Structure and functions of the bacterial microbiota of plants
Bulgarelli, Davide Schlaeppi, Klaus Spaepen, Stijn Ver Loren van Themaat, Emiel Schulze-Lefert, Paul # ×
Annual Reviews Inc.
Annual Review of Plant Biology vol:64 pages:807-838
Plants host distinct bacterial communities on and inside various plant organs of which those associated with roots and the leaf surface are best characterized. Relatively few bacterial phyla define their phylogenetic composition, including Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. A synthesis of available data suggests a two-step selection process by which the bacterial microbiota of roots is formed from the surrounding soil biome. Rhizodeposition appears to fuel a first substrate-driven community shift in the rhizosphere and converges with host genotype-dependent fine-tuning of microbiota profiles in the selection of root endophyte assemblages. Substrate-driven selection also underlies the establishment of phyllosphere communities, but takes place solely at the immediate leaf surface. Both leaf and root microbiota contain bacteria providing indirect pathogen protection, but root microbiota members appear to serve additional host functions through the acquisition of nutrients from soil for plant growth. Thus, the plant microbiota emerges as fundamental trait that includes mutualistic interactions as exemplified by numerous long-studied plant growth and plant health promoting bacteria.