ABSTRACT
Violet root rot is one of the main root diseases in the production process of Pseudostellaria heterophylla. To clarify the pathogenic species that cause the violet root rot of P. heterophylla in Fujian province, the roots and the sclerotia with violet root rot symptoms were collected from the main producing areas of P. heterophylla(Fujian province) from 2017 to 2021, and the pathogens were isolated by tissue separation method and identified by morphology and multi-gene phylogenetic analysis. Additionally, the biological characteristics of the pathogens were studied and the fungicides were determined. The results showed that 78 strains of violet root rot were isolated from the collected root samples, which belonged to one type after preliminary morphological identification. Two represen-tative strains were selected from the pathogens for multi-gene phylogenetic analysis, and they were clustered with Helicobasidium mompa together. The suitable culture conditions for the mycelium were OA medium, 25 ℃, pH 6, and ammonium oxalate as the nitrogen source. The lethal temperature of the mycelium was 50 ℃ for 10 minutes. Moreover, 99.1% propiconazole and 98.7% azoxystrobin had the optimal bacteriostatic effect, and the concentrations with the 50% bacteriostatic rate were 16.85 and 12.24 μg·mL~(-1), respectively. On the basis of the above results, the pathogen causing violet root rot of P. heterophylla in Fujian province was H. mompa. The medium type, growth temperature, pH value, nitrogen source, etc. had significant effect on the growth of mycelium.
Subject(s)
Plant Roots , Phylogeny , Temperature , Caryophyllaceae , NitrogenABSTRACT
This study was designed to identify the pathogen causing soft rot of Pinellia ternata in Qianjiang of Hubei province and screen out the effective bactericides, so as to provide a theoretical basis for the control of soft rot of P. ternata. In this study, the pathogen was identified based on molecular biology and physiological biochemistry, followed by the detection of pathogenicity and pathogenicity spectrum via plant tissue inoculation in vitro and the indoor toxicity determination using the inhibition zone method to screen out bactericide with good antibacterial effects. The control effect of the bactericide against P. ternata soft rot was verified by the leave and tuber inoculation in vitro. The phylogenetic tree was constructed based on the 16 S rDNA, dnaX gene, and recA gene sequences, respectively, and the result showed that the pathogen belonged to the same branch as the type strain Dickeya fangzhongdai JS5. The physiological and biochemical tests showed that the pathogen was identical to D. fangzhongdai, which proved that the pathogen was D. fangzhongdai. The pathogenicity test indicated that the pathogen could obviously infect leaves at 24 h and tubers in 3 d. As revealed by the indoor toxicity test, 0.3% tetramycin, 5% allicin, and 80% ethylicin had good antibacterial activities, with EC_(50) values all less than 50 mg·L~(-1). Tests in tissues in vitro showed that 5% allicin exhibited the best control effect, followed by 0.3% tetramycin and 10% zhongshengmycin oligosaccharide, and their preventive effects were better than curative effects. Therefore, 5% allicin can be used as the preferred agent for the control of P. ternata soft rot, and 0.3% tetramycin and 10% zhongshengmycin oligosaccharide as the alternatives. This study has provided a certain theoretical basis for the control of P. ternata soft rot.
