A pioneer nematode effector suppresses plant reactive oxygen species burst by interacting with the class III peroxidase.

Bursaphelenchus xylophilus is the pathogen of pine wilt disease, which can devastate the pine forest ecosystem. Usually, plant cells generate reactive oxygen species (ROS) as a defensive substance or signalling molecules to resist the infection of nematodes. However, little is known about how B. xylophilus effectors mediate the plant ROS metabolism. Here, we identified a pioneer B. xylophilus Prx3-interacting effector 1 (BxPIE1) expressed in the dorsal gland cells and the intestine. Silencing of the BxPIE1 gene resulted in reduced nematode reproduction and a delay in disease progression during parasitic stages, with the upregulation of pathogenesis-related (PR) genes PtPR-3 (class Ⅳ chitinase) and PtPR-9 (peroxidase). The protein-protein interaction assays further demonstrated that BxPIE1 interacts with a Pinus thunbergii class III peroxidase (PtPrx3), which produces H2O2 under biotic stress. The expression of BxPIE1 and PtPrx3 was upregulated during the infection stage. Furthermore, BxPIE1 effectively inhibited H2O2 generating from class III peroxidase and ascorbate can recover the virulence of siBxPIE1-treated B. xylophilus by scavenging H2O2. Taken together, BxPIE1 is an important virulence factor, revealing a novel mechanism utilized by nematodes to suppress plant immunity.

The Bursaphelenchus xylophilus candidate effector BxLip-3 targets the class I chitinases to suppress immunity in pine.

Lipase is involved in lipid hydrolysis, which is related to nematodes' energy reserves and stress resistance. However, the role of lipases in Bursaphelenchus xylophilus, a notorious plant-parasitic nematode responsible for severe damage to pine forest ecosystems, remains largely obscure. Here, we characterized a class III lipase as a candidate effector and named it BxLip-3. It was transcriptionally up-regulated in the parasitic stages of B. xylophilus and specifically expressed in the oesophageal gland cells and the intestine. In addition, BxLip-3 suppressed cell death triggered by the pathogen-associated molecular patterns PsXEG1 and BxCDP1 in Nicotiana benthamiana, and its Lipase-3 domain is essential for immunosuppression. Silencing of the BxLip-3 gene resulted in a delay in disease onset and increased the activity of antioxidant enzymes and the expression of pathogenesis-related (PR) genes. Plant chitinases are thought to be PR proteins involved in the defence system against pathogen attack. Using yeast two-hybrid and co-immunoprecipitation assays, we identified two class I chitinases in Pinus thunbergii, PtChia1-3 and PtChia1-4, as targets of BxLip-3. The expression of these two chitinases was up-regulated during B. xylophilus inoculation and inhibited by BxLip-3. Overall, this study illustrated that BxLip-3 is a crucial virulence factor that plays a critical role in the interaction between B. xylophilus and host pine.

The metagenomics of soil bacteria and fungi and the release of mechanical dormancy in hard seeds.

Persistence in the soil is a function of seed physiology, particularly non-germination and inherent lifespan. However, for seeds with mechanical dormancy, non-germination is also a function of the composition and activity of the soil microbiota. We attempted to screen out microorganisms in the soil that can specifically and rapidly decompose the hard fruit pericarps of Tilia miqueliana Maxim., a unique native tree species in China. Using the classical replica plating method, more than 100 different culturable microorganisms that could rapidly erode the pericarp were collected from the surface of pericarps under different culture conditions. At the same time, we successfully extended the concept of metagenomics and applied it to the identification of mixed artificial cultures. The decomposition process of the pericarps in soil was also simulated artificially. The physical and chemical data suggested a potential mechanism of microbial scarification and cracking in pericarp, whilst the embryos inside the eroded fruits retained good viability. Our discoveries could pave the way for the removal of physical and mechanical obstacles that prevent hard coat seeds from germinating. We anticipate that the use of this technology will improve the germination of other hard coat seeds. More research is needed to investigate the impacts on other seeds. The findings of this research can inform the design of experiments on the seed ecology of persistence.

Two Novel Bursaphelenchus xylophilus Kunitz Effector Proteins Using Different Infection and Survival Strategies to Suppress Immunity in Pine.

