A team of molecular biologists led by Dong Wang at UMass Amherst, working with the alfalfa-clover Medicago truncatula, has found how a gene in the host plant encodes a protein that recognizes the cell membrane surrounding the symbiotic bacteria, then directs other proteins to harvest the nutrients. Details appear online in the January edition of Nature Plants. As Wang explains, plants often recruit microbes to help them satisfy their nutritional needs, offering the products of photosynthesis as a reward. A process used by most land plants depends on asymbiotic relationship with mycorrhizal fungi. These form structures known as arbuscules that help plants capture phosphorus, sulfur, nitrogen and other micronutrients from the soil. This method is akin to scavenging, Wang says, because the amount of nitrogen available in soil is quite limited. Read more.