scholarly journals Effect of Mixed and Single Crops on Disease Suppressiveness of Soils

2005 ◽  
Vol 95 (11) ◽  
pp. 1325-1332 ◽  
Author(s):  
Gerbert A. Hiddink ◽  
Aad J. Termorshuizen ◽  
Jos M. Raaijmakers ◽  
Ariena H. C. van Bruggen
Keyword(s):  
White Clover ◽  
Plant Pathogens ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Cropping Systems ◽  
Gaeumannomyces Graminis ◽  
Mixed Cropping ◽  
Soilborne Pathogens ◽  
Brussels Sprouts ◽  
Gradient Gel Electrophoresis ◽  
Gaeumannomyces Graminis Var Tritici

The effect of mixed cropping on disease suppressiveness of soils was tested for two cropping systems, Brussels sprouts-barley and triticale-white clover. Disease suppressiveness of field soils was evaluated in bioassays for the soilborne pathogens Rhizoctonia solani, Fusarium oxysporum f. sp. lini, and Gaeumannomyces graminis var. tritici. For both cropping systems, mixed cropping did not enhance disease suppressiveness of the soils. In some cases, soil cropped to barley alone was significantly more suppressive to F. oxysporum f. sp. lini than soils cropped to Brussels sprouts or the mixture of Brussels sprouts and barley. Analyses of the diversity of the indigenous bacterial and fungal microflora by denaturing gradient gel electrophoresis of amplified 16S- and 18S-rDNA fragments, respectively, revealed, in most cases, no significant differences between mixed and mono-cropped soils. In conclusion, in this study, mixed cropping of soils with Brussels sprouts and barley or with triticale and white clover did not enhance microbial diversity or disease suppressiveness of soils to three different soilborne plant pathogens.

scholarly journals Bacterial Chitinolytic Communities Respond to Chitin and pH Alteration in Soil

2012 ◽  
Vol 79 (1) ◽  
pp. 263-272 ◽  
Author(s):  
Anna M. Kielak ◽  
Mariana Silvia Cretoiu ◽  
Alexander V. Semenov ◽  
Søren J. Sørensen ◽  
Jan Dirk van Elsas
Keyword(s):  
16S Rrna ◽  
Bacterial Communities ◽  
Plant Pathogens ◽  
Structural Changes ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Acid Soil ◽  
Rrna Gene ◽  
Content Type ◽  
Soil Suppressiveness ◽  
Gradient Gel Electrophoresis

ABSTRACTChitin amendment is a promising soil management strategy that may enhance the suppressiveness of soil toward plant pathogens. However, we understand very little of the effects of added chitin, including the putative successions that take place in the degradative process. We performed an experiment in moderately acid soil in which the level of chitin, next to the pH, was altered. Examination of chitinase activities revealed fast responses to the added crude chitin, with peaks of enzymatic activity occurring on day 7. PCR-denaturing gradient gel electrophoresis (DGGE)-based analyses of 16S rRNA andchiAgenes showed structural changes of the phylogenetically and functionally based bacterial communities following chitin addition and pH alteration. Pyrosequencing analysis indicated (i) that the diversity ofchiAgene types in soil is enormous and (i) that differentchiAgene types are selected by the addition of chitin at different prevailing soil pH values. Interestingly, a major role of Gram-negative bacteria versus a minor one ofActinobacteriain the immediate response to the added chitin (based on 16S rRNA gene abundance andchiAgene types) was indicated. The results of this study enhance our understanding of the response of the soil bacterial communities to chitin and are of use for both the understanding of soil suppressiveness and the possible mining of soil for novel enzymes.

scholarly journals Functional characteristics of New Zealand wheat rhizosphere Pseudomonas fluorescens isolates and their potential to inhibit invitro growth of Gaeumannomyces graminis var tritici

2016 ◽  
Vol 69 ◽  
pp. 48-56
Author(s):  
R.M. Warren ◽  
S.F. Chng ◽  
R.C. Butler
Keyword(s):  
New Zealand ◽  
Pseudomonas Fluorescens ◽  
Plant Pathogens ◽  
Gaeumannomyces Graminis ◽  
Pcr Analysis ◽  
Direct Stimulation ◽  
Soilborne Disease ◽  
Biochemical Assays ◽  
Dual Plate ◽  
Gaeumannomyces Graminis Var Tritici