Pine wilt disease, caused by Bursaphelenchus xylophilus, results in tremendous economic loss in conifer production every year. To disturb the host immune responses, plant pathogens secrete a mass of effector proteins that facilitate the infection process. Although several effectors of B. xylophilus have been identified, detailed mechanisms of their functions remain largely unexplored. Here, we reveal two novel B. xylophilus Kunitz effectors, named BxKU1 and BxKU2, using different infection strategies to suppress immunity in Pinus thunbergii. We found that both BxKU1 and BxKU2 could suppress PsXEG1-triggered cell death and were present in the nucleus and cytoplasm in Nicotiana benthamiana. However, they had different three-dimensional structures and various expression patterns in B. xylophilus infection. In situ hybridization experiments showed that BxKU2 was expressed in the esophageal glands and ovaries, whereas BxKU1 was only expressed in the esophageal glands of females. We further confirmed that the morbidity was significantly decreased in P. thunbergii infected with B. xylophilus when BxKU1 and BxKU2 were silenced. The silenced BxKU2I, but not BxKU1, affected the reproduction and feeding rate of B. xylophilus. Moreover, BxKU1 and BxKU2 targeted to different proteins in P. thunbergii, but they all interacted with thaumatin-like protein 4 (TLP4) according to yeast two-hybrid screening. Collectively, our study showed that B. xylophilus could incorporate two Kunitz effectors in a multilayer strategy to counter immune response in P. thunbergii, which could help us better understand the interaction between plant and B. xylophilus.

Correction: Aromatic amine electrochemical sensors based on a Co-MOF: a hydrogen bond-induced specific response.

Correction for 'Aromatic amine electrochemical sensors based on a Co-MOF: a hydrogen bond-induced specific response' by Xiao-qin Wu et al., Dalton Trans., 2022, 51, 16861-16869, https://doi.org/10.1039/d2dt02049a.

Transcriptomic analysis reveals differentially expressed genes associated with pine wood nematode resistance in resistant Pinus thunbergii.

Pine wilt disease (caused by the nematode Bursaphelenchus xylophilus) is extremely harmful to pine forests in East Asia. As a low-resistance pine species, Pinus thunbergii is more vulnerable to pine wood nematode (PWN) than Pinus densiflora and Pinus massoniana. Field inoculation experiments were conducted on PWN-resistant and -susceptible P. thunbergii, and the difference in transcription profiles 24 h after inoculation was analyzed. We identified 2603 differentially expressed genes (DEGs) in PWN-susceptible P. thunbergii, while 2559 DEGs were identified in PWN-resistant P. thunbergii. Before inoculation, DEGs between PWN-resistant and PWN-susceptible P. thunbergii were enriched in the REDOX (Oxidation-Reduction) activity pathway (152 DEGs), followed by the oxidoreductase activity pathway (106 DEGs). After inoculation with PWN, however, the opposite was observed; DEGs were enriched in the oxidoreductase activity pathway (119 DEGs), followed by the REDOX activity pathway (84 DEGs). Before inoculation, according to the metabolic pathway analysis results, we found more genes upregulated in phenylpropanoid metabolic pathways and enriched in lignin synthesis pathways; cinnamoyl-CoA reductase-coding genes related to lignin synthesis were upregulated in PWN-resistant P. thunbergii and downregulated in PWN-susceptible P. thunbergii, and the lignin content was always higher in resistant than in susceptible P. thunbergii. These results reveal distinctive strategies of resistant and susceptible P. thunbergii in dealing with PWN infections.

Dual inoculation with rhizosphere-promoting bacterium Bacillus cereus and beneficial fungus Peniophora cinerea improves salt stress tolerance and productivity in willow.

