Scientists Discover First Nitrogen-Fixing Organelle - Berkeley Lab – Berkeley Lab News Center
Modern biology textbooks assert that only bacteria can take nitrogen from the atmosphere and convert it into a form that is usable for life. Plants that fix nitrogen, such as legumes, do so by harboring symbiotic bacteria in root nodules. But a recent discovery upends that rule.
In two recent papers, an international team of scientists describe the first known nitrogen-fixing organelle within a eukaryotic cell. The organelle is the fourth example in history of primary endosymbiosis – the process by which a prokaryotic cell is engulfed by a eukaryotic cell and evolves beyond symbiosis into an organelle.
“It’s very rare that organelles arise from these types of things,” said Tyler Coale, a postdoctoral scholar at UC Santa Cruz and first author on one of two recent papers. “The first time we think it happened, it gave rise to all complex life. Everything more complicated than a bacterial cell owes its existence to that event,” he said, referring to the origins of the mitochondria. “A billion years ago or so, it happened again with the chloroplast, and that gave us plants,” Coale said.
The third known instance involves a microbe similar to a chloroplast. The organelle in this discovery has been named a nitroplast.
