Introduction of theSerratia marcescens chiAgene into an endophyticPseudomonas fluorescensfor the biocontrol of phytopathogenic fungi

2000 ◽  
Vol 46 (4) ◽  
pp. 363-369 ◽  
Author(s):  
Katrina J Downing ◽  
Jennifer A Thomson
Keyword(s):  
Pseudomonas Fluorescens ◽  
Biocontrol Agent ◽  
Phytopathogenic Fungi ◽  
Phytopathogenic Fungus ◽  
Broad Host Range ◽  
Root Tips ◽  
Broad Host Range Plasmid ◽  
Gene Coding ◽  
Tac Promoter ◽  
Plant Growth Chamber

An endophytic strain of Pseudomonas fluorescens was isolated from micropropagated apple plantlets and introduced into beans (Phaseolus vulgaris) via their root tips. It was shown to be present as an endophyte in the roots at a level of 1.2 × 105CFU/g fresh weight. The gene coding for the major chitinase of Serratia marcescens, chiA, was cloned under the control of the tac promoter into the broad-host-range plasmid pKT240 and the integration vector pJFF350. Pseudomonas fluorescens carrying tacchiA either on the plasmid or integrated into the chromosome is an effective biocontrol agent of the phytopathogenic fungus Rhizoctonia solani on bean seedlings under plant growth chamber conditions.Key words: endophyte, biological control, chitinase.

scholarly journals Role of Chemotaxis Toward Fusaric Acid in Colonization of Hyphae of Fusarium oxysporum f. sp. radicis-lycopersici by Pseudomonas fluorescens WCS365

2004 ◽  
Vol 17 (11) ◽  
pp. 1185-1191 ◽  
Author(s):  
Sandra de Weert ◽  
Irene Kuiper ◽  
Ellen L. Lagendijk ◽  
Gerda E. M. Lamers ◽  
Ben J. J. Lugtenberg
Keyword(s):  
Fusarium Oxysporum ◽  
Pseudomonas Fluorescens ◽  
Fusaric Acid ◽  
Chemotactic Response ◽  
Phytopathogenic Fungus ◽  
Root Tips ◽  
Tomato Root ◽  
Vitro Assay

Pseudomonas fluorescens WCS365 is an excellent competitive colonizer of tomato root tips after bacterization of seed or seedlings. The strain controls tomato foot and root rot (TFRR) caused by the phytopathogenic fungus Fusarium oxysporum f. sp. radicis-lycopersici. Under biocontrol conditions, fungal hyphae were shown to be colonized by WCS365 bacteria. Because chemotaxis is required for root colonization by WCS365 cells, we studied whether chemotaxis also is required for hyphae colonization. To that end, an in vitro assay was developed to study hyphae colonization by bacteria. The results indicated that cells of the cheA mutant FAJ2060 colonize hyphae less efficiently than cells of wild-type strain WCS365, when single strains were analyzed as well as when both strains were applied together. Cells of WCS365 show a chemotactic response toward the spent growth medium of F. oxysporum f. sp. radicis-lycopersici, but those of its cheA mutant, FAJ2060, did not. Fusaric acid, a secondary metabolite secreted by Fusarium strains, appeared to be an excellent chemo-attractant. Supernatant fluids of a number of Fusarium strains secreting different levels of fusaric acid were tested as chemo-attractants. A positive correlation was found between chemo-attractant activity and fusaric acid level. No chemotactic response was observed toward the low fusaric acid-producer FO242. Nevertheless, the hyphae of FO242 still were colonized by WCS365, suggesting that other metabolites also play a role in this process. The possible function of hyphae colonization for the bacterium is discussed.

Broad Host-Range Plasmid R1162: Replication, Incompatibility, and Copy-Number Control

1985 ◽  
pp. 173-188 ◽  
Author(s):  
Richard J. Meyer ◽  
Lung-Shen Lin ◽  
Kyunghoon Kim ◽  
Michael A. Brasch
Keyword(s):  
Host Range ◽  
Copy Number ◽  
Broad Host Range ◽  
Copy Number Control ◽  
Broad Host Range Plasmid

scholarly journals Promoters of the broad host range plasmid RK2: analysis of transcription (initiation) in five species of gram-negative bacteria.

Genetics ◽  
1992 ◽  
Vol 130 (1) ◽  
pp. 27-36 ◽  
Author(s):  
A Greener ◽  
S M Lehman ◽  
D R Helinski
Keyword(s):  
Host Range ◽  
Transcription Initiation ◽  
Promoter Activity ◽  
Firefly Luciferase ◽  
Broad Host Range ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Broad Host Range Plasmid ◽  
Transcriptional Start Sites ◽  
Plasmid Rk2

Abstract A broad host range cloning vector was constructed, suitable for monitoring promoter activity in diverse Gram-negative bacteria. This vector, derived from plasmid RSF1010, utilized the firefly luciferase gene as the reporter, since the assay for its bioluminescent product is sensitive, and measurements can be made without background from the host. Twelve DNA fragments with promoter activity were obtained from broad host range plasmid RK2 and inserted into the RSF1010 derived vector. The relative luciferase activities were determined for these fragments in five species of Gram-negative bacteria. In addition, four promoters were analyzed by primer extension to locate transcriptional start sites in each host. The results show that several of the promoters vary substantially in relative strengths or utilize different transcriptional start sites in different bacteria. Other promoters exhibited similar activities and identical start sites in the five hosts examined.

Sign in / Sign up

Export Citation Format

Share Document