Utilization of rhizosphere microorganisms to improve plant growth and salt tolerance has recently attracted widespread attention. The growth and salt tolerance of willows inoculated with Bacillus cereus JYZ-SD2 and Peniophora cinerea XC were studied under different salt stress conditions. The results showed that the chlorophyll content of willow cuttings inoculated with the XC strain increased significantly by 51.27%. After salt stress of willow cuttings inoculated with B. cereus JYZ-SD2 and P. cinerea XC (solely or in combination), the amount of sodium in the roots from the epidermis to the pericycle decreased and the content of sodium in the pericycle was significantly lower than that of the uninoculated willow, while the proportion of potassium increased. Willow cuttings inoculated with microorganisms showed increased activity of SOD and POD. At the salt concentration of 100 mmol/L, the highest SOD activity was found in B. cereus JYZ-SD2-inoculated willows, with 59.88% increase compared to uninoculated willows; the highest POD activity was found in P. cinerea XC and B. cereus JYZ-SD2 co-inoculated willows, with 51.05% increase compared to uninoculated willows. The Na-K-ATPase and Ca-Mg-ATPase activities of inoculated P. cinerea XC willow cuttings were also 59.38% and 60% higher than that of uninoculated willows, respectively. The qPCR analysis showed that the expression of vp2 gene in the microorganism-inoculated willow leaves was always higher than that in willow alone. The expression of vp2 gene in P. cinerea XC-inoculated willow cuttings was 270.81% higher than that in uninoculated willows. Further observation of the ultrastructure of root cells under salt stress revealed that most of the vesicles in the root tip cells of willow were intact and secreted phagocytic vesicles to absorb sodium ions in the cytoplasm. This study shows that the combined beneficial fungi and rhizosphere-promoting bacteria inoculation technology as a practical biotechnological approach to enhance the growth of willows in salt-affected soils.

Studies on the Requirement of Transthyretin Protein (BxTTR-52) for the Suppression of Host Innate Immunity in Bursaphelenchus xylophilus.

The pinewood nematode, Bursaphelenchus xylophilus, has been determined as one of the world's top ten plant-parasitic nematodes. It causes pine wilt, a progressive disease that affects the economy and ecologically sustainable development in East Asia. B. xylophilus secretes pathogenic proteins into host plant tissues to promote infection. However, little is known about the interaction between B. xylophilus and pines. Previous studies reported transthyretin proteins in some species and their strong correlation with immune evasion, which has also been poorly studied in B. xylophilus. In this study, we cloned and functionally validated the B. xylophilus pathogenic protein BxTTR-52, containing a transthyretin domain. An in situ hybridization assay demonstrated that BxTTR-52 was expressed mainly in the esophageal glands of B. xylophilus. Confocal microscopy revealed that BxTTR-52-RFP localized to the nucleus, cytoplasm, and plasma membrane. BxTTR-52 recombinant proteins produced by Escherichia coli could be suppressed by hydrogen peroxide and antioxidant enzymes in pines. Moreover, silencing BxTTR-52 significantly attenuated the morbidity of Pinus thunbergii infected with B. xylophilus. It also suppressed the expression of pathogenesis-related genes in P. thunbergii. These results suggest that BxTTR-52 suppresses the plant immune response in the host pines and might contribute to the pathogenicity of B. xylophilus in the early infection stages.

Thyroid dose assessments due to inhalation of 131I for nuclear medicine workers.

Background: In general, medical staff who work in nuclear medicine should be entirely safe in their professional environment. Nevertheless, we already know that the working environment of the nuclear medicine staff is not completely safe due to the handling of high amounts of radionuclides for diagnostic and therapy applications, which is especially relevant for 131I (as a non-sealed source). Purpose: The goal of this study was to assess the inhaled 131I thyroid dose in nuclear medicine workers and to introduce a simple method for internal exposure monitoring. Methods: Using 2-IN*2-in NaI (Tl) scintillation spectrometer and its supporting software (InSpector Maintenance Utility and Genie 2000), from 2019 to 2021, internal thyroid irradiation monitoring, an internal thyroid irradiation monitoring investi A NaI (Tl) scintillation spectrometer and its sugation was carried out for 3 consecutive years, between 2019 and 2021, in staff members of nuclear medicine departments engaged with iodine therapy. Results: 131I activity was found highest in the thyroid of nuclear medicine workers involved with the manual packaging and delivery of the radioisotope, while it was not detected in staff members involved with the automatic packaging and drug delivery. The activity range was found to be 30.00 ± 6.60-6070.00 ± 1335.40 Bq for the exposed personnel, and the estimated dose was 0.05-6.77 mSv. In 2021, three workers had an annual equivalent dose above 5 mSv. Conclusion: By monitoring the thyroid 131I in staff members of the nuclear medicine department, it was found that there are 131I internal occupational exposure risks. The best solution is automatic packaging and drug delivery.

