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1.
PLoS One ; 15(9): e0237460, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32911506

RESUMO

Infection of wheat by Fusarium species can lead to Fusarium Head Blight (FHB) and mycotoxin contamination, thereby reducing food quality and food safety, and leading to economic losses. Agronomic management through the implementation of various pre-harvest measures can reduce the probability of Fusarium spp. infection in the wheat field. To design interventions that could stimulate wheat farmers to (further) improve their agronomic management to reduce FHB, it is key to understand farmers' behaviour towards adapting their management. The aim of this paper was to understand the intention, underlying behavioural constructs, and beliefs of Dutch wheat farmers to adapt their agronomic management to reduce FHB and mycotoxin contamination in wheat, applying the Theory of Planned Behaviour (TPB). Data were collected from 100 Dutch wheat farmers via a questionnaire. The standard TPB analysis was extended with an assessment of the robustness of the belief results to account for the statistical validity of the analysis on TPB beliefs (i.e. to address the so-called expectancy-value muddle). Forty-six percent of the farmers had a positive intention to change their management in the next 5 years. The two behavioural constructs significantly related to this intention were attitude and social norm, whereas association with the perceived behavioural control construct was insignificant indicating that farmers did not perceive any barriers to change their behaviour. Relevant attitudinal beliefs indicated specific attributes of wheat, namely yield, quality and safety (lower mycotoxin contamination). This indicates that strengthening these beliefs-by demonstrating that a change in management will result in a higher yield and quality and lower mycotoxin levels-will result in a stronger attitude and, subsequently, a higher intention to change management. Interventions to strengthen these beliefs should preferably go by the most important referents for social norms, which were the buyers and the farmer cooperatives in this study.


Assuntos
Produção Agrícola/métodos , Fusarium/isolamento & purificação , Doenças das Plantas/prevenção & controle , Triticum/microbiologia , Agricultura/métodos , Controle Comportamental , Fazendeiros , Qualidade dos Alimentos , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Intenção , Doenças das Plantas/microbiologia , Normas Sociais , Inquéritos e Questionários
2.
Plant Dis ; 104(10): 2613-2621, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32749925

RESUMO

Bacterial wilt (BW) disease caused by Ralstonia solanacearum species complex is a devastating plant disease that inflicts heavy losses to the large number of economic host plants it infects. In this study, the potential of dried powder of the arid-land medicinal shrub Rhazya stricta to control BW of tomato was explored. Both, in vitro and in planta studies were conducted, using different concentrations of dried powder of plant parts, and applied (surface mulched or mixed) to infested soil at 0, 10, and 20 days before transplanting (DBT). Aqueous extract of leaves (16% w/v) was found to be as effective as streptomycin (100 ppm) in inhibiting the in vitro growth of R. solanacearum. As evident from the scanning electron micrograph, 16% aqueous extract of leaves produced severe morphological changes, such as rupture of the bacterial cell walls. Results from the greenhouse experiments demonstrated that the higher powder dose (succulent shoot), namely, 30 g/kg of soil mixed with infested soil 20 DBT, was found to be the most effective in controlling BW. It increased root length (cm), shoot length (cm), and plant fresh biomass (g) by 55, 42, and 40%, respectively, over control plants. Mixing of plant powder with the artificially infested (35 ml of 108 CFU/ml per kilogram of soil) pot soil was better than surface mulching. The 30 g/kg of soil dose mixed with soil increased root length (cm), shoot length (cm), and plant fresh biomass (g) of treated plants by 67, 36, and 46%, respectively, over control plants. A 37% decrease in disease severity over the control was observed with drench application of 30 g of powder per kilogram of soil applied once at 20 DBT. Our results indicated that the dried powder (30 g/kg of soil) of leaves or succulent shoots of R. stricta, thoroughly mixed with soil, 20 DBT, could act as an effective control method against BW.


Assuntos
Apocynaceae , Lycopersicon esculentum , Ralstonia solanacearum , Bactérias , Doenças das Plantas/prevenção & controle
3.
PLoS One ; 15(8): e0237545, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764829

RESUMO

Pierce's disease is of major concern for grapevine (Vitis vinifera) production wherever the bacterial pathogen Xylella fastidiosa and its vectors are present. Long-term management includes the deployment of resistant grapevines such as those containing the PdR1 locus from the wild grapevine species Vitis arizonica, which do not develop Pierce's disease symptoms upon infection. However, little is understood about how the PdR1 locus functions to prevent disease symptom development. Therefore, we assessed the concentrations of plant defense-associated compounds called phenolics in healthy and X. fastidiosa-infected PdR1-resistant and susceptible grapevine siblings over time. Soluble foliar phenolic levels, especially flavonoids, in X. fastidiosa-infected PdR1-resistant grapevines were discovered to be significantly lower than those in infected susceptible grapevines. Therefore, it was hypothesized that PdR1-resistant grapevines, by possessing lowered flavonoid levels, affects biofilm formation and causes reduced X. fastidiosa intra-plant colonization, thus limiting the ability to increase pathogen populations and cause Pierce's disease. These results therefore reveal that differences in plant metabolite levels might be a component of the mechanisms that PdR1 utilizes to prevent Pierce's disease.


