Taxonomy
Plantago asiatica mosaic virus belongs to the genus Potexvirus in the family Alphaflexiviridae of the order Tymovirales.
Virion and genome properties
Plantago asiatica mosaic virus (PlAMV) ...has flexuous virions of approximately 490–530 nm in length and 10–15 nm in width. The genome of PlAMV consists of a single‐stranded, positive‐sense RNA of approximately 6.13 kb. It contains five open reading frames (ORFs 1–5), encoding a putative viral polymerase (RdRp), movement proteins (triple gene block proteins, TGBp1‐3), and coat protein (CP), respectively.
Host range
PlAMV has an exceptionally wide host range and has been isolated from various wild plants, including Plantago asiatica, Nandina domestica, Rehmannia glutinosa, and other weed plants. Experimentally PlAMV can infect many plant species including Nicotiana benthamiana and Arabidopsis thaliana. It also infects ornamental lilies and frequently causes severe necrotic symptoms. However, host range varies depending on isolates, which show significant biological diversity within the species.
Genome diversity
PlAMV can be separated into five clades based on phylogenetic analyses; nucleotide identities are significantly low between isolates in the different clades.
Transmission
PlAMV is not reported to be transmitted by biological vectors. Virions of PlAMV are quite stable and it can be transmitted efficiently by mechanical contact.
Disease symptoms
PlAMV causes red‐rusted systemic necrosis in ornamental lilies, but it shows much weaker, if any, symptoms in wild plants such as P. asiatica.
Control
Control of the disease caused by PlAMV is based mainly on rapid diagnosis and elimination of the infected bulbs or plants.
This pathogen profile summarizes current knowledge regarding Plantago asiatica mosaic virus, including its host range, strain differentiation, host interactions, and utility as a viral vector to examine virus–host interactions.
Key message
Long-read sequencing technologies are revolutionizing the sequencing and analysis of plant and pathogen genomes and transcriptomes, as well as contributing to emerging areas of interest ...in plant-pathogen interactions, disease management techniques, and the introduction of new plant varieties or cultivars.
Long-read sequencing (LRS) technologies are progressively being implemented to study plants and pathogens of agricultural importance, which have substantial economic effects. The variability and complexity of the genome and transcriptome affect plant growth, development and pathogen responses. Overcoming the limitations of second-generation sequencing, LRS technology has significantly increased the length of a single contiguous read from a few hundred to millions of base pairs. Because of the longer read lengths, new analysis methods and tools have been developed for plant and pathogen genomics and transcriptomics. LRS technologies enable faster, more efficient, and high-throughput ultralong reads, allowing direct sequencing of genomes that would be impossible or difficult to investigate using short-read sequencing approaches. These benefits include genome assembly in repetitive areas, creating more comprehensive and exact genome determinations, assembling full-length transcripts, and detecting DNA and RNA alterations. Furthermore, these technologies allow for the identification of transcriptome diversity, significant structural variation analysis, and direct epigenetic mark detection in plant and pathogen genomic regions. LRS in plant pathology is found efficient for identifying and characterization of effectors in plants as well as known and unknown plant pathogens. In this review, we investigate how these technologies are transforming the landscape of determination and characterization of plant and pathogen genomes and transcriptomes efficiently and accurately. Moreover, we highlight potential areas of interest offered by LRS technologies for future study into plant-pathogen interactions, disease control strategies, and the development of new plant varieties or cultivars.
Disturbed activation of autophagy is implicated in the pathogenesis of inflammatory bowel disease. Accordingly, several autophagy-related genes have been identified as Crohn's disease susceptibility ...genes. We screened the autophagy activators from a library including 3,922 natural extracts using a high-throughput assay system. The extracts identified as autophagy activators were administered to mice with 2% dextran sodium sulfate (DSS). Among the autophagy inducers, Sanguisorba officinalis L. (SO) suppressed DSS-induced colitis. To identify the mechanism by which SO ameliorates colitis, epithelial cell and innate myeloid cells-specific Atg7-deficient mice (Villin-cre; Atg7
and LysM-cre; Atg7
mice, respectively) were analyzed. SO-mediated inhibition of colitis was observed in Villin-cre; Atg7
mice. However, SO and a mixture of its components including catechin acid, ellagic acid, gallic acid, and ziyuglycoside II (Mix
) did not suppressed colitis in LysM-cre; Atg7
mice. In large intestinal macrophages (Mφ) of Atg7
mice, SO and Mix
upregulated the expression of marker genes of anti-inflammatory Mφ including Arg1, Cd206, and Relma. However, these alterations were not induced in LysM-cre; Atg7
mice. These findings indicate that SO and its active components ameliorate DSS-induced colitis by providing intestinal Mφ with anti-inflammatory profiles via promotion of Atg7-dependent autophagy.