First Report of Diaporthe eres Causing Leaf Spot on Pseudocydonia sinensis in China.

Pseudocydonia sinensis is a Chinese ornamental plant with great landscaping value. Its fruit is additionally used for medicinal purposes (Lim 2012). In June 2020, a leaf spot disease was observed in the campus of Nanjing Forestry University (32°04'34.53″N 118°48'42.06″E). The symptoms began with irregular red-brown spots, which gradually enlarged, extended and overlapped, with an incidence of 85% (29/34 trees). Pieces of leaf tissue (3 to 4 mm²) from the lesion margins were surface-sterilized with 75% ethanol for 30 s and 1% NaClO for 90 s. Subsequently, the tissues were rinsed with sterile H2O, placed on potato dextrose agar (PDA) medium and incubated at 25℃ for 5 days. The same fungus was isolated from 90% of tissues. Pure cultures were obtained by monosporic isolation.The representative isolate NJMG 5-7 was used for morphological and molecular characterization. The growing fungal colony on PDA was initially white, but gradually turned grey. Pycnidia formation was observed on PDA supplemented with alfalfa stems. The pycnidia produced two different types of conidia, α and ß, which ooze out in yellow creamy mucilaginous masses. Conidiophores were hyaline, cylindrical and smooth, 16.8 to 33.1 × 1.5 to 2.6 µm (n=30). Conidiogenous cells were 13.6 to 29.3 × 1.5 to 2.7 µm (n=30). The α-conidia were, unicellular, hyaline elliptical or fusiform, bi-guttulate, 6.5 to 9.2 × 1.8 to 3.3 µm (n = 50). The ß-conidia were hyaline, aseptate, without guttules, filiform, curved, with obtuse ends, 12.5 to 25 × 1.0 to 1.8 µm (n = 50). To verify species identity, the partial sequences of the internal transcribed spacer (ITS) region, and calmodulin (CAL), translation elongation factor 1 alpha (EF1-a), and beta-tubulin genes (TUB) were amplified from isolate NJMG 5-7 with primers ITS1/ITS4 (White et al. 1990), CAL-228F/CAL-737R (Carbone & Kohn 1999), EF1-728F/EF1-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (Glass and Donaldson 1995), respectively. The sequences were deposited in GenBank (OP223050 for ITS, OP252809 for CAL, OP252807 for EF1-a, and OP252808 for TUB). A BLAST search of GenBank showed that ITS, CAL, EF1-a and TUB sequences of NJMG 5-7 were similar to those of D. eres CBS 138594 (99% identity), AR5193 (99%), AR5193 (99%) and MG281193 (100%), respectively. The morphological and molecular results identified the isolate as D. eres (Feng et al. 2015). To fulfill Koch's postulates, a pathogenicity test was conducted using three P. sinensis plants. Six leaves from each tree were wounded and inoculated with mycelial plugs (about 4 mm in diameter) of D. eres from a 3-day-old culture grown on PDA. Inoculations with sterile PDA plugs on different leaves of the same tree were used as controls. All inoculated leaves were enclosed in plastic bags together with a wet cotton ball inside. Sterile H2O was sprayed into the plastic bags to keep moisture conditions. Five days later, all inoculated points showed lesions similar to those previously observed in the field, whereas controls were asymptomatic. The pathogen was successfully reisolated from the inoculated symptomatic parts on PDA and identified from its morphology, thus fulfilling Koch's postulates. This fungus can cause a variety of diseases. To our knowledge, this is the first report of D. eres causing leaf spots on P. sinensis in the world. These findings provide a foundation for future studies on the epidemiology and control of this newly emerging disease.

Antifungal effects of volatile organic compounds produced by Trichoderma koningiopsis T2 against Verticillium dahliae.

