Diseases caused by oomycetes pose a substantial risk to agricultural production, establishing this pathogen as a principal research and control focus within agroforestry. To explore the status quo and future direction of the field of oomycetes, we used the Web of Science as our data source and conducted a bibliometric analysis of oomycete-related literature from 1985 to 2023. Additionally, CiteSpace was employed to create a knowledge graph, providing a visual representation of the findings. The publication volume analysis indicates a predominant research presence in countries such as the United States, China and Germany. Notably, China has demonstrated remarkable growth over the last five years, ascending to global prominence in this field by 2022. In terms of institutional contributions, the US Department of Agriculture, Nanjing Agricultural University, and the University of California system emerge as leading entities, both in publication volume and the impactful nature of their research. The hotspot analysis delineates that the field predominantly investigates ten specific types, including the Pythium spp., Phytophthora infestans, Ph. capsici and so on. Key research themes include systemic acquired resistance, climate change impact, and antibacterial activities. Furthermore, cluster analysis of literature co-citation unveils several evolving significant research directions within the oomycete fields, represented by RXLR effectors, convergent evolution, and virulence factors. Moreover, a detailed examination of highly cited literature underscores the raising interest in factor pathogenic mechanisms of effector, prevention and control of disease, biological control and immune signal regulation . These works are beneficial for new researchers of oomycetes to quickly understand the current research status and cutting-edge hotspots in this field, and provide some reference for predicting potential research directions of oomycetes.
Viral diseases in cucumber in Qudi are more and more serious in recent years. To detect and identify the main viruses, the plant samples of cucumber were collected from Qudi town, Jiyang district, and next-gene-ration sequencing technology (NGS), RT-PCR amplification and analysis of viral genome sequences were carried out. The results showed that the viruses infecting cucumber in the spring were cucumber green mottle mosaic virus (CGMMV) and watermelon silver mottle virus (WSMoV). Besides CGMMV and WSMoV, cucumber plants in the autumn were also infected with zucchini yellow mosaic virus (ZYMV). The detection rates of CGMMV, WSMoV and ZYMV by RT-PCR were 68.2%, 45.5% and 50.0%, respectively, and the detection rate of complex infection was 50%. Genetic sequence analysis revealed that the coat protein (CP) gene sequence of CGMMV [JY2-6 (GenBank accession number: OR591512) isolated in this study was similar to the sequence of CGMMV [SDRZ (GenBank accession number: KX185151)] isolated from cucumber in Rizhao, and the identity was 100%. The nucleocapsid (N) gene sequence of WSMoV [JY2-4 (GenBank accession number: OR591517) isolated in this study was similar to the sequence of WSMoV [W6412 (GenBank accession number: AM113765)] isolated from watermelon in Thailand, and the identity was 99.1%. The CP gene sequence of ZYMV [JY2-7 (GenBank accession number: OR591522) isolated in this study was similar to the sequence of ZYMV [Yaz.Ashk.S.Z (GenBank accession number: KX495623)] isolated from cucumber in Iran, and the identity was 97%. This study demonstrated that the cucumber in Qudi was mainly infected by CGMMV, WSMoV and ZYMV, and complex infection was also common. This study provided a basis for virus prevention of cucumber in Qudi.
