Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.133
Filtrar
1.
BMC Plant Biol ; 21(1): 358, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34348650

RESUMO

BACKGROUND: The South America pinworm, Tuta absoluta, is a destructive pest of tomato that causes important losses worldwide. Breeding of resistant/tolerant tomato cultivars could be an effective strategy for T. absoluta management but, despite the economic importance of tomato, very limited information is available about its response to this treat. To elucidate the defense mechanisms to herbivore feeding a comparative analysis was performed between a tolerant and susceptible cultivated tomato at both morphological and transcriptome level to highlight constitutive leaf barriers, molecular and biochemical mechanisms to counter the effect of T. absoluta attack. RESULTS: The tolerant genotype showed an enhanced constitutive barrier possibly as result of the higher density of trichomes and increased inducible reactions upon mild infestation thanks to the activation/repression of key transcription factors regulating genes involved in cuticle formation and cell wall strength as well as of antinutritive enzymes, and genes involved in the production of chemical toxins and bioactive secondary metabolites. CONCLUSIONS: Overall, our findings suggest that tomato resilience to the South America pinworm is achieved by a combined strategy between constitutive and induced defense system. A well-orchestrated modulation of plant transcription regulation could ensure a trade-off between defense needs and fitness costs. Our finding can be further exploited for developing T. absoluta tolerant cultivars, acting as important component of integrated pest management strategy for more sustainable production.


Assuntos
Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Folhas de Planta/genética , Transcriptoma , Animais , Perfilação da Expressão Gênica/métodos , Ontologia Genética , Interações Hospedeiro-Parasita , Larva/fisiologia , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/parasitologia , Mariposas/fisiologia , Doenças das Plantas/parasitologia , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA-Seq/métodos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Tricomas/genética , Tricomas/metabolismo , Tricomas/parasitologia
2.
Science ; 373(6556): 774-779, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34385392

RESUMO

The oomycete Phytophthora infestans is a damaging crop pathogen and a model organism to study plant-pathogen interactions. We report the discovery of a family of copper-dependent lytic polysaccharide monooxygenases (LPMOs) in plant pathogenic oomycetes and its role in plant infection by P. infestans We show that LPMO-encoding genes are up-regulated early during infection and that the secreted enzymes oxidatively cleave the backbone of pectin, a charged polysaccharide in the plant cell wall. The crystal structure of the most abundant of these LPMOs sheds light on its ability to recognize and degrade pectin, and silencing the encoding gene in P. infestans inhibits infection of potato, indicating a role in host penetration. The identification of LPMOs as virulence factors in pathogenic oomycetes opens up opportunities in crop protection and food security.


Assuntos
Lycopersicon esculentum/parasitologia , Oxigenases de Função Mista/metabolismo , Pectinas/metabolismo , Phytophthora infestans/enzimologia , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Cobre , Oxigenases de Função Mista/química , Oxigenases de Função Mista/genética , Modelos Moleculares , Oxirredução , Phytophthora infestans/genética , Phytophthora infestans/patogenicidade , Folhas de Planta/parasitologia , Polissacarídeos/metabolismo , Conformação Proteica , Domínios Proteicos , Fatores de Virulência/química , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
3.
Arch Virol ; 166(10): 2869-2873, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34292373

RESUMO

Eriophyid mites are commonly found on the leaf surface of different plant species. In the present study, a novel virus associated with an eriophyid mite species was detected using high-throughput sequencing (HTS) of total RNA from fruit tree leaves, primarily growing under greenhouse conditions. The complete genome sequence was characterized using rapid amplification of cDNA ends followed by Sanger sequencing, revealing a genome of 8885 nucleotides in length. The single positive-stranded RNA genome was predicted to encode typical conserved domains of members of the genus Iflavirus in the family Iflaviridae. Phylogenetic analysis showed this virus to be closely related to the unclassified iflavirus tomato matilda associated virus (TMaV), with a maximum amino acid sequence identity of 59% in the RNA-dependent RNA polymerase domain. This low identity value justifies the recognition of the novel virus as a potential novel iflavirus. In addition to a lack of graft-transmissibility evidence, RT-PCR and HTS detection of this virus in the putative host plants were not consistent through different years and growing seasons, raising the possibility that rather than a plant virus, this was a virus infecting an organism associated with fruit tree leaves. Identification of Tetra pinnatifidae HTS-derived contigs in all fruit tree samples carrying the novel virus suggested this mite as the most likely host of the new virus (p-value < 1e-11), which is tentatively named "eriophyid mite-associated virus" (EMaV). This study highlights the importance of a careful biological study before assigning a new virus to a particular plant host when using metagenomics data.


