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1.
BMC Plant Biol ; 21(1): 402, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34470613

RESUMO

BACKGROUND: Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. RESULTS: The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86-91 % and 43-93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18-25 % and 26-35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22-38 %) and survival rate (15-24 %) than those feeding on WT plants. CONCLUSIONS: The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection.


Assuntos
Aglutininas/farmacologia , Arabidopsis/parasitologia , Herbivoria , Marasmius/química , Nematoides/fisiologia , Aglutininas/química , Animais , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mariposas/fisiologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas
2.
Int J Mol Sci ; 22(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208611

RESUMO

Transcription factors are proteins that directly bind to regulatory sequences of genes to modulate and adjust plants' responses to different stimuli including biotic and abiotic stresses. Sedentary plant parasitic nematodes, such as beet cyst nematode, Heterodera schachtii, have developed molecular tools to reprogram plant cell metabolism via the sophisticated manipulation of genes expression, to allow root invasion and the induction of a sequence of structural and physiological changes in plant tissues, leading to the formation of permanent feeding sites composed of modified plant cells (commonly called a syncytium). Here, we report on the AtMYB59 gene encoding putative MYB transcription factor that is downregulated in syncytia, as confirmed by RT-PCR and a promoter pMyb59::GUS activity assays. The constitutive overexpression of AtMYB59 led to the reduction in A. thaliana susceptibility, as indicated by decreased numbers of developed females, and to the disturbed development of nematode-induced syncytia. In contrast, mutant lines with a silenced expression of AtMYB59 were more susceptible to this parasite. The involvement of ABA in the modulation of AtMYB59 gene transcription appears feasible by several ABA-responsive cis regulatory elements, which were identified in silico in the gene promoter sequence, and experimental assays showed the induction of AtMYB59 transcription after ABA treatment. Based on these results, we suggest that AtMYB59 plays an important role in the successful parasitism of H. schachtii on A. thaliana roots.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Arabidopsis/parasitologia , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/genética , Doenças das Plantas/parasitologia , Fatores de Transcrição/genética , Tylenchoidea/fisiologia , Animais , Arabidopsis/ultraestrutura , Resistência à Doença/genética , Interações Hospedeiro-Parasita , Fenótipo , Reguladores de Crescimento de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/parasitologia , Raízes de Plantas/ultraestrutura , Regiões Promotoras Genéticas
3.
Plant Physiol ; 185(4): 1429-1442, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33793920

RESUMO

Parasitic plants infect other plants by forming haustoria, specialized multicellular organs consisting of several cell types, each of which has unique morphological features and physiological roles associated with parasitism. Understanding the spatial organization of cell types is, therefore, of great importance in elucidating the functions of haustoria. Here, we report a three-dimensional (3-D) reconstruction of haustoria from two Orobanchaceae species, the obligate parasite Striga hermonthica infecting rice (Oryza sativa) and the facultative parasite Phtheirospermum japonicum infecting Arabidopsis (Arabidopsis thaliana). In addition, field-emission scanning electron microscopy observation revealed the presence of various cell types in haustoria. Our images reveal the spatial arrangements of multiple cell types inside haustoria and their interaction with host roots. The 3-D internal structures of haustoria highlight differences between the two parasites, particularly at the xylem connection site with the host. Our study provides cellular and structural insights into haustoria of S. hermonthica and P. japonicum and lays the foundation for understanding haustorium function.


Assuntos
Arabidopsis/parasitologia , Interações Hospedeiro-Parasita/fisiologia , Orobanchaceae/parasitologia , Orobanchaceae/ultraestrutura , Oryza/parasitologia , Raízes de Plantas/ultraestrutura , Striga/parasitologia , Striga/ultraestrutura , Arabidopsis/fisiologia , Imageamento Tridimensional , Orobanchaceae/fisiologia , Oryza/fisiologia , Raízes de Plantas/parasitologia
4.
Plant Physiol ; 185(2): 491-502, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-33721891

