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1.
Plant Sci ; 309: 110953, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34134846

RESUMO

Lysin motif receptor-like kinases (LYKs) are involved in the recognition of chitin and activation of plant immune response. In this study, we found LYK4 to be strongly induced in resistant Sinapis alba compared with susceptible Brassica juncea on challenge with Alternaria brassicicola. In silico analysis and in vitro kinase assay revealed that despite the presence of canonical protein kinase fold, B.juncea LYK4 (BjLYK4) lacks several key residues of a prototype protein kinase which renders it catalytically inactive. Transient expression analysis confirmed that fluorescently tagged BjLYK4 localizes specifically to the plasma membrane. Overexpression (OE) of BjLYK4 in B. juncea enhanced tolerance against A. brassicicola. Interestingly, the OE lines also exhibited a novel trichome dense phenotype and increased jasmonic acid (JA) responsiveness. We further showed that many chitin responsive WRKY transcription factors and JA biosynthetic genes were strongly induced in the OE lines on challenge with the pathogen. Moreover, several JA inducible trichome developmental genes constituting the WD-repeat/bHLH/MYB activator complex were also upregulated in the OE lines compared with vector control and RNA interference line. These results suggest that BjLYK4 plays an essential role in chitin-dependent activation of defense response and chitin independent trichome development likely by influencing the JA signaling pathway.


Assuntos
Alternaria/fisiologia , Ciclopentanos/metabolismo , Mostardeira/genética , Oxilipinas/metabolismo , Doenças das Plantas/imunologia , Transdução de Sinais , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Expressão Gênica , Mostardeira/enzimologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Tricomas/genética , Tricomas/metabolismo
2.
J Plant Physiol ; 261: 153433, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33990008

RESUMO

The pervasive presence of nitric oxide (NO) in cells and its role in modifying cystein residues through protein S-nitrosylation is a remarkable redox based signalling mechanism regulating a variety of cellular processes. S-NITROSOGLUTATHIONE REDUCTASE (GSNOR) governs NO bioavailability by the breakdown of S-nitrosoglutathione (GSNO), fine-tunes NO signalling and controls total cellular S-nitrosylated proteins. Most of the published data on GSNOR functional analysis is based on the model plant Arabidopsis with no previous report for its effect on in vitro regeneration of tissue cultured plants. Moreover, the effect of GSNOR overexpression (O.E) on tomato growth, development and disease resistance remains enigmatic. Here we show that SlGSNOR O.E in tomato alters multiple developmental programs from in vitro culture establishment to plant growth and fruit set. Moreover, constitutive SlGSNOR O.E in tomato showed enhanced resistance against early blight (EB) disease caused by Alternaria solani and reduction in hypersensitive response (HR)-mediated cell death after Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) infiltrations. High GSNOR transcript levels led to the inhibition of in vitro shoot proliferation in transformed explants as revealed by the fluorescence microscopy after YFP labelling. Transgenic tomato lines overexpressing SlGSNOR showed defective phenotypes exhibiting stunted plant growth and bushy-type plants due to loss of apical dominance, along with reduced seed germination and delayed flowering. Furthermore, SlGSNOR O.E plants exhibited altered leaf arrangement, fruit shape and modified locules number in tomato fruit. These findings give a novel insight into a multifaceted regulatory role of SlGSNOR in tomato plant development, reproduction and response to pathogens.


Assuntos
Aldeído Oxirredutases/genética , Alternaria/fisiologia , Regulação da Expressão Gênica , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Pseudomonas syringae/fisiologia , Aldeído Oxirredutases/metabolismo , Morte Celular , Resistência à Doença/genética , Lycopersicon esculentum/enzimologia , Doenças das Plantas/microbiologia , Brotos de Planta/enzimologia , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento
3.
Microbiol Res ; 248: 126767, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33873138

RESUMO

Xylanase secreted by Trichoderma asperellum ACCC30536 can stimulate the systemic resistance of host plants against pathogenic fungi. Following T. asperellum conidia co-culture with Populus davidiana × P. alba var. pyramidalis Louche (PdPap) seedlings, the expression of xylanases TasXyn29.4 and TasXyn24.2 in T. asperellum were upregulated, peaking at 12 h, by 106 (26.74) and 10.1 (23.34)-fold compared with the control, respectively. However, the expression of TasXyn24.4 and TasXyn24.0 was not detected. When recombinant xylanases rTasXyn29.4 and rTasXyn24.2 were heterologously expressed in Pichia pastoris GS115, their activities reached 18.9 IU/mL and 20.4 IU/mL, respectively. In PdPap seedlings induced by rTasXyn29.4 and rTasXyn24.2, the auxin and jasmonic acid signaling pathways were activated to promote growth and enhance resistance against pathogens. PdPap seedlings treated with both xylanases showed increased methyl jasmonate contents at 12 hpi, reaching 122 % (127 µg/g) compared with the control. However, neither of the xylanases could induce the salicylic acid signaling pathway in PdPap seedlings. Meanwhile, both xylanases could enhance the antioxidant ability of PdPap seedlings by improving their catalase activity. Both xylanases significantly induced systemic resistance of PdPap seedlings against Alternaria alternata, Rhizoctonia solani, and Fusarium oxysporum. However, the xylanases could only be sensed by the roots of the PdPap seedlings, not the leaves. In summary, rTasXyn29.4 and rTasXyn24.2 from T. asperellum ACCC30536 promoted growth and induced systemic resistance of PdPap seedlings, which endowed the PdPap seedlings broad-spectrum resistance to phytopathogens.