Subject(s)
Phylogeny , Pinellia/chemistry , Plant Leaves , Plant TubersABSTRACT
Trollius chinensis is a traditional Chinese medicinal material in China, the wild resource of T. chinensis are now exhausted, and commercial medicinal T. chinensis mainly depends on artificial cultivation. As one of the most severely happened diseases at the seedling period, damping off has been a serious threaten to the breeding of T. chinensis seedlings. However, no related research have been reported so far. So, the authors collected damping-off samples of T. chinensis in 2018 from seedling breeding nursery in Guyuan, Hebei province, and carried out study on taxonomic identification of the pathogen. Damping off occurs in the T. chinensis production area from mid-May to late June every year. At the beginning, brown lesions were observed on the basal stem, then the lesions circumferential expanded and constricted, and finally resulted in the fall and death of T. chinensis seedlings. Pathogenic isolate was growing rapidly on the PDA medium, well developed aerial mycelia were grey white at first, then turned brown gradually, and a great number of small dark brown sclerotia were developed in the middle and periphery of the colony. Mycelial diameter of the pathogen was about 7 to 10 μm, near right angle or acute angle branches, near branches with septa, branches and septa with constriction. After the healthy T. chinensis seedlings were inoculated by pathogenic isolate, damping-off was observed soon, and the symptom was as same as those observed in the field. Through homogenous blast, the rDNA-ITS sequence of the pathogenic isolate shown 99.49% to 99.84% homology with Rhizoctonia solani, R. solani AG-1 IC mycelium anastomosis group and Thanatephorus cucumeris, the sexual type of Rhizoctonia. Furthermore, obvious mycelial anastomosis phenomena were observed when the pathogenic isolate and R. solani AG-1 IC strain were confronting cultured. Based on the results above, the pathogenic isolate causing damping off of T. chinensis was identified as R. solani AG-1 IC mycelial anastomosis group. RESULTS:: in the present work have important significance for further research on basic biology of the pathogen and integrated control of damping off causing by it on T. chinensis.
Subject(s)
Basidiomycota , Plant Breeding , Plant Diseases , Rhizoctonia , SeedlingsABSTRACT
In recent years, the increasingly frequent contact between humans and wild animals, coupled with the continuous mutation and evolution of pathogenic microorganisms, has led to a continuous increase and frequent outbreaks in emerging infectious diseases (EIDs), which has posed big threats and challenges to the global public health. On the occasion of the next outbreak of EIDs, it is hoped that the two major questions of "what is the pathogen" and "where does the pathogen come from" can be answered accurately and quickly through the rational use of relevant technical methods, so as to timely and effectively warn and control the outbreak of EIDs from the source. This article summarizes the pathogen identification and traceability analysis techniques of current emerging infectious diseases, and discusses the advantages and disadvantages of various technologies and their respective application fields.
ABSTRACT
Los métodos fenotípicos empleados para la identificación de microorganismos dependen de procesos metabólicos que requieren de tiempos de incubación mínimos para alcanzar resultados confiables. La espectrometría de masas MALDI-TOF (desorción/ionización láser asistida por una matriz con detección de masas por tiempo de vuelo) se ha instaurado como una metodología relevante para la identificación de microorganismos mediante el análisis de proteínas, a través de la creación de un espectro de masas específico de género y especie. En esta revisión, se presenta MALDI-TOF MS como una tecnología precisa para la identificación de bacterias, levaduras, mohos, en incluso de virus ,que además, permite la reducción del tiempo para obtener un resultado de identificación, que puede impactar los costos de atención y duración de la estancia hospitalaria. La identificación de microorganismos directamente de muestras biológicas y la detección de mecanismos de resistencia a antimicrobianos, prometen un mayor impacto clínico y epidemiológico con el desarrollo e implementación de esta tecnología en los laboratorios de microbiología clínica.
Phenotypic methods used for the identification of microorganisms depend on metabolic processes that require minimum incubation times to achieve reliable results. For this reason, MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionization Mass Spectrometry) has been established as a relevant methodology for the identification of microorganisms using analysis of proteins, through the creation of a mass spectrum specific for genus and species. In the present review, MALDI TOF MS is presented as an accurate technology for identifying bacteria, yeasts, molds and viruses; Its use allows reduction of the time to obtain an identification result, which may impact the costs of care and length of hospital stay. The identification of microorganisms directly from biological samples and the detection of mechanisms of antimicrobial resistance, promise an additional clinical and epidemiological impact with the development and implementation of this technology in clinical microbiology laboratories.