Pseudomonas fluorescens are soilinhabiting plant growthpromoting rhizobacteria (PGPR) linked with suppression of takeall of wheat a soilborne disease caused by Gaeumannomyces graminis var tritici (Ggt) PGPR increase plant growth by direct stimulation producing metabolites (such as 24diacetylphloroglucinol 24DAPG) to inhibit plant pathogens or by inducing host defence mechanisms Fortythree New Zealand P fluorescens isolates collected from wheat rhizospheres of different cropping histories were characterised for secondary metabolite production using biochemical assays and PCR analysis Their ability to inhibit the growth of Ggt was determined in dual plate assays All of the bacterial isolates produced siderophores and 10 isolates produced hydrogen cyanide (HCN) However none of the isolates produced indole acetic acid and the phlD gene responsible for the production of 24DAPG was not detected Isolates that showed at least 60 inhibition of Ggt growth were found to produce either HCN or high levels of siderophore The results suggest HCN and siderophores could play a role in suppressing Ggt and managing takeall in New Zealand

scholarly journals   Effect of legume-cereal mixtures on the diversity of bacterial communities in the rhizosphere

2012 ◽  
Vol 58 (No. 4) ◽  
pp. 174-180 ◽  
Author(s):  
Y.J. Qiao ◽  
Z.H. Li ◽  
X. Wang ◽  
B. Zhu ◽  
Y.G. Hu ◽  
...  
Keyword(s):  
16S Rdna ◽  
Bacterial Communities ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Cropping Systems ◽  
Microbial Succession ◽  
Common Vetch ◽  
Soil Microbial ◽  
Rdna Sequences ◽  
Gradient Gel Electrophoresis ◽  
Belowground Diversity

Aboveground plant diversity is known to influence belowground diversity and ecosystem processes. However, there is little knowledge of soil microbial succession in legume-grass mixtures. Therefore, this study was designed to determine the effect of oat and common vetch binary mixtures at three seeding rates on soil bacterial communities. Denaturing gradient gel electrophoresis (DGGE) of 16S rDNA fragments was used to profile the structure of the bacterial community in the rhizosphere. Compared with a monoculture of common vetch and oat, the Shannon-Weaver index and species richness of the mixtures were increased. Thirteen cloned monocultures and mixtures of oat and common vetch soil 16S rDNA sequences were deposited to NCBI. Based on the sequencing results, the bands could be identified as related to Proteobacteria, Bacteroidetes and Cyanobacteria. Common vetch did not have some bacteria relatives to Sphingomonas spp. Some bacterial taxa could be detected in the ratio of 1:1 and 1:2, but not in the ratio of 1:3, e.g. Myxococcales. The results suggested that the belowground diversity could be promoted by mixed cropping systems.  

scholarly journals Genetic Soil Disinfestation, A Conceptual Framework to Reduce Inoculum Potential of Soilborne Plant Pathogens

2019 ◽  
Vol 2 (2) ◽  
Keyword(s):  
Plant Pathogens ◽  
Cropping Systems ◽  
Food Crops ◽  
Inoculum Potential ◽  
Soilborne Pathogens ◽  
Genetic Approach ◽  
Chemical Methods ◽  
Soil Disinfestation ◽  
Anaerobic Soil Disinfestation ◽  
Soilborne Plant Pathogens

Soilborne pathogens are major constraints to the production of many food and non-food crops worldwide. A wide array of strategies are employed to reduce the activities of soilborne pathogens including chemical and non-chemical methods such as solarization, fumigation, anaerobic soil disinfestation, and soil chemical treatment. This article succinctly describes these methods and proposes the concept of “genetic soil disinfestation” as an additional innovative approach for managing soilborne pathogens. Although many components of “genetic soil disinfestation” include well known and familiar tools such as crop rotation, the concept of “genetic soil disinfestation” redefines cropping systems in a unified perspective with focus on using a genetic approach to optimize the attributes of hosts and nonhosts that significantly reduce the populations of soilborne plant pathogens and the efficiency of invasiness of these pathogens.

