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1.
Thais Freitas da Silva Renata Estebanez Vollú Joana Montezano Marques Joana Falcão Salles Lucy Seldin 《Plant and Soil》2017,414(1-2):69-79
Background
The fungus Colletotrichum is a plant pathogen that causes the anthracnose disease, resulting in huge losses in various crops including the rose-scented geranium (Pelargonium graveolens). Although the bacterial community associated with plants has an important role in the establishment of plant diseases, little is known about what happens in P. graveolens.Aims
To increase the knowledge about the bacterial community associated with P. graveolens and its relationship with anthracnose disease symptoms.Methods
Quantitative PCR and high-throughput sequencing were combined to determine the presence of the fungus Colletotrichum and to reveal the bacterial communities associated with different plant parts – root, stem and leaf – and in the rhizosphere and bulk soil, and also to determine the respective bacterial communities associated with P. graveolens leaves symptomatic and asymptomatic for anthracnose disease.Results
The fungus Colletotrichum was detected in all plant parts and in the surrounding soil. Bacterial communities varied spatially in plants, and the disease symptoms also influenced the composition of the bacterial community. Abundances of operational taxonomic units (OTUs) assigned to the phylum Actinobacteria and to the genus Streptococcus were greatly increased in asymptomatic leaves.Conclusions
The bacterial community associated to geranium leaves responds to anthracnose symptoms.2.
Dong An Qiuxiang Ma Hongxia Wang Jun Yang Wenzhi Zhou Peng Zhang 《Plant molecular biology》2017,93(1-2):109-120
Key message
Reactive oxygen species (ROS) oxidize methionine to methionine sulfoxide (MetSO) and thereby inactivate proteins. Methionine sulfoxide reductase (MSR) enzyme converts MetSO back to the reduced form and thereby detoxifies the effect of ROS. Our results show that Arabidopsis thaliana MSR enzyme coding gene MSRB8 is required for effector-triggered immunity and containment of stress-induced cell death in Arabidopsis.Abstract
Plants activate pattern-triggered immunity (PTI), a basal defense, upon recognition of evolutionary conserved molecular patterns present in the pathogens. Pathogens release effector molecules to suppress PTI. Recognition of certain effector molecules activates a strong defense, known as effector-triggered immunity (ETI). ETI induces high-level accumulation of reactive oxygen species (ROS) and hypersensitive response (HR), a rapid programmed death of infected cells. ROS oxidize methionine to methionine sulfoxide (MetSO), rendering several proteins nonfunctional. The methionine sulfoxide reductase (MSR) enzyme converts MetSO back to the reduced form and thereby detoxifies the effect of ROS. Though a few plant MSR genes are known to provide tolerance against oxidative stress, their role in plant–pathogen interaction is not known. We report here that activation of cell death by avirulent pathogen or UV treatment induces expression of MSRB7 and MSRB8 genes. The T-DNA insertion mutant of MSRB8 exaggerates HR-associated and UV-induced cell death and accumulates a higher level of ROS than wild-type plants. The negative regulatory role of MSRB8 in HR is further supported by amiRNA and overexpression lines. Mutants and overexpression lines of MSRB8 are susceptible and resistant respectively, compared to the wild-type plants, against avirulent strains of Pseudomonas syringae pv. tomato DC3000 (Pst) carrying AvrRpt2, AvrB, or AvrPphB genes. However, the MSRB8 gene does not influence resistance against virulent Pst or P. syringae pv. maculicola (Psm) pathogens. Our results altogether suggest that MSRB8 function is required for ETI and containment of stress-induced cell death in Arabidopsis.3.
Rafael do Prado Apparecido Eduardo Fermino Carlos Luciano Morais Lião Luiz Gonzaga Esteves Vieira Glaucia Braz Alcantara 《Metabolomics : Official journal of the Metabolomic Society》2017,13(2):20
Introduction
Citrus canker, a disease caused by Xanthomonas axonopodis pv. citri (Xac) bacteria, has been responsible for extensive economic losses in citriculture. In this work, we report the metabolic responses of citrus plants during disease development. This information can be useful for understanding the natural mechanism of plant defense beyond helping design new varieties and/or genetically modified genotypes for tolerance/resistance against citrus canker.Objectives
To understand how primary metabolism is affected in two sweet orange genotypes during citrus canker development.Methods
1H NMR spectroscopy together with chemometrics was used to evaluate the metabolic changes caused by Xac infection at various time points (days 4, 12 and 20) in Citrus sinensis L. Osbeck leaves from non-transgenic and transgenic plants expressing the antibacterial peptide sarcotoxin.Results
The results revealed a high level of metabolic similarity between the studied genotypes without Xac infection. However, after Xac infection, the plants responded differently to disease development. The non-transgenic genotype showed altered early precursors of some secondary metabolites (tryptophan, tyrosine and putrescine) in addition to signaling metabolites of biotic stress (putrescine and dimethylamine), and the drastic reduction of gluconeogenesis was the overall metabolic cost for defense. The transgenic genotype suffered late metabolic changes due to the protective stoichiometric role of sarcotoxin. In addition, the oxidative stress response was more balanced in transgenic than in non-transgenic plants.Conclusion
An NMR-based metabolomic approach was useful for understanding plant–pathogen interactions in citrus canker. Our findings provide valuable preliminary insights into different stages of citrus canker development.4.