Systemic acquired resistance (SAR) is a plant defense mechanism that provides protection against a broad spectrum of pathogens in distal tissues. Recent studies have revealed a concerted function of ...salicylic acid (SA) and
-hydroxypipecolic acid (NHP) in the establishment of SAR against bacterial pathogens, but it remains unknown whether NHP is also involved in SAR against viruses. We found that the local application of acibenzolar-
-methyl (ASM), a synthetic analog of SA, suppressed plantago asiatica mosaic virus (PlAMV) infection in the distal leaves of
. This suppression of infection in untreated distal leaves was observed at 1 day, but not at 3 days, after application. ASM application significantly increased the expression of SAR-related genes, including
,
, and
after 1 day of application. Viral suppression in distal leaves after local ASM application was not observed in the
mutant, which is defective in
(ICS1), which is involved in salicylic acid synthesis; or in the
mutant, which is defective in the synthesis of NHP; or in the SA receptor
mutant. Finally, we found that the local application of NHP suppressed PlAMV infection in the distal leaves. These results indicate that the local application of ASM induces antiviral SAR against PlAMV through a mechanism involving NHP.
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•One hundred and six bacteria were isolated from the skin of wild Japanese frogs.•Three bacteria exhibited high antifungal activity against Colletotrichum orbiculare.•The bacteria ...were a Paenibacillus sp., a Raoultella sp. and a Citrobacter sp.•The bacteria suppressed cucumber anthracnose, tomato wilt and rice bakanae diseases.•Cell-free extract of the frog-skin bacteria inhibited the growth of C. orbiculare.
Frogs carry bacterial communities on their skin (Harris et al., 2009) that benefit the host frogs by preventing harmful pathogen infections. Our study aimed to collect culturable bacteria from the skin of wild frogs sampled in Japan and evaluate the antagonistic activity of the bacteria toward plant pathogenic fungi. A collection of 106 bacterial isolates was obtained from three species of frogs, namely Hyla japonica, Pelophylax porosus porosus and Buergeria burgeri. Using a dual-culture method, three isolates, HjD52, HjD92 and B341, were selected based on their ability to significantly inhibit the growth of Colletotrichum orbiculare, the causal fungus of cucumber anthracnose disease. These three bacterial isolates also showed a broad-spectrum of antagonistic activity against plant pathogenic fungi. Furthermore, spray treatment with the bacterial suspensions (109 cfu/ml) effectively reduced the number of anthracnose lesions in greenhouse-grown, potted cucumber plants. Based on the 16S rDNA sequence analysis and similarity search, isolates HjD57, HjD92 and B341 were identified as Paenibacillus sp., Raoultella sp. and Citrobacter sp., respectively. This is the first report showing the potential of Paenibacillus sp., Raoultella sp. and Citrobacter sp. from frog skin to serve as potent biocontrol agents against plant diseases.
A double-stranded RNA (dsRNA) mycovirus was detected in a strain of Alternaria alternata showing impaired growth phenotypes. The A. alternata strain is the Japanese pear pathotype, which produces a ...host-specific AK-toxin. Sequence analysis of the viral genome dsRNAs revealed that this mycovirus consists of five dsRNAs and is evolutionarily related to members of the family Chrysoviridae; the virus was named Alternaria alternata chrysovirus 1 (AaCV1). AaCV1-ORF2 protein accumulated in dsRNA-high-titer sub-isolates with severely impaired phenotypes; heterologous AaCV1-ORF2 overexpression in Saccharomyces cerevisiae caused growth inhibition. In contrast to this yeast growth inhibition phenomenon, the dsRNA-high-titer isolates displayed enhanced pathogenicity against Japanese pear plants, in accordance with a 13-fold increase in AK-toxin level in one such isolate. These findings indicated that AaCV1 is a novel mycovirus that exhibits two contrasting effects, impairing growth of the host fungus while rendering the host ‘hypervirulent’ to the plant.
