Genome wide comparative analyzes of ORS3257 and LCM3682, two Bradyrhizobium strains that form efficient symbiosis with cowpea and are representing dominant genotypes found in Senegal.

A phylogeogrpahic study on Cowpea Bradyrhizobium diversity in Senegal revealed that two dominant Internal Transcribed Spacer sequences (ITS) genotypes could be identified. One, (ITS I) was in great majority found in cowpea nodules recovered from the center and South in areas were rainfall levels was moderate to high (400-1000 mm / year) while another dominant genotype (ITS VI) was recovered from the Northern Senegalese river valley where rainfall levels are low (< 300mm / year). Two strains, ORS3257 and LCM3682 representing ITS Types I and VI respectively, presented contrasted growth responses upon PEG8000 or NaCl induced hyper-osmotic stresses were selected for genome wide comparative analyzes.