Key message
Plant-deleterious microbial volatiles activate the transactivation of hypoxia, MAMPs and wound responsive genes in
Arabidopsis thaliana
. AtMKK1 and AtMKK3 are involved in the ...plant-deleterious microbial volatiles-induced defense responses.
Microbial volatile compounds (mVCs) are a collection of volatile metabolites from microorganisms with biological effects on all living organisms. mVCs function as gaseous modulators of plant growth and plant health. In this study, the defense events induced by plant-deleterious mVCs were investigated.
Enterobacter aerogenes
VCs lead to growth inhibition and immune responses in
Arabidopsis thaliana
.
E
.
aerogenes
VCs negatively regulate auxin response and transport gene expression in the root tip, as evidenced by decreased expression of
DR5::GFP
,
PIN3::PIN3-GFP
and
PIN4::PIN4-GFP
. Data from transcriptional analysis suggests that
E
.
aerogenes
VCs trigger hypoxia response, innate immune responses and metabolic processes. In addition, the transcript levels of the genes involved in the synthetic pathways of antimicrobial metabolites camalexin and coumarin are increased after the
E
.
aerogenes
VCs exposure. Moreover, we demonstrate that MKK1 serves as a regulator of camalexin biosynthesis gene expression in response to
E
.
aerogenes
VCs, while MKK3 is the regulator of coumarin biosynthesis gene expression. Additionally, MKK1 and MKK3 mediate the
E
.
aerogenes
VCs-induced callose deposition. Collectively, these studies provide molecular insights into immune responses by plant-deleterious mVCs.
The COVID-19 pandemic has raised awareness of infection prevention and control. We found that the incidence of nosocomial infection in neurosurgery has changed. This study aimed to evaluate the ...impact of "coronavirus disease 2019 (COVID-19) prevention and control measures" on nosocomial infections in neurosurgery. To explore changes in nosocomial infections in neurosurgery during the COVID-19 pandemic, the clinical data of inpatients undergoing neurosurgery at Taizhou Hospital of Zhejiang Province between January 1 and April 30, 2020 (COVID-19 era) were first analyzed and then compared with those from same period in 2019 (first pre-COVID-19 era). We also analyzed data between May 1 and December 31, 2020 (post-COVID-19 era) at the same time in 2019 (second pre-COVID-19 era). The nosocomial infection rate was 7.85% (54/688) in the first pre-COVID-19 era and 4.30% (26/605) in the COVID-19 era (P = 0.01). The respiratory system infection rate between the first pre-COVID-19 and COVID-19 eras was 6.1% vs. 2.0% (P < 0.01), while the urinary system infection rate was 1.7% vs. 2.0% (P = 0.84). Between the first pre-COVID-19 and COVID-19 eras, respiratory system and urinary infections accounted for 77.78% (42/54) vs. 46.15% (12/26) and 22.22% (12/54) vs. 46.15% (12/26) of the total nosocomial infections, respectively (P < 0.01). Between the second pre-COVID-19 and post-COVID-19 eras, respiratory system and urinary accounted for 53.66% (44/82) vs. 40.63% (39/96) and 24.39% (20/82) vs. 40.63% (39/96) of the total nosocomial infections, respectively (P = 0.02). The incidence of nosocomial infections in neurosurgery reduced during the COVID-19 pandemic. The reduction was primarily observed in respiratory infections, while the proportion of urinary infections increased significantly.
The microbial profiles of peri-implantitis and periodontitis (PT) are inconclusive. The controversies mainly arise from the differences in sampling sites, targeted gene fragment, and microbiome ...analysis techniques. The objective of this study was to explore the microbiomes of peri-implantitis (PI), control implants (CI), PT and control teeth (CT), and the microbial change of PI after nonsurgical treatment (PIAT).
Twenty-two patients diagnosed with both PT and peri-implantitis were recruited. Clinical periodontal parameters and radiographic bone levels were recorded. In each patient, the subgingival and submucosal plaque samples were collected from sites with PI, CI, PT, CT, and PIAT. Microbiome diversity was analyzed by high-throughput amplicon sequencing using full-length of 16S rRNA gene by next generation sequencing.
