Abstract

Orchids are one of the most widespread plants inhabiting lands in almost all terrestrial ecosystems. Most plants from the Orchidaceae family depend on specific mycorrhizal fungi to germinate their tiny and dust-like seeds. There, mycorrhizal fungi provide the resources that the embryo needs to advance to further developmental stages. However, at seed germination and the plantlet stage orchids need other nutrients to sustain the plantlet development and completion of its life cycle. There, other soil-borne beneficial microorganisms, such as free-living and symbiotic bacteria, can associate with orchid roots establishing a special interaction that has scarcely been explored. Most of the beneficial root-associated bacteria can help plants solubilize essential nutrients such as phosphorous and nitrogen, as well as to produce diverse beneficial metabolites that can contribute to improving biomass production, stress tolerance, and biocontrol of potential phytopathogenic fungal species. This chapter will summarize the principal studies performed in orchid-associated bacteria and analyze their potential plant growth–promoting capabilities.