Aiqin Zhang Wei Zang Xiyang Zhang Yangyang Ma Xiufeng Yan Qiuying Pang 《Plant and Soil》2016,409(1-2):175-202
Background and aims
Soil salinization with high pH condition is a major abiotic stress to plant growth and crop productivity. Helianthus tuberosus L. is an important stress tolerant plant and can survive in the saline-alkali soil and semiarid areas. The aim of this study is to identify the effect of alkali stress on H. tuberosus through global proteomics analysis and improve understanding of the alkalinity resistance of plants.Methods
H. tuberosus seedlings were exposed to different level alkali stress for 7 days. Protein profiling was quantified by conducting MS-based comparative proteomics analysis. RT-PCR study was carried out to analyze the mRNA expression levels of candidate alkali stress response proteins.Results
The response of H. tuberosus to alkali stress was detected at both physiological and molecular levels. 104 differentially expressed proteins from H. tuberosus leaves response to Na2CO3 treatment were successfully identified. Functional categorization of these identified proteins showed that the accumulation level of proteins involved in glycolysis, TCA cycle, PSI system, ROS scavenging and signal transduction increased under alkali stress.Conclusions
Based on the observation of plant growth and the investigation of molecular regulation, H.tuberosus could resist certain alkali stress by modulating carbohydrate metabolism and redox homeostasis. These findings provide a new sight into the underlying molecular mechanisms of alkali resistance in plant.5.
Hafiz Muhammad Khalid Abbas Jingshu Xiang Zahoor Ahmad Lilin Wang Wubei Dong 《BMC plant biology》2018,18(1):357
Background
Pinellia ternata is a Chinese traditional medicinal herb, used to cure diseases including insomnia, eclampsia and cervical carcinoma, for hundreds of years. Non-self-recognition in multicellular organisms can initiate the innate immunity to avoid the invasion of pathogens. A design for pathogen independent, heterosis based, fresh resistance can be generated in F1 hybrid was proposed.Results
By library functional screening, we found that P. ternata genes, named as ptHR375 and ptHR941, were identified with the potential to trigger a hypersensitive response in Nicotiana benthamiana. Significant induction of ROS and Callose deposition in N. benthamiana leaves along with activation of pathogenesis-related genes viz.; PR-1a, PR-5, PDF1.2, NPR1, PAL, RBOHB and ERF1 and antioxidant enzymes was observed. After transformation into N. benthamiana, expression of pathogenesis related genes was significantly up-regulated to generate high level of resistance against Phytophthora capsici without affecting the normal seed germination and morphological characters of the transformed N. benthamiana. UPLC-QTOF-MS analysis of ptHR375 transformed N. benthamiana revealed the induction of Oxytetracycline, Cuelure, Allantoin, Diethylstilbestrol and 1,2-Benzisothiazol-3(2H)-one as bioactive compounds. Here we also proved that F1 hybrids, produced by crossing of the ptHR375 and ptHR941 transformed and non-transformed N. benthamiana, show significant high levels of PR-gene expressions and pathogen resistance.Conclusions
Heterologous plant genes can activate disease resistance in another plant species and furthermore, by generating F1 hybrids, fresh pathogen independent plant immunity can be obtained. It is also concluded that ptHR375 and ptHR941 play their role in SA and JA/ET defense pathways to activate the resistance against invading pathogens.6.