scholarly journals Diversity and Antagonistic Potential of Bacteria Associated with Bryophytes from Nutrient-Poor Habitats of the Baltic Sea Coast

2004 ◽  
Vol 70 (11) ◽  
pp. 6569-6579 ◽  
Author(s):  
Katja Opelt ◽  
Gabriele Berg
Keyword(s):  
Baltic Sea ◽  
Plant Pathogens ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Single Strand Conformation Polymorphism ◽  
Antagonistic Activity ◽  
Polymorphism Analysis ◽  
Moss Species ◽  
Gradient Gel Electrophoresis ◽  
The Baltic ◽  
Sea Coast

ABSTRACT Very little is known about the interaction of bryophytes with bacteria. Therefore, we analyzed bacteria associated with three bryophyte species, Tortula ruralis, Aulacomnium palustre, and Sphagnum rubellum, which represent typical moss species of three nutrient-poor plant communities at the southern Baltic Sea coast in Germany. By use of two cultivation-independent techniques, denaturing gradient gel electrophoresis and single-strand conformation polymorphism analysis of the 16S ribosomal DNA, a high degree of moss specificity was found for associated bacterial communities. This specificity could be further evidenced by a cultivation-dependent approach for the following parameters: (i) plate counts of bacteria on R2A medium, (ii) proportion of antagonistic isolates, (iii) antagonistic activity as well as spectrum against pathogens, and (iv) diversity and richness of antagonistic isolates. The proportion of isolates with antagonistic activity against the pathogenic model fungus Verticillium dahliae was highest for S. rubellum (31%), followed by A. palustre (17%) and T. ruralis (5%). A high percentage (99%) of moss-associated antagonistic bacteria produced antifungal compounds. The high recovery of antagonistic isolates strongly suggests that bryophytes represent an ecological niche which harbors a diverse and hitherto largely uncharacterized microbial population with yet unknown and untapped potential biotechnological applications, e.g., for biological control of plant pathogens.

scholarly journals Periodicity in Host Availability Does Not Account for Evolutionary Branching as Observed in Many Plant Pathogens: An Application to Gaeumannomyces graminis var. tritici

2010 ◽  
Vol 100 (11) ◽  
pp. 1169-1175 ◽  
Author(s):  
F. van den Berg ◽  
C. A. Gilligan ◽  
D. J. Bailey ◽  
F. van den Bosch
Keyword(s):  
Plant Pathogens ◽  
Transmission Rate ◽  
Adaptive Dynamics ◽  
Pathogen Transmission ◽  
Gaeumannomyces Graminis ◽  
Evolutionary Branching ◽  
Trade Off ◽  
Host Availability ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Periodicity in host availability is common in agricultural systems. Although it is known to have profound effects on plant pathogen abundance, the evolutionary consequences of periodicity for the pathogen population have not previously been analyzed. An epidemiological model incorporating periodic absence of the host crop is combined with the theory of adaptive dynamics to determine whether or not seasonality in host presence plays a role in the occurrence of evolutionary branching, leading to coexisting yet genetically distinct pathogen phenotypes. The study is motivated and illustrated by the specific example of take-all disease of wheat, caused by the pathogen Gaeumannomyces graminis var. tritici, for which two coexisting but genetically distinct types and a trade-off related to seasonality in host presence have been identified. Numerical simulations are used to show that a trade-off between the pathogen transmission rate and the survival of the pathogen between cropping seasons cannot account for the evolutionary branching observed in many pathogens. Model elaborations show that this conclusion holds for a broad range of putative mechanisms. Although the analysis is motivated and illustrated by the specific example of take-all of wheat, the results apply to a broad range of pathogens.

