Microorganisms in the rhizosphere of wheat colonized by the fungusGaeumannomyces graminis var.tritici

Abstract

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.

Agrobacterium tumefaciens fitness genes involved in the colonization of plant tumors and roots

“…Agrobacterium populations are common although not abundant within the root microbiota of hosts and nonhosts (Bednářová et al ., 1979; Bouzar et al ., 1993; Gomes et al ., 2001; Krimi et al ., 2002; Vogel et al ., 2003; Sanguin et al ., 2006). Some of the cell surface components and regulatory pathways that promote attachment and biofilm formation of A. tumefaciens on roots and inanimate surfaces have been characterized extensively (Heindl et al ., 2014; Matthysse, 2018; Thompson et al ., 2018; Onyeziri et al ., 2021).…”