RESUMO

The genus Cuscuta comprises stem holoparasitic plant species with wide geographic distribution. Cuscuta spp. obtain water, nutrients, proteins, and mRNA from their host plants via a parasitic organ called the haustorium. As the haustorium penetrates into the host tissue, search hyphae elongate within the host tissue and finally connect with the host's vascular system. Invasion by Cuscuta spp. evokes various reactions within the host plant's tissues. Here, we show that, when Arabidopsis (Arabidopsis thaliana) is invaded by Cuscuta campestris, ethylene biosynthesis by the host plant promotes elongation of the parasite's search hyphae. The expression of genes encoding 1-aminocylclopropane-1-carboxylic acid (ACC) synthases, ACC SYNTHASE2 (AtACS2) and ACC SYNTHASE6 (AtACS6), was activated in the stem of Arabidopsis plants upon invasion by C. campestris. When the ethylene-deficient Arabidopsis acs octuple mutant was invaded by C. campestris, cell elongation and endoreduplication of the search hyphae were significantly reduced, and the inhibition of search hyphae growth was complemented by exogenous application of ACC. In contrast, in the C. campestris-infected Arabidopsis ethylene-insensitive mutant etr1-3, no growth inhibition of search hyphae was observed, indicating that ETHYLENE RESPONSE1-mediated ethylene signaling in the host plant is not essential for parasitism by C. campestris. Overall, our results suggest that C. campestris recognizes host-produced ethylene as a stimulatory signal for successful invasion.


Assuntos
Arabidopsis/genética , Cuscuta/fisiologia , Etilenos/metabolismo , Doenças das Plantas/parasitologia , Reguladores de Crescimento de Plantas/metabolismo , Transdução de Sinais , Arabidopsis/metabolismo , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Crescimento Celular , Cuscuta/genética , Endorreduplicação , Interações Hospedeiro-Parasita , Liases/genética , Liases/metabolismo , Mutação , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo
5.
Mol Plant Microbe Interact ; 34(3): 279-285, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33166202

RESUMO

Root-knot nematodes (RKNs; Meloidogyne spp.) parasitize the roots or stems of a wide range of plant species, resulting in severe damage to the parasitized plant. The phytohormone ethylene (ET) plays an important role in signal transduction pathways leading to resistance against RKNs. However, little is currently known about the induction mechanisms of ET-dependent RKN resistance. Inoculation of Arabidopsis thaliana roots with RKNs decreased chlorophyll contents in aerial parts of the plant. We observed accumulation of phytol, a constituent of chlorophyll and a precursor of tocopherols, in RKN-parasitized roots. Application of sclareol, a diterpene that has been shown to induce ET-dependent RKN resistance, to the roots of Arabidopsis plants increased phytol contents in roots accompanied by a decrease in chlorophyll in aerial parts. Exogenously applied phytol inhibited RKN penetration of roots without exhibiting nematicidal activity. This phytol-induced inhibition of RKN penetration was attenuated in the ET-insensitive Arabidopsis mutant ein2-1. Exogenously applied phytol enhanced the production of α-tocopherol and expression of VTE5, a gene involved in tocopherol production, in Arabidopsis roots. α-Tocopherol exerted induction of RKN resistance similar to that of phytol and showed increased accumulation in roots inoculated with RKNs. Furthermore, the Arabidopsis vte5 mutant displayed no inhibition of RKN penetration in response to phytol. These results suggest that exogenously applied phytol induces EIN2-dependent RKN resistance, possibly via tocopherol production.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.


Assuntos
Arabidopsis , Resistência à Doença , Fitol , Raízes de Plantas , Transdução de Sinais , Tylenchoidea , Animais , Arabidopsis/genética , Arabidopsis/parasitologia , Resistência à Doença/efeitos dos fármacos , Etilenos/metabolismo , Regulação da Expressão Gênica de Plantas , Fitol/farmacologia , Doenças das Plantas/parasitologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/parasitologia , Tylenchoidea/fisiologia
6.
Int J Mol Sci ; 21(24)2020 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-33348829