Volatile organic compounds (VOCs) produced by microorganisms are considered promising environmental-safety fumigants for controlling soil-borne diseases. Verticillium dahliae, a notorious fungal pathogen, causes economically important wilt diseases in agriculture and forestry industries. Here, we determined the antifungal activity of VOCs produced by Trichoderma koningiopsis T2. The VOCs from T. koningiopsis T2 were trapped by solid-phase microextraction (SPME) and tentatively identified through gas chromatography-mass spectrometry (GC/MS). The microsclerotia formation, cell wall-degrading enzymes and melanin synthesis of V. dahliae exposed to the VOC mixtures and selected single standards were examined. The results showed that the VOCs produced by strain T2 significantly inhibited the growth of V. dahliae mycelium and reduced the severity of Verticillium wilt in tobacco and cotton. Six individual compounds were identified in the volatilome of T. koningiopsis T2, and the dominant compounds were 3-octanone, 3-methyl-1-butanol, butanoic acid ethyl ester and 2-hexyl-furan. The VOCs of strain T2 exert a significant inhibitory effect on microsclerotia formation and decreased the activities of pectin lyase and endo-ß-1,4-glucanase in V. dahliae. VOCs also downregulated the VdT3HR, VdT4HR, and VdSCD genes related to melanin synthesis by 29. 41-, 10. 49-, and 3.11-fold, respectively. Therefore, T. koningiopsis T2 has potential as a promising biofumigant for the biocontrol of Verticillium wilt disease.

Aromatic amine electrochemical sensors based on a Co-MOF: a hydrogen bond-induced specific response.

A 2D Co-MOF, {[Co2(L2-)2(bipy)](DMA)·2H2O}n (Co-1, H2L = 2,5-thienedioic acid; bipy = 2,2'-bipyridine; DMA = N,N'-dimethyl acetamide), was synthesized by hydrothermal method. Co-1 has excellent air stability. When modifying the surface of a glassy carbon electrode (GCE) with Co-1, the obtained electrochemical senor Co-1/GCE shows excellent sensitivity towards 1,3-dinitrobenzene (m-DNB) and 2,4-dinitroaniline (2,4-DNA), although the electrochemical conductivity of Co-1 is not that good. The detection limits were as low as 0.0286 µM and 0.161 µM, respectively. DFT studies showed that the main interaction between Co-1 and the guest molecules is via hydrogen bonding, formed by the -NO2 group and the coordinated H2O molecule from the Co-1 skeleton. Furthermore, the characteristic signals of both m-DNB and 2,3-DNA can still be observed in a mimicked industrial waste-water system containing 17 kinds of organic interferents, indicating high selectivity of the Co-1/GCE sensor.

Rahnella aquatilis JZ-GX1 alleviates iron deficiency chlorosis in Cinnamomum camphora by secreting desferrioxamine and reshaping the soil fungal community.

Plant growth-promoting rhizobacteria are important for improving plant iron nutrition, but the interactions among inoculants, host plants and soil microorganisms have not been greatly explored. Rahnella aquatilis JZ-GX1 was applied to treat the increasingly serious iron deficiency chlorosis in Cinnamomum camphora, and the resulting improvement in chlorosis was determined by assessing the contents of chlorophyll, active iron, Fe2+ and antioxidant enzymes in leaves, the effects on the soil microbial community and the metabolism in the rhizosphere by high-throughput sequencing techniques and liquid chromatography-mass spectrometry (LC-MS). The results showed that inoculation with JZ-GX1 significantly increased the chlorophyll content of C. camphora, which promoted the redistribution of active iron in roots and leaves, increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), and thus reduced membrane damage in iron-deficient C. camphora caused by reactive oxygen species. According to genome prediction and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis, the JZ-GX1 strain could secrete desferrioxamine (DFO), and the concentration of DFO in C. camphora rhizosphere was 21-fold higher than that in uninoculated soil. The exogenous application of DFO increased the SPAD and Fe2+ contents in leaves. In addition, the inoculant affected the fungal community structure and composition in the C. camphora rhizosphere soil and increased the abundances of specific taxa, such as Glomus, Mortierella, Trichoderma, and Penicillium. Therefore, R. aquatilis JZ-GX1 application promoted iron absorption in C. camphora trees by secreting DFO and alleviated iron deficiency chlorosis through interactions with the local fungal community.

Physiological and Transcriptome Analyses Revealed the Mechanism by Which Deferoxamine Promotes Iron Absorption in Cinnamomum camphora.

