaeologically well-known Bull Rock Cave). Although not found in artificially prepared samples (imitations) or authentic materials so far, according to our results the above mentioned conditions are suitable for the formation of tetrahydroxylated anthraquinone derivatives and their monitoring would be beneficial.

• Klíčová slova
• anthocyanin, degradation, hydroxyanthraquinone, phloroglucinaldehyde, wine,
• MeSH
• analýza potravin * metody   MeSH
• anthokyaniny chemie   MeSH
• anthrachinony analýza   chemie   MeSH
• chromatografie kapalinová MeSH
• hmotnostní spektrometrie MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• víno analýza   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• anthokyaniny MeSH
• anthrachinony MeSH