RESUMO

Plant parasitic nematodes, including the beet cyst nematode Heterodera schachtii, constitute a devastating problem for crops worldwide. The limited availability of sustainable management options illustrates the need for new eco-friendly control means. Plant metabolites represent an invaluable source of active compounds for the discovery of such novel antagonistic agents. Here, we evaluated the impact of eight plant terpenoids on the H. schachtii parasitism of Arabidopsis thaliana. None of the metabolites affected the plant development (5 or 10 ppm). Nootkatone decreased the number of adult nematodes on A. thaliana to 50%, with the female nematodes being smaller compared to the control. In contrast, three other terpenoids increased the parasitism and/or female size. We discovered that nootkatone considerably decreased the number of nematodes that penetrated A. thaliana roots, but neither affected the nematode viability or attraction to plant roots, nor triggered the production of plant reactive oxygen species or changed the plant's sesquiterpene profile. However, we demonstrated that nootkatone led to a significant upregulation of defense-related genes involved in salicylic and jasmonic acid pathways. Our results indicate that nootkatone is a promising candidate to be developed into a novel plant protection agent acting as a stimulator of plant immunity against parasitic nematodes.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Doenças das Plantas/imunologia , Imunidade Vegetal/efeitos dos fármacos , Raízes de Plantas/imunologia , Sesquiterpenos Policíclicos/farmacologia , Tylenchoidea/crescimento & desenvolvimento , Animais , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Feminino , Doenças das Plantas/parasitologia , Extratos Vegetais/farmacologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/parasitologia , Tylenchoidea/efeitos dos fármacos
7.
Nat Chem Biol ; 16(12): 1420-1426, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32989301

RESUMO

The metabolic adaptations by which phloem-feeding insects counteract plant defense compounds are poorly known. Two-component plant defenses, such as glucosinolates, consist of a glucosylated protoxin that is activated by a glycoside hydrolase upon plant damage. Phloem-feeding herbivores are not generally believed to be negatively impacted by two-component defenses due to their slender piercing-sucking mouthparts, which minimize plant damage. However, here we document that glucosinolates are indeed activated during feeding by the whitefly Bemisia tabaci. This phloem feeder was also found to detoxify the majority of the glucosinolates it ingests by the stereoselective addition of glucose moieties, which prevents hydrolytic activation of these defense compounds. Glucosylation of glucosinolates in B. tabaci was accomplished via a transglucosidation mechanism, and two glycoside hydrolase family 13 (GH13) enzymes were shown to catalyze these reactions. This detoxification reaction was also found in a range of other phloem-feeding herbivores.


Assuntos
Arabidopsis/parasitologia , Glucosinolatos/química , Glicosídeo Hidrolases/metabolismo , Hemípteros/enzimologia , Proteínas de Insetos/metabolismo , Floema/parasitologia , Animais , Arabidopsis/imunologia , Arabidopsis/metabolismo , Comportamento Alimentar/fisiologia , Expressão Gênica , Glucosinolatos/metabolismo , Glicosídeo Hidrolases/classificação , Glicosídeo Hidrolases/genética , Glicosilação , Hemípteros/classificação , Hemípteros/genética , Interações Hospedeiro-Parasita/imunologia , Proteínas de Insetos/classificação , Proteínas de Insetos/genética , Floema/imunologia , Floema/metabolismo , Filogenia , Imunidade Vegetal
8.
Mol Plant ; 13(10): 1434-1454, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-32896643

RESUMO

The molecular mechanism by which plants defend against plant root-knot nematodes (RKNs) is largely unknown. The plant receptor kinase FERONIA and its peptide ligands, rapid alkalinization factors (RALFs), regulate plant immune responses and cell expansion, which are two important factors for successful RKN parasitism. In this study, we found that mutation of FERONIA in Arabidopsis thaliana resulted in plants showing low susceptibility to the RKN Meloidogyne incognita. To identify the underlying mechanisms associated with this phenomenon, we identified 18 novel RALF-likes from multiple species of RKNs and showed that two RALF-likes (i.e., MiRALF1 and MiRALF3) from M. incognita were expressed in the esophageal gland with high expression during the parasitic stages of nematode development. These nematode RALF-likes also possess the typical activities of plant RALFs and can directly bind to the extracellular domain of FERONIA to modulate specific steps of nematode parasitism-related immune responses and cell expansion. Genetically, both MiRALF1/3 and FERONIA are required for RKN parasitism in Arabidopsis and rice. Collectively, our study suggests that nematode-encoded RALFs facilitate parasitism via plant-encoded FERONIA and provides a novel paradigm for studying host-pathogen interactions.