Assuntos
Infecções/tratamento farmacológico , Fenóis/farmacologia , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/genética , Vitis/efeitos dos fármacos , Xylella/efeitos dos fármacos , Xylella/patogenicidade , Progressão da Doença , Suscetibilidade a Doenças , Infecções/metabolismo , Infecções/microbiologia , Mutação , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Vitis/crescimento & desenvolvimento , Xylella/metabolismo
4.
PLoS One ; 15(8): e0238148, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822425

RESUMO

Root treatment with oxathiapiprolin, benthiavalicarb or their mixture Zorvec-Endavia [ZE (3+7, w/w)] was shown to provide prolonged systemic protection against foliar oomycete pathogens attacking cucumber, tomato and basil. Here we report that these fungicides can effectively protect potato plants against late blight when applied to the soil in which such potato plants are grown. In two field experiments, performed in 2019 and 2020, potato plants grown in 64 L containers were treated with a soil drench of oxathiapiprolin, benthiavalicarb or ZE at 12.5, 25 or 50 mg ai/five plants in a container. Artificial inoculations with Phytophthora infestans revealed that such treated plants were protected against late blight in a dose-dependent manner all along the season. Interestingly, oxathiapiprolin persisted in the treated soil for at least 139 days, providing systemic protection against late blight to the following potato crops grown in that treated soils. Potato plants grown in loess soil in the field were either sprayed or drenched with ZE. Plants treated via the soil were significantly better protected against late blight compared to the plants treated by a spray. The data demonstrate a new strategy for season-long protection of potato against late blight by a single soil application of ZE. The systemic nature of oxathiapiprolin and benthiavalicarb composing ZE assures the translocation to the foliage of two fungicides with different modes of action. This shall minimize the risk of developing resistance against either fungicide in the treated crops.


Assuntos
Hidrocarbonetos Fluorados/administração & dosagem , Hidrocarbonetos Fluorados/farmacologia , Doenças das Plantas/prevenção & controle , Pirazóis/administração & dosagem , Pirazóis/farmacologia , Resistência à Doença/genética , Fungicidas Industriais/farmacologia , Phytophthora infestans/efeitos dos fármacos , Phytophthora infestans/patogenicidade , Raízes de Plantas/efeitos dos fármacos , Plantas Geneticamente Modificadas/efeitos dos fármacos , Solo , Solanum tuberosum/microbiologia
5.
PLoS One ; 15(8): e0233665, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804955

RESUMO

Oligomycins are macrolide antibiotics, produced by Streptomyces spp. that show antagonistic effects against several microorganisms such as bacteria, fungi, nematodes and the oomycete Plasmopara viticola. Conidiogenesis, germination of conidia and formation of appressoria are determining factors pertaining to pathogenicity and successful diseases cycles of filamentous fungal phytopathogens. The goal of this research was to evaluate the in vitro suppressive effects of two oligomycins, oligomycin B and F along with a commercial fungicide Nativo® 75WG on hyphal growth, conidiogenesis, conidial germination, and appressorial formation of the wheat blast fungus, Magnaporthe oryzae Triticum (MoT) pathotype. We also determined the efficacy of these two oligomycins and the fungicide product in vivo in suppressing wheat blast with a detached leaf assay. Both oligomycins suppressed the growth of MoT mycelium in a dose dependent manner. Between the two natural products, oligomycin F provided higher inhibition of MoT hyphal growth compared to oligomycin B with a minimum inhibitory concentration of 0.005 and 0.05 µg/disk, respectively. The application of the compounds completely halted conidial formation of the MoT mycelium in agar medium. Further bioassays showed that these compounds significantly inhibited MoT conidia germination and induced lysis. The compounds also caused abnormal germ tube formation and suppressed appressorial formation of germinated spores. Interestingly, the application of these macrolides significantly inhibited wheat blast on detached leaves of wheat. This is the first report on the inhibition of mycelial growth, conidiogenesis, germination of conidia, deleterious morphological changes in germinated conidia, and suppression of blast disease of wheat by oligomycins from Streptomyces spp. Further study is needed to unravel the precise mode of action of these natural compounds and consider them as biopesticides for controlling wheat blast.