•A novel mycovirus exhibiting two contrasting effects, attenuating and hypervirulent.•High-titer mycovirus causes a severe impaired growth phenotype in host fungus.•Mycoviral protein is highly expressed in isolates with high dsRNA titer.•Expression of mycoviral protein in S. cerevisiae induces cytological damage.•High-titer mycovirus confers host fungus with hypervirulence in a plant infection.
Tomato wilt pathogen Fusarium oxysporum f. sp. lycopersici (Fol) is grouped into three races based on their pathogenicity to different host cultivars. Rapid detection and discrimination of Fol races ...in field soils is important to prevent tomato wilt disease. Although five types of point mutations in secreted in xylem 3 (SIX3) gene, which are characteristic of race 3, have been reported as a molecular marker for the race, detection of these point mutations is laborious. The aim of this study is to develop a rapid and accurate method for the detection of point mutations in SIX3 of Fol. Loop-mediated isothermal amplification (LAMP) of SIX3 gene with the universal QProbe as well as two joint DNAs followed by annealing curve analysis allowed us to specifically detect Fol and discriminate race 3 among other races in about one hour. Our developed method is applicable for detection of races of other plant pathogenic fungi as well as their pesticide-resistant mutants that arise through point mutations in a particular gene.
Background/Aim: We investigated the effect of Kumaizasa leaf extract (KLE) on innate immunity using the HEK293 and RAW 264.7 cell lines. Materials and Methods: KLE, lipopolysaccharides (LPS), or KLE ...with LPS were added to RAW 264.7 cells. The TNF-α and IL-1β mRNA expression was then quantified. The expression of MAPKs, NFĸB, TNF-α and IL-1β proteins was also quantified. In addition, KLE was added to HEK293 cells and the IL-8 concentration was measured. Results: In RAW 264.7 cells, KLE increased the levels of TNF-α and IL-1β mRNA. By contrast, when KLE and LPS were added to RAW 264.7 cells, the increase in TNF-α and IL-1β mRNA was ameliorated. Similarly, the expression of JNK and ERK proteins was reduced. The addition of KLE to HEK293 cells induced IL-8 production. Conclusion: Based on these results, a KLE-mediated mechanism may regulate immunity by suppressing the expression of JNK and ERK, which are involved in inflammatory signal transduction.
Bakanae disease, caused by
, is an economically important seed-borne disease of rice.
is horizontally transmitted to rice flowers and vertically transmitted to the next generation via seeds. The ...fungus induces typical symptoms such as abnormal tissue elongation and etiolation. Sanitation of seed farms and seed disinfection are the only effective means to control bakanae disease at present; however, the efficacy of these methods is often insufficient. Therefore, alternative and innovative control methods are necessary. We developed a novel method for applying nonpathogenic fusaria as biocontrol agents by spraying spore suspensions onto rice flowers to reduce the incidence of seed-borne bakanae. We visualized the interaction between
W5, a nonpathogenic fusarium, and
using transformants expressing two different fluorescent proteins on/in rice plants. W5 inhibited hyphal extension of
on/in rice flowers and seedlings, possibly by competing with the pathogen, and survived on/in rice seeds for at least 6 months.
We demonstrated that a spray treatment of rice flowers with the spores of nonpathogenic fusaria mimicked the disease cycle of the seed-borne bakanae pathogen
and effectively suppressed the disease. Spray treatment of nonpathogenic fusaria reduced the degree of pathogen invasion of rice flowers and vertical transmission of the pathogen to the next plant generation via seeds, thereby controlling the bakanae disease. The most promising isolate,
W5, colonized seeds and seedlings via treated flowers and successfully inhibited pathogen invasion, suggesting that competition with the pathogen was the mode of action. Seed-borne diseases are often controlled by seed treatment with chemical fungicides. Establishing an alternative method is a pressing issue from the perspectives of limiting fungicide resistance and increasing food security. This work provides a potential solution to these issues using a novel application technique to treat rice flowers with biocontrol agents.
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