Assuntos
Frutas/parasitologia , Ácaros/virologia , Vírus de RNA de Cadeia Positiva/classificação , Árvores/parasitologia , Sequência de Aminoácidos , Animais , Frutas/virologia , Genoma Viral/genética , Metagenômica , Filogenia , Extratos Vegetais , Folhas de Planta/parasitologia , Folhas de Planta/virologia , Vírus de RNA de Cadeia Positiva/genética , RNA Viral/genética , RNA Polimerase Dependente de RNA , Árvores/virologia
4.
BMC Plant Biol ; 21(1): 306, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34193042

RESUMO

BACKGROUND: Outbreaks of insect pests in paddy fields cause heavy losses in global rice yield annually, a threat projected to be aggravated by ongoing climate warming. Although significant progress has been made in the screening and cloning of insect resistance genes in rice germplasm and their introgression into modern cultivars, improved rice resistance is only effective against either chewing or phloem-feeding insects. RESULTS: In this study, the results from standard and modified seedbox screening, settlement preference and honeydew excretion tests consistently showed that Qingliu, a previously known leaffolder-resistant rice variety, is also moderately resistant to brown planthopper (BPH). High-throughput RNA sequencing showed a higher number of differentially expressed genes (DEGs) at the infestation site, with 2720 DEGs in leaves vs 181 DEGs in sheaths for leaffolder herbivory and 450 DEGs in sheaths vs 212 DEGs in leaves for BPH infestation. The leaf-specific transcriptome revealed that Qingliu responds to leaffolder feeding by activating jasmonic acid biosynthesis genes and genes regulating the shikimate and phenylpropanoid pathways that are essential for the biosynthesis of salicylic acid, melatonin, flavonoids and lignin defensive compounds. The sheath-specific transcriptome revealed that Qingliu responds to BPH infestation by inducing salicylic acid-responsive genes and those controlling cellular signaling cascades. Taken together these genes could play a role in triggering defense mechanisms such as cell wall modifications and cuticular wax formation. CONCLUSIONS: This study highlighted the key defensive responses of a rarely observed rice variety Qingliu that has resistance to attacks by two different feeding guilds of herbivores. The leaffolders are leaf-feeder while the BPHs are phloem feeders, consequently Qingliu is considered to have dual resistance. Although the defense responses of Qingliu to both insect pest types appear largely dissimilar, the phenylpropanoid pathway (or more specifically phenylalanine ammonia-lyase genes) could be a convergent upstream pathway. However, this possibility requires further studies. This information is valuable for breeding programs aiming to generate broad spectrum insect resistance in rice cultivars.


Assuntos
Herbivoria/fisiologia , Oryza/genética , Oryza/parasitologia , Floema/parasitologia , Folhas de Planta/parasitologia , Transcriptoma/genética , Animais , Parede Celular/metabolismo , Ciclopentanos/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Hemípteros/fisiologia , Metabolismo dos Lipídeos , Oxilipinas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Ácido Salicílico/metabolismo , Ácido Chiquímico/metabolismo , Transcrição Genética
5.
Food Microbiol ; 99: 103816, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34119101

RESUMO

Protozoan contamination in produce is of growing importance due to their capacity to cause illnesses in consumers of fresh leafy greens. Viability assays are essential to accurately estimate health risk caused by viable parasites that contaminate food. We evaluated the efficacy of reverse transcription quantitative PCR (RT-qPCR), propidium monoazide coupled with (q)PCR, and viability staining using propidium iodide through systematic laboratory spiking experiments for selective detection of viable Cryptosporidium parvum, Giardia enterica, and Toxoplasma gondii. In the presence of only viable protozoa, the RT-qPCR assays could accurately detect two to nine (oo)cysts/g spinach (in 10 g processed). When different proportions of viable and inactivated parasite were spiked, mRNA concentrations correlated with increasing proportions of viable (oo)cysts, although low levels of false-positive mRNA signals were detectable in the presence of high amounts of inactivated protozoa. Our study demonstrated that among the methods tested, RT-qPCR performed more effectively to discriminate viable from inactivated C. parvum, G. enterica and T. gondii on spinach. This application of viability methods on leafy greens can be adopted by the produce industry and regulatory agencies charged with protection of human public health to screen leafy greens for the presence of viable protozoan pathogen contamination.