CELL BIOLOGY, PHYSIOLOGY, BIOCHEMISTRY, AND MOLECULAR BIOLOGY
Fusarium sacchari is one of the major pathogenic fungus that cause sugarcane pokkah boeng. In order to explore the function of metalloproteinase effector proteins in F. sacchari, we used the genomic data of F. sacchari to predict the secretory metalloproteinase proteins, and successfully amplified a zinc-type metalloproteinase effector protein gene Fs03538. The results showed that Fs03538 contained a typical ZnMc super family domain, and the 1-18 amino acid sequences at the N-terminal of the protein contain specific signal sequences. Subcellular localization showed that Fs03538 could be localized in the nucleus of Nicotiana benthamiana; qRT-PCR analysis showed that the expression level of Fs03538 was induced and reached the highest peak at 12 h post F. sacchari infection. Agrobacterium tumefaciens mediated transient expression system confirmed that Fs03538 could inhibit the necrosis of tobacco cells induced by mouse Bcl-2-associated X protein (BAX). As compared with the wild type F. sacchari strain CNO-1, the Fs03538 knock-out mutant showed no significant difference on mycelial growth and conidia production, but the pathogenicity on sugarcane was significantly decreased. Taken together, the results of the study suggest that Fs03538 is an important virulence factor of F. sacchari, which highly expressed at the time of infection and could inhibit the host immune responses by entering the host cell nucleus.
Fusarium solani, known for its extensive host range, is the causal agent of the destructive root rot disease in agriculture production. Secreted proteins play important roles in the infection of host plants by phytopathogenic fungi. To identify the secreted proteins and effectors in F. solani, we performed an in-depth analysis of the F. solani genome in this study. Among the total 17654 genomic proteins, 1032 proteins were predicted to be the candidate secreted proteins by using SignalP, TMHMM, WoLF PSORT and PredGPI softwares, accounting for 5.85% of the total proteins in F. solani. Among them, 258 proteins were predicated to be carbohydrate-active enzymes (CAZymes) by using the dbCAN3 software, with the glycoside hydrolase family being the most abundant. Furthermore, 185 secreted proteins were predicated to be candidate effectors, with 183 sequences being annotated in the PHI database. By employing a virus-based transient expression system, we investigated the effect of the 5 candidate effectors annotated for increased virulence on BAX-triggered programmed cell death, and the result showed that the two effectors (XP_046140852.1 and XP_046131041.1) could suppress BAX-triggered programmed cell death in N. benthamiana. These findings provide not only an important reference for further analysis of the pathogenic molecular mechanism of F. solani but also a theoretical basis for understanding the interactions between F. solani and host plants.
Rice is an important grain crop in the world. Although some genes that confer resistance to rice blast and bacterial blight, two important diseases threatening rice production, have been identified in rice plants, the corresponding resistance gene resources remain scarce. In this study, we found that the transcription factor OsEIL4 is involved in regulating rice resistance to these two rice diseases. Quantitative real-time PCR (qPCR) assays showed that the expression of OsEIL4 was markedly induced upon Magnaporthe oryzae (M. oryzae) or Xanthomonas oryzae pv. oryzae (Xoo) infection. Moreover, compared with wild-type rice plants, Oseil4 (CRISPR/Cas9-based OsEIL4 knockout) and OsEIL4-RNAi rice lines were more susceptible, while OsEIL4-OX (overexpression) plants were more resistant to M. oryzae and Xoo. Further qPCR analysis of the transcript levels of the marker genes of ethylene pathway and defense-related genes OsPR1a and OsPR5 exhibited that they were downregulated in Oseil4 lines but upregulated in OsEIL4-OX lines, suggesting that OsEIL4, which functions as a positive regulator in ethylene pathway, mediates rice resistance by modulating PR genes expression. Subcellular localization and yeast-one-hybrid assay results confirmed that OsEIL4 has transcriptional activity, indicating that it may regulate rice disease resistance by exercising transcriptional regulatory function. This study explores a gene resource with broad-spectrum resistance, providing a new possibility for molecular breeding of rice disease resistance.