Assuntos
Endo-1,4-beta-Xilanases/farmacologia , Proteínas Fúngicas/farmacologia , Hypocreales/enzimologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/farmacologia , Populus/crescimento & desenvolvimento , Alternaria/fisiologia , Ciclopentanos/imunologia , Resistência à Doença , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fusarium/fisiologia , Regulação Fúngica da Expressão Gênica , Hypocreales/química , Hypocreales/genética , Ácidos Indolacéticos/imunologia , Oxilipinas/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Populus/efeitos dos fármacos , Populus/imunologia , Populus/microbiologia , Rhizoctonia/fisiologia
4.
J Biosci Bioeng ; 132(1): 25-32, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33867273

RESUMO

Most commercially circulating mushrooms are produced via cultivation using artificially produced mushroom substrates. However, after mushroom harvesting, the disposal of spent mushroom substrates (SMSs) is a serious problem for the mushroom industry owing to the need for a disposal site and the cost involved. Thus, in view of the possibility of recycling SMSs as a soil modifier, we examined the effect of soil mixed with SMSs on the infection of Arabidopsis leaves by Alternaria brassicicola, the causal agent of cabbage leaf spot. The mixing of SMSs used for Hypsizygus marmoreus, Pholiota microspora, Lyophyllum decastes, and Auricularia polytricha into culture soil suppressed the lesion formation caused by A. brassicicola. The defense responses of Arabidopsis were not induced by the culturing of these seedlings in soils containing SMSs. Suppressed lesion formation was observed after the seedlings were treated with volatiles emitted from SMSs that were incubated with soil for 7 days and used for H. marmoreus, P. microspora, L. decastes, A. polytricha, Lentinula edodes, and Cyclocybe cylindracea. The volatiles from the SMSs reduced the elongation of A. brassicicola hyphae. GC-MS analyses of extracts from the SMS containing soils led to the detection of various volatile compounds; among these, skatole, 2,4-di-tert-butylphenol, γ-dodecalactone, butyric acid, guaiacol, 6-amyl-2-pyrone, and 1-octen-3-ol were examined for inhibitory activity on A. brassicicola and found to suppress hyphae elongation. These findings indicate that the antifungal volatile compounds emitted by the SMSs suppress A. brassicicola infection.


Assuntos
Agaricales/química , Alternaria/fisiologia , Compostos Orgânicos Voláteis/farmacologia , Alternaria/efeitos dos fármacos , Arabidopsis/microbiologia , Brassica/microbiologia , Doenças das Plantas/microbiologia , Solo , Resíduos/análise
5.
Cells ; 10(5)2021 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-33922952

RESUMO

The necrotrophic fungus Alternaria alternata contains different pathotypes that produce different mycotoxins. The pathotype Ageratina adenophora secretes the non-host-selective toxin tenuazonic acid (TeA), which can cause necrosis in many plants. Although TeA is thought to be a central virulence factor of the A. adenophora pathotype, the precise role of TeA in different stages of host infection by pathogens remains unclear. Here, an A. alternata wild-type and the toxin-deficient mutant ΔHP001 with a 75% reduction in TeA production were used. It was observed that wild-type pathogens could induce the reactive oxygen species (ROS) bursts in host leaves and killed photosynthetic cells before invading hyphae. The ROS interceptor catalase remarkably inhibited hyphal penetration and invasive hyphal growth and expansion in infected leaves and suppressed necrotic leaf lesion. This suggests that the production of ROS is critical for pathogen invasion and proliferation and disease symptom formation during infection. It was found that the mutant pathogens did not cause the formation of ROS and cell death in host leaves, showing an almost complete loss of disease susceptibility. In addition, the lack of TeA resulted in a significant reduction in the ability of the pathogen to penetrate invasive hyphal growth and spread. The addition of exogenous TeA, AAL-toxin, and bentazone to the mutant ΔHP001 pathogens during inoculation resulted in a significant restoration of pathogenicity by increasing the level of cell death, frequency of hyphal penetration, and extent of invasive hyphal spread. Our results suggest that cell death triggered by TeA is the essential requirement for successful colonization and disease development in host leaves during infection with A. adenophora pathogens.