Assuntos
Cryptosporidium parvum/isolamento & purificação , Parasitologia de Alimentos/métodos , Giardia/isolamento & purificação , Spinacia oleracea/parasitologia , Toxoplasma/isolamento & purificação , Animais , Azidas/química , Cryptosporidium parvum/química , Cryptosporidium parvum/genética , Cryptosporidium parvum/crescimento & desenvolvimento , Contaminação de Alimentos/análise , Giardia/química , Giardia/genética , Giardia/crescimento & desenvolvimento , Oocistos/química , Oocistos/crescimento & desenvolvimento , Oocistos/isolamento & purificação , Folhas de Planta/parasitologia , Propídio/análogos & derivados , Propídio/química , Reação em Cadeia da Polimerase em Tempo Real , Coloração e Rotulagem , Toxoplasma/química , Toxoplasma/genética , Toxoplasma/crescimento & desenvolvimento
6.
Int J Mol Sci ; 22(10)2021 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-34068250

RESUMO

Chinese galls are the result of hyperplasia in host plants induced by aphids. The metabolism and gene expression of these galls are modified to accommodate the aphids. Here, we highlight the molecular and histologic features of horned galls according to transcriptome and anatomical structures. In primary pathways, genes were found to be unevenly shifted and selectively expressed in the galls and leaves near the galls (LNG). Pathways for amino acid synthesis and degradation were also unevenly shifted, favoring enhanced accumulation of essential amino acids in galls for aphids. Although galls enhanced the biosynthesis of glucose, which is directly available to aphids, glucose content in the gall tissues was lower due to the feeding of aphids. Pathways of gall growth were up-regulated to provide enough space for aphids. In addition, the horned gall has specialized branched schizogenous ducts and expanded xylem in the stalk, which provide a broader feeding surface for aphids and improve the efficiency of transportation and nutrient exchange. Notably, the gene expression in the LNG showed a similar pattern to that of the galls, but on a smaller scale. We suppose the aphids manipulate galls to their advantage, and galls lessen competition by functioning as a medium between the aphids and their host plants.


Assuntos
Afídeos/fisiologia , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Parasita , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Tumores de Planta/genética , Animais , Perfilação da Expressão Gênica , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Tumores de Planta/parasitologia
7.
Molecules ; 26(10)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34069787

RESUMO

We evaluated photosystem II (PSII) functionality in potato plants (Solanum tuberosum L.) before and after a 15 min feeding by the leaf miner Tuta absoluta using chlorophyll a fluorescence imaging analysis combined with reactive oxygen species (ROS) detection. Fifteen minutes after feeding, we observed at the feeding zone and at the whole leaf a decrease in the effective quantum yield of photosystem II (PSII) photochemistry (ΦPSII). While at the feeding zone the quantum yield of regulated non-photochemical energy loss in PSII (ΦNPQ) did not change, at the whole leaf level there was a significant increase. As a result, at the feeding zone a significant increase in the quantum yield of non-regulated energy loss in PSII (ΦNO) occurred, but there was no change at the whole leaf level compared to that before feeding, indicating no change in singlet oxygen (1O2) formation. The decreased ΦPSII after feeding was due to a decreased fraction of open reaction centers (qp), since the efficiency of open PSII reaction centers to utilize the light energy (Fv'/Fm') did not differ before and after feeding. The decreased fraction of open reaction centers resulted in increased excess excitation energy (EXC) at the feeding zone and at the whole leaf level, while hydrogen peroxide (H2O2) production was detected only at the feeding zone. Although the whole leaf PSII efficiency decreased compared to that before feeding, the maximum efficiency of PSII photochemistry (Fv/Fm), and the efficiency of the water-splitting complex on the donor side of PSII (Fv/Fo), did not differ to that before feeding, thus they cannot be considered as sensitive parameters to monitor biotic stress effects. Chlorophyll fluorescence imaging analysis proved to be a good indicator to monitor even short-term impacts of insect herbivory on photosynthetic function, and among the studied parameters, the reduction status of the plastoquinone pool (qp) was the most sensitive and suitable indicator to probe photosynthetic function under biotic stress.


Assuntos
Enterobius/fisiologia , Luz , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/parasitologia , Folhas de Planta/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Solanum tuberosum/parasitologia , Solanum tuberosum/efeitos da radiação , Animais , Transporte de Elétrons , Comportamento Alimentar , Peróxido de Hidrogênio/metabolismo , Teoria Quântica
8.
PLoS One ; 16(5): e0251134, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33945577

RESUMO

The efficacy and non-target arthropod effects of transgenic DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 Bt cotton, expressing proteins Cry1Ac, Cry1F and Vip3Aa19, was examined through field trials in Brazil. Fifteen field efficacy experiments were conducted from 2014 through the 2020 growing season across six different states in Brazil to evaluate performance against key lepidopteran pests through artificial infestations of Chrysodeixis includens (Walker), Spodoptera frugiperda (J.E. Smith,1797), Spodoptera cosmioides (Walker, 1858) and Chloridea virescens (F., 1781), and natural infestations of Alabama argillacea (Hübner) and S. frugiperda. The impact of this Bt cotton technology on the non-target arthropod community in Brazilian cotton production systems was also assessed in a multi-site experiment. DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton significantly reduced the feeding damage caused by S. frugiperda, S. cosmioides, C. includens, C. virescens and A. argillacea, causing high levels of mortality (greater than 99%) to all target lepidopteran pests evaluated during vegetative and/or reproductive stages of crop development. Non-target arthropod community-level analyses confirmed no unintended effects on the arthropod groups monitored. These results demonstrate the value of transgenic Bt cotton containing event DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 for consideration as part of an integrated approach for managing key lepidopteran pests in Brazilian cotton production systems.


