Phytophthora infestans is the pathogen of potato late blight, which is one of the most serious diseases of the potato. Myxobacteria, especially Myxococcus, become a valuable biological control resource due to their preponderant abilities to produce various secondary metabolites with novel structure and remarkable biological activity. In a previous study, Myxococcus fulvus B25-I-3 with antagonistic activity against P. infestans was isolated from an environmental sample by rabbit fecal induction method. The biocontrol mechanism of M. fulvus B25-I-3 against P. infestans and its control efficiency on potato late blight were studied. The results showed that the active substances produced by strain B25-I-3 had strong inhibitory effect on the asexual reproduction and sexual reproduction of P. infestans. In addition, the active substances could reduce the content of soluble proteins and the activity of the protective enzymes (polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, superoxide dismutase) in P. infestans and increase the oxidative damage and permeability of cell membrane. And the active substances could inhibit the infection of the detached potato leaves by P. infestans significantly. In conclusion, M. fulvus B25-I-3 can produce active substances against P. infestans and has potential value to develop into biological pesticides for the control of potato late blight. The completion of this work may provide basic data for the isolation and identification of active substances and the development of pesticides against potato late blight.

• MeSH
• biologická kontrola škůdců * metody   MeSH
• mikrobiální interakce fyziologie   MeSH
• Myxococcus * fyziologie   MeSH
• nemoci rostlin * parazitologie   prevence a kontrola   MeSH
• Phytophthora infestans * fyziologie   MeSH
• Solanum tuberosum * mikrobiologie   parazitologie   MeSH
• Publikační typ
• časopisecké články MeSH

Virus diseases of strawberry present several complex problems. More than 25 viruses have been described in the genus Fragaria thus far. Here, we describe a novel rhabdovirus, tentatively named strawberry virus 1 (StrV-1), that infects F.ananassa and F.vesca plants. Genomic sequences of three distinct StrV-1 genotypes co-infecting a single F.ananassa host were obtained using combined Illumina and Ion Proton high-throughput sequencing. StrV-1 was transmitted to herbaceous plants via Aphisfabae and A.ruborum, further mechanically transmitted to Nicotianaoccidentalis 37B and sub-inoculated to N.benthamiana, N.benthamiana DCL2/4i, N.occidentalis 37B, and Physalisfloridana plants. Irregular chlorotic sectors on leaf blades and the multiplication of calyx leaves seem to be the diagnostic symptoms for StrV-1 on indexed F.vesca clones. StrV-1 was detected in asymptomatic grafted plants and in 49 out of 159 field strawberry samples via RT-PCR followed by Sanger sequencing. The bacilliform shape of the virions, which have a cytoplasm-limited distribution, their size, and phylogenetic relationships support the assignment of StrV-1 to a distinct species of the genus Cytorhabdovirus. Acyrthosiphonmalvae, A.fabae, and A.ruborum were shown to transmit StrV-1 under experimental conditions.

• MeSH
• fylogeneze MeSH
• genom virový MeSH
• jahodník virologie   MeSH
• listy rostlin virologie   MeSH
• mšice fyziologie   virologie   MeSH
• nemoci rostlin parazitologie   virologie   MeSH
• Rhabdoviridae klasifikace   genetika   izolace a purifikace   MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Ozonated water (O3 wat) soil drench and/or foliar spray applications were evaluated for their potential to control the root-knot nematode Meloidogyne incognita (RKN) and the airborne pathogen Tomato spotted wilt virus (TSWV) in tomato. We investigated how O3 wat modulates the salicylic acid/jasmonic acid/ethylene (SA/JA/ET) signalling network in the host, locally and systemically, to induce resistance to nematode and virus. RESULTS: The application as soil drench was effective in reducing the number of galls and egg masses, but did not reduce the incidence and severity of TSWV infection. Conversely, O3 wat applied by foliar spray decreased TSWV disease incidence and severity (-20%), but was not able to control M. incognita infection. SA-related genes were generally upregulated in both locally treated and systemically reached tissues, showing a positive action of the O3 wat treatment on SA signalling. Neither O3 wat application method significantly altered JA-related gene expression in either direction. ET-related genes were differentially regulated by root or leaf treatments, indicating that O3 wat may have different effects on ET-mediated signalling in different organs. JA/ET/SA related pathways were differentially modulated by O3 wat in the presence of either RKN or TSWV. CONCLUSION: O3 wat had a higher efficacy when applied directly to organs challenged by the pathogens, although it was potentially able to stimulate defence responses through the activation of SA signalling. Owing to its safety and effectiveness in controlling nematode and virus infections, O3 wat can be considered as a possible alternative tool for sustainable disease management practices. © 2019 Society of Chemical Industry.

