Dead Zone May be Reduced with New, Plant-Based Technique

Dead zones in the ocean can be a huge issue. They can reduce the amount of biodiversity in an area, and greatly impact fisheries as fish move to other locations to avoid low-oxygen regions. Now, scientists have found a possible way to reduce the dead zones in the ocean.

Dead zones occur when nitrogen and phosphorus from agricultural fertilizers and sewage washes downstream and into the ocean. These nutrients can feed huge blooms of toxic algae. This, in turn, can leech oxygen from an area and also cause major havoc for ecosystems.

"If we can find better ways of getting nitrogen to plants, then we can improve the environmental impact of farming," said Paul "Skip" Price, lead author of the new study, in a news release. "We want to improve this process so we don't have to add as much fertilizer to fields. With active rhizobia, we can have productive crops while still protecting the environment and keeping our waterways safer."

In this latest study, the researchers focused on naturally-occurring bacteria called rhizobia, which may be able to stem the tide of oversaturation with nitrogen-based fertilizers. These tiny bacteria attach to a plant host, usually inside the tiny nodules on the plant's roots, and then work with the plant to turn nitrogen gas into a consumable form. This relationship exists for many plants, including crops like soybeans and peas. If rhizobia worked at a higher rate, they would be able to reduce the amount of nitrogen-based fertilizer placed in the soil by farmers.

Currently, the researchers are looking at the effects of HrrP, a gene that can switch rhizobia from being helpful to harmful. When the gene is switched, a plant gets no benefit from rhizobia, which then behaves more like a disease. The bacteria begin to live a very self-centered existence.

Understanding these different mechanisms can go a long way toward better understanding the bacteria as a whole. If researchers can learn a bit more about the mechanisms of the rhizobia, they can potentially alter them to use more nitrogen and feed it to plants.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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