Assuntos
Proteínas de Arabidopsis/metabolismo , Peptídeos/química , Peptídeos/metabolismo , Fosfotransferases/metabolismo , Doenças das Plantas/parasitologia , Arabidopsis/enzimologia , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Fosfotransferases/genética
9.
Plant Physiol ; 184(2): 1083-1096, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32732351

RESUMO

O-Acetylation of polysaccharides predominantly modifies plant cell walls by changing the physicochemical properties and, consequently, the structure and function of the cell wall. Expression regulation and specific function of cell wall-acetylating enzymes remain to be fully understood. In this report, we cloned a previously identified stunted growth mutant named sucrose uncoupled1 (sun1) in Arabidopsis (Arabidopsis thaliana). SUN1 encodes a member of the TRICHOME BIREFRINGEN-LIKE family, AtTBL37 AtTBL37 is highly expressed in fast-growing plant tissues and encodes a Golgi apparatus-localized protein that regulates secondary cell wall thickening and acetylation. In sun1, jasmonate signaling and expression of downstream chemical defense genes, including VEGETATIVE STORAGE PROTEIN1 and BRANCHED-CHAIN AMINOTRANSFERASE4, are increased but, unexpectedly, sun1 is more susceptible to insect feeding. The central transcription factor in jasmonate signaling, MYC2, binds to and induces AtTBL37 expression. MYC2 also promotes the expression of many other TBLs Moreover, MYC activity enhances cell wall acetylation. Overexpression of AtTBL37 in the myc2-2 background reduces herbivore feeding. Our study highlights the role of O-acetylation in controlling plant cell wall properties, plant development, and herbivore defense.


Assuntos
Arabidopsis/genética , Arabidopsis/parasitologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Parede Celular/metabolismo , Herbivoria/genética , Insetos/parasitologia , Células Vegetais/metabolismo , Tricomas/metabolismo , Acetilação , Animais , Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Regulação da Expressão Gênica de Plantas , Variação Genética , Genótipo , Herbivoria/efeitos dos fármacos , Mutação , Tricomas/genética
10.
Commun Biol ; 3(1): 407, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32733024

RESUMO

Tissue adhesion between plant species occurs both naturally and artificially. Parasitic plants establish intimate relationship with host plants by adhering tissues at roots or stems. Plant grafting, on the other hand, is a widely used technique in agriculture to adhere tissues of two stems. Here we found that the model Orobanchaceae parasitic plant Phtheirospermum japonicum can be grafted on to interfamily species. To understand molecular basis of tissue adhesion between distant plant species, we conducted comparative transcriptome analyses on both infection and grafting by P. japonicum on Arabidopsis. Despite different organs, we identified the shared gene expression profile, where cell proliferation- and cell wall modification-related genes are up-regulated. Among genes commonly induced in tissue adhesion between distant species, we showed a gene encoding a secreted type of ß-1,4-glucanase plays an important role for plant parasitism. Our data provide insights into the molecular commonality between parasitism and grafting in plants.


Assuntos
Arabidopsis/genética , Glicosídeo Hidrolases/genética , Orobanchaceae/genética , Plantas Geneticamente Modificadas/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/parasitologia , Regulação da Expressão Gênica de Plantas/genética , Interações Hospedeiro-Parasita/genética , Orobanchaceae/efeitos adversos , Plantas Geneticamente Modificadas/parasitologia , Simbiose/genética , Aderências Teciduais/genética , Aderências Teciduais/parasitologia , Transcriptoma/genética
11.
Int J Mol Sci ; 21(15)2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32756498

RESUMO

Reactive oxygen species are a byproduct of aerobic metabolic processes but are also produced by plants in defense against pathogens. In addition, they can function as signaling molecules that control various aspects of plant life, ranging from developmental processes to responses to abiotic and biotic stimuli. In plants, reactive oxygen species can be produced by respiratory burst oxidase homologues. Arabidopsis contains 10 genes for respiratory burst oxidase homologues that are involved in different aspects of plant life. Plant pathogenic cyst nematodes such as Heterodera schachtii induce a syncytium in the roots of host plants that becomes a feeding site which supplies nutrients throughout the life of the nematode. In line with this function, the transcriptome of the syncytium shows drastic changes. One of the genes that is most strongly downregulated in syncytia codes for respiratory burst oxidase homologue B. This gene is root-specific and we confirm here the downregulation in nematode feeding sites with a promoter::GUS (ß-glucuronidase) line. Overexpression of this gene resulted in enhanced resistance against nematodes but also against leaf-infecting pathogens. Thus, respiratory burst oxidase homologue B has a role in resistance. The function of this gene is in contrast to respiratory burst oxidase homologues D and F, which have been found to be needed for full susceptibility of Arabidopsis to H. schachtii. However, our bioinformatic analysis did not find differences between these proteins that could account for the opposed function in the interaction with nematodes.


