The population of microorganisms in wheat rhizosphere changed in the presence of the fungus Gaeumannomyces graminis var. tritici causing the take-all of wheat. In the majority of cases when the soil was artificially contaminated by the fungus, both the number of bacteria in the rhizosphere and the bacteria/fungi ratio temporarily increased. At the beginning bacteria growing in the presence of NH4+ predominated, later bacteria utilizing organic N-substances prevailed. Pseudomonas fluorescens and the related species colonized the rhizosphere and the soil to a greater extent in the presence of G. graminis. The wheat rhizosphere with G. graminis was found to contain a higher level of the slime-producing bacterium Agrobacterium spp.; this microorganism occurred on hyphal surfaces (in hyphosphere) of both G. graminis growing in soil and Mucor spp. Changes in microbial populations in the wheat rhizosphere during the first stage of colonization by G. graminis can be partly explained by a simultaneous rhizosphere colonization by microorganisms which accompany this fungus in soil. In the period of increase in the number of bacteria in rhizosphere a temporary stimulation of wheat growth was observed.

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Microb Ecol. 1975 Sep;2(3):177-85 PubMed

Folia Microbiol (Praha). 1970;15(6):468-78 PubMed

Control of microorganisms in the rhizosphere of wheat by inoculation of seeds with Pseudomonas putida and by foliar application of urea

Fluorescent pseudomonads in the rhizosphere of plants and their relation to root exudates

Effect of bacterial polysaccharides on the growth of Gaeumannomyces graminis var. tritici and wheat roots