Assuntos
Ageratina/microbiologia , Alternaria/fisiologia , Morte Celular , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Ácido Tenuazônico/toxicidade , Ageratina/efeitos dos fármacos , Antibióticos Antineoplásicos/toxicidade , Doenças das Plantas/imunologia , Folhas de Planta/efeitos dos fármacos
6.
Am Nat ; 197(2): E55-E71, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33523787

RESUMO

AbstractIn symbiotic interactions, spatiotemporal variation in the distribution or population dynamics of one species represents spatial and temporal heterogeneity of the landscape for the other. Such interdependent demographic dynamics result in situations where the relative importance of biotic and abiotic factors in determining ecological processes is complicated to decipher. Using a detailed survey of three metapopulations of the succulent plant Cakile maritima and the necrotrophic fungus Alternaria brassicicola located along the southeastern Australian coast, we developed a series of statistical analyses-namely, synchrony analysis, patch occupancy dynamics, and a spatially explicit metapopulation model-to understand how habitat quality, weather conditions, dispersal, and spatial structure determine metapopulation dynamics. Climatic conditions are important drivers, likely explaining the high synchrony among populations. Host availability, landscape features facilitating dispersal, and habitat conditions also impact the occurrence and spread of disease. Overall, we show that the collection of extensive data on host and pathogen population dynamics, in combination with spatially explicit epidemiological modeling, makes it possible to accurately predict disease dynamics-even when there is extreme variability in host population dynamics. Finally, we discuss the importance of genetic information for predicting demographic dynamics in this pathosystem.


Assuntos
Alternaria/fisiologia , Brassicaceae/microbiologia , Interações Hospedeiro-Patógeno , Doenças das Plantas/microbiologia , Clima , Ecossistema , New South Wales , Dinâmica Populacional , Dispersão de Sementes
7.
Int J Mol Sci ; 21(23)2020 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-33276577

RESUMO

In plants, thioredoxin (TRX) family proteins participate in various biological processes by regulating the oxidative stress response. However, their role in phytohormone signaling remains largely unknown. In this study, we investigated the functions of TRX proteins in Arabidopsis thaliana. Quantitative polymerase chain reaction (qPCR) experiments revealed that the expression of ARABIDOPSIS NUCLEOREDOXIN 1 (AtNRX1) is specifically induced by the application of jasmonic acid (JA) and upon inoculation with a necrotrophic fungal pathogen, Alternaria brassicicola. The AtNRX1 protein usually exists as a low molecular weight (LMW) monomer and functions as a reductase, but under oxidative stress AtNRX1 transforms into polymeric forms. However, the AtNRX1M3 mutant protein, harboring four cysteine-to-serine substitutions in the TRX domain, did not show structural modification under oxidative stress. The Arabidopsisatnrx1 null mutant showed greater resistance to A. brassicicola than wild-type plants. In addition, plants overexpressing both AtNRX1 and AtNRX1M3 were susceptible to A. brassicicola infection. Together, these findings suggest that AtNRX1 normally suppresses the expression of defense-responsive genes, as if it were a safety pin, but functions as a molecular sensor through its redox-dependent structural modification to induce disease resistance in plants.


Assuntos
Alternaria/fisiologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Resistência à Doença , Interações Hospedeiro-Patógeno , Oxirredução , Oxirredutases/metabolismo , Sequência de Aminoácidos , Oxirredutases/química , Fenótipo , Doenças das Plantas/microbiologia , Ligação Proteica , Multimerização Proteica , Transporte Proteico
8.
BMC Plant Biol ; 20(1): 548, 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33287718

RESUMO

BACKGROUND: Prolonged mechanical stress (MS) causes thigmomorphogenesis, a stress acclimation response associated with increased disease resistance. What remains unclear is if; 1) plants pre-exposed to a short period of repetitive MS can prime defence responses upon subsequent challenge with necrotrophic pathogens, 2) MS mediates plant immunity via jasmonic acid (JA) signalling, and 3) a short period of repetitive MS can cause long-term changes in gene expression resembling a stress-induced memory. To address these points, 10-days old juvenile Arabidopsis seedlings were mechanically stressed for 7-days using a soft brush and subsequently challenged with the necrotrophic pathogens, Alternaria brassicicola, and Botrytis cinerea. Here we assessed how MS impacted structural cell wall appositions, disease symptoms and altered gene expression in response to infection. RESULTS: The MS-treated plants exhibited enhanced cell wall appositions and jasmonic acid (JA) accumulation that correlated with a reduction in disease progression compared to unstressed plants. The expression of genes involved in JA signalling, callose deposition, peroxidase and phytoalexin biosynthesis and reactive oxygen species detoxification were hyper-induced 4-days post-infection in MS-treated plants. The loss-of-function in JA signalling mediated by the JA-insensitive coronatine-insensitive 1 (coi1) mutant impaired the hyper-induction of defense gene expression and promoted pathogen proliferation in MS-treated plants subject to infection. The basal expression level of PATHOGENESIS-RELATED GENE 1 and PLANT DEFENSIN 1.2 defense marker genes were constitutively upregulated in rosette leaves for 5-days post-MS, as well as in naïve cauline leaves that differentiated from the inflorescence meristem well after ceasing MS. CONCLUSION: This study reveals that exposure of juvenile Arabidopsis plants to a short repetitive period of MS can alter gene expression and prime plant resistance upon subsequent challenge with necrotrophic pathogens via the JA-mediated COI1 signalling pathway. MS may facilitate a stress-induced memory to modulate the plant's response to future stress encounters. These data advance our understanding of how MS primes plant immunity against necrotrophic pathogens and how that could be utilised in sustainable agricultural practices.


