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1.
Plant Dis ; 104(9): 2391-2397, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32689885

RESUMO

Chinese mesona (Platostoma palustre) plays an important role as special crop in Southeast Asia and Taiwan for the production of herbal tea, grass jelly, and further processed food. In order to assess the potential threat of fungi to Chinese mesona, we surveyed isolates from symptomless plants in the area of mesona production, as well as from leaf spots of potted plants in a garden shop and a plantation in a botanical garden in Taiwan. From leaves, stems, and roots of 15 symptomless plants sampled at five collection events over two years, 154 isolates from 810 surface-sterilized plant fragments were obtained and identified based on DNA sequence data of the internal transcribed spacer region, and partially of the ß-tubulin and histone H3 genes. The most common species belonged to the genera Cercospora, Colletotrichum, and Fusarium and were considered to be potential plant pathogens. Latent pathogenicity was confirmed by an infection experiment with an endophytic strain of Corynespora cassiicola. Observation of leaf spot disease associated with Cercospora kikuchii suggested pathogenicity of this fungus, which was also isolated as an endophyte from symptomless leaves. We hypothesize that the most common endophytic fungi are latent pathogens in the host and may cause plant disease when the host becomes weakened by senescence or changed cultivation condition. Leaf spots of plants in the botanical garden were associated with a species of Pseudocercospora, which was not found among the endophytic isolates and is newly described based on morphology and analysis of translation elongation factor 1 alpha gene sequences.


Assuntos
Colletotrichum , Lamiaceae , Patologia Vegetal , Endófitos , Taiwan
2.
Annu Rev Phytopathol ; 58: 313-341, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32511041

RESUMO

Plant pathology must contribute to improving food security in a safe operating space, which is shrinking as a result of declining natural resources, climate change, and the growing world population. This review analyzes the position of plant pathology in a nexus of relationships, which is mapped and where the coupled dynamics of crop growth, disease, and yield losses are modeled. We derive a hierarchy of pathogens, whereby pathogens reducing radiation interception (RI), radiation use efficiency (RUE), and harvest index increasingly impact crop yields in the approximate proportions: 1:4.5:4,700. Since the dawn of agriculture, plant breeding has targeted the harvest index as a main objective for domesticated plants. Surprisingly, the literature suggests that pathogens that reduce yields by directly damaging harvestable plant tissues have received much less attention than those that reduce RI or RUE. Ecological disease management needs to target diverse production situations and therefore must consider variation in attainable yields; this can be achieved through the reengineering of agrosystems to incorporate built-in dynamic diversity of genes, plants, and crop stands.


Assuntos
Produtos Agrícolas , Patologia Vegetal , Agricultura , Mudança Climática , Abastecimento de Alimentos
3.
Annu Rev Phytopathol ; 58: 161-180, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32543952

RESUMO

Public-private partnerships (PPPs) can be an effective and advantageous way to accomplish extension and outreach objectives in plant pathology. The greatest opportunities for extension-focused PPPs may be in response to large-scale or emerging disease management concerns or in addressing complex issues that impact agriculture, such as climate change, digital technology, and public perception of science. The most fertile ground for forming PPPs is where the needs and strengths of the public and private sectors are complementary. Developing PPPs depends as much on professional relationships as on technical skills or contracts. Defining and making room for the success of all partners, identifying and addressing barriers to success, and earning and maintaining trust are components that contribute to the effectiveness of PPPs. Case studies in plant pathology demonstrate the positive impact PPPs can have on partners and stakeholders and provide guidance on the formation of PPPs in the future.


Assuntos
Patologia Vegetal , Parcerias Público-Privadas , Estados Unidos
4.
Gene ; 753: 144802, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32454178

RESUMO

Synchronous and timely regulation of multiple genes results in an effective defense response that decides the fate of the host when challenged with pathogens or unexpected changes in environmental conditions. One such gene, which is downregulated in response to multiple bacterial pathogens, is a putative nonspecific lipid transfer protein (nsLTP) of unknown function that we have named DISEASE RELATED NONSPECIFIC LIPID TRANSFER PROTEIN 1 (DRN1). We show that upon pathogen challenge, DRN1 is strongly downregulated, while a putative DRN1-targeting novel microRNA (miRNA) named DRN1 Regulating miRNA (DmiR) is reciprocally upregulated. Furthermore, we provide evidence that DRN1 is required for defense against bacterial and fungal pathogens as well as for normal seedling growth under salinity stress. Although nsLTP family members from different plant species are known to be a significant source of food allergens and are often associated with antimicrobial properties, our knowledge on the biological functions and regulation of this gene family is limited. Our current work not only sheds light on the mechanism of regulation but also helps in the functional characterization of DRN1, a putative nsLTP family member of hitherto unknown function.


