Specific guanine rich nucleic acid sequences can form non-canonical structures, like the four stranded G-quadruplex (GQ). We studied the GQ-forming sequence (named HepB) found in the genome of the hepatitis B virus. Fluorescence-, infrared- and CD-spectroscopy were used. HepB shows a hybrid form in presence of K⁺, but Na⁺, Li⁺, and Rb⁺ induce parallel structure. Higher concentrations of metal ions increase the unfolding temperature, which was explained by a short thermodynamic calculation. Temperature stability of the GQ structure was determined for all these ions. Na⁺ has stronger stabilizing effect on HepB than K⁺, which is highly unusual. The transition temperatures were 56.6, 53.8, 58.5 and 54.4 °C for Na⁺, K⁺, Li⁺, and Rb⁺ respectively. Binding constants for Na⁺ and K⁺ were 10.2 mM and 7.1 mM respectively. Study of three ligands designed in cancer research for GQ targeting (TMPyP4, BRACO19 and PhenDC3) showed unequivocally their binding to HepB. Binding was proven by the increased stability of the bound form. The stabilization was higher than 20 °C for TMPyP4 and PhenDC3, while it was considerably lower for BRACO19. These results might have medical importance in the fight against the hepatitis B virus.

Carbendazim resistance was detected using 4,701 Fusarium graminearum species complex isolates collected from major wheat-producing regions in China from 2018 to 2020. A total of 348 carbendazim-resistant isolates were identified. The majority of carbendazim-resistant isolates were detected in Jiangsu and Anhui Provinces. In total, 227 and 88 isolates were obtained from each of the Jiangsu and Anhui Provinces, with a high resistance frequency of 41.12 and 20.56%, respectively. The predominant resistant isolates harboring point mutations were F167Y (79.31%), followed by E198Q (16.38%) and F200Y (4.31%). Compared with F. graminearum, F. asiaticum isolates were more likely to produce carbendazim resistance. In this study, we first detected carbendazim-resistant isolates in Hebei, Shaanxi, Sichuan, and Hunan Provinces. In Jiangsu, Anhui, and Zhejiang, the frequency of carbendazim-resistant isolates maintained a high level, resulting in stable carbendazim-resistant populations. We also found the dynamic of carbendazim-resistance frequency in most provinces showed similar trends to the epidemic of Fusarium Head Blight (FHB). Our results facilitate the understanding of the current situation of carbendazim resistance of FHB pathogens and will be helpful for fungicides selection in different wheat-producing areas in China.

In this study, DNA sequence data were used to characterize 290 Fusarium strains isolated during a survey of root-colonizing endophytic fungi of agricultural and nonagricultural plants in northern Kazakhstan. The Fusarium collection was screened for species identity using partial translation elongation factor 1-α (TEF1) gene sequences. Altogether, 16 different Fusarium species were identified, including eight known and four novel species, as well as the discovery of the phylogenetically divergent F. steppicola lineage. Isolates of the four putatively novel fusaria were further analyzed phylogenetically with a multilocus data set comprising partial sequences of TEF1, RNA polymerase II largest (RPB1) and second-largest (RPB2) subunits, and calmodulin (CaM) to assess their genealogical exclusivity. Based on the molecular phylogenetic and comprehensive morphological analyses, four new species are formally described herein: F. campestre, F. kazakhstanicum, F. rhizicola, and F. steppicola.

The species composition of the genus Fusarium associated with Fusarium head blight (FHB) in wheat fields of Hungary in the year 2019 was assessed. Symptomatic wheat heads were collected at 20 geographical locations representing different ecosystems. A total of 256 Fusarium strains were isolated and identified by partial sequences of the translation elongation factor 1-alpha gene and, where required, the second-largest subunit of the DNA-directed RNA polymerase gene. Overall, Fusarium graminearum (58.2%) proved to be the dominant species, followed by F. annulatum (formerly F. proliferatum) (17.2%) and F. verticillioides (7.4%). The presence of all other species, including F. culmorum, in the population was less than 5%. F. graminearum was identified as the main species associated with FHB at 14 sampling sites. Fumonisin-producing F. annulatum, primarily known as the pathogen of maize in Hungary, was detected nearly as frequently as F. graminearum at three locations and dominated at two other sites. F. poae was not found during the survey. F. vorosii, a species that is believed to be of Asian origin and was already found in Hungary in 2002, was identified at two locations.