Assuntos
Magnaporthe/efeitos dos fármacos , Magnaporthe/patogenicidade , Oligomicinas/farmacologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Triticum/microbiologia , Agentes de Controle Biológico/farmacologia , Grão Comestível/microbiologia , Microbiologia de Alimentos , Fungicidas Industriais/farmacologia , Hifas/efeitos dos fármacos , Hifas/crescimento & desenvolvimento , Magnaporthe/crescimento & desenvolvimento , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento
6.
Proc Natl Acad Sci U S A ; 117(29): 17409-17417, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32616567

RESUMO

Proteolytic cascades regulate immunity and development in animals, but these cascades in plants have not yet been reported. Here we report that the extracellular immune protease Rcr3 of tomato is activated by P69B and other subtilases (SBTs), revealing a proteolytic cascade regulating extracellular immunity in solanaceous plants. Rcr3 is a secreted papain-like Cys protease (PLCP) of tomato that acts both in basal resistance against late blight disease (Phytophthora infestans) and in gene-for-gene resistance against the fungal pathogen Cladosporium fulvum (syn. Passalora fulva) Despite the prevalent model that Rcr3-like proteases can activate themselves at low pH, we found that catalytically inactive proRcr3 mutant precursors are still processed into mature mRcr3 isoforms. ProRcr3 is processed by secreted P69B and other Asp-selective SBTs in solanaceous plants, providing robust immunity through SBT redundancy. The apoplastic effector EPI1 of P. infestans can block Rcr3 activation by inhibiting SBTs, suggesting that this effector promotes virulence indirectly by preventing the activation of Rcr3(-like) immune proteases. Rcr3 activation in Nicotiana benthamiana requires a SBT from a different subfamily, indicating that extracellular proteolytic cascades have evolved convergently in solanaceous plants or are very ancient in the plant kingdom. The frequent incidence of Asp residues in the cleavage region of Rcr3-like proteases in solanaceous plants indicates that activation of immune proteases by SBTs is a general mechanism, illuminating a proteolytic cascade that provides robust apoplastic immunity.


Assuntos
Lycopersicon esculentum/metabolismo , Peptídeo Hidrolases/metabolismo , Doenças das Plantas/imunologia , Imunidade Vegetal , Proteólise , Cladosporium , Lycopersicon esculentum/genética , Peptídeo Hidrolases/genética , Phytophthora infestans , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/metabolismo , Isoformas de Proteínas , Virulência
7.
PLoS One ; 15(7): e0235344, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32628728

RESUMO

A Glycine max (soybean) hemicellulose modifying gene, xyloglucan endotransglycoslase/hydrolase (XTH43), has been identified as being expressed within a nurse cell known as a syncytium developing within the soybean root undergoing the process of defense to infection by the parasitic nematode, Heterodera glycines. The highly effective nature of XTH43 overexpression in suppressing H. glycines parasitism in soybean has led to experiments examining whether the heterologous expression of XTH43 in Gossypium hirsutum (upland cotton) could impair the parasitism of Meloidogyne incognita, that form a different type of nurse cell called a giant cell that is enclosed within a swollen root structure called a gall. The heterologous transgenic expression of XTH43 in cotton resulted in an 18% decrease in the number of galls, 70% decrease in egg masses, 64% decrease in egg production and a 97% decrease in second stage juvenile (J2) production as compared to transgenic controls. The heterologous XTH43 expression does not significantly affect root mass. The results demonstrate XTH43 expression functions effectively in impairing the development of M. incognita at numerous life cycle stages occurring within the cotton root. The experiments reveal that there are highly conserved aspects of the defense response of G. max that can function effectively in G. hirsutum to impair M. incognita having a different method of parasitism.


Assuntos
Glicosiltransferases/genética , Gossypium/parasitologia , Doenças das Plantas/prevenção & controle , Proteínas de Soja/genética , Soja/enzimologia , Tylenchoidea , Animais , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Glicosiltransferases/metabolismo , Gossypium/genética , Doenças das Plantas/parasitologia , Raízes de Plantas/parasitologia , Plantas Geneticamente Modificadas , Proteínas de Soja/metabolismo , Soja/genética
8.
PLoS Comput Biol ; 16(7): e1007823, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32614829

RESUMO

Cassava brown streak disease (CBSD) is a rapidly spreading viral disease that affects a major food security crop in sub-Saharan Africa. Currently, there are several proposed management interventions to minimize loss in infected fields. Field-scale data comparing the effectiveness of these interventions individually and in combination are limited and expensive to collect. Using a stochastic epidemiological model for the spread and management of CBSD in individual fields, we simulate the effectiveness of a range of management interventions. Specifically we compare the removal of diseased plants by roguing, preferential selection of planting material, deployment of virus-free 'clean seed' and pesticide on crop yield and disease status of individual fields with varying levels of whitefly density crops under low and high disease pressure. We examine management interventions for sustainable production of planting material in clean seed systems and how to improve survey protocols to identify the presence of CBSD in a field or quantify the within-field prevalence of CBSD. We also propose guidelines for practical, actionable recommendations for the deployment of management strategies in regions of sub-Saharan Africa under different disease and whitefly pressure.


