Nodule-Specific Induction of Host Genes in Yellow Lupin

There is a substantial progress in our knowledge about genetic contribution of host plant to the process of symbiotic association between legume plants and Rhizobium species. This progress has been initiated recently by an elegant series of papers published by D.P.S. Verma concerning identification and synthesis in vitro of about 20 nodule-specific soybean polypeptides (nodulins).1,2 These studies revealed that soybean nodulins account for 7–11% of the total nodule proteins and that they represent a class of 12–20kd polypeptides. The most abundant nodule-specific protein is leghaemoglobin. The organization of leghaemoglobin genes in soybean has been proposed recently.3,4,5