Soil conditions are seldom ideal. When the situation in the soil shifts from sanguine to stressful, plants make the logical move: they ask for help.
Plants under abiotic duress enhance their ability to deal with the dilemma by recruiting endophytes to assist with the necessities of living. In return, plants offer the comforts of home to those microbes they take in. An endophyte is a plant endosymbiont – most commonly a bacterium or fungus – in a mutual or commensal relationship.
95% of plants get fed with help from friendly molds. Fungi attach to plant roots and then shoot out fibrous filaments, infiltrating bacterial corpses. Then fungi feast on the succulent cellular matter. Spillover provides plants with nutrients such as nitrogen and phosphorus.
The bacteria that live in stems and branches provide nutrients to their host plants, including nitrogen fixation, in return for a high-rise home and free meals.
Not only do endophytes sup with their vegetative friends, they often provide protection. Extensive colonization of plant tissue by endophytes creates a barrier against invasion. Endophytes outcompete their rivals, preventing pathogenic organisms from taking hold by producing chemicals which inhibit the growth of the competition.
Fungi actively shield plants from various diseases, bacteria, insects, and roundworms. They can also promote production of alkaloids that deter herbivores.
Some endophytes are host-specific, but many colonize numerous plant species. Likewise, a single plant sports many endophyte species, both fungal and bacteria.
A plant’s microbiome can even vary among different plant parts. One branch on a plant may have a substantially different microbial community than another.