Endophytic fungi live asymptomatically and intercellularly within plant tissues.
They have been found in all plant species studied, and they are belived to be as common as root inhabiting mycorrhical fungi. Endophytes were recognized for the first time in New Zealand and USA in the end of 1940's when livestock grazing on some pastures suffered from serious, unexplained symptoms. Thereafter, toxic compounds produced by endophytes were found from the grasses on these pastures. Recently number of studies have reported that, in addition to increasing plant resistance to herbivores, endophytes may also enhance plant competitive abilities, germination success, resistance to drought and water stress. Thus, endophytic fungi and their hosts appear to be quintessential mutualists although the endophyte-plant studies have mainly focused on few cultivars of economically important pasture and turf grasses.