Determine the Symbiotic nitrogen fixation bacterial community structure in legume crops

Abstract

The legume symbiosis with rhizobia (Root Nodulating Bacteria, BNLs) has been recognized as essential to sustainable agriculture since the intimate partnership has the ability to relieve host legumes from nitrogen fertilizer reliance and boost soil fertility. Legume–BNL interactions take place in the rhizosphere, where the two symbiotic partners exchange signals (such as flavonoids released by the host plant and Nod factors produced by the bacterium). Subsequently, the cortical cells in the roots divide, triggering an infection process that allows the bacteria to enter the nodule cells. Rhizobia fall into seven bacterial families (Rhizobiaceae, Bradyrhizobiaceae, Phyllobacteriaceae, Methylobacteriaceae, Brucellaceae, Hyphomicrobiaceae from α-Proteobacteria, and Burkholderiaceae from β-Proteobacteria). The first step in studying legume/BNL symbioses is to understand the methods for isolating and characterizing bacteria. Here, we provide a simple procedure for employing culture-dependent and culture-independent techniques for determining the bacterial community structure involved in the symbiotic nitrogen fixation in legume crops.