Assuntos
Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-dissulfônico/análogos & derivados , Artrópodes/crescimento & desenvolvimento , Gossypium/metabolismo , Gossypium/parasitologia , Ácido 4-Acetamido-4'-isotiocianatostilbeno-2,2'-dissulfônico/metabolismo , Animais , Brasil , Controle de Insetos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Controle Biológico de Vetores/métodos , Folhas de Planta/parasitologia , Plantas Geneticamente Modificadas/parasitologia , Spodoptera/crescimento & desenvolvimento
9.
Mol Plant Pathol ; 22(6): 658-672, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33934492

RESUMO

Cucurbit downy mildew (DM), caused by the obligate biotroph Pseudoperonospora cubensis, is a destructive disease in cucumber. A valuable source of DM resistance is the Indian cucumber accession PI 197088, which harbours several quantitative trait loci (QTLs) contributing to quantitatively inherited DM resistance. With a combination of fine-mapping and transcriptomics, we identified Amino Acid Permease 2A (CsAAP2A) as a candidate gene for QTL DM4.1.3. Whole-genome and Sanger sequencing revealed the insertion of a Cucumis Mu-like element (CUMULE) transposon in the allele of the resistant near-isogenic line DM4.1.3. To confirm whether loss of CsAAP2A contributes to partial DM resistance, we performed targeting induced local lesions in genomes on a DM-susceptible cucumber genotype to identify an additional csaap2a mutant, which indeed was partially DM resistant. In view of the loss of the putative function as amino acid transporter, we measured amino acids in leaves. We found that DM-inoculated leaves of line DM4.1.3 (with the csaap2a mutation) contained significantly fewer amino acids than wild-type cucumber. The decreased flow of amino acids towards infected leaves in csaap2a plants compared to the wild type might explain the resistant phenotype of the mutant, as this would limit the available nutrients for the pathogen and thereby its fitness. To examine whether AAP genes play a conserved role as susceptibility factors in plant-oomycete interactions, we made targeted mutations in two AAP genes from tomato and studied the effect on susceptibility to Phytophthora infestans. We conclude that not only CsAAP2A but also SlAAP5A/SlAAP5B are susceptibility genes for oomycete pathogens.


Assuntos
Sistemas de Transporte de Aminoácidos/metabolismo , Cucumis sativus/genética , Interações Hospedeiro-Patógeno , Lycopersicon esculentum/genética , Oomicetos/fisiologia , Doenças das Plantas/parasitologia , Alelos , Sistemas de Transporte de Aminoácidos/genética , Transporte Biológico , Cucumis sativus/parasitologia , Cucumis sativus/fisiologia , Elementos de DNA Transponíveis/genética , Resistência à Doença/genética , Suscetibilidade a Doenças , Genótipo , Lycopersicon esculentum/parasitologia , Mutação , Fenótipo , Folhas de Planta/genética , Folhas de Planta/parasitologia , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas/genética
10.
Nat Commun ; 12(1): 2658, 2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33976202

RESUMO

Many herbivorous insects selectively accumulate plant toxins for defense against predators; however, little is known about the transport processes that enable insects to absorb and store defense compounds in the body. Here, we investigate how a specialist herbivore, the horseradish flea beetle, accumulates glucosinolate defense compounds from Brassicaceae in the hemolymph. Using phylogenetic analyses of coleopteran major facilitator superfamily transporters, we identify a clade of glucosinolate-specific transporters (PaGTRs) belonging to the sugar porter family. PaGTRs are predominantly expressed in the excretory system, the Malpighian tubules. Silencing of PaGTRs leads to elevated glucosinolate excretion, significantly reducing the levels of sequestered glucosinolates in beetles. This suggests that PaGTRs reabsorb glucosinolates from the Malpighian tubule lumen to prevent their loss by excretion. Ramsay assays corroborated the selective retention of glucosinolates by Malpighian tubules of P. armoraciae in situ. Thus, the selective accumulation of plant defense compounds in herbivorous insects can depend on the ability to prevent excretion.