Assuntos
Adenosina Trifosfatases/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Nematoides/patogenicidade , Doenças das Plantas/genética , Animais , Arabidopsis/parasitologia , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas/genética , Nematoides/genética , Doenças das Plantas/parasitologia , Raízes de Plantas/genética , Raízes de Plantas/parasitologia , Regiões Promotoras Genéticas
12.
Mol Plant Pathol ; 21(9): 1248-1254, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32725725

RESUMO

The cucumber mosaic virus (CMV) 2a RNA-dependent RNA polymerase protein has an additional function in Arabidopsis thaliana, which is to stimulate feeding deterrence (antixenosis) against aphids. Antixenosis is thought to increase the probability that aphids, after acquiring CMV particles from brief probes of an infected plant's epidermal cells, will be discouraged from settling and instead will spread inoculum to neighbouring plants. The amino acid sequences of 2a proteins encoded by a CMV strain that induces antixenosis in A. thaliana (Fny-CMV) and one that does not (LS-CMV) were compared to identify residues that might determine the triggering of antixenosis. These data were used to design reassortant viruses comprising Fny-CMV RNAs 1 and 3, and recombinant CMV RNA 2 molecules encoding chimeric 2a proteins containing sequences derived from LS-CMV and Fny-CMV. Antixenosis induction was detected by measuring the mean relative growth rate and fecundity of aphids (Myzus persicae) confined on infected and on mock-inoculated plants. An amino acid sequence determining antixenosis induction by CMV was found to reside between 2a protein residues 200 and 300. Subsequent mutant analysis delineated this to residue 237. We conjecture that the Fny-CMV 2a protein valine-237 plays some role in 2a protein-induced antixenosis.


Assuntos
Afídeos/fisiologia , Arabidopsis/enzimologia , Cucumovirus/enzimologia , Defesa das Plantas contra Herbivoria/genética , Doenças das Plantas/imunologia , Proteínas Virais/metabolismo , Animais , Arabidopsis/genética , Arabidopsis/parasitologia , Arabidopsis/virologia , Cucumovirus/genética , Interações Hospedeiro-Parasita , Mutação , Doenças das Plantas/parasitologia , Doenças das Plantas/virologia , RNA Polimerase Dependente de RNA/genética , RNA Polimerase Dependente de RNA/metabolismo , Proteínas Virais/genética
13.
Mol Plant Pathol ; 21(9): 1179-1193, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32725756

RESUMO

Phytophthora species are destructive plant pathogens that cause significant crop losses worldwide. To understand plant susceptibility to oomycete pathogens and to explore novel disease resistance strategies, we employed the Arabidopsis thaliana-Phytophthora parasitica model pathosystem and screened for A. thaliana T-DNA insertion mutant lines resistant to P. parasitica. This led to the identification of the resistant mutant 267-31, which carries two T-DNA insertion sites in the promoter region of the ethylene-responsive factor 19 gene (ERF019). Quantitative reverse transcription PCR (RT-qPCR) assays showed that the expression of ERF019 was induced during P. parasitica infection in the wild type, which was suppressed in the 267-31 mutant. Additional erf019 mutants were generated using CRISPR/Cas9 technology and were confirmed to have increased resistance to P. parasitica. In contrast, ERF019 overexpression lines were more susceptible. Transient overexpression assays in Nicotiana benthamiana showed that the nuclear localization of ERF019 is crucial for its susceptible function. RT-qPCR analyses showed that the expression of marker genes for multiple defence pathways was significantly up-regulated in the mutant compared with the wild type during infection. Flg22-induced hydrogen peroxide accumulation and reactive oxygen species burst were impaired in ERF019 overexpression lines, and flg22-induced MAPK activation was enhanced in erf019 mutants. Moreover, transient overexpression of ERF019 strongly suppressed INF-triggered cell death in N. benthamiana. These results reveal the importance of ERF019 in mediating plant susceptibility to P. parasitica through suppression of pathogen-associated molecular pattern-triggered immunity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Proteínas de Ligação a DNA/metabolismo , Padrões Moleculares Associados a Patógenos/metabolismo , Phytophthora/fisiologia , Doenças das Plantas/imunologia , Fatores de Transcrição/metabolismo , Arabidopsis/imunologia , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Proteínas de Ligação a DNA/genética , Resistência à Doença , Suscetibilidade a Doenças , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/parasitologia , Imunidade Vegetal , Fatores de Transcrição/genética
14.
Mol Plant Pathol ; 21(9): 1227-1239, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32686295