In order to clarify the protein-protein interaction of Botrytis cinerea and further explore the molecular mechanism of B. cinerea pathogenicity, a protein-protein interaction network (PPI) map of B. cinerea containing 2 296 proteins and 9 376 pairs of interactions was constructed by homology mapping (Interolog) method. The domain-domain interactions (Domain-domain interactions) method was used to further screen and optimize the protein-protein interaction network map of B. cinerea. A high-confidence protein-protein interaction network containing 1 233 proteins and 2 585 pairs of interactions was constructed. The network diagram was divided into 27 functional modules by MCODE algorithm, and the interaction protein subnetwork of known pathogenic proteins GB1, RAS2, BMP1, and BMP3 were analyzed. The molecular mechanism of its pathogenicity was predicted. The interaction between BofuT4_P103090 and BofuT4_P056160 and BofuT4_P007800 proteins in the protein interaction network was verified by yeast two-hybrid technique. The interaction between BofuT4_P103090 and BofuT4_P056160 and BofuT4_P007800 proteins was determined, and the reliability of the protein-protein interaction network constructed in this study was verified. The results of this study laid a foundation for elucidating the molecular mechanism of B. cinerea pathogenesis, and provided a reference for the study of protein-protein interaction networks and pathogenesis of other species.
Pythium myriotylum is a soil-borne oomycete that can infect a wide range of economically important crops such as soybeans, tomatoes and wheat. It causes root rot and stem base rot resulting in serious harm. In this study, we identified and characterized a carbonic anhydrase family protein-PmCA1 in P. myriotylum. We found that PmCA1 was upregulated during plant infection. In addition, PmCA1 inhibited flg22 induced reactive oxygen species burst and defense related gene expression, promoting the infection of Phytophthora capsici. These results indicate that PmCA1 may be a virulence factor of P. myriotylum, promoting pathogen colonization by inhibiting plant PTI immune response. Taken together, our results provide a basis for the functional study of the secreted proteins by P. myriotylum, as well as theoretical support for exploring the interaction between P. myriotylum and host plants.
Apple-replanting disease is a typical disease caused by soil microecological imbalance. Regulating soil microbial community structure and developing disease-suppressive soil is the key to effectively control this disease. To identify the type and mechanism of key control microbial communities in disease-suppressive soil, we investigated the effect of 7 soil control measures on the growth of Malus micromalus, the soil physicochemical properties and seasonal dynamic changes of microbial diversity in rhizosphere soil. The results showed that all these 7 biological measures increased the main nutrient content, enzyme activity and the diversity of microorga-nisms in apple-replanting soil, promoting the formation of disease-suppressive soil. At phyla level, the core microorganisms in disease-suppressive soil were Proteobacteria and Acidobacteria for bacteria, Ascomycetes and Basidiomycetes for fungi; at genus level, the dominant bacteria were MND1, Nitrospira and Sphingomonas, and the relative content of potential pathogenic fungi such as Fusarium, Ilyonectria and Alternaria decreased significantly. Correlation analysis showed that 55 genera including Nitrospira and Trichoderma were key dominant microorganisms, among which Nitrospira was the core of microbial regulatory interaction in disease-suppressive soil; thirty-two genera of rhizosphere bacteria, which were divided into 3 functional groups, showed significant positive correlation with soil nitrogen and phosphorus conversion through soil global overview pathway, carbohydrate metabolism and amino acid metabolism; twenty-three genera of symbiotic or saprophytic fungi, were positively correlated with the content of soil organic matter (SOM) and the activities of sucrase, urease, alkaline phosphatase and catalase. The key microbiome in disease-suppressive soil promotes plant growth by antagonizing pathogen, activating plant immunity and producing special metabolites.
Cucumber seedling damping-off caused by Pythium aphidermatum is one of the main soil-borne diseases seriously affecting the survival of cucumber seedlings. With the expansion of eggplant cultivation area in greenhouse, the occurrence and damages of the disease are increasing year by year. In this study, a bacterial strain ZF514, capable of producing volatile substance with antagonistic effect against P. aphidermatum, was isolated from rhizosphere soil of healthy cucumber plants in Hangzhou, China. According to morphological cha-racteristics, physiological and biochemical properties, and multi-gene (16S rDNA-gyrA-rpoB) phylogenetic analysis, strain ZF514 was identified as Bacillus velezensis. Strain ZF514 also exhibited significant antagonistic effects on the 5 common phytopathogenic fungi by dual culture on two-section of a Petri dish. The results of pot experiments showed that simulated fumigation treatment of soil with strain ZF514 significantly reduced disease incidence of cucumber seedling damping-off, and the control effect reached 63.69%. In summary, the volatile substance-producing B. velezensis strain ZF514 has potential to be explored as an environment-friendly microbial fumigant against soil-borne diseases.
