New York: A study into the significance of the plant microbiomes has found the first direct evidence that nitrogen fixation can occur in the branches of trees with no root nodule required. The study has significant implications for common agricultural crop plants as there is a strongly held belief that only plants with root nodules can benefit from the symbiotic relationship with the nitrogen-fixing bacteria. Led by plant microbiologist Sharon Doty from University of Washington, the team demonstrated that poplar trees growing in rocky, inhospitable terrain contain bacteria within them that could provide valuable nutrients to help the plant grow. The researchers found that microbial communities are highly diverse, varying dramatically even in cuttings next to each other. "This variability made it especially difficult to quantify the activity but is the key to the biology since it is probably only specific groupings of microorganisms that are working together to provide this nutrient to the host," said Doty. The microbes the team isolated from wild poplar and willow plants have helped corn, tomatoes and peppers, as well as turf grasses and forest trees to grow with less fertiliser. "Having access to the key microbial strains that help wild plants thrive on just rocks and sand will be crucial for moving agriculture, bioenergy and forestry away from a dependence on chemical fertilizers and towards a more natural way of boosting plant productivity," Doty noted in a paper published in the journal PLOS ONE. Nitrogen fixation is a natural process that is essential to sustain all forms of life. In naturally occurring low-nutrient environments such as rocky, barren terrain, plants associate with nitrogen-fixing bacteria to acquire this essential nutrient.