Genetic and phenotypic diversity of microsymbionts nodulating promiscuous soybeans from diferent agro-climatic conditions

Abstract

Background: Global food supply is highly dependent on feld crop production that is currently severely threatened by changing climate, poor soil quality, abiotic, and biotic stresses. For instance, one of the major challenges to sustainable crop production in most developing countries is limited nitrogen in the soil. Symbiotic nitrogen fxation of legumes such as soybean (Glycine max (L.) Merril) with rhizobia plays a crucial role in supplying nitrogen sufcient to maintain good crop productivity. Characterization of indigenous bradyrhizobia is a prerequisite in the selection and development of efective bioinoculants. In view of this, bradyrhizobia were isolated from soybean nodules in four agro-climatic zones of eastern Kenya (Embu Upper Midland Zone, Embu Lower Midland Zone, Tharaka Upper Midland Zone, and Tharaka Lower Midland Zone) using two soybean varieties (SB8 and SB126). The isolates were characterized using biochemical, morphological, and genotypic approaches. DNA fngerprinting was carried out using 16S rRNA gene and restricted by enzymes HaeIII, Msp1, and EcoRI.