Clubroot caused by Plasmodiophora brassicae has been a major threat to the production of crucife-rous vegetables, screening and identifying antagonistic bacteria with potential application is therefore most important for the bio-control of the disease. In this study, endophytic bacteria were isolated from root tissues of healthy Chinese cabbage in the field where clubroot disease occurred seriously. Using Phytophthora capsici as an indicator, a bacterial strain JP2 with biocontrol effect on Chinese cabbage clubroot was obtained by both dual-culture test and pot experiment in greenhouse. Combined with morphological characteristics, physiological and biochemical properties, and 16S rDNA-based phylogenetic analysis, the strain JP2 was identified as Pseudomonas brassicacearum. The fermentation broth of JP2 (culturing for 48 h) displayed a chitinase activity of 0.034 U·mL-1, cellulose decomposition capacity (H value) of 1.89, and siderophore activity of 57.24%. Fluorescein siderophore (PVD)- and 2, 4-diacetylphloroglucinol (DAPG)-synthesizing genes were identified in the genome of strain JP2. In addition, JP2 exhibited good antagonistic effects on the six common phytopathogenic fungi, indicating its broad inhibitory spectrum against plant fungal diseases. The crude extract of JP2 showed good lethal effect on resting spores of P. brassicae, with a mortality rate of 44.44%. At 30 d post-inoculation, the colonization density of JP2 in the rhizosphere soil of Chinese cabbage remained at 3.03×102 CFU·g-1, significantly reducing the number of resting spores of P. brassicae in the soil. The control effect of JP2 on P. brassicae in pot experiment was 58.83 %. These results indicate that JP2 strain has good biocontrol potential against Chinese cabbage clubroot.
Pogostone (Po) was synthesized in one step and its structure was characterized by 1H NMR, 13C NMR, HRMS and X-ray single crystal diffraction analysis. Its antifungal and antioomycete activities were evaluated against ten phytopathogens. The in vitro bioassays revealed that Po displayed significant inhibition on the mycelial growth of Sclerotinia sclerotiorum, Rhizoctonia solani and Pythium recalcitrans with EC50 values of 5.32, 5.53 and 7.83 μg·mL-1, respectively, being potent than the control, carvacrol. At a concentration of 200 μg·mL-1, Po exhibited a protective efficacy of 97.9% against sclerotinia rot (S. sclerotiorum) on detached rape leaves, which was comparable to the boscalid (15 μg·mL-1, 99.0%) and carvacrol (1 000 μg·mL-1, 99.7%). Pot experiments showed that the protective efficacies of Po were 94.6% and 91.8% at 500 μg·mL-1 against the soybean seedling blight (R. solani) and tobacco damping-off (P. recalcitrans), respectively, which were comparable to those of carvacrol at 1 000 μg·mL-1(93.1% and 91.2%, respectively). The protective efficacy of Po at 100 μg·mL-1 against wheat powdery mildew was 94.1%, which was similar to that of carbendazim at 50 μg·mL-1 (93.5%) or carvacrol at 500 μg·mL-1 (93.0%). The results of this study could serve as a basis for the development and application of Po as botanical fungicide.