Assuntos
Simulação por Computador , Monitoramento Ambiental/métodos , Manihot , Doenças das Plantas , África ao Sul do Saara , Animais , Resistência à Doença , Abastecimento de Alimentos , Hemípteros , Modelos Estatísticos , Doenças das Plantas/prevenção & controle , Doenças das Plantas/estatística & dados numéricos
9.
Plant Dis ; 104(10): 2704-2712, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32716274

RESUMO

Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, is the most damaging disease of soybean in Brazil. Effective management is achieved by means of calendar-timed sprays of fungicide mixtures, which do not explicitly consider weather-associated disease risk. Two rain-based action thresholds of disease severity values (DSV50 and DSV80) were proposed and compared with two leaf wetness duration-temperature thresholds of daily values of infection probability (DVIP6 and DVIP9) and with a calendar program, with regard to performance and profitability. An unsprayed check treatment plot was included for calculating relative control. Disease severity and yield data were obtained from 29 experiments conducted at six sites across four states in Brazil during the 2012-13, 2014-15, and 2015-16 growing seasons, which represented different growing regions and climatic conditions. The less conservative rainfall action threshold (DSV80) resulted in fewer fungicide sprays compared with the other treatments, and the more conservative one (DSV50) resulted in fewer sprays than the DVIP thresholds. Yield was generally higher with the increase in spray number, but the economic analysis showed no significant differences in the risk of not offsetting the costs of fungicide sprays regardless of the system. Therefore, based on the simplicity and the profitability of the rain-based model, the system is a good candidate for incorporating into the management of SBR in soybean production fields in Brazil.


Assuntos
Fungicidas Industriais/farmacologia , Soja , Brasil , Doenças das Plantas/prevenção & controle , Chuva
10.
PLoS One ; 15(7): e0235918, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645090

RESUMO

Leaves of lettuce, pepper, tomato and grapevine plants grown in greenhouse conditions were exposed to UV-C light for either 60 s or 1 s, using a specific LEDs-based device, and wavelengths and energy were the same among different light treatments. Doses of UV-C light that both effectively stimulated plant defences and were innocuous were determined beforehand. Tomato plants and lettuce plants were inoculated with Botrytis cinerea, pepper plants with Phytophthora capsici, and grapevine with Plasmopara viticola. In some experiments we investigated the effect of a repetition of treatments over periods of several days. All plants were inoculated 48 h after exposure to the last UV-C treatment. Lesions on surfaces were measured up to 12 days after inoculation, depending on the experiment and the pathogen. The results confirmed that UV-C light stimulates plant resistance; they show that irradiation for one second is more effective than irradiation for 60 s, and that repetition of treatments is more effective than single light treatments. Moreover a systemic effect was observed in unexposed leaves that were close to exposed leaves. The mechanisms of perception and of the signalling and metabolic pathways triggered by flashes of UV-C light vs. 60 s irradiation exposures are briefly discussed, as well as the prospects for field use of UV-C flashes in viticulture and horticulture.


Assuntos
Alface/efeitos da radiação , Lycopersicon esculentum/efeitos da radiação , Piper/efeitos da radiação , Raios Ultravioleta , Botrytis/patogenicidade , Clorofila/química , Alface/microbiologia , Lycopersicon esculentum/microbiologia , Redes e Vias Metabólicas/efeitos dos fármacos , Phytophthora/patogenicidade , Piper/parasitologia , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Folhas de Planta/microbiologia , Folhas de Planta/parasitologia , Folhas de Planta/efeitos da radiação , Transdução de Sinais/efeitos dos fármacos
11.
Cytogenet Genome Res ; 160(6): 329-334, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32683370

RESUMO

Rubus yellow net virus (RYNV) infects Rubus spp., causing a severe decline when present in mixed infections with other viruses. RYNV belongs to the family Caulimoviridae, also known as plant pararetroviruses, which can exist as episomal or integrated elements (endogenous). Most of integrated pararetroviruses are noninfectious; however, a few cases have been reported where they excised from the plant genome and formed infectious particles. Graft transmission onto indicator plants R. occidentalis "Munger" has been the standard test method for RYNV detection in certification programs. Previously, it was noticed that some RYNV PCR-positive plants did not induce symptoms on "Munger", suggesting an integration event. In this study, bio-indexing and different molecular techniques were employed to differentiate between integrated and episomal RYNV sequences. Reverse transcription-PCR using RYNV-specific oligonucleotides after DNase treatment generated positive results for the virus in graft transmissible isolates (episomal) only. To confirm these results, rolling circle amplification on DNA preparations from the same samples resulted in amplicons identified as RYNV only from plants with graft transmissible RYNV. High-throughput sequencing was used to identify the RYNV-like sequences present in the host DNA. These results indicate the integration of RYNV into the red raspberry genome and highlight the necessity to recognize this phenomenon (integration) in future Rubus quarantine and certification programs.