Assuntos
Arabidopsis/genética , Proteínas de Transferência de Fosfolipídeos/genética , Estresse Salino/genética , Ácido Abscísico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Resistência à Doença/genética , Secas , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Proteínas de Transferência de Fosfolipídeos/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Patologia Vegetal , Plantas Geneticamente Modificadas , Salinidade , Tolerância ao Sal/genética , Plântula/genética , Estresse Fisiológico/genética
5.
Phytopathology ; 110(1): 6-9, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31910089

RESUMO

Given the importance of and rapid research progress in plant virology in recent years, this Focus Issue broadly emphasizes advances in fundamental aspects of virus infection cycles and epidemiology. This Focus Issue comprises three review articles and 18 research articles. The research articles cover broad research areas on the identification of novel viruses, the development of detection methods, reverse genetics systems and functional genomics for plant viruses, vector and seed transmission studies, viral population studies, virus-virus interactions and their effect on vector transmission, and management strategies of viral diseases. The three review articles discuss recent developments in application of prokaryotic clustered regularly interspaced short palindromic repeats/CRISPR-associated genes (CRISPR/Cas) technology for plant virus resistance, mixed viral infections and their role in disease synergism and cross-protection, and viral transmission by whiteflies. The following briefly summarizes the articles appearing in this Focus Issue.


Assuntos
Patologia Vegetal , Vírus de Plantas , Doenças das Plantas/virologia , Vírus de Plantas/fisiologia
6.
Phytopathology ; 110(1): 18-28, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31433273

RESUMO

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated genes (Cas) is a prokaryotic adaptive immune system which has been reprogrammed into a precise, simple, and efficient gene targeting technology. This emerging technology is revolutionizing various areas of life sciences, medicine, and biotechnology and has raised significant interest among plant biologists, both in basic science and in plant protection and breeding. In this review, we describe the basic principles of CRISPR/Cas systems, and how they can be deployed to model plants and crops for the control, monitoring, and study of the mechanistic aspects of plant virus infections. We discuss how Cas endonucleases can be used to engineer plant virus resistance by directly targeting viral DNA or RNA, as well as how they can inactivate host susceptibility genes. Additionally, other applications of CRISPR/Cas in plant virology such as virus diagnostics and imaging are reviewed. The review also provides a systemic comparison between CRISPR/Cas technology and RNA interference approaches, the latter of which has also been used for development of virus-resistant plants. Finally, we outline challenges to be solved before CRISPR/Cas can produce virus-resistant crop plants which can be marketed.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Patologia Vegetal , Vírus de Plantas , Sistemas CRISPR-Cas , Doenças das Plantas/virologia
8.
Phytopathology ; 110(2): 245-253, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31680649

RESUMO

The challenge of feeding the current and future world population is widely recognized, and the management of plant diseases has an important role in overcoming this. This paper explores the ways in which international plant pathology has contributed and continues to support efforts to secure adequate, safe and culturally appropriate nourishment and livelihoods for present and future generations. For the purposes of this paper, "international plant pathology" refers to the work that plant pathologists do when they work across international borders, with a focus on enhancing food security in tropical regions. Significant efforts involve public and philanthropic resources from the global North for addressing plant disease concerns in the global South, where food security is a legitimate and pressing concern. International disease management efforts are also aimed at protecting domestic food security, for example when pathogens of major staples migrate across national borders. In addition, some important crops are largely produced in tropical countries and consumed globally, including in industrialized countries; the diseases of these crops are of international interest, and they are largely managed by the private sector. Finally, host-microbe interactions are fascinating biological systems, and basic research on plant diseases of international relevance has often yielded insights and technologies with both scientific and practical implications.