Iron deficiency causes chlorosis and growth inhibition in Cinnamomum camphora, an important landscaping tree species. Siderophores produced by plant growth-promoting rhizobacteria have been widely reported to play an indispensable role in plant iron nutrition. However, little to date has been determined about how microbial siderophores promote plant iron absorption. In this study, multidisciplinary approaches, including physiological, biochemical and transcriptome methods, were used to investigate the role of deferoxamine (DFO) in regulating Fe availability in C. camphora seedlings. Our results showed that DFO supplementation significantly increased the Fe2+ content, SPAD value and ferric-chelate reductase (FCR) activity in plants, suggesting its beneficial effect under Fe deficiency. This DFO-driven amelioration of Fe deficiency was further supported by the improvement of photosynthesis. Intriguingly, DFO treatment activated the metabolic pathway of glutathione (GSH) synthesis, and exogenous spraying reduced glutathione and also alleviated chlorosis in C. camphora. In addition, the expression of some Fe acquisition and transport-related genes, including CcbHLH, CcFRO6, CcIRT2, CcNramp5, CcOPT3 and CcVIT4, was significantly upregulated by DFO treatment. Collectively, our data demonstrated an effective, economical and feasible organic iron-complexing agent for iron-deficient camphor trees and provided new insights into the mechanism by which siderophores promote iron absorption in plants.

The key molecular pattern BxCDP1 of Bursaphelenchus xylophilus induces plant immunity and enhances plant defense response via two small peptide regions.

The migratory plant-parasitic nematode Bursaphelenchus xylophilus is the pathogen of the pine wilt disease (PWD), causing serious damage to pine forests in China. During the process of plant resistance to multiple pathogens, plant immunity plays a key role. In this current study, the pathogen-associated molecular pattern (PAMP) BxCDP1 in B. xylophilus has been identified, but the host target protein of BxCDP1 and its key amino acid region inducing the plant immunity have yet to be elucidated. We found that BxCDP1 could trigger superoxide production, H2O2 production, and callose deposits. A RING-H2 finger protein 1 (RHF1) of Pinus thunbergii was screened and characterized as a target protein of BxCDP1 by yeast two-hybrid and co-immunoprecipitation (Co-IP). Moreover, two peptides (namely M9 and M16) proved to be key regions of BxCDP1 to induce PAMP-triggered immunity (PTI) in Nicotiana benthamiana, which also induced the expression of pathogenesis-related (PR) genes (PtPR-3, PtPR-4, and PtPR-5) in P. thunbergii and enhanced the resistance of the host to B. xylophilus. These results indicate that BxCDP1 plays a critical role in the interaction between B. xylophilus and P. thunbergii, and both peptides M9 and M16 have the potential to be developed and utilized as immune inducers of pines against B. xylophilus in future.

Effects of Volatile Organic Compounds Produced by Pseudomonas aurantiaca ST-TJ4 against Verticillium dahliae.

Verticillium dahliae is one of the most destructive fungal pathogens, causing substantial economic losses in agriculture and forestry. The use of plant growth-promoting rhizobacteria (PGPR) is an effective and environmentally friendly strategy for controlling diseases caused by V. dahliae. In this study, 90 mm in diameter Petri plates were used to test the effect of volatile organic compounds (VOCs) produced by different concentrations of Pseudomonasaurantiaca ST-TJ4 cells suspension on V. dahliae mycelia radial growth and biomass. The mycelial morphology was observed by using scanning electron microscopy. The conidia germination and microsclerotia formation of V. dahliae were evaluated. The VOCs with antifungal activity were collected by headspace solid-phase microextraction (SPME), and their components were analyzed by gas chromatography-mass spectrometry (GC-MS). The VOCs produced by strain ST-TJ4 significantly inhibited the growth of mycelium of V. dahliae. The morphology of the hyphae was rough and wrinkled when exposed to VOCs. The VOCs of strain ST-TJ4 have a significant inhibitory effect on V. dahliae conidia germination and microsclerotia formation. At the same time, the VOCs also reduce the expression of genes related to melanin synthesis in V. dahliae. In particular, the expression of the hydrophobin gene (VDAG-02273) was down-regulated the most, about 67-fold. The VOCs effectively alleviate the severity of cotton root disease. In the volatile profile of strain ST-TJ4, 2-undecanone and 1-nonanol assayed in the range 10-200 µL per plate revealed a significant inhibitory effect on V. dahliae mycelial radial growth. These compounds may be useful to devise new control strategies for control of Verticillium wilt disease caused by V. dahliae.