Assuntos
Arabidopsis/genética , Ciclopentanos/metabolismo , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Oxilipinas/metabolismo , Doenças das Plantas/genética , Plântula/genética , Alternaria/fisiologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Botrytis/fisiologia , Modelos Genéticos , Mutação , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Ácido Salicílico/metabolismo , Plântula/metabolismo , Plântula/microbiologia , Estresse Mecânico
9.
Int J Biol Macromol ; 165(Pt B): 1881-1888, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33096179

RESUMO

Bell peppers are susceptible to postharvest diseases caused by the fungus Alternaria alternata that limit its commercialization. Nowadays, nanotechnology allows encapsulation of natural components such as terpenes. The objective of this work was to develop chitosan nanoparticles with α-pinene (P-CSNPs) and a nanostructured edible coating (EC-P-CSNPs). The P-CSNPs were characterized by TEM (Transmission Electron Microscopy), FTIR (Fourier-Transform Infrared Spectroscopy), DLS (Dynamic Light Scattering) and ζ potential. The P-CSNPs and the EC-P-CSNPs were applied to the bell peppers inoculated with A. alternata under cold storage for either 0, 7, 14 and 21 days at 12 ±â€¯2 °C followed by a shelf-life period of 5 days at 20 ±â€¯2 °C to assess their post-harvest quality. Nanoparticles size was 3.9 ±â€¯0.5 nm and the ζ potential value was between 13.4 and 14.9 mV. The incorporation of α-pinene was corroborated by FTIR. Significant changes in weight loss were obtained for P-CSNPs and EC-P-CSNPs at percentage of 3 and 6% compared to the control. For firmness, color, total soluble solids, titratable acids, maturity index, total flavonoid content and antioxidant capacity, no differences were found. Total carotenes were higher in bell peppers without A. alternata. The chitosan nanoparticles and edible coating inhibited A. alternata during the cold storage period of bell pepper and preserved the physicochemical quality.


Assuntos
Alternaria/fisiologia , Monoterpenos Bicíclicos/farmacologia , Capsicum/crescimento & desenvolvimento , Capsicum/microbiologia , Quitosana/química , Nanoestruturas/química , Doenças das Plantas/prevenção & controle , Antioxidantes/análise , Carotenoides/análise , Etilenos/metabolismo , Flavonoides/análise , Frutas/química , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Pigmentação , Solubilidade
10.
Cells ; 9(10)2020 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-33092216

RESUMO

Black spot disease, caused by Alternaria brassicicola in Brassica species, is one of the most devastating diseases all over the world, especially since there is no known fully resistant Brassica cultivar. In this study, the visualization of black spot disease development on Brassica oleracea var. capitata f. alba (white cabbage) leaves and subsequent ultrastructural, molecular and physiological investigations were conducted. Inter- and intracellular hyphae growth within leaf tissues led to the loss of host cell integrity and various levels of organelle disintegration. Severe symptoms of chloroplast damage included the degeneration of chloroplast envelope and grana, and the loss of electron denseness by stroma at the advanced stage of infection. Transcriptional profiling of infected leaves revealed that photosynthesis was the most negatively regulated biological process. However, in infected leaves, chlorophyll and carotenoid content did not decrease until 48 hpi, and several chlorophyll a fluorescence parameters, such as photosystem II quantum yield (Fv/Fm), non-photochemical quenching (NPQ), or plant vitality parameter (Rdf) decreased significantly at 24 and 48 hpi compared to control leaves. Our results indicate that the initial stages of interaction between B. oleracea and A. brassicicola are not uniform within an inoculation site and show a complexity of host responses and fungal attempts to overcome host cell defense mechanisms. The downregulation of photosynthesis at the early stage of this susceptible interaction suggests that it may be a part of a host defense strategy, or, alternatively, that chloroplasts are targets for the unknown virulence factor(s) of A. brassicicola. However, the observed decrease of photosynthetic efficiency at the later stages of infection is a result of the fungus-induced necrotic lesion expansion.