Assuntos
Brassicaceae/metabolismo , Besouros/metabolismo , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Glucosinolatos/metabolismo , Hemolinfa/metabolismo , Túbulos de Malpighi/metabolismo , Animais , Transporte Biológico , Brassicaceae/parasitologia , Besouros/fisiologia , Herbivoria/fisiologia , Modelos Biológicos , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Açúcares/metabolismo
11.
Mol Plant Pathol ; 22(6): 727-736, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33829627

RESUMO

The green peach aphid (Myzus persicae) is a phloem-feeding insect that causes economic damage on a wide array of crops. Using a luminol-based assay, a superoxide-responsive reporter gene (Zat12::luciferase), and a probe specific to hydrogen peroxide (HyPer), we demonstrated that this aphid induces accumulation of reactive oxygen species (ROS) in Arabidopsis thaliana. Similar to the apoplastic oxidative burst induced by pathogens, this response to aphids was rapid and transient, with two peaks occurring within 1 and 4 hr after infestation. Aphid infestation also induced an oxidative response in the cytosol and peroxisomes, as measured using a redox-sensitive variant of green fluorescent protein (roGFP2). This intracellular response began within minutes of infestation but persisted 20 hr or more after inoculation, and the response of the peroxisomes appeared stronger than the response in the cytosol. Our results suggest that the oxidative response to aphids involves both apoplastic and intracellular sources of ROS, including ROS generation in the peroxisomes, and these different sources of ROS may potentially differ in their impacts on host suitability for aphids.


Assuntos
Afídeos/fisiologia , Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/parasitologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Genes Reporter , Peróxido de Hidrogênio/metabolismo , Oxirredução , Peroxissomos/metabolismo , Folhas de Planta/genética , Folhas de Planta/parasitologia , Folhas de Planta/fisiologia
12.
PLoS Pathog ; 17(4): e1009477, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33857257

RESUMO

The lack of efficient methods to control the major diseases of crops most important to agriculture leads to huge economic losses and seriously threatens global food security. Many of the most important microbial plant pathogens, including bacteria, fungi, and oomycetes, secrete necrosis- and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs), which critically contribute to the virulence and spread of the disease. NLPs are cytotoxic to eudicot plants, as they disturb the plant plasma membrane by binding to specific plant membrane sphingolipid receptors. Their pivotal role in plant infection and broad taxonomic distribution makes NLPs a promising target for the development of novel phytopharmaceutical compounds. To identify compounds that bind to NLPs from the oomycetes Pythium aphanidermatum and Phytophthora parasitica, a library of 587 small molecules, most of which are commercially unavailable, was screened by surface plasmon resonance. Importantly, compounds that exhibited the highest affinity to NLPs were also found to inhibit NLP-mediated necrosis in tobacco leaves and Phytophthora infestans growth on potato leaves. Saturation transfer difference-nuclear magnetic resonance and molecular modelling of the most promising compound, anthranilic acid derivative, confirmed stable binding to the NLP protein, which resulted in decreased necrotic activity and reduced ion leakage from tobacco leaves. We, therefore, confirmed that NLPs are an appealing target for the development of novel phytopharmaceutical agents and strategies, which aim to directly interfere with the function of these major microbial virulence factors. The compounds identified in this study represent lead structures for further optimization and antimicrobial product development.


Assuntos
Phytophthora/patogenicidade , Doenças das Plantas/prevenção & controle , Pythium/patogenicidade , Solanum tuberosum/genética , Simulação de Dinâmica Molecular , Necrose , Phytophthora/genética , Doenças das Plantas/parasitologia , Folhas de Planta/genética , Folhas de Planta/parasitologia , Pythium/genética , Solanum tuberosum/parasitologia , Ressonância de Plasmônio de Superfície , Tabaco/genética , Tabaco/parasitologia
13.
Mol Plant Pathol ; 22(6): 644-657, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33764635

RESUMO

A cascade formed by phosphorylation events of mitogen-activated protein kinases (MAPKs) takes part in plant stress responses. However, the roles of these MAPKs in resistance of potato (Solanum tuberosum) against Phytophthora pathogens is not well studied. Our previous work showed that a Phytophthora infestans RXLR effector targets and stabilizes the negative regulator of MAPK kinase 1 of potato (StMKK1). Because in Arabidopsis thaliana the AtMPK4 is the downstream phosphorylation target of AtMKK1, we performed a phylogenetic analysis and found that potato StMPK4/6/7 are closely related and are orthologs of AtMPK4/5/11/12. Overexpression of StMPK4/7 enhances plant resistance to P. infestans and P. parasitica. Yeast two-hybrid analysis revealed that StMPK7 interacts with StMKK1, and StMPK7 is phosphorylated on flg22 treatment and by expressing constitutively active StMKK1 (CA-StMKK1), indicating that StMPK7 is a direct downstream signalling partner of StMKK1. Overexpression of StMPK7 in potato enhances potato resistance to P. infestans. Constitutively active StMPK7 (CA-StMPK7; StMPK7D198G, E202A ) was found to promote immunity to Phytophthora pathogens and to trigger host cell death when overexpressed in Nicotiana benthamiana leaves. Cell death triggered by CA-StMPK7 is SGT1/RAR1-dependent. Furthermore, cell death triggered by CA-StMPK7 is suppressed on coexpression with the salicylate hydroxylase NahG, and StMPK7 activation promotes salicylic acid (SA)-responsive gene expression. We conclude that potato StMPK7 is a downstream signalling component of the phosphorelay cascade involving StMKK1 and StMPK7 plays a role in immunity to Phytophthora pathogens via an SA-dependent signalling pathway.


