Identification of <i>nif</i> genes of heterotrophic and endophytic diazotrophs associated with rice (<i>Oryza sativa</i> 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.