Assuntos
Alternaria/ultraestrutura , Brassica/genética , Brassica/microbiologia , Regulação para Baixo , Interações Hospedeiro-Patógeno/genética , Fotossíntese , Doenças das Plantas/microbiologia , Transcrição Genética , Alternaria/fisiologia , Brassica/fisiologia , Brassica/ultraestrutura , Clorofila A/metabolismo , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Suscetibilidade a Doenças , Regulação da Expressão Gênica de Plantas , Ontologia Genética , Células do Mesofilo/microbiologia , Células do Mesofilo/ultraestrutura , Fotossíntese/genética , Folhas de Planta/microbiologia , Folhas de Planta/ultraestrutura , Fatores de Tempo
11.
Plant Signal Behav ; 15(12): 1823120, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-32985920

RESUMO

Arabidopsis thaliana exhibits durable 'non-host' resistance against the hemibiotrophic fungal pathogen Colletotrichum tropicale that infects mulberry plants. Arabidopsis non-host resistance comprises two layers of defense: preinvasive and postinvasive resistance. The EDR1 protein kinase contributes to Arabidopsis preinvasive resistance against C. tropicale by inducing the expression of plant defensin (PDF) genes. Here we report that the expressions of multiple PDF genes were strongly induced in Arabidopsis upon invasion by C. tropicale. Invasion by a necrotrophic pathogen, Alternaria brassicicola, also induced PDF expression. Importantly, PDF expression triggered upon invasion by both pathogens was inhibited in edr1 mutants, indicating the requirement of EDR1 for PDF expression in postinvasive resistance by Arabidopsis. Analysis of ora59 mutants also revealed that this gene is critical for induced PDF expression following pathogen invasion. Furthermore, inoculation assays of A. brassicicola indicated that ORA59 is involved in postinvasive resistance against the pathogen, suggesting invasion-triggered PDF expression contributes to postinvasive resistance in Arabidopsis.


Assuntos
Alternaria/fisiologia , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/microbiologia , Defensinas/genética , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/microbiologia , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Defensinas/metabolismo , Resistência à Doença , Doenças das Plantas/genética , Fatores de Transcrição/genética
12.
Appl Biochem Biotechnol ; 192(3): 965-978, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32617842

RESUMO

Indian mustard (Brassica juncea L.) is an important edible oilseed crop in India. Low productivity is the major concern which is adversely affected by biotic stresses. Alternaria blight (Alternaria brassicae) is one among major diseases that has no resistant cultivar until now. Keeping in view, an experiment was conducted for isolation of Alternaria blight-tolerant mutants in Indian mustard using gamma radiation and EMS mutagens during four consecutive years in Rabi (winter season). Furthermore, the morphologically and economically superior mutants of Brassica juncea were screened artificially at cotyledonary and adult stage against Alternaria blight. Tolerance to Alternaria blight is observed in DRMR-M-163 (11.7%), DRMR-M-158 (13.1%), DRMR-M-174 (13.8%) and DRMR-M-177 (18.6%) with minimum conidia in infected cotyledons. Mutant DRMR-M-178 (19.8%) had the highest radical scavenging activity, while DRMR-M-162 (104.9 mg/g AAE), DRMR-M-169 (96.9) and DRMR-M-161 (96.9) had higher antioxidant capacity that appears to act as defence to pathogen. DRMR-M-168 (8.4%), DRMR-M-173 (8.3), DRMR-M-171 (7.9), DRMR-M-165 (7.4), DRMR-M-175 (7.2) and DRMR-M-172 (6.9) had higher phenol content which may be responsive for resistance, although DRMR-M-161 (192.7 mg/g), DRMR-M-163 (187.7 mg/g), DRMR-M-164 (132.7 mg/g), DRMR-M-167 (149.3 mg/g), DRMR-M-173 (196.0 mg/g) and DRMR-M-178 (192.7 mg/g) mutants are found to contain low levels of total soluble sugar compared with susceptible Rohini (379.3). Based on biochemical parameter's similarity, mutants are grouped in 4 major clusters. Cluster 4 contained significantly different mutant DRMR-M-172. Relative expression of mitogen-activated protein kinase 3 (MAPK3) gene was found highest in DRMR-M-177, DRMR-M-174, DRMR-M-175, DRMR-M-178, DRMR-M-170, DRMR-M-176, DRMR-M-172 and DRMR-M-173 which resulted the better response to AB stress. Based on biochemical analysis, realtime PCR and cluster analysis, DRMR-M-172 mutant appears more tolerant to Alternaria. DRMR-M-178, DRMR-M-167 and DRMR-M-177 mutants seem tolerant and could be utilized for further breeding programme.