Assuntos
Caulimoviridae/genética , Genoma de Planta/genética , Vírus de Plantas/genética , Rubus/genética , Rubus/virologia , Integração Viral/genética , Caulimoviridae/isolamento & purificação , Doenças das Plantas/genética , Doenças das Plantas/prevenção & controle , Doenças das Plantas/virologia , Vírus de Plantas/isolamento & purificação , Plasmídeos/genética
12.
Proc Natl Acad Sci U S A ; 117(31): 18385-18392, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32690686

RESUMO

Transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt) can suppress pests and reduce insecticide sprays, but their efficacy is reduced when pests evolve resistance. Although farmers plant refuges of non-Bt host plants to delay pest resistance, this tactic has not been sufficient against the western corn rootworm, Diabrotica virgifera virgifera In the United States, some populations of this devastating pest have rapidly evolved practical resistance to Cry3 toxins and Cry34/35Ab, the only Bt toxins in commercially available corn that kill rootworms. Here, we analyzed data from 2011 to 2016 on Bt corn fields producing Cry3Bb alone that were severely damaged by this pest in 25 crop-reporting districts of Illinois, Iowa, and Minnesota. The annual mean frequency of these problem fields was 29 fields (range 7 to 70) per million acres of Cry3Bb corn in 2011 to 2013, with a cost of $163 to $227 per damaged acre. The frequency of problem fields declined by 92% in 2014 to 2016 relative to 2011 to 2013 and was negatively associated with rotation of corn with soybean. The effectiveness of corn rotation for mitigating Bt resistance problems did not differ significantly between crop-reporting districts with versus without prevalent rotation-resistant rootworm populations. In some analyses, the frequency of problem fields was positively associated with planting of Cry3 corn and negatively associated with planting of Bt corn producing both a Cry3 toxin and Cry34/35Ab. The results highlight the central role of crop rotation for mitigating impacts of D. v. virgifera resistance to Bt corn.


Assuntos
Besouros/fisiologia , Produção Agrícola/métodos , Endotoxinas/farmacologia , Doenças das Plantas/parasitologia , Plantas Geneticamente Modificadas/imunologia , Zea mays/imunologia , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Besouros/efeitos dos fármacos , Produção Agrícola/economia , Endotoxinas/genética , Endotoxinas/metabolismo , Resistência a Inseticidas , Iowa , Controle Biológico de Vetores/economia , Doenças das Plantas/economia , Doenças das Plantas/imunologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Soja/crescimento & desenvolvimento , Zea mays/genética , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
13.
PLoS One ; 15(7): e0235700, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32701965

RESUMO

The dosage sprayed upon per unit area is an important index to measure the effects of pesticide application. Owing to the fact that parameters such as flight height, flight speed, and spray swath can change at any given time, it is impossible to ensure a consistent amount of pesticide application per unit area during the course of aerial variable spray. In order to ensure a consistent amount of pesticide application per unit area, a set of control models of aerial variable spray using an unmanned aerial vehicle (UAV) was proposed, and the corresponding control system was developed based on the technology of aerial variable spray. According to the change of flight parameters, this system was able to adjust the opening degree of solenoid valve through the control model of aerial variable spray. After that, the amount per unit time would change to ensure a consistent amount of pesticide application per unit area, which effectively avoided the phenomenon of uneven pesticide application and improved the accuracy. According to the actual demand for the area in need of pesticide application, the operator can manually control the amount of pesticide applied and change the dosage sprayed upon per unit area to achieve a better effect. Through field tests, it was verified that the system has high accuracy of variable control. The deviation range was between 0.11% and 9.79%, which met the demands of agricultural aviation pesticide application. Furthermore, the system had strong stability for working continuously for more than 6 h at 30°C to meet the environmental requirements of pesticide application via UAV. All the data related to the pesticide application were stored in this system, which provided a reference for the further study of the precision technology in pesticide application. The model proposed in this paper also provided a theoretical basis for the technology development of aerial variable spray.