Assuntos
Doenças das Plantas , Patologia Vegetal , Produtos Agrícolas , Abastecimento de Alimentos
9.
Microbiol Res ; 231: 126353, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31707299

RESUMO

Cladosporium spp. is a cosmopolitan fungal genus. In the literature, it has been reported as a biological agent for controlling several plant diseases, but its mechanism of action has never been clarified. The present study aims to identify Cladosporium spp. based on the DNA phylogeny of nine isolates obtained from the phylloplane of rice and their potential antagonistic activity against the main fungal pathogens that affect rice crop. Nine isolates of Cladosporium spp. were identified based on DNA phylogeny, molecular and morphological characterization, and their antagonistic effects with the rice pathogens C. miyabeanus, M. oryzae, M. albescens and S. oryzae. Four isolates were selected to study lytic enzymes such as ß-1,3-glucanase, chitinase and protease, and only one isolate was selected for a conidial germination and appressoria formation assay. The nine isolates were identified as C. cladosporioides, C. tenuissimum and C. subuliforme. Four isolates, identified as C. cladosporioides, inhibited the mycelial growth of rice pathogens such as C1H (68.59%) of S. oryzae, C5 G (74.32%) of C. miyabeanus, C11 G (75.97%) of M. oryzae and C24 G (77.39%) of M. albescens. C24 G showed a high activity of lytic enzymes, was tested against C. miyabeanus and M. oryzae, and inhibited conidial germination and appressorium formation by more than 59.36%. The characterization of C. cladosporioides suggested this species as a potential bioagent for the management of several rice diseases, especially rice blast. This is the first time that a potential biological agent from the genus Cladosporium identified at the species level was isolated from the rice phylloplane, and some of its mechanisms of action were demonstrated, such as increasing lytic enzyme activity against rice pathogens.


Assuntos
Cladosporium , Folhas de Planta/microbiologia , Patologia Vegetal , Antibiose , Ascomicetos/crescimento & desenvolvimento , Agentes de Controle Biológico , Quitinases/metabolismo , Cladosporium/enzimologia , Cladosporium/genética , Cladosporium/isolamento & purificação , DNA Ribossômico , Fungos não Classificados/crescimento & desenvolvimento , Glicosídeo Hidrolases/metabolismo , Magnaporthe/crescimento & desenvolvimento , Micoses , Oryza/microbiologia , Peptídeo Hidrolases/metabolismo , Filogenia , Doenças das Plantas
10.
Phytopathology ; 110(4): 734-743, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31859585

RESUMO

Studies in plant pathology, agronomy, and plant breeding requiring disease severity assessment often use quantitative ordinal scales (i.e., a special type of ordinal scale that uses defined numeric ranges); a frequently used example of such a scale is the Horsfall-Barratt scale. Parametric proportional odds models (POMs) may be used to analyze the ratings obtained from quantitative ordinal scales directly, without converting ratings to percent area affected using range midpoints of such scales (currently a standard procedure). Our aim was to evaluate the performance of the POM for comparing treatments using ordinal estimates of disease severity relative to two alternatives, the midpoint conversions (MCs) and nearest percent estimates (NPEs). A simulation method was implemented and the parameters of the simulation estimated using actual disease severity data from the field. The criterion for comparison of the three approaches was the power of the hypothesis test (the probability to reject the null hypothesis when it is false). Most often, NPEs had superior performance. The performance of the POM was never inferior to using the MC at severity <40%. Especially at low disease severity (≤10%), the POM was superior to using the MC method. Thus, for early onset of disease or for comparing treatments with severities <40%, the POM is preferable for analyzing disease severity data based on quantitative ordinal scales when comparing treatments and at severities >40% is equivalent to other methods.