RESUMO

While numerous effectors that suppress plant immunity have been identified from bacteria, fungi, and oomycete pathogens, relatively little is known for nematode effectors. Several dozen effectors have been reported from the soybean cyst nematode (SCN). Previous studies suggest that a hypersensitive response-like programmed cell death is triggered at nematode feeding sites in soybean during an incompatible interaction. However, virulent SCN populations overcome this incompatibility using unknown mechanisms. A soybean BAG6 (Bcl-2 associated anthanogene 6) gene previously reported by us to be highly up-regulated in degenerating feeding sites induced by SCN in a resistant soybean line was attenuated in response to a virulent SCN population. We show that GmBAG6-1 induces cell death in yeast like its Arabidopsis homolog AtBAG6 and also in soybean. This led us to hypothesize that virulent SCN may target GmBAG6-1 as part of their strategy to overcome soybean defence responses during infection. Thus, we used a yeast viability assay to screen SCN effector candidates for their ability to specifically suppress GmBAG6-1-induced cell death. We identified several effectors that strongly suppressed cell death mediated by GmBAG6-1. Two effectors identified as suppressors showed direct interaction with GmBAG6-1 in yeast, suggesting that one mechanism of cell death suppression may occur through an interaction with this host protein.


Assuntos
Arabidopsis/imunologia , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/imunologia , Proteínas de Plantas/metabolismo , Soja/genética , Tylenchoidea/fisiologia , Animais , Arabidopsis/genética , Arabidopsis/parasitologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Morte Celular , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Doenças das Plantas/parasitologia , Proteínas de Plantas/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Soja/parasitologia
15.
Plant Physiol ; 184(2): 1172-1180, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32669418

RESUMO

Wound-response plant growth restriction requires the synthesis of potent mediators called jasmonates (JAs). Four 13-lipoxygenases (13-LOXs) produce JA precursors in Arabidopsis (Arabidopsis thaliana) leaves, but the 13-LOXs responsible for growth restriction have not yet been identified. Through loss-of-function genetic analyses, we identified LOX3 and LOX4 as the principal 13-LOXs responsible for vegetative growth restriction after repetitive wounding. Additional genetic studies were carried out in the gain-of-function fatty acid oxygenation 2 (fou2) mutant that, even when undamaged, shows JA-dependent leaf growth restriction. The fou2 lox3 lox4 triple mutant suppressed the fou2 JA-dependent growth phenotype, confirming that LOX3 and LOX4 function in leaf growth restriction. The fou2 mutation affects the TWO PORE CHANNEL1 (TPC1) ion channel. Additional genetic approaches based on this gene were used to further investigate LOX3 function in relation to leaf growth. To activate LOX3-dependent JA production in unwounded plants, we employed hyperactive TPC1 variants. Expression of the TPC1ΔCa i variant in phloem companion cells caused strongly reduced rosette growth in the absence of wounding. Summarizing, in parallel to their established roles in male reproductive development in Arabidopsis, LOX3 and LOX4 control leaf growth rates after wounding. The process of wound-response growth restriction can be recapitulated in unwounded plants when the LOX3 pathway is activated genetically using a hyperactive vacuolar cation channel.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/parasitologia , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Spodoptera/parasitologia , Animais , Arabidopsis/crescimento & desenvolvimento , Precursores Enzimáticos/genética , Precursores Enzimáticos/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Lipoxigenase/genética , Lipoxigenase/metabolismo , Mutação , Fenótipo
16.
Development ; 147(14)2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32586973