Study of Low-Dose Radiation Workers Ionizing Radiation Sensitivity Index and Radiation Dose-Effect Relationship.

BACKGROUND: In the present study, we analyzed radiation injuries to Chinese workers exposed to low-dose radiation. We discuss the relationships between dose and injury. METHODS: This study randomly selected 976 radiation workers who underwent occupational health monitoring. The radiation workers were divided into 5 different types of work: radiation diagnosis, radiation therapy, interventional therapy, nuclear medicine, and industrial inspection. This research was approved by the Bioethics Committee at the Gansu Provincial Center for Disease Control and Prevention. RESULTS: The average annual cumulative dose to interventional radiation workers was the highest, i.e., 0.86 mSv. The detection rate of lens opacity was 37%, but 99.70% of lens opacities occurred in the peripheral cortex. Posterior subcapsular opacification was detected less than 1.00% of the time. The rate of chromosomal aberrations was highest for radiological workers with more than 20 years of service. Annual cumulative dose reached 2.04 mSv, and the monitoring dose for 3 months was as high as 1.62 mSv. Dicentric chromosomes were also detected. The manual packaging and drug delivery nuclear medicine staffs totaled 14 individuals. 131 131 was detected in the thyroids of 4 workers (28.57%). The detection rate of thyroid 131 I was higher in the hand-packed and administered group than in the automatic administration group. CONCLUSION: Radiation workers exposed to low doses of radiation can sustain injuries. Interventional radiology workers receive the highest doses and sustain the most significant effects. This study suggests that chromosome aberration analysis is an important index in occupational health monitoring of radiological workers. Monitoring of internal radiation exposure cannot be ignored for nuclear medicine staff.

First Report of Botryosphaeria dothidea Causing Leaf Blight on Cornus officinalis in Jiangsu Province, China.

Cornus officinalis Sieb. et Zucc., belonging to the family Cornaceae, is often used as an ornamental plant and is widely distributed in Shandong, Jiangsu, and Zhejiang provinces and other places in China. Since 2020, a new disease with high incidence has been found in Xuanwu Lake Park (32°04'34.53″N 118°48'42.06″E) in Nanjing, Jiangsu Province, China. The symptoms began as small brown lesions formed along the leaf tips, which gradually expanded and became dark brown with a light brown border. A survey of C. officinalis trees in Xuanwu Lake Park showed that approximately 90% of thirty trees were infected, which decreased the ornamental value of C. officinalis. Pieces of leaf tissue (3 to 4 mm²) from the lesion margins were surface sterilized with 75% ethanol for 30 s and 1% NaClO for 90 s. Subsequently, the tissues were rinsed with sterile H2O, placed on potato dextrose agar (PDA) medium and incubated at 25℃ for 5 days. The same fungus was isolated in 90% of the tissues. Pure cultures were obtained by monosporic isolation. A representative isolate, SZY 2-2, was used for morphological and molecular characterization. The colonies were initially white, gradually turning gray green to black with copious gray aerial mycelium after 1 week in culture. Conidia were one-celled, hyaline, smooth, and fusoid to ellipsoid. Conidia measurements were 23.6±1.9×7.2±0.56 µm (n = 50). The morphology of SZY 2-2 matched the description of Botryosphaeria dothidea (Slippers et al. 2004). To verify species identity, the partial sequences of the internal transcribed spacer (ITS) region, translation elongation factor 1 alpha (EF1-a) gene, and beta-tubulin gene (TUB), were amplified from isolate SZY 2-2 with primers ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Koho 1999), and ßt2a/ßt2b (Glass and Donaldson 1995), respectively. The sequences were deposited in GenBank (ON171471 for ITS, ON185540 for EF1-a, and ON185541 for TUB). A BLAST search of GenBank showed that ITS, EF1-a and TUB sequences of SZY 2-2 were similar to those of B. dothidea MN633360 (identity=517/517 bp; 100%), MK783294 (identity=299/299 bp; 100%), and KF005081 (identity=461/461 bp; 100%), respectively. The morphological and molecular results identified the isolate as B. dothidea (Zhai et al. 2014). To fulfill Koch's postulates, a pathogenicity test was conducted using three C. officinalis plants. Five leaves from each tree were wounded and inoculated with mycelial plugs (about 4 mm in diameter) of B. dothidea from a 5-day-old culture grown on PDA, and inoculation with sterile PDA plugs on different leaves of the same tree served as negative controls. The leaves were enclosed in plastic bag along with the branches with a wet cotton ball inside. Sterile H2O2 was sprayed into the plastic bags to keep moisture conditions.Five days later, all inoculated points showed lesions similar to those previously observed in the field, whereas controls were asymptomatic. The pathogen was successfully reisolated from the inoculated symptomatic parts on PDA and had morphology as characterized before, thus fulfilling Koch's postulates. B. dothidea is known as a ubiquitous fungus and operates as both an endophyte and an opportunistic pathogen of trees (Slippers and Wingfield 2007, Zhao et al 2020). Stress factors that predispose trees to disease expression by B. dothidea include drought, defoliation (Theodore et al. 1997), competition, and physical damage (Slippers and Wingfield 2007). This is consistent with the occurrence of the disease in September and association of B. dothidea with the presence of wounds. More investigation is needed to determine the relationship between possible endophytic growth of B. dothidea on C. officinalis and the leaf blight found in Jiangsu Province.