Fludioxonil is the main fungicide used for the prevention and control of vegetable gray mold caused by Botrytis cinerea. To determine the resistance status of B. cinerea to fludioxonil in Shanxi Province, 312 B. cinerea isolates were obtained from Shanxi Province and their resistance level to fludioxonil was investigated by using the hyphal growth rate method. The mutation sites in the Bos1 gene and biological phenotypes of fludioxonil-resistant B. cinerea isolates, and the cross-resistance between fludioxonil and the other 4 fungicides (pyraclostrobin, difenoconazole, pyrimethanil and prochloraz) in these resistant isolates were studied. The results showed that the resistance frequency of the tested B. cinerea isolates to fludioxonil was 7.37%, with the resistance level mainly in a low and medium level, and only 2 isolates showing high resistance to fludioxonil were found. All the resistant isolates had mutation in Bos1 gene, mainly in the TAR, HAMP and REC domains, with resistance types of F127S, V287G, I365N, I365S, Q369P+N373S, V1136I and A1259T. Additionally, it was found that the hyphal growth rate, sclerotium production, sporulation capacity and pathogenicity of the resistant isolates were lower than those of the susceptible isolates, indicating compromised fitness. There was no cross-resistance between fludioxonil and the 4 tested fungicides, and fludioxonil can therefore be used to control grey mold in rotation or in combination with these fungicides. This study provides a theoretical basis for rational utilization of fungicides in chemical control of grey mold disease.
Alternaria panax is one of the main pathogens to infect leaves, stems and fruits, leading to leaf blight, stem necrosis and fruit shriveled of ginseng that seriously threatens ginseng yield and quality. In this study, an Agrobacterium tumefaciens-mediated transformation system was constructed for Al. panax. To further evaluate the feasibility of the transformation system, the lysine biosynthesis related gene ApLYS2 was knocked out from Al. panax JY15 using this method. The results showed that 23 transformants /106·mL-1 were obtained under the optimal conditions (48 h and 22℃ for co-cultivation, concentration for OD600 0.6 of AGL-1 and 106·mL-1protoplast) and the Hyg gene was successfully introduced into Al. panax JY15. Besides, the ApLYS2 was successfully knocked out. The null mutants ΔAplys2-4 andΔAplys2-7 could not grow on MM media. When lysine was added into MM media, the growth defects of the null mutants ΔAplys2-4 andΔAplys2-7 were recovered. This study indicated that Agrobacterium tumefaciens-mediated transformation system for Al. panax was successfully constructed and verified by the knockout of ApLYS2, providing an effective genetic transformation technique for studying the pathogenic mechanism of Al. panax.
In this study, the fungal strain LD-11 was isolated from the infected plant of Lonicera caerulea (cv Lanjingling) collected in the horticulture experimental station of Northeast Agricultural University, Harbin, Heilongjiang Province. The strain was identified as Epicoccum nigrum by morphology, rDNA-ITS, LSU, TUB, RPB2 gene sequence amplification and phylogenetic tree construction. The experimental results showed that E. nigrum LD-11 could grow on PDA, OA and MEA medium. The optimal culture medium was OA, and the optimal culture conditions were growth temperature of 25 ℃, pH 6, carbon source is starch and nitrogen source is yeast extract, and full light conditions were conducive to mycelial growth. This study is the first time to isolate and identify E. nigrum, the pathogen of leaf spot disease in L. caerulea, which will provide an important source of pathogenic fungi for future research on control of plantdisease.
Polygonatum kingianum Coll. et Hemsl., a perennial herbaceous plant belonging to the family Liliaceae, has special medicinal and dietary values. Rhizome rot, usually leading to the decrease of yield and quality, is a frequently occurred disease on P. kingianum in Yunnan Province. In this study, diseased P. kingianum samples with typical symptoms of rhizome rot were collected, and a representative fungal strain 19-1 was obtained by tissue isolation and single spore purification. The pathogenicity of strain 19-1 to P. kingianum was tested and confirmed by irrigating inoculation of plant seedlings with spore suspension (1×106 spores·mL-1). According to morphological characteristics and multigene-based phylogenetic analysis results, strain 19-1 was identified as Fusarium concentricum. This is the first report of F. concentricum causing rhizome rot on P. kingianum. Our results provide a theoretical basis for further investigation of the epidemiology and integrated control of the disease.
