Functional Importance of the Plant Endophytic Microbiome: Implications for Agriculture, Forestry, and Bioenergy

Abstract

Just as the human microbiome is important for our health [1], so too the plant microbiome is necessary for plant health, but perhaps more so. Since plants cannot move, they face more challenges in acquiring sufficient nutrients from a given site, defending against herbivores and pathogens, and tolerating abiotic stresses including drought, salinity, and pollutants. The plant microbiome may help plants overcome these challenges. Since genetic adaptation is relatively slow in plants, there is a distinct advantage to acquiring an effective microbiome able to more rapidly adapt to a changing environment. Although rhizospheric microorganisms have been extensively studied for decades, the more intimate associations of plants with endophytes, the microorganisms living fully within plants, have been only recently studied. It is now clear, though, that the plant microbiome can have profound impacts on plant growth and health. Comprising an ecosystem within plants, endophytes are involved in nutrient acquisition and cycling, interacting with each other in complex ways. The specific members of the microbiome can vary depending on the environment, plant genotype, and abiotic or biotic stresses [2–6]. The microbiome is so integral to plant survival that the microorganisms within plants can explain as much or more of the phenotypic variation as the plant genotype [7]. In plant biology research, an individual plant should thus be viewed as a whole, the plant along with intimately associated microbiota (a “holobiont”), with the microbiome playing a fundamental role in the adaptation of the plant to environmental challenges [8–10].