The 16S rRNA gene sequencing analysis revealed 512 OTUs in oral microbiome and 377 OTUs reached strain levels. The PI and PT groups possessed their own unique core microbiome. Treponema denticola was predominant in PI with probing depth of 8-10 mm. Interestingly, Thermovirga lienii DSM 17291 and Dialister invisus DSM 15470 were found to associate with PI. Nonsurgical treatment for peri-implantitis did not significantly alter the microbiome, except Rothia aeria.
Our study suggests Treponemas species may play a pivotal role in peri-implantitis. Nonsurgical treatment did not exert a major influence on the peri-implantitis microbiome in short-term follow-up. PT and peri-implantitis possess the unique microbiome profiles, and different therapeutic strategies may be suggested in the future.
The estuarine delta of the Yellow River is a region of strong land-ocean-human interactions that undergoes a unique evolutionary process. The delta is formed by deposition of large quantities of ...sediments carried by the Yellow River, especially during the annual water and sediment regulation period; more than one-third of the total annual sediments is deposited to the estuary area. The seagrass
Zostera japonica
is located at the forefront of the Yellow River delta. To study the impact of the different sediment environments on the
Z. japonica
growth, its growth and water quality and sediment parameters were measured on the northern and southern sides of the estuary from April to October in 2019. The action of wind and tides have re-suspended and dispersed sediments over time, producing shores on the southern delta characterized by nutrient-enriched clays and shores on the northern delta characterized by coarser sands and silts with poor nutrients. During the monitoring period, the concentrations of TC, TN, and TP in the root-zone sediments at the southern site were 1.56%, 0.04%, and 0.06%, respectively, whereas they were 0.69%, 0.007%, and 0.06%, respectively, at the northern site. Sufficient nutrients supported the growth of
Z. japonica
at the southern site, while poor nutrition limited the continuous growth of
Z. japonica
at the northern site. In July, the plant height, biomass, and shoot density of
Z. japonica
at the southern site reached the maximum values of 23.6 cm, 0.14 g/shoot, and 3245 shoots/m
2
, respectively, whereas they were 16.4 cm, 0.06 g/shoot, and 2740 shoots/m
2
, respectively, at the northern site. The sediment grain size and their nutrients contributed to different growth patterns of
Z. japonica
at the southern and northern sites. Our research could provide important implication for the conservation of
Z. japonica
habitats in the Yellow River estuary in China.
The influence of external environmental factors on secondary metabolites of medicinal plants has always been studied. However, little is known about the relationships between endophytes and host ...metabolites, especially the relationship differences between different plant species. Thus, we used high-throughput sequencing methods to compare endophyte diversity from roots of two closely related species, Gentiana officinalis and G. siphonantha, from the same production area, and analyze the association with four secondary metabolites (Gentiopicroside, Loganic acid, Swertiamarine and Sweroside).
The fungal and bacteria communities' richness and diversity of G. siphonantha was higher than G. officinalis. Ascomycota and Proteobacteria were dominant fungal and bacterial phylum of the two closely related species. At the genus level, Tetracladium and Cadophora were dominant fungal genus in G. officinalis and G. siphonantha samples, respectively. While Pseudomonas was dominant bacterial genus in two closely related species, with relative abundances were 8.29 and 8.05%, respectively. Spearman analysis showed that the content of loganic acid was significantly positively correlated with endophytic fungi, the content of gentiopicroside, swertiamarine and sweroside were significantly positively correlated with endophytic bacteria in the two related species. PICRUSt and FUNGuild predictive analysis indicated that metabolism and saprotroph was primary function of endophytic bacteria and fungi in the two related species.
Our results will expand the knowledge on relationships of plant-microbe interactions and offer pivotal information to reveal the role of endophytes in the production of Gentiana plant and its important secondary metabolite.