RESUMO

Parasitic plants form vascular connections with host plants for efficient material transport. The haustorium is the responsible organ for host invasion and subsequent vascular connection. After invasion of host tissues, vascular meristem-like cells emerge in the central region of the haustorium, differentiate into tracheary elements and establish a connection, known as a xylem bridge, between parasite and host xylem systems. Despite the importance of this parasitic connection, the regulatory mechanisms of xylem bridge formation are unknown. Here, we show the role of auxin and auxin transporters during the process of xylem bridge formation using an Orobanchaceae hemiparasitic plant, Phtheirospermum japonicum The auxin response marker DR5 has a similar expression pattern to tracheary element differentiation genes in haustoria. Auxin transport inhibitors alter tracheary element differentiation in haustoria, but biosynthesis inhibitors do not, demonstrating the importance of auxin transport during xylem bridge formation. The expression patterns and subcellular localization of PIN family auxin efflux carriers and AUX1/LAX influx carriers correlate with DR5 expression patterns. The cooperative action of auxin transporters is therefore responsible for controlling xylem vessel connections between parasite and host.


Assuntos
Arabidopsis/parasitologia , Ácidos Indolacéticos/metabolismo , Orobanchaceae/fisiologia , Xilema/fisiologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Orobanchaceae/crescimento & desenvolvimento , Orobanchaceae/metabolismo , Fenilacetatos/farmacologia , Ftalimidas/farmacologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Interferência de RNA , Receptores do Ligante Indutor de Apoptose Relacionado a TNF/metabolismo , Xilema/efeitos dos fármacos , Xilema/metabolismo
17.
Sci Rep ; 10(1): 10319, 2020 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-32587286

RESUMO

The plant hormones salicylic acid (SA) and jasmonic acid (JA) regulate defense mechanisms capable of overcoming different plant stress conditions and constitute distinct but interconnected signaling pathways. Interestingly, several other molecules are reported to trigger stress-specific defense responses to biotic and abiotic stresses. In this study, we investigated the effect of 14 elicitors against diverse but pivotal types of abiotic (drought) and biotic (the chewing insect Ascia monuste, the hemibiotrophic bacterium Pseudomonas syringae DC 3000 and the necrotrophic fungus Alternaria alternata) stresses on broccoli and Arabidopsis. Among the main findings, broccoli pre-treated with SA and chitosan showed the highest drought stress recovery in a dose-dependent manner. Several molecules led to increased drought tolerance over a period of three weeks. The enhanced drought tolerance after triggering the SA pathway was associated with stomata control. Moreover, methyl jasmonate (MeJA) reduced A. monuste insect development and plant damage, but unexpectedly, other elicitors increased both parameters. GUS reporter assays indicated expression of the SA-dependent PR1 gene in plants treated with nine elicitors, whereas the JA-dependent LOX2 gene was only expressed upon MeJA treatment. Overall, elicitors capable of tackling drought and biotrophic pathogens mainly triggered the SA pathway, but adversely also induced systemic susceptibility to chewing insects. These findings provide directions for potential future in-depth characterization and utilization of elicitors and induced resistance in plant protection.


Assuntos
Arabidopsis/imunologia , Brassica/imunologia , Resistência à Doença , Doenças das Plantas/imunologia , Acetatos/metabolismo , Alternaria/patogenicidade , Animais , Arabidopsis/microbiologia , Arabidopsis/parasitologia , Brassica/microbiologia , Brassica/parasitologia , Borboletas/patogenicidade , Ciclopentanos/metabolismo , Secas , Regulação da Expressão Gênica de Plantas/imunologia , Oxilipinas/metabolismo , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Proteínas de Plantas/metabolismo , Pseudomonas syringae/patogenicidade , Ácido Salicílico/metabolismo
18.
Sci Rep ; 10(1): 8836, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32483126

RESUMO

In plants, growth-defense tradeoffs are essential for optimizing plant performance and adaptation under stress conditions, such as pathogen attack. Root-knot nematodes (RKNs) cause severe economic losses in many crops worldwide, although little is known about the mechanisms that control plant growth and defense responses during nematode attack. Upon investigation of Arabidopsis thaliana infected with RKN (Meloidogyne incognita), we observed that the atypical transcription factor DP-E2F-like 1 (DEL1) repressed salicylic acid (SA) accumulation in RKN-induced galls. The DEL1-deficient Arabidopsis mutant (del1-1) exhibited excessive SA accumulation in galls and is more resistant to RKN infection. In addition, excessive lignification was observed in galls of del1-1. On the other hand, the root growth of del1-1 is reduced after RKN infection. Taken together, these findings suggest that DEL1 plays an important role in the balance between plant growth and defense responses to RKN infection by controlling SA accumulation and lignification.


