scholarly journals Genetic Diversity and Biological Control Activity of Novel Species of Closely Related Pseudomonads Isolated from Wheat Field Soils in South Australia

2000 ◽  
Vol 66 (4) ◽  
pp. 1609-1616 ◽  
Author(s):  
Ian L. Ross ◽  
Younes Alami ◽  
Paul R. Harvey ◽  
Wafa Achouak ◽  
Maarten H. Ryder
Keyword(s):  
Genetic Diversity ◽  
Biological Control ◽  
Novel Species ◽  
Acid Methyl Ester ◽  
South Australia ◽  
Gaeumannomyces Graminis ◽  
Control Activity ◽  
Wheat Field ◽  
Field Soils ◽  
Take All

ABSTRACT Rhizobacteria closely related to two recently described species of pseudomonads, Pseudomonas brassicacearum andPseudomonas thivervalensis, were isolated from two geographically distinct wheat field soils in South Australia. Isolation was undertaken by either selective plating or immunotrapping utilizing a polyclonal antibody raised against P. brassicacearum. A subset of 42 isolates were characterized by amplified 16S ribosomal DNA restriction analysis (ARDRA), BIOLOG analysis, and gas chromatography-fatty acid methyl ester (GC-FAME) analysis and separated into closely related phenetic groups. More than 75% of isolates tested by ARDRA were found to have >95% similarity to either Pseudomonas corrugata or P. brassicacearum-P. thivervalensis type strains, and all isolates had >90% similarity to either type strain. BIOLOG and GC-FAME clustering showed a >70% match to ARDRA profiles. Strains representing different ARDRA groups were tested in two soil types for biological control activity against the soilborne plant pathogen Gaeumannomyces graminis var. tritici, the causative agent of take-all of wheat and barley. Three isolates out of 11 significantly reduced take-all-induced root lesions on wheat plants grown in a red-brown earth soil. Only one strain, K208, was consistent in reducing disease symptoms in both the acidic red-brown earth and a calcareous sandy loam. Results from this study indicate that P. brassicacearum and P. thivervalensis are present in Australian soils and that a level of genetic diversity exists within these two novel species but that this diversity does not appear to be related to geographic distribution. The result of the glasshouse pot trial suggests that some isolates of these species may have potential as biological control agents for plant disease.

Potential Biological Control Activity and Genetic Diversity of Pseudomonas syringae pv. syringae Strains

2005 ◽  
Vol 153 (11-12) ◽  
pp. 654-666 ◽  
Author(s):  
G. Cirvilleri ◽  
A. Bonaccorsi ◽  
G. Scuderi ◽  
M. Scortichini
Keyword(s):  
Genetic Diversity ◽  
Biological Control ◽  
Pseudomonas Syringae ◽  
Control Activity

scholarly journals Bacillus sp. L324-92 for Biological Control of Three Root Diseases of Wheat Grown with Reduced Tillage

1997 ◽  
Vol 87 (5) ◽  
pp. 551-558 ◽  
Author(s):  
Dal-Soo Kim ◽  
R. James Cook ◽  
David M. Weller
Keyword(s):  
Biological Control ◽  
Root Rot ◽  
Gaeumannomyces Graminis ◽  
Limiting Factors ◽  
Bacillus Species ◽  
Bacillus Sp ◽  
Pythium Irregulare ◽  
Root Diseases ◽  
Rhizoctonia Root Rot ◽  
Take All

Strain L324-92 is a novel Bacillus sp. with biological activity against three root diseases of wheat, namely take-all caused by Gaeumannomyces graminis var. tritici, Rhizoctonia root rot caused by Rhizoctonia solani AG8, and Pythium root rot caused mainly by Pythium irregulare and P. ultimum, that exhibits broad-spectrum inhibitory activity and grows at temperatures from 4 to 40°C. These three root diseases are major yieldlimiting factors for wheat in the U.S. Inland Pacific Northwest, especially wheat direct-drilled into the residue of a previous cereal crop. Strain L324-92 was selected from among approximately 2,000 rhizosphere/rhizoplane isolates of Bacillus species isolated from roots of wheat collected from two eastern Washington wheat fields that had long histories of wheat. Roots were washed, heat-treated (80°C for 30 min), macerated, and dilution-plated on 1/10-strength tryptic soy agar. Strain L324-92 inhibited all isolates of G. graminis var. tritici, Rhizoctonia species and anastomosis groups, and Pythium species tested on agar at 15°C; provided significant suppression of all three root diseases at 15°C in growth chamber assays; controlled either Rhizoctonia root rot, takeall, or both; and increased yields in field tests in which one or more of the three root diseases of wheats were yield-limiting factors. The ability of L324-92 to grow at 4°C probably contributes to its biocontrol activity on direct-drilled winter and spring wheat because, under Inland Northwest conditions, leaving harvest residues of the previous crop on the soil surface keeps soils cooler compared with tilled soils. These results suggest that Bacillus species with desired traits for biological control of wheat root diseases are present within the community of wheat rhizosphere microorganisms and can be recovered by protocols developed earlier for isolation of fluorescent Pseudomonas species effective against take-all.

scholarly journals Biological Control of Wheat Root Diseases by the CLP-Producing Strain Pseudomonas fluorescens HC1-07

