A microrganism (fungus or bacteria) that lives inside
vascular tissues of plants (in spaces between plant cells). At least one company has incorporated the gene for a protein toxic to insects (taken from Bacillus thuringiensis) into an endophyte to confer insect resistance to a crop plant.
During 2002, Regina Redman and Russell Rodriguez discovered that certain fungi (which live inside a grass that grows in hot soils adjacent to magma-heated geysers) impart heat tolerance to the grass they live in. Redman, Rodriguez, and Joan Henson were later able to show that when these fungi were inserted into tomato and watermelon seedlings, those plants/roots were able to withstand far higher temperatures than before.