Assuntos
Arabidopsis/metabolismo , Fatores de Transcrição/metabolismo , Tylenchoidea/fisiologia , Animais , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/parasitologia , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Parasita , Lignina/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/parasitologia , Tumores de Planta/genética , Tumores de Planta/parasitologia , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , Plantas Geneticamente Modificadas/parasitologia , Ácido Salicílico/metabolismo , Fatores de Transcrição/deficiência , Fatores de Transcrição/genética
19.
Int J Mol Sci ; 21(10)2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32429304

RESUMO

Plant-parasitic nematodes secrete a series of effectors to promote parasitism by modulating host immunity, but the detailed molecular mechanism is ambiguous. Animal parasites secrete macrophage migration inhibitory factor (MIF)-like proteins for evasion of host immune systems, in which their biochemical activities play essential roles. Previous research demonstrated that MiMIF-2 effector was secreted by Meloidogyne incognita and modulated host immunity by interacting with annexins. In this study, we show that MiMIF-2 had tautomerase activity and protected nematodes against H2O2 damage. MiMIF-2 expression not only decreased the amount of H2O2 generation during nematode infection in Arabidopsis, but also suppressed Bax-induced cell death by inhibiting reactive oxygen species burst in Nicotiana benthamiana. Further, RNA-seq transcriptome analysis and RT-qPCR showed that the expression of some heat-shock proteins was down regulated in MiMIF-2 transgenic Arabidopsis. After treatment with flg22, RNA-seq transcriptome analysis indicated that the differentially expressed genes in MiMIF-2 expressing Arabidopsis were pointed to plant hormone signal transduction, compound metabolism and plant defense. RT-qPCR and metabolomic results confirmed that salicylic acid (SA) related marker genes and SA content were significantly decreased. Our results provide a comprehensive understanding of how MiMIF-2 modulates plant immunity and broaden knowledge of the intricate relationship between M. incognita and host plants.


Assuntos
Proteínas de Helminto/metabolismo , Ácido Salicílico/metabolismo , Tylenchoidea/enzimologia , Animais , Antioxidantes/metabolismo , Arabidopsis/genética , Arabidopsis/parasitologia , Regulação para Baixo/efeitos dos fármacos , Escherichia coli , Flagelina/farmacologia , Regulação da Expressão Gênica de Plantas , Redes e Vias Metabólicas/efeitos dos fármacos , Parasitos/metabolismo , Raízes de Plantas/parasitologia , Plantas Geneticamente Modificadas , Interferência de RNA , Espécies Reativas de Oxigênio/metabolismo , Proteínas Recombinantes/metabolismo
20.
J Plant Res ; 133(3): 419-428, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32246281

RESUMO

Phytoparasitic nematodes parasitize many species of rooting plants to take up nutrients, thus causing severe growth defects in the host plants. During infection, root-knot nematodes induce the formation of a characteristic hyperplastic structure called a root-knot or gall on the roots of host plants. Although many previous studies addressed this abnormal morphogenesis, the underlying mechanisms remain uncharacterized. To analyze the plant-microorganism interaction at the molecular level, we established an in vitro infection assay system using the nematode Meloidogyne incognita and the model plant Arabidopsis thaliana. Time-course mRNA-seq analyses indicated the increased levels of procambium-associated genes in the galls, suggesting that vascular stem cells play important roles in the gall formation. Conversely, genes involved in the formation of secondary cell walls were decreased in galls. A neutral sugar analysis indicated that the level of xylan, which is one of the major secondary cell wall components, was dramatically reduced in the galls. These observations were consistent with the hypothesis of a decrease in the number of highly differentiated cells and an increase in the density of undifferentiated cells lead to gall formation. Our findings suggest that phytoparasitic nematodes modulate the developmental mechanisms of the host to modify various aspects of plant physiological processes and establish a feeding site.


Assuntos
Arabidopsis/parasitologia , Parede Celular/parasitologia , Nematoides/patogenicidade , Doenças das Plantas/parasitologia , Raízes de Plantas/parasitologia , Animais , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Parasita
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