Harley M. Smith Catherine W. Clarke Brady P. Smith Bernadette M. Carmody Mark R. Thomas Peter R. Clingeleffer Kevin S. Powell 《BMC plant biology》2018,18(1):360
Background
Grape phylloxera (Daktulosphaira vitifoliae Fitch) is a major insect pest that negatively impacts commercial grapevine performance worldwide. Consequently, the use of phylloxera resistant rootstocks is an essential component of vineyard management. However, the majority of commercially available rootstocks used in viticulture production provide limited levels of grape phylloxera resistance, in part due to the adaptation of phylloxera biotypes to different Vitis species. Therefore, there is pressing need to develop new rootstocks better adapted to specific grape growing regions with complete resistance to grape phylloxera biotypes.Results
Grapevine rootstock breeding material, including an accession of Vitis cinerea and V. aestivalis, DRX55 ([M. rotundifolia x V. vinifera] x open pollinated) and MS27-31 (M. rotundifolia specific hybrid), provided complete resistance to grape phylloxera in potted plant assays. To map the genetic factor(s) of grape phylloxera resistance, a F1 V. cinerea x V. vinifera Riesling population was screened for resistance. Heritability analysis indicates that the V. cinerea accession contained a single allele referred as RESISTANCE TO DAKTULOSPHAIRA VITIFOLIAE 2 (RDV2) that confers grape phylloxera resistance. Using genetic maps constructed with pseudo-testcross markers for V. cinerea and Riesling, a single phylloxera resistance locus was identified in V. cinerea. After validating SNPs at the RDV2 locus, interval and linkage mapping showed that grape phylloxera resistance mapped to linkage group 14 at position 16.7 cM.Conclusion
The mapping of RDV2 and the validation of markers linked to grape phylloxera resistance provides the basis to breed new rootstocks via marker-assisted selection that improve vineyard performance.7.
Mahboobeh Ziaei Mostafa Motallebi Mohammad Reza Zamani Nasim Zarin Panjeh 《Biotechnology letters》2016,38(6):1021-1032
Objectives
Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum is one of the major fungal diseases of canola. To develop resistance against this fungal disease, the chit42 from Trichoderma atroviride with chitin-binding domain and polygalacturonase-inhibiting protein 2 (PG1P2) of Phaseolus vulgaris were co-expressed in canola via Agrobacterium-mediated transformation.Results
Stable integration and expression of transgenes in T0 and T2 plants was confirmed by PCR, Southern blot and RT-PCR analyses. Chitinase activity and PGIP2 inhibition were detected by colorimetric and agarose diffusion assay in transgenic lines but not in untransformed plants. The crude proteins from single copy transformant leaves having high chitinase and PGIP2 activity (T16, T8 and T3), showed up to 44 % inhibition of S. sclerotiorum hyphal growth. The homozygous T2 plants, showing inheritance in Mendelian fashion (3:1), were further evaluated under greenhouse conditions for resistance to S. sclerotiorum. Intact plants contaminated with mycelia showed resistance through delayed onset of the disease and restricted size and expansion of lesions as compared to wild type plants.Conclusions
Combined expression of chimeric chit42 and pgip2 in Brassica napus L. provide subsequent protection against SSR disease and can be helpful in increasing the canola production in Iran.8.
BACKGROUND
Microbes affect the growth of plants. In this study, the diversity and plant growth-supporting activities of wheat rhizospheric bacteria were examined.METHODS
Sampling was performed thrice at different phases of plant growth. Microbes associated with the rhizoplane of three wheat varieties (Seher, Lasani, and Faisalabad) were cultured and assessed for their plant growth-promoting abilities based on auxin production, hydrogen cyanide production, phosphate solubilization, and nitrogen fixation.RESULTS
Bacterial load (CFU/mL) declined, and the succession of bacterial diversity occurred as the plants aged. Most auxin-producing bacteria and the highest concentrations of auxin (77 μg/mL) were observed during the second sampling point at the tillering stage. The Seher variety harbored the most auxin-producing as well as phosphate-solubilizing bacteria. Most of the bacteria belonged to Bacillus and Pseudomonas. Planomicrobium, Serratia, Rhizobium, Brevundimonas, Stenotrophomonas, and Exiguobacterium sp. were also found.CONCLUSION
These results suggest that the rhizoplane microbiota associated with higher-yield plant varieties have better plant growth-promoting abilities as compared to the microbiota associated with lower-yield plant varieties.9.
10.
11.