A Bursaphelenchus xylophilus Effector, BxSCD3, Suppresses Plant Defense and Contributes to Virulence.

Bursaphelenchus xylophilus is the most economically important species of migratory plant-parasitic nematodes (PPNs) and causes severe damage to forestry in China. The successful infection of B. xylophilus relies on the secretion of a repertoire of effector proteins. The effectors, which suppress the host pine immune response, are key to the facilitation of B. xylophilus parasitism. An exhaustive list of candidate effectors of B. xylophilus was predicted, but not all have been identified and characterized. Here, an effector, named BxSCD3, has been implicated in the suppression of host immunity. BxSCD3 could suppress pathogen-associated molecular patterns (PAMPs) PsXEG1- and INF1-triggered cell death when it was secreted into the intracellular space in Nicotiana benthamiana. BxSCD3 was highly up-regulated in the early infection stages of B. xylophilus. BxSCD3 does not affect B. xylophilus reproduction, either at the mycophagous stage or the phytophagous stage, but it contributes to the virulence of B. xylophilus. Moreover, BxSCD3 significantly influenced the relative expression levels of defense-related (PR) genes PtPR-3 and PtPR-6 in Pinus thunbergii in the early infection stage. These results suggest that BxSCD3 is an important toxic factor and plays a key role in the interaction between B. xylophilus and host pine.

Medium optimization to analyze the protein composition of Bacillus pumilus HR10 antagonizing Sphaeropsis sapinea.

A previous study found that a biocontrol bacterium, Bacillus pumilus HR10, inhibited the Sphaeropsis shoot blight disease of pine, and the fermentation broth of HR10 strain contained protein antifungal substances. The optimal formulation of the fermentation medium for the antagonistic substance of B. pumilus HR10 was finally obtained by single-factor test, Packett-Burman test, steepest ascent test and Box-Behnken Design (BBD) response surface test, and the best formulation of the fermentation medium for the antagonistic substance of B. pumilus HR10 was 12 g/L corn meal, 15 g/L beef extract and 13 g/L magnesium sulfate, with a predicted bacterial inhibition rate of 89%. The fermentation filtrate of B. pumilus HR10 cultured with the optimized medium formulation was verified to have an inhibition rate of (87.04 ± 3.2) % on the growth of Sphaeropsis sapinea by three replicate tests. The antagonistic crude protein of B. pumilus HR10 were further isolated and identified using HiTrap Capto Q strong Ion-Exchange Chromatography and LC-MS-MS, and it was speculated that glycoside hydrolase (Ghy), beta-glucanase (Beta), arabinogalactan endonuclease ß-1,4-galactanase (Arab), and immunosuppressant A (ImA) are proteins with antagonistic activity against S. sapinea in the B. pumilus HR10.