• MeSH
• imunita rostlin * účinky léků   MeSH
• nemoci rostlin parazitologie   prevence a kontrola   virologie   MeSH
• ozon aplikace a dávkování   MeSH
• regulátory růstu rostlin fyziologie   MeSH
• signální transdukce účinky léků   MeSH
• Solanum lycopersicum účinky léků   fyziologie   MeSH
• Tospovirus fyziologie   MeSH
• Tylenchoidea fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Hormonal dynamics after Plasmodiophora brassicae infection were compared in two Brassica napus cultivars-more resistant SY Alister and more sensitive Hornet, in order to elucidate responses associated with efficient defense. Both cultivars responded to infection by the early transient elevation of active cytokinins (predominantly cis-zeatin) and auxin indole-3-acetic acid (IAA) in leaves and roots, which was longer in Hornet. Moderate IAA levels in Hornet roots coincided with a high expression of biosynthetic gene nitrilaseNIT1 (contrary to TAA1, YUC8, YUC9). Alister had a higher basal level of salicylic acid (SA), and it stimulated its production (via the expression of isochorismate synthase (ICS1)) in roots earlier than Hornet. Gall formation stimulated cytokinin, auxin, and SA levels-with a maximum 22 days after inoculation (dai). SA marker gene PR1 expression was the most profound at the time point where gall formation began, in leaves, roots, and especially in galls. Jasmonic acid (JA) was higher in Hornet than in Alister during the whole experiment. To investigate SA and JA function, SA was applied before infection, and twice (before infection and 15 dai), and JA at 15 dai. Double SA application diminished gall formation in Alister, and JA promoted gall formation in both cultivars. Activation of SA/JA pathways reflects the main differences in clubroot resistance.

• MeSH
• aminohydrolasy genetika   MeSH
• Brassica napus růst a vývoj   metabolismus   parazitologie   MeSH
• cyklopentany analýza   MeSH
• cytokininy analýza   MeSH
• intramolekulární transferasy genetika   MeSH
• kořeny rostlin růst a vývoj   metabolismus   parazitologie   MeSH
• kyseliny indoloctové analýza   MeSH
• listy rostlin růst a vývoj   metabolismus   parazitologie   MeSH
• nemoci rostlin parazitologie   MeSH
• odolnost vůči nemocem MeSH
• oxylipiny analýza   MeSH
• Plasmodiophorida patogenita   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin analýza   MeSH
• rostlinné proteiny genetika   MeSH
• vývojová regulace genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

Plasmodiophora brassicae is a soil-borne pathogen that belongs to Rhizaria, an almost unexplored eukaryotic organism group. This pathogen requires a living host for growth and multiplication, which makes molecular analysis further complicated. To broaden our understanding of a plasmodiophorid such as P. brassicae, we here chose to study immunophilins, a group of proteins known to have various cellular functions, including involvement in plant defense and pathogen virulence. Searches in the P. brassicae genome resulted in 20 putative immunophilins comprising of 11 cyclophilins (CYPs), 7 FK506-binding proteins (FKBPs) and 2 parvulin-like proteins. RNAseq data showed that immunophilins were differentially regulated in enriched life stages such as germinating spores, maturing spores, and plasmodia, and infected Brassica hosts (B. rapa, B. napus and B. oleracea). PbCYP3 was highly induced in all studied life stages and during infection of all three Brassica hosts, and hence was selected for further analysis. PbCYP3 was heterologously expressed in Magnaporthe oryzae gene-inactivated ΔCyp1 strain. The new strain ΔCyp1+ overexpressing PbCYP3 showed increased virulence on rice compared to the ΔCyp1 strain. These results suggest that the predicted immunophilins and particularly PbCYP3 are activated during plant infection. M. oryzae is a well-studied fungal pathogen and could be a valuable tool for future functional studies of P. brassicae genes, particularly elucidating their role during various infection phases.

