Endophytic

An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; however, most of the endophyte/plant relationships are not well understood. Some endophytes may enhance host growth, nutrient acquisition and improve the plant's ability to tolerate abiotic stresses, such as drought, and decrease biotic stresses by enhancing plant resistance to insects, pathogens and herbivores.

Endophytes were first described by the German botanist Heinrich Friedrich link in 1809. They were thought to be plant parasitic fungi and they were later termed as "microzymas" by the French scientist Béchamp. There was a belief that plants were healthy under sterile conditions and it was not until 1887 when Victor Galippe discovered bacteria normally occurring in the inside of plant tissues.

Endophytes may be transmitted either vertically (directly from parent to offspring) or horizontally (among individuals). Vertically transmitted fungal endophytes are typically considered clonal and transmit via fungal hyphae penetrating the embryo within the host’s seeds, while reproduction of the fungi through asexual conidia or sexual spores leads to horizontal transmission, where endophytes may spread between plants in a population or community.

Most endophyte-plant relationships are still not well understood. Endophytes and plants often engage in mutualism, with endophytes primarily aiding in the health and survival of the host plant with issues such as pathogens and disease, water stress, heat stress, nutrient availability and poor soil quality, salinity, and herbivory. In exchange the endophyte receives carbon for energy from the plant host. Plant-microbe interactions are not strictly mutualistic, endophytic fungi can potentially become pathogens or saprotrophs. Endophytes may become active and reproduce under specific environmental conditions or when their host plants are stressed or begin to senesce, thereby limiting the amount of carbon provided to the endophyte.

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