Biological nitrogen fixation and nifH gene expression in dry beans (Phaseolus vulgaris L.)

Abstract

Akter, Z., Pageni, B. B., Lupwayi, N. Z. and Balasubramanian, P. M. 2014. Biological nitrogen fixation andnifH gene expression in dry beans (Phaseolus vulgarisL.). Can. J. Plant Sci. 94: 203-212. Dry bean (Phaseolus vulgaris L.) is one of the least efficient nitrogen (N2) fixers among legumes (approximately 30 to 50 kg N ha-1). To identify efficient N2 fixers, 22 dry bean genotypes were screened for symbiotic N2-fixation in potted low-N soil in the greenhouse under four treatments: (1) uninoculated, (2) inoculated with commercial Rhizobium leguminosarum bv. phaseoli inoculant Nitrastik-D®, (3) inoculated with commercial Rhizobium inoculant Nodulator®, and (4) fertilizer N added. Expression of nitrogenase reductase (nifH) gene in selected uninoculated genotypes (nodulated by indigenous rhizobia) was quantified by reverse transcription polymerase chain reaction (RT-PCR) to know if expression of this gene was an indicator of N2-fixation. Nitrogen fixation potential varied among the genotypes and between the ...