Jan 11, 2011

Glossary

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Endophytes

Fungi or bacteria that live inside plants

Endophytes (from the Greek endo = inside, phyton = plant) can harm the host plant, but can also live in a mutually beneficial symbiotic relationship with the plant. The line between these two states is fluid. For instance, an endophyte can suddenly trigger a disease if the plant is weakened.

Plants colonised by endophytic fungi generally grow better, are more resistant to drought because they form a bigger root mass, or are better protected against insects and diseases.

Endophytic fungi often produce alkaloids, which protect the plant against chewing pests, but also make the plant unusable as fodder because they are very toxic to sheep, cows and horses (e.g. in tall fescue, a type of forage grass).

According to some definitions, root-colonising mycorrhizal fungi are also classed as endophytes. However, only some of them grow inside plants. Mycorrhizal fungi live in symbiosis with most terrestrial plants and also have a positive effect on plant growth and plant health.

Various species of endophytic bacteria can also be identified in plants. As well as bacterial pathogens, e.g. Agrobacterium tumefaciens, there are some endophytic bacteria that are beneficial to plants. For instance, some promote plant growth by binding nitrogen from the atmosphere and transferring it to the plant, and some stimulate growth by producing plant hormones. Trials in the USA succeeded in significantly increasing the growth of poplar trees for the production of biofuel by inoculating them with endophytic bacteria.