Assuntos
Resistência à Doença , Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Phytophthora infestans/fisiologia , Doenças das Plantas/imunologia , Solanum tuberosum/genética , Morte Celular , Expressão Gênica , Proteínas Quinases Ativadas por Mitógeno/genética , Filogenia , Doenças das Plantas/parasitologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ácido Salicílico/metabolismo , Solanum tuberosum/imunologia , Solanum tuberosum/parasitologia , Tabaco/genética , Tabaco/imunologia , Tabaco/parasitologia
14.
Mol Plant Pathol ; 22(5): 495-507, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33709540

RESUMO

TAXONOMY: Phylum Nematoda; class Chromadorea; order Rhabditida; suborder Tylenchina; infraorder Tylenchomorpha; superfamily Tylenchoidea; family Heteroderidae; subfamily Heteroderinae; Genus Globodera. BIOLOGY: Potato cyst nematodes (PCN) are biotrophic, sedentary endoparasitic nematodes. Invasive (second) stage juveniles (J2) hatch from eggs in response to the presence of host root exudates and subsequently locate and invade the host. The nematodes induce the formation of a large, multinucleate syncytium in host roots, formed by fusion of up to 300 root cell protoplasts. The nematodes rely on this single syncytium for the nutrients required to develop through a further three moults to the adult male or female stage. This extended period of biotrophy-between 4 and 6 weeks in total-is almost unparalleled in plant-pathogen interactions. Females remain at the root while adult males revert to the vermiform body plan of the J2 and leave the root to locate and fertilize the female nematodes. The female body forms a cyst that contains the next generation of eggs. HOST RANGE: The host range of PCN is limited to plants of the Solanaceae family. While the most economically important hosts are potato (Solanum tuberosum), tomato (Solanum lycopersicum), and aubergine (Solanum melongena), over 170 species of Solanaceae are thought to be potential hosts for PCN (Sullivan et al., 2007). DISEASE SYMPTOMS: Symptoms are similar to those associated with nutrient deficiency, such as stunted growth, yellowing of leaves and reduced yields. This absence of specific symptoms reduces awareness of the disease among growers. DISEASE CONTROL: Resistance genes (where available in suitable cultivars), application of nematicides, crop rotation. Great effort is put into reducing the spread of PCN through quarantine measures and use of certified seed stocks. USEFUL WEBSITES: Genomic information for PCN is accessible through WormBase ParaSite.


Assuntos
Genoma Helmíntico/genética , Interações Hospedeiro-Parasita , Lycopersicon esculentum/parasitologia , Doenças das Plantas/parasitologia , Solanum tuberosum/parasitologia , Tylenchoidea/fisiologia , Animais , Resistência à Doença/genética , Feminino , Genômica , Especificidade de Hospedeiro/genética , Lycopersicon esculentum/genética , Lycopersicon esculentum/imunologia , Masculino , Doenças das Plantas/prevenção & controle , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/parasitologia , Raízes de Plantas/genética , Raízes de Plantas/imunologia , Raízes de Plantas/parasitologia , Solanum tuberosum/genética , Solanum tuberosum/imunologia , Tylenchoidea/genética
15.
PLoS One ; 16(2): e0247325, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33606799

RESUMO

The human enteric bacterial pathogen Salmonella enterica causes approximately 1.35 million cases of food borne illnesses annually in the United States. Of these salmonellosis cases, almost half are derived from the consumption of fresh, raw produce. Although epiphytic S. enterica populations naturally decline in the phyllosphere, a subset of phytophagous insects have recently been identified as biological multipliers, consequently facilitating the growth of bacterial populations. We investigated whether tomato leaves with macroscopic feeding damage, caused by infestation of adult Western flower thrips (Frankliniella occidentalis), support higher S. enterica populations. To explore this hypothesis, we assessed S. enterica populations in response to thrips feeding by varying insect density, plant age, and the gender of the insect. As a reference control, direct leaf damage analogous to thrips feeding was also evaluated using directed, hydraulic pressure. In a supplementary set series of experiments, groups of F. occidentalis infested tomato plants were later inoculated with S. enterica to determine how prior insect infestation might influence bacterial survival and persistence. Following an infestation period, leaves visibly damaged by adult F. occidentalis supported significantly higher S. enterica populations and resulted in greater amounts of electrolyte leakage (measured as electrical conductivity) than leaves lacking visible feeding damage. Plant age did not significantly influence S. enterica populations or estimates of electrolyte leakage, independent of initial infestation. Additionally, the gender of the insect did not uniquely influence S. enterica population dynamics. Finally, applications of aggressive water bombardment resulted in more electrolyte leakage than leaves damaged by F. occidentalis, yet supported comparable S. enterica populations. Together, this study indicates that F. occidentalis feeding is one of the many potential biological mechanisms creating a more habitable environment for S. enterica.