Assuntos
Controle de Insetos/métodos , Modelos Teóricos , Agricultura , Aeronaves , Controle de Insetos/instrumentação , Doenças das Plantas/prevenção & controle , Robótica
14.
Proc Natl Acad Sci U S A ; 117(27): 16043-16054, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571919

RESUMO

In the indeterminate nodules of a model legume Medicago truncatula, ∼700 nodule-specific cysteine-rich (NCR) peptides with conserved cysteine signature are expressed. NCR peptides are highly diverse in sequence, and some of these cationic peptides exhibit antimicrobial activity in vitro and in vivo. However, there is a lack of knowledge regarding their structural architecture, antifungal activity, and modes of action against plant fungal pathogens. Here, the three-dimensional NMR structure of the 36-amino acid NCR044 peptide was solved. This unique structure was largely disordered and highly dynamic with one four-residue α-helix and one three-residue antiparallel ß-sheet stabilized by two disulfide bonds. NCR044 peptide also exhibited potent fungicidal activity against multiple plant fungal pathogens, including Botrytis cinerea and three Fusarium spp. It inhibited germination in quiescent spores of B. cinerea In germlings, it breached the fungal plasma membrane and induced reactive oxygen species. It bound to multiple bioactive phosphoinositides in vitro. Time-lapse confocal and superresolution microscopy revealed strong fungal cell wall binding, penetration of the cell membrane at discrete foci, followed by gradual loss of turgor, subsequent accumulation in the cytoplasm, and elevated levels in nucleoli of germlings. Spray-applied NCR044 significantly reduced gray mold disease symptoms caused by the fungal pathogen B. cinerea in tomato and tobacco plants, and postharvest products. Our work illustrates the antifungal activity of a structurally unique NCR peptide against plant fungal pathogens and paves the way for future development of this class of peptides as a spray-on fungistat/fungicide.


Assuntos
Antifúngicos/farmacologia , Peptídeos/metabolismo , Peptídeos/farmacologia , Doenças das Plantas/prevenção & controle , Proteínas de Plantas/metabolismo , Proteínas de Plantas/farmacologia , Simbiose , Sequência de Aminoácidos , Botrytis/metabolismo , Membrana Celular/metabolismo , Parede Celular/metabolismo , Cisteína/química , Fusarium/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Espectroscopia de Ressonância Magnética , Medicago truncatula/microbiologia , Pichia/metabolismo , Doenças das Plantas/microbiologia , Tabaco/metabolismo , Tabaco/microbiologia
15.
Int J Food Microbiol ; 330: 108713, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-32512363

RESUMO

Sodium metabisulfite (SMBS), potassium metabisulfite (PMBS), aluminum sulfate (AlS) and aluminum potassium sulfate (AlPS), common sulfur-containing salts used as food additives, were evaluated for their antifungal activity against Penicillium digitatum, Penicillium italicum and Geotrichum citri-aurantii, the most economically important pathogens causing postharvest diseases of citrus fruits. In vitro radial mycelial growth was measured on potato dextrose agar (PDA) Petri dishes amended with five different concentrations of the salts (10, 20, 30, 50, 100 mM) after 7 d of incubation at 25 °C. SMBS and PMBS at all concentrations, and AIS and AIPS above 20 mM, completely inhibited the growth of these fungi. The curative antifungal activity of the four salts to control citrus green (GM) and blue (BM) molds and sour rot (SR) was evaluated on 'Valencia' oranges artificially inoculated in rind wounds with P. digitatum, P. italicum and G. citri-aurantii, respectively. In vivo primary screenings showed no significant antifungal activity of AlS and AlPS to control the three diseases at any dose tested, but SMBS and PMBS reduced the incidence and severity of GM, BM and SR at various concentrations. Effective salts and concentrations were selected for in vivo dip treatments in small-scale trials. Dips at room temperature (20 °C) in SMBS and PMBS at 20 and 50 mM for 60 or 120 s significantly reduced the incidence and severity of GM and BM, with PMBS at 50 mM for 120 s the most effective treatment. Conversely, dips in SMBS and PMBS at 50 mM for 60 or 120 s did not reduce SR incidence and severity. SMBS and PMBS treatments are potentially new tools to be included in reduced-risk non-polluting strategies to control Penicillium diseases, but not SR, on citrus fruits.


