Plants as the Extended Phenotype of Endophytes—The Actual Source of Bioactive Compounds

Abstract

For thousands of years, plants have been used for their medicinal properties. The industrial production of plant-beneficial compounds is facing many drawbacks, such as seasonal dependence and troublesome extraction and purification processes, which have led to many species being on the edge of extinction. As the demand for compounds applicable to, e.g., cancer treatment, is still growing, there is a need to develop sustainable production processes. The industrial potential of the endophytic microorganisms residing within plant tissues is undeniable, as they are often able to produce, in vitro, similar to or even the same compounds as their hosts. The peculiar conditions of the endophytic lifestyle raise questions about the molecular background of the biosynthesis of these bioactive compounds in planta, and the actual producer, whether it is the plant itself or its residents. Extending this knowledge is crucial to overcoming the current limitations in the implementation of endophytes for larger-scale production. In this review, we focus on the possible routes of the synthesis of host-specific compounds in planta by their endophytes.

Antimicrobial Action Mechanisms of Natural Compounds Isolated from Endophytic Microorganisms

“…Five prenylated benzaldehyde derivative compounds (dihydroauroglaucin ( 16), tetrahydroauroglaucin (17) (18), isotetrahydroauroglaucin (19), and flavoglaucin ( 20)) have been isolated for the first time from Aspergillus amstelodami (MK215708), an endophyte of Ammi majus L. Among these compounds, 16 showed high activities against Escherichia coli, Streptococcus mutans, and Staphylococcus aureus, with MICs of 1.95 µg/mL, 1.95 µg/mL, and 3.9 µg/mL, respectively. Additionally, 16 showed potent antibiofilm activity, with a minimum biofilm inhibitory concentration (MBIC) of 7.81 µg/mL against S. aureus and E. coli biofilms.…”

“…They constitute the plant endosphere (which includes the endorhizosphere and endophyllosphere) and are an integral part of the plant microbiome along with the phyllosphere and rhizosphere. These microorganisms, including fungi, bacteria, and archaea [ 17 ], have long since attracted the attention of biologists and pharmacologists because of their diverse bioactivities and potential pharmacological applications [ 18 , 19 , 20 ]. Many natural compounds obtained from endophytes exhibit robust antimicrobial and anticancer properties [ 21 ].…”

In vitro screening of fungal endophytes from sandalwood (Santalum album) as antagonists to phytopathogens

“…Endophytic microbes can produce rare and important bioactive compounds like their host plants. In that case, endophytes can reduce their dependence on raw material sources from their host plants, thereby preserving the existing biodiversity (Alam et al 2021;Rutkowska et al 2023). In addition, using microbes as a source of efficacious secondary metabolite products can be carried out in an easier and more economical process to produce products at more competitive prices (Chitnis et al 2020).…”

Diversity of endophytic bacteria in different tissues of sengon (Falcataria moluccana)

“…Each higher plant may contain several endophytic microorganisms capable of producing biological compounds or secondary metabolites, which are thought to be the result of co-evolution or genetic transfer of the host plant into the endophytic microorganisms (Rutkowska et al 2023). Secondary metabolites produced by endophytic microorganisms can stimulate plant growth or repel plant pathogens.…”