The Hidden World within Plants: Ecological and Evolutionary Considerations for Defining Functioning of Microbial Endophytes

Abstract

SUMMARY All plants are inhabited internally by diverse microbial communities comprising bacterial, archaeal, fungal, and protistic taxa. These microorganisms showing endophytic lifestyles play crucial roles in plant development, growth, fitness, and diversification. The increasing awareness of and information on endophytes provide insight into the complexity of the plant microbiome. The nature of plant-endophyte interactions ranges from mutualism to pathogenicity. This depends on a set of abiotic and biotic factors, including the genotypes of plants and microbes, environmental conditions, and the dynamic network of interactions within the plant biome. In this review, we address the concept of endophytism, considering the latest insights into evolution, plant ecosystem functioning, and multipartite interactions.

Assembly of seed-associated microbial communities within and across successive plant generations

“…Although the contributions of seed-associated microorganisms to the composition of the plant microbiota is mostly unknown, there are observations of seedassociated microorganisms that are conserved across multiple plant generations (Johnston-Monje and Raizada 2011; Hardoim et al 2015). These observations suggest that some members of the plant microbiota are vertically transmitted.…”

Editorial special issue: soil, plants and endophytes

“…Despite the inception of the endophyte research dates back to the nineteenth century, studies on this topic have only recently bloomed, producing a fast-growing body of literature (Compant et al 2012;Hardoim et al 2015;Saikkonen et al 2016). Several definitions of endophyte have been furthermore proposed; while some have been criticized, others have been suggested to better define this particular lifestyle.…”

“…Several definitions of endophyte have been furthermore proposed; while some have been criticized, others have been suggested to better define this particular lifestyle. We currently describe endophytes as any microbe that can be isolated from asymptomatic plant tissue (Chanway 1995;Wilson 1995;Hardoim et al 2015). This definition includes neutral, commensal and/or beneficial microorganisms as well as dormant saprobes and pathogens during their latent phase of their life cycle.…”

“…This definition includes neutral, commensal and/or beneficial microorganisms as well as dormant saprobes and pathogens during their latent phase of their life cycle. These microorganisms engage an intimate association within their host plants, establishing a microbial community in the plant endosphere and could be found in various plant parts (Hardoim et al 2015).…”

Promoting fruit seedling growth by encapsulated microorganisms

“…This can occur when the microorganisms used present some incompatibility with the native microbiota associated with the plant rhizosphere, which will generate competition between them, altering the positive effects of the target microorganism and, consequently, an unsuitable development of seedlings. Another possible result is due to variable root colonization due to inoculum survival problems or to unfavorable conditions for microorganisms, since the rhizosphere colonization depends on a set of abiotic and biotic factors, including plant genotypes and microorganisms, environmental conditions and the dynamic network of plant interactions (HARDOIM et al, 2015). However, for C. cainito (caimito) and L. chinensis (lychee) species, the opposite occurred, that is, larger stem diameter was observed in both species when seedlings were inoculated with microorganisms (Table 3).…”