Identification of nif genes of heterotrophic and endophytic diazotrophs associated with rice (Oryza sativa L.,) by targeted DNA finger printing

Abstract

Heterotrophic and endophytic diazotrophs were isolated from rhizosphere soil, rhizoplane, roots and stems of different rice varieties. A total of thirteen isolates obtained were subjected to acetylene reduction assay (ARA) and eight isolates recorded significant amount of nitrogenase activity in a range
of 31.65 to 91.95 nmoles of ethylene mg-1 cells h-1 . Targeted PCR fingerprinting using nif H primers generated specific DNA band of approximately 750 bp, confirming the presence of nif genes in these
isolates. Two isolates of heterotrophic diazotrophs, HDM 7 and HDT 1, generated multiple bands ranging from 500 – 1000 bp.