Application of biochemical studies to improving nitrogen fixation

Improvement of symbiotic nitrogen fixation requires a multidisciplinary app roach with a comprehensive program ranging from microbial ecology to plant breeding and genomics. Achievement of symbiotic nitrogen fixation requires at least 100 genes from each partner interacting in a favorable environment . The more information that we obtain from applied and fundamental studies of Rhizobium-legume and Frankia-non-legume symbioses, the greater are our c hances to extend nitrogen fixation to non-fixing species. Studies with alfa lfa (Medicago sativa L.) aimed at improving symbiotic nitrogen fixation hav e resulted in significant advances in germplasm development, plant biochemi stry, microbial ecology and the understanding of plant genes involved in no dule nitrogen and carbon metabolism. However, translation to field improvem ent of symbiotic nitrogen fixation has proven elusive.