Assuntos
Antifúngicos/farmacologia , Citrus/microbiologia , Aditivos Alimentares/farmacologia , Doenças das Plantas/prevenção & controle , Enxofre/farmacologia , Aditivos Alimentares/química , Conservação de Alimentos/métodos , Frutas/microbiologia , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Temperatura , Fatores de Tempo
16.
PLoS One ; 15(6): e0234390, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525917

RESUMO

Fungicide use in the United States to manage soybean diseases has increased in recent years. The ability of fungicides to reduce disease-associated yield losses varies greatly depending on multiple factors. Nonetheless, historical data are useful to understand the broad sense and long-term trends related to fungicide use practices. In the current study, the relationship between estimated soybean yield losses due to selected foliar diseases and foliar fungicide use was investigated using annual data from 28 soybean growing states over the period of 2005 to 2015. For national and regional (southern and northern United States) scale data, mixed effects modeling was performed considering fungicide use as a fixed and state and year as random factors to generate generalized R2 values for marginal (R2GLMM(m); contains only fixed effects) and conditional (R2GLMM(c); contains fixed and random effects) models. Similar analyses were performed considering soybean production data to see how fungicide use affected production. Analyses at both national and regional scales showed that R2GLMM(m) values were significantly smaller compared to R2GLMM(c) values. The large difference between R2 values for conditional and marginal models indicated that the variation of yield loss as well as production were predominantly explained by the state and year rather than the fungicide use, revealing the general lack of fit between fungicide use and yield loss/production at national and regional scales. Therefore, regression models were fitted across states and years to examine their importance in combination with fungicide use on yield loss or yield. In the majority of cases, the relationship was nonsignificant. However, the relationship between soybean yield and fungicide use was significant and positive for majority of the years in the study. Results suggest that foliar fungicides conferred yield benefits in most of the years in the study. Furthermore, the year-dependent usefulness of foliar fungicides in mitigating soybean yield losses suggested the possible influence of temporally fluctuating abiotic factors on the effectiveness of foliar fungicides and/or target disease occurrence and associated loss magnitudes.


Assuntos
Fungicidas Industriais/farmacologia , Doenças das Plantas/prevenção & controle , Soja/crescimento & desenvolvimento , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/microbiologia , Fungos/efeitos dos fármacos , Fungos/patogenicidade , Fungicidas Industriais/administração & dosagem , Fungicidas Industriais/provisão & distribução , Modelos Biológicos , Doenças das Plantas/microbiologia , Folhas de Planta/efeitos dos fármacos , Soja/efeitos dos fármacos , Soja/microbiologia , Análise Espaço-Temporal , Estados Unidos
17.
PLoS One ; 15(6): e0233911, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32479550

RESUMO

Promoters are very important for transcriptional regulation and gene expression, and have become invaluable tools for genetic engineering. Owing to the characteristics of obligate biotrophs, molecular research into obligate biotrophic fungi is seriously lagging behind, and very few of their endogenous promoters have been developed. In this study, a WY7 fragment was predicted in the genome of Oidium heveae Steinmann using PromoterScan. Its promoter function was verified with transient transformations (Agrobacterium tumefaciens-mediated transformation, ATMT) in Nicotiana tabacum cv. Xanthi nc. The analysis of the transcription range showed that WY7 could regulate GUS expression in both monocots (Zea mays Linn and Oryza sativa L. spp. Japonica cv. Nipponbare) and dicots (N. tabacum and Hylocereus undulates Britt). The results of the quantitative detection showed that the GUS transient expression levels when regulated by WY7 was more than 11.7 times that of the CaMV 35S promoter in dicots (N. tabacum) and 5.13 times that of the ACT1 promoter in monocots (O. sativa). GUS staining was not detected in the T1 generation of the WY7-GUS transgenic N. tabacum. This showed that WY7 is an inducible promoter. The cis elements of WY7 were predicted using PlantCARE, and further experiments indicated that WY7 was a low temperature- and salt-inducible promoter. Soluble proteins produced by WY7-hpa1Xoo transgenic tobacco elicited hypersensitive responses (HR) in N. tabacum leaves. N. tabacum transformed with pBI121-WY7-hpa1Xoo exhibited enhanced resistance to the tobacco mosaic virus (TMV). The WY7 promoter has a lot of potential as a tool for plant genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms of O. heveae.


Assuntos
Fungos/genética , Regulação Fúngica da Expressão Gênica , Engenharia Genética/métodos , Doenças das Plantas/prevenção & controle , Regiões Promotoras Genéticas , Fungos/patogenicidade , Genoma Fúngico , Hevea/genética , Hevea/microbiologia , Interações Hospedeiro-Patógeno/genética , Magnoliopsida/genética , Magnoliopsida/microbiologia , Oryza/genética , Oryza/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas , Tabaco/genética , Tabaco/microbiologia , Transformação Genética , Zea mays/genética , Zea mays/microbiologia
18.
World J Microbiol Biotechnol ; 36(6): 90, 2020 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-32524202