Species identification of Nocardia is not straightforward due to rapidly evolving taxonomy, insufficient discriminatory power of conventional phenotypic methods and also of single gene locus analysis ...including 16S rRNA gene sequencing. Here we evaluated the ability of a 5-locus (16S rRNA, gyrB, secA1, hsp65 and rpoB) multilocus sequence analysis (MLSA) approach as well as that of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in comparison with sequencing of the 5'-end 606 bp partial 16S rRNA gene to provide identification of 25 clinical isolates of Nocardia. The 5'-end 606 bp 16S rRNA gene sequencing successfully assigned 24 of 25 (96%) clinical isolates to species level, namely Nocardia cyriacigeorgica (n = 12, 48%), N. farcinica (n = 9, 36%), N. abscessus (n = 2, 8%) and N. otitidiscaviarum (n = 1, 4%). MLSA showed concordance with 16S rRNA gene sequencing results for the same 24 isolates. However, MLSA was able to identify the remaining isolate as N. wallacei, and clustered N. cyriacigeorgica into three subgroups. None of the clinical isolates were correctly identified to the species level by MALDI-TOF MS analysis using the manufacturer-provided database. A small "in-house" spectral database was established incorporating spectra of five clinical isolates representing the five species identified in this study. After complementation with the "in-house" database, of the remaining 20 isolates, 19 (95%) were correctly identified to species level (score ≥ 2.00) and one (an N. abscessus strain) to genus level (score ≥ 1.70 and < 2.00). In summary, MLSA showed superior discriminatory power compared with the 5'-end 606 bp partial 16S rRNA gene sequencing for species identification of Nocardia. MALDI-TOF MS can provide rapid and accurate identification but is reliant on a robust mass spectra database.
ABSTRACT
Increasing evidence suggests that in disease-suppressive soils, microbial volatile compounds (mVCs) released from bacteria may inhibit the growth of plant-pathogenic fungi. However, the ...antifungal activities and molecular responses of fungi to different mVCs remain largely undescribed. In this study, we first evaluated the responses of pathogenic fungi to treatment with mVCs from
Paenarthrobacter ureafaciens
. Then, we utilized the well-characterized fungal model organism
Saccharomyces cerevisiae
to study the potential mechanistic effects of the mVCs. Our data showed that exposure to
P. ureafaciens
mVCs leads to reduced growth of several pathogenic fungi, and in yeast cells, mVC exposure prompts the accumulation of reactive oxygen species. Further experiments with
S. cerevisiae
deletion mutants indicated that Slt2/Mpk1 and Hog1 MAPKs play major roles in the yeast response to
P. ureafaciens
mVCs. Transcriptomic analysis revealed that exposure to mVCs was associated with 1,030 differentially expressed genes (DEGs) in yeast. According to gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses, many of these DEGs are involved in mitochondrial dysfunction, cell integrity, mitophagy, cellular metabolism, and iron uptake. Genes encoding antimicrobial proteins were also significantly altered in the yeast after exposure to mVCs. These findings suggest that oxidative damage and mitochondrial dysfunction are major contributors to the fungal toxicity of mVCs. Furthermore, our data showed that cell wall, antioxidant, and antimicrobial defenses are induced in yeast exposed to mVCs. Thus, our findings expand upon previous research by delineating the transcriptional responses of the fungal model.
IMPORTANCE
Since the use of bacteria-emitted volatile compounds in phytopathogen control is of considerable interest, it is important to understand the molecular mechanisms by which fungi may adapt to microbial volatile compounds (mVCs).
Paenarthrobacter ureafaciens
is an isolated bacterium from disease-suppressive soil that belongs to the
Actinomycetota
phylum.
P. ureafaciens
mVCs showed a potent antifungal effect on phytopathogens, which may contribute to disease suppression in soil. However, our knowledge about the antifungal mechanism of mVCs is limited. This study has proven that mVCs are toxic to fungi due to oxidative stress and mitochondrial dysfunction. To deal with mVC toxicity, antioxidants and physical defenses are required. Furthermore, iron uptake and CAP proteins are required for antimicrobial defense, which is necessary for fungi to deal with the thread from mVCs. This study provides essential foundational knowledge regarding the molecular responses of fungi to inhibitory mVCs.
Since the use of bacteria-emitted volatile compounds in phytopathogen control is of considerable interest, it is important to understand the molecular mechanisms by which fungi may adapt to microbial volatile compounds (mVCs).
Paenarthrobacter ureafaciens
is an isolated bacterium from disease-suppressive soil that belongs to the
Actinomycetota
phylum.
P. ureafaciens
mVCs showed a potent antifungal effect on phytopathogens, which may contribute to disease suppression in soil. However, our knowledge about the antifungal mechanism of mVCs is limited. This study has proven that mVCs are toxic to fungi due to oxidative stress and mitochondrial dysfunction. To deal with mVC toxicity, antioxidants and physical defenses are required. Furthermore, iron uptake and CAP proteins are required for antimicrobial defense, which is necessary for fungi to deal with the thread from mVCs. This study provides essential foundational knowledge regarding the molecular responses of fungi to inhibitory mVCs.
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