Assuntos
Lycopersicon esculentum/parasitologia , Salmonella enterica/fisiologia , Tisanópteros/fisiologia , Ração Animal , Animais , Comportamento Animal , Feminino , Microbiologia de Alimentos , Lycopersicon esculentum/microbiologia , Masculino , Viabilidade Microbiana , Folhas de Planta/microbiologia , Folhas de Planta/parasitologia , Tisanópteros/microbiologia
16.
BMC Plant Biol ; 21(1): 12, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407137

RESUMO

BACKGROUND: Aphid attack induces defense responses in plants activating several signaling cascades that led to the production of toxic, repellent or antinutritive compounds and the consequent reorganization of the plant primary metabolism. Pepper (Capsicum annuum L.) leaf proteomic response against Myzus persicae (Sulzer) has been investigated and analyzed by LC-MS/MS coupled with bioinformatics tools. RESULTS: Infestation with an initially low density (20 aphids/plant) of aphids restricted to a single leaf taking advantage of clip cages resulted in 6 differentially expressed proteins relative to control leaves (3 proteins at 2 days post-infestation and 3 proteins at 4 days post-infestation). Conversely, when plants were infested with a high density of infestation (200 aphids/plant) 140 proteins resulted differentially expressed relative to control leaves (97 proteins at 2 days post-infestation, 112 proteins at 4 days post-infestation and 105 proteins at 7 days post-infestation). The majority of proteins altered by aphid attack were involved in photosynthesis and photorespiration, oxidative stress, translation, protein folding and degradation and amino acid metabolism. Other proteins identified were involved in lipid, carbohydrate and hormone metabolism, transcription, transport, energy production and cell organization. However proteins directly involved in defense were scarce and were mostly downregulated in response to aphids. CONCLUSIONS: The unexpectedly very low number of regulated proteins found in the experiment with a low aphid density suggests an active mitigation of plant defensive response by aphids or alternatively an aphid strategy to remain undetected by the plant. Under a high density of aphids, pepper leaf proteome however changed significantly revealing nearly all routes of plant primary metabolism being altered. Photosynthesis was so far the process with the highest number of proteins being regulated by the presence of aphids. In general, at short times of infestation (2 days) most of the altered proteins were upregulated. However, at longer times of infestation (7 days) the protein downregulation prevailed. Proteins involved in plant defense and in hormone signaling were scarce and mostly downregulated.


Assuntos
Afídeos/fisiologia , Capsicum/metabolismo , Capsicum/parasitologia , Interações Hospedeiro-Parasita/genética , Interações Hospedeiro-Parasita/fisiologia , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/metabolismo , Animais , Proteoma
17.
PLoS One ; 16(1): e0245398, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33471798

RESUMO

Robinia pseudoacacia L. is an interesting example of how one plant species can be considered invasive or useful depending on its environment. In the past this tree species was planted for decorative purposes and for wood in Poland. For many years it was recommended in poor and degraded habitats because it facilitated late-successional plant species. The aim of this study was to verify if black locust can still be regarded as a resistant tree species in urban greenery. The health condition of old tree specimens growing along streets and in parks was compared. The occurrence of pests and pathogens on R. pseudoacacia trees was assessed and the content of mineral elements in leaves was examined. The research results showed that the health of black locust trees growing in the urban environment in Polish cities, especially along streets (in comparison to park sites), deteriorated significantly due to the interaction of harmful biotic and abiotic factors. Increased level of toxic metals (Fe, Zn, Pb, Mn and Cd) in plant tissues and the accumulation of pests and pathogens negatively influenced the health of R. pseudoacacia.