Assuntos
Doenças das Plantas , Patologia Vegetal , Coleta de Dados , Probabilidade , Projetos de Pesquisa
11.
ISME J ; 14(2): 492-505, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31666657

RESUMO

The impact of modern agriculture on the evolutionary trajectory of plant pathogens is a central question for crop sustainability. The Green Revolution replaced traditional rice landraces with high-yielding varieties, creating a uniform selection pressure that allows measuring the effect of such intervention. In this study, we analyzed a unique historical pathogen record to assess the impact of a major resistance gene, Xa4, in the population structure of Xanthomonas oryzae pv. oryzae (Xoo) collected in the Philippines in a span of 40 years. After the deployment of Xa4 in the early 1960s, the emergence of virulent pathogen groups was associated with the increasing adoption of rice varieties carrying Xa4, which reached 80% of the total planted area. Whole genomes analysis of a representative sample suggested six major pathogen groups with distinctive signatures of selection in genes related to secretion system, cell-wall degradation, lipopolysaccharide production, and detoxification of host defense components. Association genetics also suggested that each population might evolve different mechanisms to adapt to Xa4. Interestingly, we found evidence of strong selective sweep affecting several populations in the mid-1980s, suggesting a major bottleneck that coincides with the peak of Xa4 deployment in the archipelago. Our study highlights how modern agricultural practices facilitate the adaptation of pathogens to overcome the effects of standard crop improvement efforts.


Assuntos
Resistência à Doença/genética , Genética Microbiana , Oryza/microbiologia , Seleção Artificial/genética , Xanthomonas/genética , Genes de Plantas , Genética Populacional , Genoma Bacteriano , Oryza/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Patologia Vegetal , Proteínas de Plantas/genética , Xanthomonas/patogenicidade
12.
Molecules ; 24(20)2019 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-31635046

RESUMO

Sciadopitys verticillata (Sv) produces a white, sticky, latex-like resin with antimicrobial properties. The aims of this research were to evaluate the effects of this resin (Sv resin) on bacterial populations and to determine the impact of its primary volatile components on bioactivity. The impact of sample treatment on chemical composition of Sv resin was analyzed using Fourier transform infrared spectroscopy (FTIR) coupled with principal component analysis. The presence and concentration of volatiles in lyophilized resin were determined using gas chromatography/mass spectrometry (GC/MS). Changes in bacterial population counts due to treatment with resin or its primary volatile components were monitored. Autoclaving of the samples did not affect the FTIR spectra of Sv resin; however, lyophilization altered spectra, mainly in the CH and C=O regions. Three primary bioactive compounds that constituted >90% of volatiles (1R-α-pinene, tricyclene, and ß-pinene) were identified in Sv resin. Autoclaved resin impacted bacterial growth. The resin was stimulatory for some plant and foodborne pathogens (Pseudomonas fluorescens, P. syringae, and Xanthomonas perforans) and antimicrobial for others (Escherichia coli, Bacillus cereus, Agrobacterium tumefaciens, and Erwinia amylovora). Treatment with either 1R-α-pinene or ß-pinene reduced B. cereus population growth less than did autoclaved resin. The complex resin likely contains additional antimicrobial compounds that act synergistically to inhibit bacterial growth.


Assuntos
Anti-Infecciosos/farmacologia , Resinas Vegetais/química , Traqueófitas/metabolismo , Compostos Orgânicos Voláteis/farmacologia , Anti-Infecciosos/química , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Sinergismo Farmacológico , Microbiologia de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Patologia Vegetal , Análise de Componente Principal , Espectroscopia de Infravermelho com Transformada de Fourier , Compostos Orgânicos Voláteis/química
13.
Plant Dis ; 103(10): 2559-2568, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432752

RESUMO

Olive (Olea europaea L.) is one of the most important fruit crops in the Mediterranean Basin, because it occupies significant acreage in these countries and often has important cultural heritage and landscape value. This crop can be infected by several Meloidogyne species (M. javanica, M. arenaria, and M. incognita, among others), and only a few cultivars with some level of resistance to these nematodes have been found. Innovations in intensive olive growing using high planting densities, irrigation, and substantial amounts of fertilizers could increase the nematode population to further damaging levels. To further understand the interactions involved between olive and pathogenic nematodes and in the hope of finding solutions to the agricultural risks, this research aimed to determine the reaction of important olive cultivars in Spain and wild olives to M. javanica infection, including genotypes of the same and other O. europaea subspecies. All olive cultivars tested were good hosts for M. javanica, but high levels of nematode reproduction found in three cultivars (Gordal Sevillana, Hojiblanca, and Manzanilla de Sevilla) were substantially different. In the wild accessions, O. europaea subsp. cerasiformis (genotype W147) and O. europaea subsp. europaea var. sylvestris (genotype W224) were resistant to M. javanica at different levels, with strong resistance in W147 (reproduction factor [Rf] = 0.0003) and moderate resistance in W224 (Rf = 0.79). The defense reaction of W147 to M. javanica showed a strong increase of phenolic compounds but no hypersensitive reaction.


