https://www.nature.com/articles/d41586-024-01046-z Skip to main content Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Advertisement Advertisement Nature * View all journals * Search * Log in * Explore content * About the journal * Publish with us * Subscribe * Sign up for alerts * RSS feed 1. nature 2. news 3. article * NEWS * 11 April 2024 Scientists discover first algae that can fix nitrogen -- thanks to a tiny cell structure A newly discovered 'organelle' that converts nitrogen gas into a useful form could pave the way for engineered plants that require less fertilizer. By * Carissa Wong 1. Carissa Wong View author publications You can also search for this author in PubMed Google Scholar * Twitter * Facebook * Email 1000x magnification micrograph of Braarudospharea bigelowii cell. A Braarudosphaera bigelowii cell magnified 1,000-fold.Credit: Tyler Coale Researchers have discovered a type of organelle, a fundamental cellular structure, that can turn nitrogen gas into a form that is useful for cell growth. The discovery of the structure, called a nitroplast, in algae could bolster efforts to genetically engineer plants to convert, or 'fix', their own nitrogen, which could boost crop yields and reduce the need for fertilizers. The work was published in Science on 11 April^1. [d41586-024] New cellular 'organelle' discovered inside fruit-fly intestines "The textbooks say nitrogen fixation only occurs in bacteria and archaea," says ocean ecologist Jonathan Zehr at the University of California, Santa Cruz, a co-author of the study. This species of algae is the "first nitrogen-fixing eukaryote", he adds, referring to the group of organisms that includes plants and animals. In 2012, Zehr and his colleagues reported that the marine algae Braarudosphaera bigelowii interacted closely with a bacterium called UCYN-A that seemed to live in, or on, the algal cells^2. The researchers hypothesised that UCYN-A converts nitrogen gas into compounds that the algae use to grow, such as ammonia. In return, the bacteria were thought to gain a carbon-based energy source from the algae. But in the latest study, Zehr and his colleagues conclude that UCYN-A should be classed as organelles inside the algae, rather than as a separate organism. According to genetic analysis from a previous study, ancestors of the algae and bacteria entered a symbiotic relationship around 100 million years ago, says Zehr. Eventually, this gave rise to the nitroplast organelle, now seen in B. bigelowii. Defining organelles Researchers use two key criteria to decide whether a bacterial cell has become an organelle in a host cell. First, the cell structure in question must be passed down through generations of the host cell. Second, the structure must be reliant on proteins provided by the host cell. By imaging dozens of algae cells at various stages of cell division, the team found that the nitroplast splits in two just before the whole algae cell divides. In this way, one nitroplast is passed down from the parent cell to its offspring, as happens with other cell structures. [d41586-024] A seagrass harbours a nitrogen-fixing bacterial partner Next, the researchers found that the nitroplast gets the proteins it needs to grow from the wider algae cell. The nitroplast itself -- which makes up more than 8% of the volume of each host cell -- lacks key proteins required for photosynthesis and making genetic material, says Zehr. "A lot of these proteins [from the algae] are just filling those gaps in metabolism," he says. The discovery was made possible thanks to work by study author Kyoko Hagino at Kochi University in Japan, who spent around a decade fine-tuning a way to grow the algae in the lab -- which allowed it to be studied in more detail, says Zehr. "It's quite remarkable," says Siv Andersson, who studies how organelles evolve at Uppsala University in Sweden. "They really see all these hallmarks that we think are characteristic of organelles." Upgraded plants Understanding how the nitroplast interacts with its host cell could support efforts to engineer crops that can fix their own nitrogen, says Zehr. This would reduce the need for nitrogen-based fertilizers and avoid some of the environmental damage they cause. "The tricks that are involved in making this system work could be used in engineering land plants," he says. "Crop yields are majorly limited by availability of nitrogen," says Eva Nowack, who studies symbiotic bacteria at the Heinrich Heine University Dusseldorf in Germany. "Having a nitrogen-fixing organelle in a crop plant would be, of course, fantastic." But introducing this ability into plants will be no easy feat, she warns. Plant cells containing the genetic code for the nitroplast would need to be engineered in such a way that the genes were transferred stably from generation to generation, for example. "That would be the most difficult thing to do," she says. "It's both a pleasure and very impressive to see this work build up to what is certainly a major stepping stone in understanding," says Jeffrey Elhai, a cell biologist at Virginia Commonwealth University in Richmond, Vriginia. doi: https://doi.org/10.1038/d41586-024-01046-z References 1. Coale, T. H. et al. Science 384, 217-222 (2024). Article Google Scholar 2. Thompson, A. W. et al. Science 337,1546-1550 (2012). Article PubMed Google Scholar Download references Reprints and permissions Related Articles * [d41586-024] New cellular 'organelle' discovered inside fruit-fly intestines * [d41586-024] Model system might reveal how coral cells take up and evict algae * [d41586-024] A seagrass harbours a nitrogen-fixing bacterial partner * Nitrogen pollution soars in China * Fossil algae hold clues to origin of modern photosynthesis Subjects * Microbiology Latest on: Microbiology Blocking cell death limits lung damage and inflammation from influenza Blocking cell death limits lung damage and inflammation from influenza News & Views 10 APR 24 Distal colonocytes targeted by C. rodentium recruit T-cell help for barrier defence Distal colonocytes targeted by C. rodentium recruit T-cell help for barrier defence Article 10 APR 24 Bird flu outbreak in US cows: why scientists are concerned Bird flu outbreak in US cows: why scientists are concerned News Explainer 08 APR 24 Nature Careers Jobs * Junior Group Leader Position at IMBA - Institute of Molecular Biotechnology The Institute of Molecular Biotechnology (IMBA) is one of Europe's leading institutes for basic research in the life sciences. IMBA is located on t... Austria (AT) IMBA - Institute of Molecular Biotechnology [] * Open Rank Faculty, Center for Public Health Genomics Center for Public Health Genomics & UVA Comprehensive Cancer Center seek 2 tenure-track faculty members in Cancer Precision Medicine/Precision Health. Charlottesville, Virginia Center for Public Health Genomics at the University of Virginia [] * Husbandry Technician I Memphis, Tennessee St. Jude Children's Research Hospital (St. Jude) [] * Lead Researcher - Department of Bone Marrow Transplantation & Cellular Therapy Memphis, Tennessee St. Jude Children's Research Hospital (St. Jude) [] * Researcher in the Center for In Vivo Imaging and Therapy Memphis, Tennessee St. Jude Children's Research Hospital (St. Jude) [] You have full access to this article via your institution. Download PDF Related Articles * [d41586-024] New cellular 'organelle' discovered inside fruit-fly intestines * [d41586-024] Model system might reveal how coral cells take up and evict algae * [d41586-024] A seagrass harbours a nitrogen-fixing bacterial partner * Nitrogen pollution soars in China * Fossil algae hold clues to origin of modern photosynthesis Subjects * Microbiology Advertisement Sign up to Nature Briefing An essential round-up of science news, opinion and analysis, delivered to your inbox every weekday. Email address [ ] [ ] Yes! Sign me up to receive the daily Nature Briefing email. I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. Sign up * Close Nature Briefing Sign up for the Nature Briefing newsletter -- what matters in science, free to your inbox daily. Email address [ ] Sign up [ ] I agree my information will be processed in accordance with the Nature and Springer Nature Limited Privacy Policy. 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