RESUMO

A chitinolytic bacterium Chitinophaga sp. S167 producing extracellular chitinases was isolated from a soil sample in India. The extracellular chitinases produced by S167 were concentrated by ammonium sulphate precipitation (AS70) and seven bands corresponding to chitinases were observed by zymography. Optimum temperature and pH of AS70 were between 40 and 45 °C and pH 6.0 respectively with high stability at 20-40 °C and pH 5-7. AS70 inhibited the growth of Fusarium oxysporum, Alternaria alternata and Cladosporium sp. in vitro. The culture conditions for the high level production of extracellular chitinases were optimized resulting in 48-folds higher chitinase production. As the combination of chitinases could be more potent in biocontrol of plant diseases, it was checked if AS70 could control postharvest fungal infection caused by Fusarium oxysporum on tomatoes. AS70 treated tomatoes showed significant lower incidence of infection (11%) by F. oxysporum as compared with 100% in the control at 5 days post inoculation. Further, AS70 caused significant mortality in second stage juveniles of root knot nematode, Meloidogyne incognita, a major agriculture pest responsible for economic losses in agriculture. This study highlights the antifungal and nematicidal activity of chitinases produced by Chitinophaga sp. S167. To the best of our knowledge, this is the first report of the biocontrol potential of the chitinases produced by Chitinophaga sp.


Assuntos
Antifúngicos/farmacologia , Bacteroidetes/isolamento & purificação , Quitinases/farmacologia , Doenças das Plantas/prevenção & controle , Alternaria/efeitos dos fármacos , Sulfato de Amônio , Bacteroidetes/enzimologia , Precipitação Química , Quitinases/metabolismo , Cladosporium/efeitos dos fármacos , Estabilidade Enzimática , Fusarium/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Microbiologia do Solo , Temperatura
19.
PLoS One ; 15(5): e0233014, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433657

RESUMO

Citrus trees produce flushes throughout the year, but there are no criteria established for a precise shoot monitoring in orchards under tropical climate. Methods for quantification of flush dynamics would be useful for horticultural and pest management studies because different insect vectors feed and reproduce on flushes. We estimated the minimum number and distribution of trees for sampling and determined the flushing pattern over time in 'Valencia Late' orange trees grafted onto 'Swingle' citrumelo rootstock. Shoots within a square frame (0.25 m2) on two sides of the canopy were counted and classified by their phenological stage. The minimum number of samples was estimated using the mean number of shoots and area under the flush shoot dynamics (AUFSD). The temporal and spatial distribution analysis was performed by Taylor's power law and by multiple correspondence analysis (MCA). Additionally, a shoot maturity index (SMI) based on visual qualitative assessment of flushes is proposed. Considering the mean number of shoots, it was necessary to sample two sides of 16 trees to reach a relative sampling error (Er) of 25%, whereas by the AUFSD, only five trees were necessary to reach an Er of 10%. Flushes were predominantly randomly distributed over time and space. Testing eight transects, sampled trees should be distributed throughout the block, avoiding sampling concentration in a certain area. MCA showed that the west side and the upper sampling positions of trees were more likely to be associated with younger shoots. AUFSD and the evaluation of both sides of the canopy yielded a smaller number of trees to be assessed. The SMI was a reliable metric to estimate the shoot phenology of orange trees, and correlated well (R2 > 70%) with the mean number of shoots within the square frame. Therefore, SMI has the potential to make shoot monitoring in the field more practical.


Assuntos
Citrus/crescimento & desenvolvimento , Animais , Brasil , Citrus/parasitologia , Citrus sinensis/crescimento & desenvolvimento , Citrus sinensis/parasitologia , Produtos Agrícolas/crescimento & desenvolvimento , Vetores de Doenças , Monitorização de Parâmetros Ecológicos , Interações Hospedeiro-Patógeno , Controle de Pragas/métodos , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Brotos de Planta/crescimento & desenvolvimento , Tamanho da Amostra , Clima Tropical , Tempo (Meteorologia)
20.
Adv Exp Med Biol ; 1194: 243-251, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32468540

RESUMO

Olive oil is a key ingredient in the Mediterranean diet and offers many health benefits. However, many factors affect the quality and quantity of olive oil such as olive tree diseases and olive-related pests. Unfortunately, the procedure of identifying pests or the outbreak of a disease is time-consuming, and it depends heavily on the size of the olive grove. Through the use of ICT, remote monitoring of the olive grove can be achieved, by collecting environment-related data and having an overview of the olive grove's overall health. In this paper we propose a low-cost dense network of sensors that collects daily data regarding the olive grove, thus, providing the possibility to prevent infestation of olive fruit fly and/or the outbreak of olive tree-related disease.


Assuntos
Azeite de Oliva , Preparações Farmacêuticas , Tecnologia de Sensoriamento Remoto , Dieta Mediterrânea , Frutas/química , Olea/química , Azeite de Oliva/química , Azeite de Oliva/isolamento & purificação , Doenças das Plantas/prevenção & controle , Óleos Vegetais/isolamento & purificação , Tecnologia de Sensoriamento Remoto/tendências
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