• MeSH
• Brassica klasifikace   parazitologie   MeSH
• cyklofiliny klasifikace   genetika   metabolismus   MeSH
• fylogeneze MeSH
• imunofiliny genetika   metabolismus   MeSH
• interakce hostitele a patogenu MeSH
• kořeny rostlin parazitologie   MeSH
• nemoci rostlin parazitologie   MeSH
• Plasmodiophorida genetika   metabolismus   fyziologie   MeSH
• protozoální proteiny genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• spory protozoální genetika   MeSH
• stanovení celkové genové exprese metody   MeSH
• Publikační typ
• časopisecké články MeSH

The entomopathogenic fungus Lecanicillium muscarium (Petch) Zare and Gams is currently being developed as a biocontrol agent against insect pests, as well as some plant-pathogenic fungi and bacteria. Data about its activity against plant-parasitic nematodes exist, but are relatively limited. To expand this understanding, we investigated the biocontrol efficiency of three isolates of L. muscarium (Lm) against the root knot nematode, Meloidogyne incognita, in both in vitro and in vivo conditions. In our experiments, the maximum number of nematode eggs, juveniles (J2s), females, and egg masses that were parasitized were quantified after a 72-h exposure to the fungus. The isolate Lm1 was designated as the best biocontrol agent against nematode eggs as well as J2s. It showed the highest colonization of eggs and significantly decreased egg hatching events. The results from two additional isolates, Lm2 and Lm3, were also significant (P = 0.05) but less pronounced than those observed with Lm1. L. muscarium treatments had significant (P = 0.05) positive effects on plant shoot and root growth compared with the growth of control plants. These results suggest the effectiveness of the fungus may be due to either the infection of eggs and J2s, or the production of secondary metabolites that induced plant defense mechanisms and lead to systemic resistance. Our study demonstrates that L. muscarium could be used as a potential biocontrol agent against root knot nematodes.

• MeSH
• Ascomycota fyziologie   MeSH
• biologická kontrola škůdců * MeSH
• nemoci rostlin parazitologie   prevence a kontrola   MeSH
• Solanum lycopersicum parazitologie   MeSH
• Tylenchoidea mikrobiologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

During 2010-14 surveys in the major sesame growing areas of Fars, Yazd and Isfahan provinces (Iran), genetic diversity and vector transmission of phytoplasmas associated with sesame phyllody were studied. Virtual RFLP, phylogenetic, and DNA homology analyses of partial 16S ribosomal sequences of phytoplasma strains associated with symptomatic plants revealed the presence of phytoplasmas referable to three ribosomal subgroups, 16SrII-D, 16SrVI-A, and 16SrIX-C. The same analyses using 16S rDNA sequences from sesame phyllody-associated phytoplasmas retrieved from GenBank database showed the presence of phytoplasmas clustering with strains in the same subgroups in other Iranian provinces including Bushehr and Khorasan Razavi. Circulifer haematoceps and Orosius albicinctus, known vectors of the disease in Iran, were tested for transmission of the strains identified in this study. C. haematoceps transmitted 16SrII-D, 16SrVI-A, and 16SrIX-C phytoplasmas, while O. albicinctus only transmitted 16SrII-D strains. Based on the results of the present study and considering the reported presence of phytoplasmas belonging to the same ribosomal subgroups in other crops, sesame fields probably play an important role in the epidemiology of other diseases associated with these phytoplasmas in Iran.

• MeSH
• DNA bakterií genetika   MeSH
• fylogeneze * MeSH
• Hemiptera mikrobiologie   MeSH
• hmyz - vektory mikrobiologie   MeSH
• nemoci rostlin mikrobiologie   parazitologie   MeSH
• Phytoplasma klasifikace   genetika   patogenita   MeSH
• polymorfismus délky restrikčních fragmentů MeSH
• restrikční enzymy chemie   MeSH
• ribotypizace MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvenční analýza DNA MeSH
• Sesamum mikrobiologie   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Írán MeSH

Plant defense metabolites are well known to be regulated developmentally. The optimal defense (OD) theory posits that a tssue's fitness values and probability of attack should determine defense metabolite allocations. Young leaves are expected to provide a larger fitness value to the plant, and therefore their defense allocations should be higher when compared with older leaves. The mechanisms that coordinate development with defense remain unknown and frequently confound tests of the OD theory predictions. Here we demonstrate that cytokinins (CKs) modulate ontogeny-dependent defenses in Nicotiana attenuata. We found that leaf CK levels highly correlate with inducible defense expressions with high levels in young and low levels in older leaves. We genetically manipulated the developmental patterns of two different CK classes by using senescence- and chemically inducible expression of CK biosynthesis genes. Genetically modifying the levels of different CKs in leaves was sufficient to alter ontogenic patterns of defense metabolites. We conclude that the developmental regulation of growth hormones that include CKs plays central roles in connecting development with defense and therefore in establishing optimal patterns of defense allocation in plants.

