Tiny strands of fungi weave through the roots of an estimated nine out of 10 plants on Earth, an underground symbiosis in which the plant gives the fungus pre-made sugars and the fungus sends the plant basic nutrients in return. Scientists are interested in enhancing this mechanism as a way to help plants grow on nutrient-poor lands. Their success could lead to increased production of plant-based biofuels without having to compete with food crops for fertile farmland.