Assuntos
Alternaria/fisiologia , Brassica/microbiologia , Brassica/fisiologia , Resistência à Doença , Doenças das Plantas/microbiologia , Brassica/metabolismo , Mutação , Fenóis/metabolismo , Solubilidade , Açúcares/química , Açúcares/metabolismo
13.
PLoS One ; 15(6): e0233783, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497087

RESUMO

Managing pests in carrot production is challenging. Endophytic microbes have been demonstrated to improve the health and productivity of many crops, but factors affecting endophyte dynamics in carrot is still not well understood. The goal of this study was to determine how crop management system and carrot genotype interact to affect the composition and potential of endophytes to mitigate disease caused by Alternaria dauci, an important carrot pathogen. Twenty-eight unique isolates were collected from the taproots of nine diverse genotypes of carrot grown in a long-term trial comparing organic and conventional management. Antagonistic activity was quantified using an in vitro assay, and potential for individual isolates to mitigate disease was evaluated in greenhouse trials using two carrot cultivars. Results confirm that carrot taproots are colonized by an abundant and diverse assortment of bacteria and fungi representing at least distinct 13 genera. Soils in the organic system had greater total organic matter, microbial biomass and activity than the conventional system and endophyte composition in taproots grown in this system were more abundant and diverse, and had greater antagonistic activity. Carrot genotype also affected endophyte abundance as well as potential for individual isolates to affect seed germination, seedling growth and tolerance to A. dauci. The benefits of endophytes on carrot growth were greatest when plants were subject to A. dauci stress, highlighting the importance of environmental conditions in the functional role of endophytes. Results of this study provide evidence that endophytes can play an important role in improving carrot performance and mediating resistance to A. dauci, and it may someday be possible to select for these beneficial plant-microbial relationships in carrot breeding programs. Implementing soil-building practices commonly used in organic farming systems has potential to promote these beneficial relationships and improve the health and productivity of carrot crops.


Assuntos
Alternaria/fisiologia , Produção Agrícola/métodos , Daucus carota/genética , Daucus carota/microbiologia , Endófitos/fisiologia , Genótipo , Doenças das Plantas/microbiologia , Proteção de Cultivos/métodos , Daucus carota/crescimento & desenvolvimento , Endófitos/isolamento & purificação , Germinação , Solo/química , Microbiologia do Solo
14.
Arch Virol ; 165(9): 2105-2109, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32556598

RESUMO

Here, we describe the molecular characterization of a novel mycovirus isolated from a phytopathogenic fungus, Alternaria dianthicola, which we have named "Alternaria dianthicola dsRNA virus 1" (AdRV1). AdRV1 has a genome of 3,014 bp that contains two non-overlapping open reading frames (ORF1 and 2) coding for a hypothetical protein and an RNA-dependent RNA polymerase (RdRp), respectively. Based on the RdRp, AdRV1 is phylogenetically related to some unclassified dsRNA mycoviruses, including Alternaria longipes dsRNA virus 1, and shows a distant relationship to members of the family Partitiviridae. To the best of our knowledge, this is the first report of mycovirus infecting A. dianthicola.


Assuntos
Alternaria/virologia , Micovírus/isolamento & purificação , Doenças das Plantas/microbiologia , Vírus de RNA/isolamento & purificação , Alternaria/genética , Alternaria/fisiologia , Sequência de Aminoácidos , Micovírus/classificação , Micovírus/genética , Genoma Viral , Fases de Leitura Aberta , Filogenia , Vírus de RNA/classificação , Vírus de RNA/genética , RNA Polimerase Dependente de RNA/química , RNA Polimerase Dependente de RNA/genética , RNA Polimerase Dependente de RNA/metabolismo , Alinhamento de Sequência , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/metabolismo
15.
Sci Rep ; 10(1): 9514, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32528037

RESUMO

Bud necrosis (BN) is a common disorder that affects Vitis vinifera L. and reduces its potential yield. To minimize the losses caused by BN, the double pruning management was applied in Brazilian Southeast vineyards. In this management strategy plants are pruned at the winter to promote a vegetative cycle and then, at summer, to promote the reproductive cycle at optimal environmental conditions. To investigate the relationship of BN and the double pruning management RNA-seq libraries were sequenced from healthy and necrotic tissues at four different stages of the year. The comparison of differentially expressed genes in necrotic and non-necrotic tissues showed an enhanced expression of genes related to cell death possibly induced by endophytic microorganisms in the necrotic tissues. The de novo assembly, characterization and quantification of transcripts within the RNA-seq libraries showed that genes from the endophytic fungus Alternaria alternata, responsible for the production of toxic compounds were highly expressed under BN. Here we propose a model in which unfavorable conditions and reduced carbohydrate levels in buds can promote the switch from a biotrophic lifestyle to a necrotrophic lifestyle in the endophytic fungi, which seems to be involved in the development of BN.