• MeSH
• acetáty metabolismus   farmakologie   MeSH
• býložravci fyziologie   MeSH
• časové faktory MeSH
• cyklopentany metabolismus   farmakologie   MeSH
• cytokininy metabolismus   MeSH
• geneticky modifikované rostliny MeSH
• interakce hostitele a parazita účinky léků   MeSH
• listy rostlin genetika   metabolismus   parazitologie   MeSH
• Manduca fyziologie   MeSH
• nemoci rostlin genetika   parazitologie   MeSH
• oxylipiny metabolismus   farmakologie   MeSH
• regulace genové exprese u rostlin účinky léků   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• tabák genetika   metabolismus   parazitologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Cucurbit downy mildew (CDM), caused by the obligate oomycete Pseudoperonospora cubensis, has resurged around the world during the past three decades. A new pathotype or genetic recombinant of P. cubensis have been suggested as possible reasons for the resurgence of CDM in the United States in 2004. In total, 22 isolates collected between 2004 and 2014, mainly in the eastern United States, were tested for their compatibility with a set of 15 cucurbit host types. The virulence structure within these isolates was evaluated on a set of 12 differential genotypes from eight genera. All isolates were highly compatible with the susceptible cultivar of Cucumis sativus, whereas the least compatibility was observed with Luffa cylindrica and Momordica charantia. Based on the compatibility with the differential host set, five pathotypes (1, 3, 4, 5, and 6) were identified among the 22 isolates examined. Pathotypes 1 and 3 had not been previously described in the United States and isolates of these two new pathotypes were also compatible with 'Poinsett 76', a cultivar of C. sativus known to be resistant to CDM prior to 2004. Virulence within the pathogen population was expressed based on virulence factors, virulence phenotypes, and virulence complexity. The number of virulence factors ranged from two to eight, indicating a complex virulence structure, with 77% of the isolates having five to eight virulence factors. Thirteen virulence phenotypes were identified; the mean number of virulence factors per isolate and mean number of virulence factors per virulence phenotype was 5.05 and 5.23, respectively, indicating that complex isolates and phenotypes contributed equally to the complex virulence structure of P. cubensis. Gleason and Shannon indices of diversity were 3.88 and 2.32, respectively, indicating a diverse virulence structure of P. cubensis within the United States population. The diverse virulence and high virulence complexity within the pathogen population indicate that host resistance alone in available cucurbit cultivars will not be effective to control CDM. An integrated approach involving a combination of fungicide application and introduction of cultivars with new resistance genes will be required for effective management of CDM.

• MeSH
• Cucumis sativus parazitologie   MeSH
• fenotyp MeSH
• genotyp MeSH
• hostitelská specificita MeSH
• nemoci rostlin parazitologie   MeSH
• oomycety patogenita   MeSH
• virulence genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Spojené státy americké MeSH

We studied a community of frugivorous Lepidoptera in the lowland rainforest of Papua New Guinea. Rearing revealed 122 species represented by 1,720 individuals from 326 woody plant species. Only fruits from 52% (171) of the plant species sampled were attacked. On average, Lepidoptera were reared from 1 in 89 fruits and a kilogram of fruit was attacked by 1.01 individuals. Host specificity of Lepidoptera was notably low: 69% (33) of species attacked plants from >1 family, 8% (4) fed on single family, 6% (3) on single genus and 17% (8) were monophagous. The average kilogram of fruits was infested by 0.81 individual from generalist species (defined here as feeding on >1 plant genus) and 0.07 individual from specialist species (feeding on a single host or congeneric hosts). Lepidoptera preferred smaller fruits with both smaller mesocarp and seeds. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialist and generalist species. The very low incidence of seed damage suggests that pre-dispersal seed predation by Lepidoptera does not play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen-Connell hypothesis.

• MeSH
• býložravci * MeSH
• deštný prales * MeSH
• fyziologie rostlin MeSH
• hostitelská specificita MeSH
• Lepidoptera fyziologie   MeSH
• nemoci rostlin parazitologie   MeSH
• ovoce parazitologie   fyziologie   MeSH
• rostliny parazitologie   MeSH
• semena rostlinná parazitologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Papua Nová Guinea MeSH