The Plant Microbiome

How do we define the ‘plant microbiome’ and what is its significance to the plant genome? Before addressing what the microbiome is in relation to plants, it is important to first understand the concept of the microbiome; what this means in relation to the host becomes an extension of this working concept. Conceptualizing the microbiome requires a fusion of microbial ecology and bioinformatics, integrated with an understanding of both host biology and ecology. The analysis of microbiome structure and function was pioneered in studies of human hosts and has become widely recognized as essential to understanding genetic and functional capacity otherwise attributed to the host, including important aspects of metabolism and physiology. Plants are teeming with microbial organisms, including those that colonize internal tissues, in addition to those that adhere to external surfaces. Combined with the vast diversity of microorganisms in the soil rhizosphere, these plant–soil-associated microbes comprise the plant microbiome. The microbiome is intricately involved in plant health and serves as a reservoir of additional genes that plants can access when needed. Understanding the regulation of plant trait expression, hence plant performance and how this in turn impacts ecosystem function, requires that we study the impacts of the plant microbiome. Herein, the importance of the plant microbiome to plant