ABSTRACT
Traditional approaches used to confront abiotic stresses such as inadequate water and fertility include supplementary irrigation and soil mineral additives. The exploitation of a mutualistic symbiosis between fungal endophytes and certain turfgrass species offers a new approach in reducing damage which results from abiotic stress. The differential growth response of endophyte-infected grasses to nitrogen fertilization, as well as the abundance of nitrogen-rich intermediates arising from fungal metabolism, suggests that basic nitrogen metabolism in the host plant is altered by this symbiosis. Nitrogen nutrition also plays a role in seedling growth of endophyte-infected tall fescue and perennial ryegrass. Infected seedlings were less vigorous than endophyte-free seedlings at low nitrogen levels, but more vigorous when nitrogen was in excess. The regulation of water loss in endophyte-infected grasses by leaf rolling has been reported in several studies comparing cloned genotypes of tall fescue.
