Endophytic nitrogen fixation in dune grasses (Ammophila arenaria and Elymus mollis) from Oregon.

Several tropical grasses harbor symbiotic nitrogen-fixing bacteria within their stem and rhizome tissue that may contribute to the nitrogen nutrition of the host plant. We present evidence here that sand dune grasses (Ammophila arenaria and Elymus mollis) from Oregon also contain nitrogen-fixing bacteria. Surface-sterilized stem and rhizome tissue from these species possess acetylene reduction (nitrogen fixation) activity and large populations (10(5) to 10(6) cfu/g fresh weight) of bacteria.