Assuntos
Ecossistema , Robinia/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Cidades , Meio Ambiente , Metais Pesados/análise , Parques Recreativos , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Folhas de Planta/parasitologia , Polônia , Robinia/química , Robinia/microbiologia , Robinia/parasitologia , Árvores/química , Árvores/microbiologia , Árvores/parasitologia
18.
Sci Rep ; 11(1): 1358, 2021 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-33446699

RESUMO

The Asian citrus psyllid (ACP), Diaphorina citri, is a harmful pest of citrus trees that transmits Candidatus Liberibacter spp. which causes Huanglongbing (HLB) (citrus greening disease); this is considered to be the most serious bacterial disease of citrus plants. Here we detail an anatomical study of the external and internal anatomy (excluding the reproductive system) using micro-computed tomography (micro-CT). This is the first complete 3D micro-CT reconstruction of the anatomy of a psylloid insect and includes a 3D reconstruction of an adult feeding on a citrus leaf that can be used on mobile devices. Detailed rendered images and videos support first descriptions of coxal and scapus antennal glands and sexual differences in the internal anatomy (hindgut rectum, mesothoracic ganglion and brain). This represents a significant advance in our knowledge of ACP anatomy, and of psyllids in general. Together the images, videos and 3D model constitute a unique anatomical atlas and are useful tools for future research and as teaching aids.


Assuntos
Citrus/parasitologia , Hemípteros/anatomia & histologia , Imageamento Tridimensional , Folhas de Planta/parasitologia , Microtomografia por Raio-X , Animais , Feminino , Hemípteros/fisiologia , Masculino
19.
Sci Rep ; 11(1): 628, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436688

RESUMO

This study was conducted to determine the root system architecture and biochemical responses of three potato (Solanum tuberosum L.) cultivars to drought and aphid (Myzus persicae Sulzer) infestation under greenhouse conditions. A factorial experiment comprising three potato cultivars (Qingshu 9, Longshu 3, and Atlantic), two levels of water (Well watered and drought) application and aphid infestation (Aphids and no aphids) was conducted. The results show that drought stress and aphid infestation significantly increased the root-projected area, root surface area, number of root tips, and number of root forks of all cultivars, relative to their corresponding control plants. The least root projected area, root surface area, number of root tips, and number of root forks occurred on DXY under both drought and aphid infestation. Nevertheless, the greatest root projected area, root surface area, number of root tips and number of root forks occurred on QS9 plants. Moreover, increased SOD, CAT, and POD activities were observed across all cultivars, under drought and aphid stress. The highest SOD, POD, and CAT activities occurred in QS9; under drought and aphid stress, while the least SOD, POD, and CAT activities was observed in DXY. The Atlantic cultivar, which possesses a root system sensitive to water deficit, demonstrated greater resistance to aphid infestation under well-watered and drought-stressed conditions. Conversely, Qingshu 9, which possesses a root system tolerant to water deficit, was highly susceptible to aphids. This study shows that the root architectural and biochemical traits that enhance potato tolerance to drought do not necessarily correlate to a plant's tolerance to aphids.


Assuntos
Antioxidantes/metabolismo , Afídeos/fisiologia , Secas , Regulação Enzimológica da Expressão Gênica , Folhas de Planta/imunologia , Solanum tuberosum/imunologia , Estresse Fisiológico , Animais , Folhas de Planta/parasitologia , Solanum tuberosum/enzimologia , Solanum tuberosum/parasitologia
20.
BMC Plant Biol ; 21(1): 1, 2021 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-33386069

RESUMO

BACKGROUND: Galls or the neoplastic growth on plants result from a complex type of interaction between the inducers (Acari, Insects, Microbes and Nematodes) and plants. The present study sheds light on the gall inducing habit of a highly host specific eriophyid mite, Aceria pongamiae, on the leaves of Pongamia pinnata leading to the production of abnormal pouch like outgrowths on the adaxial and abaxial surfaces of the foliage. Each leaf gall is a highly complex, irregular massive structure, and the formation of which often leads to complete destruction of leaves, especially during heavy mite infestation, and thereby adversely affecting the physiology and growth of the host plant. RESULTS: The study was carried out by making comparative observations on FE-SEM histological sections of galls representing four different growth stages categorized on the basis of difference in age groups. Apart from variations in cell metaplasia, a dramatic change was observed in the abaxial-adaxial polarity of the laminar surfaces also throughout the developmental sequence of galls, in all the four growth stages. Significant variations could be observed in the anti-oxidative potency as well as elemental composition in the all the four age groups of galls, and also revealed ATR-FTIR pattern of gall formation. CONCLUSION: Being the first attempt to unravel the mystery of gall induction by eriophyids in general and by A. pongamiae in particular, on its host plant P.pinnata, by shedding light on the structural and histological alterations taking place during leaf gall formation under the influence of the mite, the current study is to be treated as the model of plant-animal interactive system.


Assuntos
Ácaros e Carrapatos/parasitologia , Millettia/parasitologia , Folhas de Planta/anatomia & histologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/parasitologia , Tumores de Planta/parasitologia , Animais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...