2014 ◽  
Vol 104 (3) ◽  
pp. 248-256 ◽  
Author(s):  
Ming-Ming Yang ◽  
Shan-Shan Wen ◽  
Dmitri V. Mavrodi ◽  
Olga V. Mavrodi ◽  
Diter von Wettstein ◽  
...  
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Root Rot ◽  
Gaeumannomyces Graminis ◽  
Protease Production ◽  
Ionization Mass ◽  
Soilborne Disease ◽  
Rhizoctonia Root Rot ◽  
Take All

Pseudomonas fluorescens HC1-07, previously isolated from the phyllosphere of wheat grown in Hebei province, China, suppresses the soilborne disease of wheat take-all, caused by Gaeumannomyces graminis var. tritici. We report here that strain HC1-07 also suppresses Rhizoctonia root rot of wheat caused by Rhizoctonia solani AG-8. Strain HC1-07 produced a cyclic lipopeptide (CLP) with a molecular weight of 1,126.42 based on analysis by electrospray ionization mass spectrometry. Extracted CLP inhibited the growth of G. graminis var. tritici and R. solani in vitro. To determine the role of this CLP in biological control, plasposon mutagenesis was used to generate two nonproducing mutants, HC1-07viscB and HC1-07prtR2. Analysis of regions flanking plasposon insertions in HC1-07prtR2 and HC1-07viscB revealed that the inactivated genes were similar to prtR and viscB, respectively, of the well-described biocontrol strain P. fluorescens SBW25 that produces the CLP viscosin. Both genes in HC1-07 were required for the production of the viscosin-like CLP. The two mutants were less inhibitory to G. graminis var. tritici and R. solani in vitro and reduced in ability to suppress take-all. HC1-07viscB but not HC-07prtR2 was reduced in ability to suppress Rhizoctonia root rot. In addition to CLP production, prtR also played a role in protease production.

Death of the root cortex of winter wheat in field conditions; effects of break crops and possible implications for the take-all fungus and its biological control agent, Phialophora radicicola var. graminicola

1981 ◽  
Vol 96 (3) ◽  
pp. 579-585 ◽  
Author(s):  
J. W. Deacon ◽  
Christine M. Henry
Keyword(s):  
Biological Control ◽  
Winter Wheat ◽  
Biological Control Agent ◽  
Control Agent ◽  
Gaeumannomyces Graminis ◽  
Nuclear Staining ◽  
Root Cortex ◽  
Significant Difference ◽  
Cell Layers ◽  
Take All

SUMMARYNuclear staining with acridine orange was used to study death of the root cortex of winter wheat grown after grass and non-graminaceous break crops in a field trial site in 1978. The top 5·4 cm of first seminal root axes had several anucleate cortical cell layers by late-February, and nearly five dead cell layers (of a maximum six) by mid-April. One of the next pair of roots to emerge (designated ‘2’) showed similar cortical death, but one of the subsequent pair (designated ‘4“)showed substantially less death at these times.Significantly more root cortex death was seen in first to third wheat crops after 1 or 2 years of grass than after swedes-potatoes, and in one replicate block compared with the other in the trial. But there was no significant difference in cortical death between first, second, third and 16th successive wheat crops.Root cortex death could not be attributed to infection by Gaeumannomyces graminis, Phialophora radicicola var. graminicola or the nematode Rotylenchus robustus. But its implications for root–infecting parasites are considered and, in particular, the enhanced cortical death in some crops compared with others may help to explain the reported differences in infection of wheat by P. radicicola var. graminicola, a biological control agent of take-all.

The role of the chi1 gene from the endophytic bacteria Serratia proteamaculans 336x in the biological control of wheat take-all

2014 ◽  
Vol 60 (8) ◽  
pp. 533-540 ◽  
Author(s):  
Miao Wang ◽  
Yuwan Xing ◽  
Junfang Wang ◽  
Yubin Xu ◽  
Gang Wang
Keyword(s):  
Biological Control ◽  
Endophytic Bacterium ◽  
Chitinase Activity ◽  
Gaeumannomyces Graminis ◽  
Partial Restoration ◽  
Biocontrol Efficacy ◽  
Serratia Proteamaculans ◽  
Take All

Take-all, a disease caused by the fungus Gaeumannomyces graminis var. tritici, is the most important root disease of wheat and causes severe yield losses worldwide. Using microorganisms as biological agents to control the disease is important because no resistant cultivars or effective chemical fungicides are available. In this study, we tested the biological control capability of a chitinase produced by the endophytic bacterium Serratia proteamaculans 336x against wheat take-all. The chitinase gene chi1 of S. proteamaculans 336x was cloned and heterologously expressed in Escherichia coli. The recombinant protein exhibited chitinase activity and in vitro antifungal activity against G. graminis var. tritici. With in-frame deletion of the chi1 gene by homologous recombination, the chi1-deleted mutant was devoid of chitinase activity and the biocontrol efficacy was reduced by 42.5%. The complementation of the Δchi1 mutant strain by the chi1 gene resulted in the partial restoration of the chitinase activity and biocontrol efficacy. These results support a role for the Chi1 protein in the biocontrol process of S. proteamaculans 336x against wheat take-all.

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