b'This maize sports extensive networks of aerial roots that secrete aCorn stalk with aerial roots. Photo provided by Jean-Michel Anrich mucilageand in that carbohydrate-rich medium are many species of bacteria with the ability to fix nitrogen. Photo provided by Jean-Michel Anto oversell. We need good science and good data to back up ourberries, wheat and rice and barley in California and Europe. Doty claims. So, everyone must be patient. Whatever we provide tonotes that these bacteria can be delivered to the seed at planting growers must be reliable.through a bead that contains a bacterial culture, entering the And as de Leon explains, aerial root production only occursplant through natural cracks in lateral roots. They can also be when the plant is large enough.sprayed on leaves and enter a crop plant through the stomata.We can get the plant quickly to that stage with fertilizer orThe plants recognize that they are part of the plant microbi-we can do that in another way, he says. ome and let them in, Doty explains. Our data shows that N fixa-An says that along with nitrogen-fixing plants, theyre alsotion is amplified in microbial communities, and so it will need to going to nitrogen-fixing soil bacteria if they are going to signifi-cantly reduce the need for nitrogen fertilizer. These bacteria are similar to those found in the root nodules of legumes.Its been very difficult to break the dogma that Its not just a plant or microbe solution, he says. As we pro- nitrogen fixation only happens in legume root gress through pre-breeding, the development of N-fixing bacte-ria products are making steady progress. Pivot Bio in California,nodules. Sharon Dotyfor example, sells genetically modified [legume-nodule sourced] bacteria as a seed coating that converts a significant amount of soil and air nitrogen to a plant-available form for crop absorption,be communities that are added to plants. We are also seeing that reducing the need for fertilizer.these endophytic bacteria make plants more resilient to drought Pivot Bio has worked with 22 universities to independentlystress, with their survival in some cases depending on the pres-evaluate its products, which in 2023 were applied to corn andence of these endophytes. Its a very exciting time, as these small grain seeds planted on about five million acres in the U.S.microbes are stable, long-lasting and cheaper than N fertilizers and do not have the emissions and leaching issues. Harnessing Endophyte Bacteria At the same time, systemic endophyte bacteria are being testedEditors note:for benefits to crop plants by California-based IntrinsyxBio,The pursuit of naturally nitrogen-fixing crops represents a prom-based on the work of Sharon Doty of University of Washington.ising frontier in our industry that holds the potential to reduce Doty follows in the footsteps of Johanna Dobereiner, who diddependency on synthetic fertilizers. By harnessing the natural pioneering work in Brazil in the 1990s showing that symbioticsymbiotic relationships between plants and bacteria, scientists bacteria fix nitrogen within the sugarcane plant. are paving the way for more sustainable practices. The innova-Its been very difficult to break the dogma that nitrogen fixa- tive work led by Jean-Michel An and his colleagues offers hope tion only happens in legume root nodules, Doty says. Ive beenfor improving crop resilience and yield, particularly in regions working on this since 2001. I first proved that black cottonwoodwhere access to fertilizers is limited. As this research progresses, can grow on nothing but rock and sand, through symbioticit will be crucial to maintain a balanced perspective, ensuring nitrogen-fixing bacteria. There are lots of symbiotic bacteria thatthat scientific advancements are met with careful evaluation and fix nitrogen in plants and trees, in grasses and monocots andpublic acceptance. With continued investment in research and conifers, which are all groups that diverged millions of years ago.technology, the dream of widespread nitrogen-fixing crops could This is an ancient relationship.become a reality.SWIntrinsyxBio purchased the licence to bring these develop-ments to commercialization the from University of Washington. They have already field-tested a few strains in tomatoes, straw-40/ SEEDWORLD.COMSEPTEMBER 2024'