Assuntos
Resistência à Doença , Olea , Patologia Vegetal , Tylenchoidea , Animais , Resistência à Doença/genética , Variação Genética , Genótipo , Olea/parasitologia , Espanha , Tylenchoidea/fisiologia
14.
Curr Opin Plant Biol ; 50: 156-162, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31387067

RESUMO

Determination and characterization of resistance reactions of crops against fungal pathogens are essential to select resistant genotypes. In plant breeding, phenotyping of genotypes is realized by time consuming and expensive visual plant ratings. During resistance reactions and during pathogenesis plants initiate different structural and biochemical defence mechanisms, which partly affect the optical properties of plant organs. Recently, intensive research has been conducted to develop innovative optical methods for an assessment of compatible and incompatible plant pathogen interaction. These approaches, combining classical phytopathology or microbiology with technology driven methods - such as sensors, robotics, machine learning, and artificial intelligence - are summarized by the term digital phenotyping. In contrast to common visual rating, detection and assessment methods, optical sensors in combination with advanced data analysis methods are able to retrieve pathogen induced changes in the physiology of susceptible or resistant plants non-invasively and objectively. Phenotyping disease resistance aims different tasks. In an early breeding step, a qualitative assessment and characterization of specific resistance action is aimed to link it, for example, to a genetic marker. Later, during greenhouse and field screening, the assessment of the level of susceptibility of different genotypes is relevant. Within this review, recent advances of digital phenotyping technologies for the detection of subtle resistance reactions and resistance breeding are highlighted and methodological requirements are critically discussed.


Assuntos
Patologia Vegetal , Inteligência Artificial , Resistência à Doença , Humanos , Aprendizado de Máquina , Fenótipo
16.
Methods Mol Biol ; 2028: 261-272, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31228120

RESUMO

Cross-protection is a phenomenon in which a plant that is infected with a virus becomes immune to a secondary infection by the same or related viruses. Although molecular mechanisms underlying this phenomenon are not completely understood, cross-protection induced by an attenuated strain with mild symptoms has been successfully used to prevent damage by more severe strains. In the development and selection of an effective attenuated strain among candidate isolates, evaluating their infectivity and efficiency of cross-protection is important. We describe two protocols to check the infection efficiency and distribution in a plant based on immunostaining results. In addition, a practical inoculation method that uses a spray gun to apply attenuated viruses to a large number of seedlings is presented.


Assuntos
Interações Hospedeiro-Patógeno , Doenças das Plantas/virologia , Vírus de Plantas/fisiologia , Virologia/métodos , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Patologia Vegetal
19.
Plant Biotechnol J ; 17(6): 1010-1026, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30677208

RESUMO

Recent metagenomic studies have provided an unprecedented wealth of data, which are revolutionizing our understanding of virus diversity. A redrawn landscape highlights viruses as active players in the phytobiome, and surveys have uncovered their positive roles in environmental stress tolerance of plants. Viral infectious clones are key tools for functional characterization of known and newly identified viruses. Knowledge of viruses and their components has been instrumental for the development of modern plant molecular biology and biotechnology. In this review, we provide extensive guidelines built on current synthetic biology advances that streamline infectious clone assembly, thus lessening a major technical constraint of plant virology. The focus is on generation of infectious clones in binary T-DNA vectors, which are delivered efficiently to plants by Agrobacterium. We then summarize recent applications of plant viruses and explore emerging trends in microbiology, bacterial and human virology that, once translated to plant virology, could lead to the development of virus-based gene therapies for ad hoc engineering of plant traits. The systematic characterization of plant virus roles in the phytobiome and next-generation virus-based tools will be indispensable landmarks in the synthetic biology roadmap to better crops.


Assuntos
Biotecnologia , Metagenômica , Patologia Vegetal , Vírus de Plantas , Biologia Sintética , Biotecnologia/tendências , Humanos , Patologia Vegetal/tendências , Vírus de Plantas/genética , Vírus de Plantas/fisiologia , Plantas/virologia , Biologia Sintética/tendências
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