Assuntos
Alternaria/fisiologia , Endófitos/fisiologia , Perfilação da Expressão Gênica , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Vitis/genética , Vitis/microbiologia , Necrose/genética , Brotos de Planta/genética , Brotos de Planta/microbiologia , Reprodução
16.
Biomolecules ; 10(5)2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32392805

RESUMO

Trichoderma species are widely used as biofungicides for the control of fungal plant pathogens. Several studies have been performed to identify the main genes and compounds involved in Trichoderma-plant-microbial pathogen cross-talks. However, there is not much information about the exact mechanism of this profitable interaction. Peptaibols secreted mainly by Trichoderma species are linear, 5-20 amino acid residue long, non-ribosomally synthesized peptides rich in α-amino isobutyric acid, which seem to be effective in Trichoderma-plant pathogenic fungus interactions. In the present study, reversed phase (RP) high-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) mass spectrometry (MS) was used to detect peptaibol profiles of Trichoderma strains during interactions with fungal plant pathogens. MS investigations of the crude extracts deriving from in vitro confrontations of Trichoderma asperellum and T. longibrachiatum with different plant pathogenic fungi (Fusarium moniliforme, F. culmorum, F. graminearum, F. oxysporum species complex, Alternaria solani and Rhizoctonia solani) were performed to get a better insight into the role of these non-ribosomal antimicrobial peptides. The results revealed an increase in the total amount of peptaibols produced during the interactions, as well as some differences in the peptaibol profiles between the confrontational and control tests. Detection of the expression level of the peptaibol synthetase tex1 by qRT-PCR showed a significant increase in T. asperellum/R. solani interaction in comparison to the control. In conclusion, the interaction with plant pathogens highly influenced the peptaibol production of the examined Trichoderma strains.


Assuntos
Antibiose , Peptaibols/metabolismo , Trichoderma/metabolismo , Alternaria/efeitos dos fármacos , Alternaria/fisiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fusarium/efeitos dos fármacos , Fusarium/fisiologia , Peptaibols/química , Peptaibols/toxicidade , Proteínas Citotóxicas Formadoras de Poros/química , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Proteínas Citotóxicas Formadoras de Poros/toxicidade , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/fisiologia , Trichoderma/fisiologia
17.
Fungal Biol ; 124(6): 562-570, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32448447

RESUMO

To well cope with various external carbon sources, fungi have evolved an adaptive mechanism to overcome the adversity of carbon source deficiency. The sucrose non-fermenting (SNF1) protein kinase mainly mediates the utilization of non-fermentable carbon sources. In this study, we determined the function of Snf1, coding the α-subunit of SNF1 kinase, in the phytopathogenic fungus Alternaria alternata via analyzing the Snf1 deletion mutants (ΔAasnf1). Aasnf1 is required for growth, development of aerial mycelium, and conidiation. Results of pathogenicity test showed that ΔAasnf1 induced smaller lesions on detached citrus leaves. Moreover, in the carbon utilization assay, ΔAasnf1 showed growth inhibition on the minimal medium supplemented with polygalacturonic acid, sucrose or alcohol as the only carbon source. Compared to the wild type, ΔAasnf1 also exhibited stronger resistance to cell wall stressors of sodium dodecyl sulfate and congo red. In conclusion, Aasnf1 played important roles in the carbon utilization, vegetative growth, conidiation, cell wall functions and pathogenicity of A. alternata. This study is the first report on the functions of Aasnf1 and our results suggest that Snf1 is critical for the conidiogenesis and pathogenesis of the A. alternata tangerine pathotype.


Assuntos
Alternaria/fisiologia , Alternaria/patogenicidade , Citrus/microbiologia , Doenças das Plantas/microbiologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Alternaria/genética , Carbono/metabolismo , Parede Celular/efeitos dos fármacos , Parede Celular/fisiologia , Vermelho Congo/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Deleção de Genes , Folhas de Planta/microbiologia , Proteínas Serina-Treonina Quinases/química , Dodecilsulfato de Sódio/farmacologia , Esporos Fúngicos/crescimento & desenvolvimento
18.
PLoS One ; 15(4): e0231961, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32324785

RESUMO

Potato Alternaria leaf blight is one of the economically most important disease in potato production worldwide. A recent study reported a quick method to distinguish main Alternaria pathogens A. tenuissima, A. alternata, and A. solani using partial histone H3 gene sequences. Using this method, our collection of 79 isolates from 8 provinces in China were presumably separated into A. tenussima and A. alternata. But in depth morphological and genetic analysis casted doubt on this identification. Culture morphologies of six presumed A. alternata isolates (PresA_alt) and six presumed A. tenuissima isolates (PresA_ten) were not significantly different. PresA_ten isolates also produced conidia in branched chains which supposed to be A. aternata. Phylogenetic analyses were conducted using internal transcribed spacer region (ITS) and five genes commonly used for species identification including glyceraldehyde-3-phosphate dehydrogenase (GPDH), translation elongation factor 1-alpha (TEF1), ß-tubulin, plasma membrane ATPase (ATPase), and calmodulin genes. The results showed that GPDH and TEF1 sequences of PresA_alt and PresA_ten isolates were identical. The 12 isolates did not cluster by presumed species neither by individual or concatenated sequence comparisons. The phylogeny-trait association analysis confirmed that the two group isolates were undistinguishable by those molecular markers. Analysis of histone H3 gene sequences revealed variable intron sequences between PresA_ten and PresA_alt isolates, but the amino acid sequences were identical. Our results indicate that the previously published method to distinguish Alternaria species based on histone H3 gene sequence variation is inaccurate and that the prevalence of A. tenuissima isolates in China was likely overestimated.


