Bacterial Community Composition and Activity in Rhizosphere of Roots Colonized by Arbuscular Mycorrhizal Fungi

摘要: Rhizosphere microbial communities can be regarded as a subset of the soil community. As root tip grows through soil, microorganisms in its pathway will first colonisers. During rapid growth, zone elongation immediately behind tips is only sparsely colonised by microorganisms. Thereafter, population densities increase rapidly tips, where high concentrations soluble, insoluble and volatile exudates utilised for growth metabolism. In contrast, along older parts, compounds present rhizosphere are dominated cellulose other recalcitrant cell wall materials from sloughed cortex tissues. Here density often lower than younger regions closer to rot tip. The species composition differs that bulk (Foster 1986; Marilley Aragno 1999). This clear indication plants have strong influence on populations their roots. Indeed, many cases different plant growing same distinct (Ibekwe Kennedy 1998) may even very similar community soils (Grayston et al. 1998; Miethling 2000). Plant roots release 1–25% net photosynthesis soluble into (Merbach Among ecologists there currently consensus differences exudate amount likely affect because differ ability metabolise compete carbon sources. Therefore, competitiveness hence survival species. A wide range factors