Allelopathic and Medicinal plant. 26. Millettia speciosa

2020 ◽  
Vol 51 (2) ◽  
pp. 125-146
Author(s):  
Nasiruddin Nasiruddin ◽  
Yu Zhangxin ◽  
Ting Zhao Chen Guangying ◽  
Minghui Ji
Keyword(s):  
Community Structure ◽  
Medicinal Plant ◽  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Wiener Index ◽  
Pseudomonas Spp ◽  
Evenness Index ◽  
Gradient Gel Electrophoresis ◽  
Rhizosphere Pseudomonas

We grew cucumber in pots in greenhouse for 9-successive cropping cycles and analyzed the rhizosphere Pseudomonas spp. community structure and abundance by PCR-denaturing gradient gel electrophoresis and quantitative PCR. Results showed that continuous monocropping changed the cucumber rhizosphere Pseudomonas spp. community. The number of DGGE bands, Shannon-Wiener index and Evenness index decreased during the 3rd cropping and thereafter, increased up to the 7th cropping, however, however, afterwards they decreased again. The abundance of Pseudomonas spp. increased up to the 5th successive cropping and then decreased gradually. These findings indicated that the structure and abundance of Pseudomonas spp. community changed with long-term cucumber monocropping, which might be linked to soil sickness caused by its continuous monocropping.

MICROBIAL COMMUNITY DURING BIOREMEDIATION EXPERIMENTAL ON OIL SPILL IN COASTAL OF PARI ISLAND

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Lies Indah Sutiknowati
Keyword(s):  
Oil Spill ◽  
Deoxyribonucleic Acid ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Gas Chromatography Mass Spectrometry ◽  
Oil Degradation ◽  
Sequence Determination ◽  
Blast Search ◽  
Degrading Bacteria ◽  
Gradient Gel Electrophoresis

There is an information how to identify hydrocarbon degrading bacteria for bioremediation of marine oil spill. We have Bioremediation treatment for degradation of oil spill on Pari island and need two kind of experiment there are tanks experiment (sampling 0 to 90 days) and semi enclosed system (sampling 0 to 150 days). Biostimulation with nutrients (N and P) was done to analyze biodegradation of hydrocarbon compounds. Experiment design using fertilizer Super IB and Linstar will stimulate bacteria can degrade oil, n-alkane, and alkane as poly aromatic hydrocarbon. The bacteria communities were monitored and analyzed by Denaturing Gradient Gel Electrophoresis (DGGE) and Clone Library; oil chemistry was analyzed by Gas Chromatography Mass Spectrometry (GCMS). DNA (deoxyribonucleic acid) was extracted from colonies of bacteria and sequence determination of the 16S rDNA was amplified by primers U515f and U1492r. Strains had been sequence and had similarity about 90-99% to their closest taxa by homology Blast search and few of them suspected as new species. The results showed that fertilizers gave a significant effect on alkane, PAH and oil degradation in tanks experiment but not in the field test. Dominant of the specific bacteria on this experiment were Alcanivorax, Marinobacter and Prosthecochloris. Keywords: Bioremediation, Biostimulation, DGGE, PAH, Pari Island

The comparison of the diversity of activated sludge plants

1998 ◽  
Vol 37 (4-5) ◽  
pp. 71-78 ◽  
Author(s):  
Thomas P. Curtis ◽  
Noel G. Craine
Keyword(s):  
Cluster Analysis ◽  
Activated Sludge ◽  
Treatment Process ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Optimal Sampling ◽  
Bacterial Populations ◽  
Large Numbers ◽  
Probable Presence ◽  
Gradient Gel Electrophoresis ◽  
Sampling Regime

The explicit engineering of bacterial populations requires that we know which organisms perform which tasks. The comparison of the bacterial diversity of activated sludge plants may give important information about the functions of different bacteria. This difficult task may be made easier by the use of technologies based on 16S rRNA based techniques. In this study we have used denaturing gradient gel electrophoresis (DGGE) to determine the optimal sampling regime for comparative studies and used cluster analysis to show how plants may be quantitatively compared. We sought evidence of spatial, diurnal and intrasample variation in a number of sites. No evidence for variation was found in the plants studied and we concluded that a single sample of an activated sludge plant was sufficient for a plant to plant comparison. The cluster analysis was able to distinguish between plants, though further work is required to find the most appropriate basis for such comparisons. We found organisms from raw sewage in the mixed liquor samples, these organisms may have no functional significance in the treatment process and thus complicate plant to plant comparisons as will the probable presence of heteroduplex rDNA products. Nevertheless we believe that these drawbacks do not outweigh the advantages of being able to take and compare relatively large numbers of samples.

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