The Flavobacterium Genus in the Plant Holobiont: Ecological, Physiological, and Applicative Insights

Members of the Flavobacterium genus are widely distributed in nature where they are often associated with the capacity to degrade complex organic compounds. A myriad of recent studies indicate that the class Flavobacteria, and specifically the genus Flavobacterium, represent a significant fraction of root- and leaf-associated microbiomes in a broad range of plant species. Several of these studies have shown that the relative abundance of members of this genus increases substantially along the soil, rhizosphere, and rhizoplane continuum, indicating a specialized capacity to proliferate in plant environments and suggesting a role in plant functioning. Unlike other plant-associated genera such as Pseudomonas and Bacillus that have been exhaustively documented, little is known about the ecology of Flavobacteriumstrains in plant environments. This chapter summarizes current knowledge of Flavobacteriumstrains in plant habitats. It explores their abundance and diversity in the rhizosphere and the phyllosphere of a large range of plant species, elucidates the potential role of unique flavobacterial gliding-motility and gliding-secretion mechanisms in plant-Flavobacterium interactions, and explores the potential role of Flavobacteriumstrains in plant growth and protection.