By Shawn Vestal
Most major crops, such as wheat and corn, require expensive nitrogen fertilizer to flourish. But what if bacteria could help those plants draw nitrogen from the atmosphere, as peas and beans do?
New research from Washington State University takes an important step in that direction, identifying a key cluster of genes that can be moved from rhizobia bacteria that harvest nitrogen into bacteria that don't—raising the possibility that microbes that dwell in cereal crops could eventually be engineered to atmospherically harvest nitrogen as well.
It's a proof-of-concept finding that shines light on how plants and microbes have evolved to work together over tens of millions of years, as well as signaling future potential for reducing fertilizer use at a time of shortages and skyrocketing costs for farmers.
Researchers move nitrogen-fixing gene clusters
"These challenges emphasize the importance of finding more natural pathways for getting nitrogen to crops," said Stephanie Porter, associate professor of biological sciences at WSU Vancouver. "We developed a new way to successfully move a big cluster of genes that allow the bacteria to harvest nitrogen and colonize host plants into new bacteria that could not do these things at all. We can convert these regular bacteria into ones that are able to harvest nitrogen to fertilize plants in one single step."
These findings, arising from research spanning a decade and published in the journal Current Biology, focus on a key evolutionary process: endosymbiosis, in which microbes and host cells unite into one organism. Here, the microbes live inside of the plant cells. Such endosymbiotic organisms are crucial to understanding how plants evolved and function within an ecosystem, driving diverse processes such as nitrogen fixation for plants and photosynthesis for corals on reefs.
Porter, who was the senior author of the new publication, studies such "mutualisms"—or cooperation between species—in her lab. Angeliqua Montoya, a postdoctoral scholar in Porter's lab, was the lead author of the paper, and researchers at Brigham Young University were co-authors.
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