Assuntos
Alternaria/genética , Alternaria/fisiologia , Histonas/genética , Solanum tuberosum/microbiologia , Alternaria/classificação , Marcadores Genéticos/genética , Filogenia , Doenças das Plantas/microbiologia , Especificidade da Espécie
19.
BMC Plant Biol ; 20(1): 146, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32268888

RESUMO

BACKGROUND: Lysin motif (LysM)-containing proteins are involved in the recognition of fungal and bacterial pathogens. However, few studies have reported on their roles in the defense responses of woody plants against pathogens. A previous study reported that the apple MdCERK1 gene was induced by chitin and Rhizoctonia solani, and its protein can bind to chitin. However, its effect on defense responses has not been investigated. RESULTS: In this study, a new apple CERK gene, designated as MdCERK1-2, was identified. It encodes a protein that shares high sequence identity with the previously reported MdCERK1 and AtCERK1. Its chitin binding ability and subcellular location are similar to MdCERK1 and AtCERK1, suggesting that MdCERK1-2 may play a role in apple immune defense responses as a pattern recognition receptor (PRR). MdCERK1-2 expression in apple was induced by 2 fungal pathogens, Botryosphaeria dothidea and Glomerella cingulate, but not by the bacterial pathogen, Erwinia amylovora, indicating that MdCERK1-2 is involved in apple anti-fungal defense responses. Further functional analysis by heterologous overexpression (OE) in Nicotiana benthamiana (Nb) demonstrated that MdCERK1-2 OE improved Nb resistance to the pathogenic fungus, Alternaria alternata. H2O2 accumulation and callose deposition increased after A. alternata infection in MdCERK1-2 OE plants compared to wild type (WT) and empty vector (EV)-transformed plants. The induced expression of NbPAL4 by A. alternata significantly (p < 0.01, n = 4) increased in MdCERK1-2 OE plants. Other tested genes, including NbNPR1, NbPR1a, NbERF1, and NbLOX1, did not exhibit significant changes after A. alternata infection in OE plants compared to EV or WT plants. OE plants also accumulated more polyphenols after A. alternata infection. CONCLUSIONS: Heterologous MdCERK1-2 OE affects multiple defense responses in Nb plants and increased their resistance to fungal pathogens. This result also suggests that MdCERK1-2 is involved in apple defense responses against pathogenic fungi.


Assuntos
Alternaria/fisiologia , Resistência à Doença , Interações Hospedeiro-Patógeno , Proteínas de Plantas/metabolismo , Tabaco/metabolismo , Proteínas de Arabidopsis , Malus/genética , Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinases , Tabaco/imunologia
20.
Toxins (Basel) ; 12(2)2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-32075318

RESUMO

Black spot caused by Alternaria alternata is one of the important diseases of pear fruit during storage. Isothiocyanates are known as being strong antifungal compounds in vitro against different fungi. The aim of this study was to assess the antifungal effects of the volatile compound 2-phenylethyl isothiocyanate (2-PEITC) against A. alternata in vitro and in pear fruit, and to explore the underlying inhibitory mechanisms. The in vitro results showed that 2-PEITC significantly inhibited spore germination and mycelial growth of A. alternata-the inhibitory effects showed a dose-dependent pattern and the minimum inhibitory concentration (MIC) was 1.22 mM. The development of black spot rot on the pear fruit inoculated with A. alternata was also significantly decreased by 2-PEITC fumigation. At 1.22 mM concentration, the lesion diameter was only 39% of that in the control fruit at 7 days after inoculation. Further results of the leakage of electrolyte, increase of intracellular OD260, and propidium iodide (PI) staining proved that 2-PEITC broke cell membrane permeability of A. alternata. Moreover, 2-PEITC treatment significantly decreased alternariol (AOH), alternariolmonomethyl ether (AME), altenuene (ALT), and tentoxin (TEN) contents of A. alternata. Taken together, these data suggest that the mechanisms underlying the antifungal effect of 2-PEITC against A. alternata might be via reduction in toxin content and breakdown of cell membrane integrity.


Assuntos
Alternaria/efeitos dos fármacos , Antifúngicos/farmacologia , Contaminação de Alimentos/prevenção & controle , Isotiocianatos/farmacologia , Micotoxinas/biossíntese , Pyrus/microbiologia , Alternaria/metabolismo , Alternaria/fisiologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Frutas/microbiologia , Germinação/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Esporos/efeitos dos fármacos , Esporos/crescimento & desenvolvimento , Compostos Orgânicos Voláteis/farmacologia
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