Wars between microbes on roots and fruits.

Microbes in nature often live in unfavorable conditions. To survive, they have to occupy niches close to food sources and efficiently utilize nutrients that are often present in very low concentrations. Moreover, they have to possess an arsenal of attack and defense mechanisms against competing bacteria.

Genome Analysis of Pseudomonas fluorescens PCL1751: A Rhizobacterium that Controls Root Diseases and Alleviates Salt Stress for Its Plant Host.

Pseudomonas fluorescens PCL1751 is a rod-shaped Gram-negative bacterium isolated from the rhizosphere of a greenhouse-grown tomato plant in Uzbekistan. It controls several plant root diseases caused by Fusarium fungi through the mechanism of competition for nutrients and niches (CNN). This mechanism does not rely on the production of antibiotics, so it avoids the concerns of resistance development and is environmentally safe.

Is L-arabinose important for the endophytic lifestyle of Pseudomonas spp.?

Twenty endophytic bacteria were isolated from surface-sterilized stems and roots of cucumber plants. After removal of potential siblings and human pathogens, the remaining seven strains were identified based on their 16S rDNA as Pseudomonas fluorescens (2 strains) and P. putida (5 strains).

Characterization of Bacillus subtilis HC8, a novel plant-beneficial endophytic strain from giant hogweed.

Thirty endophytic bacteria were isolated from various plant species growing near Saint-Petersburg, Russia. Based on a screening for various traits, including plant-beneficial properties and DNA fragment patterns, potential siblings were removed. The remaining isolates were taxonomically identified using 16S rDNA sequences and potential human and plant pathogens were removed.

Monitoring of pathogenic and non-pathogenic Fusarium oxysporum strains during tomato plant infection.

Monitoring of pathogenic strains of Fusarium oxysporum (Fox), which cause wilt and rots on agricultural and ornamental plants, is important for predicting disease outbreaks. Since both pathogenic and non-pathogenic strains of Fox are ubiquitous and are able to colonize plant roots, detection of Fox DNA in plant material is not the ultimate proof of an ongoing infection which would cause damage to the plant. We followed the colonization of tomato plants by strains Fox f.

Plant-growth-promoting rhizobacteria.

Several microbes promote plant growth, and many microbial products that stimulate plant growth have been marketed. In this review we restrict ourselves to bacteria that are derived from and exert this effect on the root. Such bacteria are generally designated as PGPR (plant-growth-promoting rhizobacteria).

Biocontrol strain Pseudomonas fluorescens WCS365 inhibits germination of Fusarium oxysporum spores in tomato root exudate as well as subsequent formation of new spores.

Fusarium oxysporum f.sp.radicis-licopersici (Forl) is a soilborne pathogenic fungus which can cause tomato foot and root rot (TFRR).

High incidence of plant growth-stimulating bacteria associated with the rhizosphere of wheat grown on salinated soil in Uzbekistan.

Soil salinization is increasing steadily in many parts of the world and causes major problems for plant productivity. Under these stress conditions, root-associated beneficial bacteria can help improve plant growth and nutrition. In this study, salt-tolerant bacteria from the rhizosphere of Uzbek wheat with potentially beneficial traits were isolated and characterized.

Collimonas fungivorans, an unpredicted in vitro but efficient in vivo biocontrol agent for the suppression of tomato foot and root rot.

Although bacteria from the genus Collimonas have demonstrated in vitro antifungal activity against many different fungi, they appeared inactive against the plant-pathogenic fungus Fusarium oxysporum f.sp. radicis-lycopersici (Forl), the causal agent of tomato foot and root rot (TFRR).

Effects of the tomato pathogen Fusarium oxysporum f. sp. radicis-lycopersici and of the biocontrol bacterium Pseudomonas fluorescens WCS365 on the composition of organic acids and sugars in tomato root exudate.

The effects of the pathogenic fungus Fusarium oxysporum f. sp. radicis-lycopersici and of the bacterial biocontrol strain Pseudomonas fluorescens WCS365, and of both microbes, on the amounts and composition of root exudate components of tomato plants grown in a gnotobiotic stonewool substrate system were studied.

Organic acids, sugars, and L-tryptophane in exudates of vegetables growing on stonewool and their effects on activities of rhizosphere bacteria.

The influence of stonewool substrate on the exudation of the major soluble carbon nutrients and of the auxin precursor tryptophane for Pseudomonas biocontrol agents was studied. To this end, the composition of the organic acids and sugars, as well that of tryptophane, of axenically collected exudates of seed, seedlings, and roots of tomato, cucumber, and sweet pepper was determined. The major results were as follows.

Enrichment for enhanced competitive plant root tip colonizers selects for a new class of biocontrol bacteria.

Our group studies tomato foot and root rot, a plant disease caused by the fungus Forl (Fusarium oxysporum f.sp. radicis-lycopersici ).