A genome-scale metabolic model of potato late blight suggests a photosynthesis suppression mechanism
Background
Phytophthora infestans is a plant pathogen that causes an important plant disease known as late blight in potato plants (Solanum tuberosum) and several other solanaceous hosts. This disease is the main factor affecting potato crop production worldwide. In spite of the importance of the disease, the molecular mechanisms underlying the compatibility between the pathogen and its hosts are still unknown.Results
To explain the metabolic response of late blight, specifically photosynthesis inhibition in infected plants, we reconstructed a genome-scale metabolic network of the S. tuberosum leaf, PstM1. This metabolic network simulates the effect of this disease in the leaf metabolism. PstM1 accounts for 2751 genes, 1113 metabolic functions, 1773 gene-protein-reaction associations and 1938 metabolites involved in 2072 reactions. The optimization of the model for biomass synthesis maximization in three infection time points suggested a suppression of the photosynthetic capacity related to the decrease of metabolic flux in light reactions and carbon fixation reactions. In addition, a variation pattern in the flux of carboxylation to oxygenation reactions catalyzed by RuBisCO was also identified, likely to be associated to a defense response in the compatible interaction between P. infestans and S. tuberosum.Conclusions
In this work, we introduced simultaneously the first metabolic network of S. tuberosum and the first genome-scale metabolic model of the compatible interaction of a plant with P. infestans.12.
Margarita Stritzler Ana Diez Tissera Gabriela Soto Nicolás Ayub 《Biotechnology letters》2018,40(9-10):1419-1423
Objectives
Identification of novel microbial factors contributing to plant protection against abiotic stress.Results
The genome of plant growth-promoting bacterium Pseudomonas fluorescens FR1 contains a short mobile element encoding a novel type of extracellular polyhydroxybutyrate (PHB) polymerase (PhbC) associated with a type I secretion system. Genetic analysis using a phbC mutant strain and plants showed that this novel extracellular enzyme is related to the PHB production in planta and suggests that PHB could be a beneficial microbial compound synthesized during plant adaptation to cold stress.Conclusion
Extracellular PhbC can be used as a new tool for improve crop production under abiotic stress.13.
14.
Teppei Sugawara Ekaterina A. Trifonova Alex V. Kochetov Yoshinori Kanayama 《BMC plant biology》2016,16(3):246
Background
The apoplast plays an important role in plant defense against pathogens. Some extracellular PR-4 proteins possess ribonuclease activity and may directly inhibit the growth of pathogenic fungi. It is likely that extracellular RNases can also protect plants against some viruses with RNA genomes. However, many plant RNases are multifunctional and the direct link between their ribonucleolytic activity and antiviral defense still needs to be clarified. In this study, we evaluated the resistance of Nicotiana tabacum plants expressing a non-plant single-strand-specific extracellular RNase against Cucumber mosaic virus.Results
Severe mosaic symptoms and shrinkage were observed in the control non-transgenic plants 10 days after inoculation with Cucumber mosaic virus (CMV), whereas such disease symptoms were suppressed in the transgenic plants expressing the RNase gene. In a Western blot analysis, viral proliferation was observed in the uninoculated upper leaves of control plants, whereas virus levels were very low in those of transgenic plants. These results suggest that resistance against CMV was increased by the expression of the heterologous RNase gene.Conclusion
We have previously shown that tobacco plants expressing heterologous RNases are characterized by high resistance to Tobacco mosaic virus. In this study, we demonstrated that elevated levels of extracellular RNase activity resulted in increased resistance to a virus with a different genome organization and life cycle. Thus, we conclude that the pathogen-induced expression of plant apoplastic RNases may increase non-specific resistance against viruses with RNA genomes.15.
Luhong Zhou He Li Haihua Shen Yunping Xu Yinghui Wang Aijun Xing Yankun Zhu Shangzhe Zhou Jingyun Fang 《Plant and Soil》2018,425(1-2):217-230
Background
This study started from typical replant disease symptoms limited to specific foci within three multi-generation orchards showing homogeneous growth.Methods
A plant growth assay was conducted using soil from symptomatic and asymptomatic tree root zones along planted rows and from strip-rows. Root colonizing fungal communities were investigated, then the study turned to pathogenicity of Cylindrocarpon-like fungi (Dactylonectria and Ilyonectria spp) and their extracellular exudates.Results
Growth of apple rootstock plantlets in soil from symptomatic trees was significantly lower than in those observed in soil from asymptomatic trees and from strip-rows. Among the main group of endophytic filamentous fungi isolated from roots, Cylindrocapon-like fungi (Dactylonectria torresensis and, to a lesser extent, Ilyonectria robusta), along with binucleate Rhizoctonia spp., prevailed mostly in plantlets grown in soil collected from planted rows. On the other hand, Fusarium spp. prevailed in plantlets grown in soil from the strip-rows. Cylindrocarpon-like fungi was found to be the most negatively correlated with plant growth. As findings of artificial inoculation with main root colonizing fungal species were not in line with what was observed in native soils, a further investigation was performed on secondary metabolites through which Dactylonectria torresensis exerts pathogenicity; this analysis revealed that both phytotoxins (tentoxin, HC toxin and zearalenone) and cytotoxic compounds (rabelomycin and nidulin) may be involved.Conclusion
Findings suggest that extracellular compounds released by D. torresensis may have contributed to the severe growth reduction associated with replant disease-like symptoms.16.