Subject(s)
Humans , Urinary Tract , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Laboratories , Microbiology , Mass Spectrometry , Bacteria , Viruses , Gender-Specific Needs , Anti-Infective AgentsABSTRACT
Gray mold disease is one of the most important diseases of planted Paris polyphylla var. yunnanensis, the disease appeared primarily as blossom blights and fruit rots, but also as stem rots, leaf rots.In this study, the pathogenetic fungi was isolated from plant tissue or sclerotia that covering the fruit of diseased P. polyphylla var. yunnanensis, the pathogen was certified according to Koch's Postulation. The pathogen produced abundant black, irregular sclerotia on surface of diseased plants and potato dextrose agar. The conidiophores and clusters of oval conidia resembled a grape-like cluster, the size of conidia was 9.70-13.70 μm [average of (11.32±0.82)μm]×7.05-9.12 μm [average of (8.24±0.48)μm], the microconidia produced on potato dextrose agar were spherical,and the size was （3.34±0.31） μm,the pathogen was identified as Botrytis sp based on morphological characteristics. The DNA sequence analysis of the G3PDH, HSP60, RPB2 genes placed the pathogen in a single clade that outside defined species of Botrytis, so the pathogen could be identified as a new species of Botrytis. The pathogen requires 20 °C, pH 8, darkness or low light condition for the best growth.
ABSTRACT
Objective: To identify the pathogen of Menispermum dauricum target spot (a new plant disease in China) and study its biological characteristics and susceptibility to fungicides. Methods: Tissue isolation method was used to obtain the isolates from diseased-leaf. The pathoginicity of the isolates was fulfilled according to Koch's postulate. The identification of the pathogen was carried out according to the morphological and cultural characteristics and rDNA-ITS sequence analysis. The effects of culture medium, temperature, pH value, carbon and nitrogen sources, and light on mycelium growth and sclerotia production of the pathogen were studied. The mycelium growth rate was used to test the susceptibility of pathogen for 14 fungicides. Results: The M. dauricum target spot was caused by Streptobotrys caulophylli. The optimal medium for mycelium growth was PDA; PDA and PSA media were suitable for the sclerotium production. The optimal temperature ranges for mycelium growth and spore production were 20-28℃ and 10-30℃ and were suitable for sclerotium production. The suitable pH values for mycelium growth and sclerotium production were 4-9 and 5-11, respectively. Sucrose and L-glutamine were the optimal carbon and nitrogen sources for mycelium growth. Synanthrin and sucrose were the optimal carbon source and sodium nitrate was nitrogen source for sclerotium production. The total light could promote mycelium growth, while the darkness could promote sclerotium production. The pathogen was sensitive to procymidone, cyprodinil, iprodione, fludioxonil, metalaxyl•mancozeb, and pyraclostrobin•metiram with EC50 < 1.0 mg/L and EC90 < 5.0 mg/L. Conclusion: It is the first report on M. dauricum target spot caused by S. caulophylli in China. The suitable conditions (culture medium, temperature, pH value, carbon and nitrogen sources, and light) for mycilium growth and sclerotium production are determined. The above six fungicides are screened as further field trial agents for disease control.
ABSTRACT
Objective: To investigate the viral pathogens in cultivated Crocus sativus. Methods: Viral pathogen identification was carried out by the observation of virus particle morphology and cytopathology as well as the detection of DAS-ELISA, RT-PCR, and sequencing. Results: Linear virus particles of 600-900 nm in length were observed in C. sativus by negative staining under transmission electron microscope (TEM). Bundles of linear virus particles, cylindrical inclusion bodies of subdivision II, and amorphous inclusion bodies were observed in the cells of C. sativus under TEM after ultrathin-section. These observations resembled the cytopathology of infectious Bean yellow mosaic virus (BYMV). Positive result of DAS-ELISA was obtained from the leaves of C. sativus by using monoclonal antiserum against BYMV capsid protein. Positive result of RT-PCR induced by the Potyvirus specific primers (Sprimer and M4) was also obtained. Sequencing after RT-PCR revealed that the viral sequence in this diseased C. sativus had a homology of 99% with the BYMV sequence. Conclusion: The pathogenic virus of this C. sativus disease is identified as BYMV.