Plant Endophytes

Abstract

Endophytes are defined as microorganisms colonising the interior of plants without causing disease. They comprise mainly fungi and bacteria, and their lifestyle range from merely receiving shelter and nutrients from the host to interactions benefitting both themselves and the host plant. In recent years, there has been an increased interest in understanding the communities of organisms inside plants; how they influence the host and how they can be utilised to benefit plants and humans. Therefore, the transmission and recruitment of endophytes, as well as methods to study the composition of endophytic communities, are important issues for successful exploitation. Beneficial effects include protection against biotic stress caused by pests and pathogens as well as against abiotic stress, for instance, drought, salinity and temperature. Furthermore, endophytes can promote growth by production of plant hormones and nutrient acquisition and some endophytes can be used for bioremediation and production of pharmaceuticals and nutraceuticals. Key Concepts Endophytes are organisms living inside plants without causing disease. Most endophytes are commensalistic, but some are mutualistic. Most endophytes are bacteria and fungi. Endophyte communities can be studied by culture‐dependent and culture‐independent methods. Recruitment of endophytes can be from environment or from mother plants. Endophytes can protect plants from biotic and abiotic stress. Endophytes can help in nutrient acquisition for the plant and cause growth promotion. Endophytes can help in bioremediation and participate in the production of specialised metabolites with industrial application.

A 2-kb Mycovirus Converts a Pathogenic Fungus into a Beneficial Endophyte for Brassica Protection and Yield Enhancement

“…Endophytic fungi typically live inside plants without harming them; many appear to promote plant growth and enhance plant resistance to biotic and abiotic stresses (Hiruma et al, 2016;Jørgensen et al, 2020). Endophytes are extremely common and diverse in nature, but the origin of endophytic fungi is largely unclear.…”

Biological control of plant diseases – What has been achieved and what is the direction?

“…Most successful BCAs are effective competitors in the harsh biotic environment of soil and in the plant holobiome (the combination of the plant and its associated microbiome), as they have evolved mechanisms for tolerating toxins from other organisms and are adapted to stressed conditions in those environments, which include growth on roots, stems, leaves and flowers and in wounded tissue. Endophytes, defined as microorganisms colonizing the interior of plants (the endosphere) without causing disease (Jørgensen et al, 2020; Figure 3), are adapted to the ecological niche of the endosphere and are also partly protected from the external environment (and colonize the same niche as pathogens). Therefore, it is suggested that endophytes have the potential to be more consistent as BCAs than purely epiphytic organisms, especially those in the phyllosphere.…”

“…Many of the organisms identified occur naturally in several of these niches. In essence, there is a continuum from soil to rhizosphere (root surface) to endosphere (inside the plant) and phyllosphere (above‐ground plant surface) (Jørgensen et al, 2020).…”

“…Nevertheless, most endophytes will be specialized to some extent to survive inside a plant and would be predicted to compete poorly with microbes outside the plant endosphere. Despite this, there is a continuum in lifestyle, and the same organism may behave as an endophyte, epiphyte or pathogen under different environmental conditions (Jørgensen et al, 2020). Of course, this must be considered in the selection of potential BCAs to prevent accidental selection of plant pathogens.…”

Bioengineering of fungal endophytes through the CRISPR/Cas9 system

“…Fungal endophytes are fungal species living within plant tissues that have no harmful effect on the plant but are useful to the host for a number of reasons ( Collinge et al, 2019 ; Jørgensen et al, 2020 ). They are abundant within the intercellular spaces of the roots, stems, and leaves of plants.…”