Jyoti Singla Linda Lüthi Thomas Wicker Urmil Bansal Simon G. Krattinger Beat Keller 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(1):1-12
Key message
Here, we describe a strategy to improve broad-spectrum leaf rust resistance by marker-assisted combination of two partial resistance genes. One of them represents a novel partial adult plant resistance gene, named Lr75.Abstract
Leaf rust caused by the fungal pathogen Puccinia triticina is a damaging disease of wheat (Triticum aestivum L.). The combination of several, additively-acting partial disease resistance genes has been proposed as a suitable strategy to breed wheat cultivars with high levels of durable field resistance. The Swiss winter wheat cultivar ‘Forno’ continues to show near-immunity to leaf rust since its release in the 1980s. This resistance is conferred by the presence of at least six quantitative trait loci (QTL), one of which is associated with the morphological trait leaf tip necrosis. Here, we used a marker-informed strategy to introgress two ‘Forno’ QTLs into the leaf rust-susceptible Swiss winter wheat cultivar ‘Arina’. The resulting backcross line ‘ArinaLrFor’ showed markedly increased leaf rust resistance in multiple locations over several years. One of the introgressed QTLs, QLr.sfr-1BS, is located on chromosome 1BS. We developed chromosome 1B-specific microsatellite markers by exploiting the Illumina survey sequences of wheat cv. ‘Chinese Spring’ and mapped QLr.sfr-1BS to a 4.3 cM interval flanked by the SSR markers gwm604 and swm271. QLr.sfr-1BS does not share a genetic location with any of the described leaf rust resistance genes present on chromosome 1B. Therefore, QLr.sfr-1BS is novel and was designated as Lr75. We conclude that marker-assisted combination of partial resistance genes is a feasible strategy to increase broad-spectrum leaf rust resistance. The identification of Lr75 adds a novel and highly useful gene to the small set of known partial, adult plant leaf rust resistance genes.17.
Sayaka Okuzono Masataka Ishimura Shunsuke Kanno Motoshi Sonoda Noriyuki Kaku Yoshitomo Motomura Hisanori Nishio Utako Oba Masuo Hanada Jun-ichi Fukushi Michiyo Urata Dongchon Kang Hidetoshi Takada Shouichi Ohga 《Annals of clinical microbiology and antimicrobials》2018,17(1):31
Background
Streptococcus pyogenes is an uncommon pathogen of purpura fulminans, and the pathogenesis of S. pyogenes-purpura fulminans remains unclear because of paucity of cases. We reported a pediatric case of S. pyogenes-purpura fulminans with literature review of the disease.Case presentation
A 3-year-old boy showed limping, lethargy and acral gangrene within 24 h. A diagnosis of S. pyogenes-purpura fulminans was made for bacterial isolation from throat and peripheral blood. Intensive therapy led to a survival with amputation of the left distal metatarsal bone, and normal development. The isolated M12 carried no mutation of csrS/R or rgg. Thrombophilia or immunodeficiency was excluded.Discussion
Twelve-reported cases (9 pediatric and 3 elderly) of S. pyogenes-purpura fulminans started with shock and coagulopathy. Five patients age <?8 years had no underlying disease and survived. One youngest and two immunocompromised patients died.Conclusion
Streptococcus pyogenes-acute infectious purpura fulminans is a distinctive rare form of aggressive GAS infections.18.
Anne Caroline Wiik Ernst-Otto Ropstad Ellen Bjerkås Frode Lingaas 《BMC veterinary research》2008,4(1):23
Background
A genetic study was performed to identify candidate genes associated with day blindness in the standard wire haired dachshund. Based on a literature review of diseases in dogs and human with phenotypes similar to day blindness, ten genes were selected and evaluated as potential candidate genes associated with day blindness in the breed.Results
Three of the genes, CNGB3, CNGA3 and GNAT2, involved in cone degeneration and seven genes and loci, ABCA4, RDH5, CORD8, CORD9, RPGRIP1, GUCY2D and CRX, reported to be involved in cone-rod dystrophies were studied. Polymorphic markers at each of the candidate loci were studied in a family with 36 informative offspring. The study revealed a high frequency of recombinations between the candidate marker alleles and the disease.Conclusion
Since all of the markers were at the exact position of the candidate loci, and several recombinations were detected for each of the loci, all ten genes were excluded as causal for this canine, early onset cone-rod dystrophy. The described markers may, however, be useful to screen other canine resource families segregating eye diseases for association to the ten genes.19.