ABSTRACT
Objective: Starting 31 July 2021, a SARS-CoV-2 outbreak occurred in Yantai, Shandong Province. The investigation showed that this outbreak was closely related to the epidemic at Nanjing Lukou Airport. In view of the fact that there were many people involved in this outbreak and these people had a complex activity area, the transmission route cannot be analyzed by simple epidemiological investigation. Here we combined the SARS-COV-2 whole-genome sequencing with epidemiology to determine the epidemic transmission route of Yantai. Methods: Thirteen samples of SARS-CoV-2 outbreak cases from 31 July to 4 August 2021 were collected and identified by fluorescence quantitative PCR, then whole-genome deep sequencing based on NGS was performed, and the data were analyzed and processed by biological software. Results: All sequences were over 29,000 bases in length and all belonged to B.1.617.2, which was the Delta strain. All sequences shared two amino acid deletions and 9 amino acid mutations in Spike protein compared with reference sequence NC_045512.2 (Wuhan virus strain). Compared with the sequence of Lukou Airport Delta strain, the homology was 99.99%. In order to confirm the transmission relationship between patients, we performed a phylogenetic tree analysis. The results showed that patient 1, patient 2, and patient 9 belong to an independent branch, and other patients have a close relationship. Combined with the epidemiological investigation, we speculated that the epidemic of Yantai was transmitted by two routes at the same time. Based on this information, our prevention and control work was carried out in two ways and effectively prevented the further spread of this epidemic.
ABSTRACT
BACKGROUND: As the causal agent of pine wilt disease, Bursaphelenchus xylophilus, is a serious pathogen of forest pine trees. Esteya vermicola is a nematophagous fungus of B. xylophilus and exhibits great potential as a biological control agent. However, the in vivo infection mechanism of E. vermicola on B. xylophilus is unclear. Experiments were conducted to study the colonization of host plant and infection of B. xylophilus by E. vermicola inside pine tree xylem. RESULTS: A green fluorescent protein (GFP)-tagged E. vermicola transformant was constructed as a biomarker to study the in vivo colonization and infection of B. xylophilus in pine trees. The in vitro infection of B. xylophilus by E. vermicola was observed through GFP expression. The bacilloid conidia produced by trophic hyphae in the body of the nematode are described. Additionally, the monitoring of in vivo colonization by GFP-tagged E. vermicola showed the germination and hyphal extension of this fungus after inoculation. Moreover, B. xylophilus infected by this biocontrol agent were extracted from healthy seedlings and observed in the xylem of trees that were wilting due to pine wilt disease. CONCLUSION: Evidence of fungal colonization and infection of B. xylophilus by E. vermicola is provided to improve our understanding of the in vivo infection mechanisms used by this nematophagous fungus against B. xylophilus. The infection of B. xylophilus by E. vermicola was inferred to begin with the implantation of propagules, and this inference will require future investigation. The colonization of Esteya vermicola in host pine tree xylem and the in vivo infection of pinewood nematode by E. vermicola were investigated using the green fluorescence protein transformant. © 2020 Society of Chemical Industry.
Subject(s)
Ophiostomatales , Pinus , Animals , Rhabditida , Spores, FungalABSTRACT
Variation in atmospheric carbon dioxide (CO2) concentration can dictate plant growth and development and shape plant evolution. For paired populations of 31 Arabidopsis accessions, respectively, grown under 100 or 380 ppm CO2, we compared phenotypic traits related to vegetative growth and flowering time. Four accessions showed the least variation in measured growth traits between 100 ppm CO2 and 380 ppm CO2 conditions, though all accessions exhibited a dwarf stature with reduced biomass under low CO2. Our comparison of accessions also incorporated the altitude (indicated in meters) above sea level at which they were originally collected. Notably, An-1 (50 m), Est (50 m), Ws-0 (150 m), and Ler-0 (600 m) showed the least differences (lower decrease or increase) between treatments in flowering time, rosette leaf number, specific leaf weight, stomatal density, and less negative δ13C values. When variations for all traits and seedset were considered together, Ws-0 exhibited the least change between treatments. Our results showed that physiological and phenotypic responses to low CO2 varied among these accessions and did not correlate linearly with altitude, thus suggesting that slower growth or smaller stature under ambient CO2 may potentially belie a fitness advantage for sustainable growth under low CO2 availability.