Pittosporum tobira is used as a evergreen plant in urban landscape. In recent years, a serious leaf disease was found on P. tobira in Chongqing, which seriously affected the ecological and landscape benefits. Disease incidence ranged from 20% to 50% in the affected fields. In this study, the pathogens of this disease were isolated and verified by Koch’s rule. The strain were identified as Colletotrichum fioriniae based on morphological characteristics and rDNA-internal transcribed space(ITS)、actin(ACT)、β-tubulin(TUB2) and glyceraldehyde-3-phosphate dehydrogenase(GAPDH) gene sequence analysis. The identification of the pathogen of anthracnose in P. tobira will provide theoretical basis for further study of disease monitoring and control.
Avena sativa is an important crop for food and feed in the world. During the investigation of oat diseases in Hohhot in 2022, a new disease was found which produced long spindle-shaped necrotic lesions on oat sheath with black spots in the center. More strains with the same colony morphology were generated from the diseased sheath tissues. One representative strain QSH2-3-2 was selected for pathogenicity test. The results show that strain QSH2-3-2 can cause necrotic spots on oat leaves and sheaths. It was identified as Didymella glomerata by morphological characteristics and multi-locus DNA sequence analysis. To our knowledge, this is the first report that D. glomerata was the pathogen of oat spot blight.
Grapevine (Vitis vinifera L.), is known as the first of the world’s four fruits, both fruit and medicinal value. Recently, ‘shine muscat’ and ‘Christmas Rose’ were premium varieties of grapevine. From May 2022 to May 2023, a fruit drop and rot disease was found on grapevine in Zhaoqin city, Guangdong province. To clarify the reason of this phenomenon, the pathogen was isolated and purified by tissue separation method, and its pathogenicity was confirmed based on the Koch’s postulates. According to morphological features and phylogenetic analysis of rDNA-ITS and EF-1α gene, the pathogen was identified as Aspergillus aculeatus. To our knowledge, this is the first report of A. aculeatus causing fruit rot on grapevine in China. The results will provide scientific basis for effective control of the disease on grapevine.
In 2023, a typical sample of root rot of Idesia polycarpa was collected in Zunyi city, Guizhou Pro-vince, China, and the pathogenic strain was obtained by tissue separation method. According to Koch’s rule, pathogenicity test, morphological characteristics and ITS, TEF1-α and TUB multigene phylogenetic analysis, the pathogen was identified as Fusarium solani. The results provided a theoretical basis for the field control of the root rot of Idesia polycarpa. This is the first time to report the root rot of I. polycarpa induced by F. solani in China.
Xinjiang wild apricot (Prunus armeniaca) has strong resistance to drought and cold. It is an important genetic resource for breeding. In 2021, twenty leaf samples of Xinjiang wild apricot were collected in the wild forests of Tianshan Mountain in YiLi, Xinjiang. Using high-throughput sequencing and RT-PCR, peach chlorotic leaf spot virus (PCLSV) and mume-associated luteovirus (MaLV) were identified. Whole genomes of these two viruses were obtained by RT-PCR and RACE. After removing poly (A), the genome of PCLSV from Prunus armeniaca (PCLSV-YX) contains 7 462 nucleotides (nts) with three overlapping open reading frames (ORFs). The genome of MaLV from Prunus armeniaca (MaLV-YX)contains 5 753 nts, and has six ORFs. Phylogenetic analysis showed that PCLSV-YX was closely related to isolates of ‘PR19-2’ and ‘TaTao’. MaLV-YX was closely related to cherry-associated luteovirus (ChALV), prunus mahaleb-associated luteovirus (PmALV), peach-associated luteovirus (PaLV) and peach-associated luteovirus 2 (PaLV2).
Journal Information
Superintendent： China Association for Science and Technology
Sponsored by： Chinese Society for Plant Pathology
China Agricultural University
Editor in Chief: FAN Jun
Started in 1955
ISSN 0412-0914
CN 11-2184/Q
