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Fungus Protects Rice from Challenges of Climate Change

Spores help rice cope with drought and rising salt concentrations in soil
climate change, global warming, rice, fungus, agriculture, food crisis



IRRI Images/Wikimedia Commons

To ward off famine and potentially save millions of lives, researchers are looking for a little help from a tiny fungus.

By colonizing seeds with spores from naturally occurring fungi, experiments show that rice -- a major world food source -- is able to withstand stresses associated with climate change, such as drought and soil salinity. The results were published by the U.S. Geological Survey (USGS) in the journal PLoS ONE.

"What makes this remarkable is that we can move these fungi around," said USGS researcher Rusty Rodriguez. "The contemporary thought is that the plant itself adapts to the stress, but what we've been observing is that that isn't always the case. Plants can have associations with fungi and then tolerate certain types of stresses."

The team first examined dune grass, which can tolerate high levels of salt, and discovered that its adaptive ability comes from the presence of a fungus. The same fungus was then applied to rice, and remarkably the crop thrived, achieving a notable increase in salt tolerance.

The same experiment was tried with plants that can tolerate high degrees of heat and produced the same result. Both tests were done on rice varieties that did not have natural abilities to withstand these stresses.

This new area of research is dubbed "symbiogenetics," for symbiosis-altered gene expression. The process does not change the DNA of the rice; instead, it recreates a phenomenon already taking place in nature.

"Rather than target individual genes, in essence we're moving an entire genome, because the fungus is colonizing the entire plant. You have two genomes within the plant, and they interact," said Rodriguez.

While scientists still don't fully understand the mechanism that gives fungi this special protective ability, their tests show that so long as the fungus is present in the plant, the plant behaves differently when exposed to stress. It's as though the plant doesn't see it. When the fungus is removed, the plant can no longer adapt to the salty or hot conditions.

Using the fungi -- called endophytes -- is one of the few available options in mitigating the effects of climate change on agricultural ecosystems, said Rodriguez.

Strengthening a plant that feeds the world
Rice provides nearly half of the daily caloric intake of the world's population. But in places where there have been tidal surges, hurricanes or tsunamis, the soil is too salty for food production. Crops similarly struggle in extremely hot regions. Salt, heat, heavy metals, other kinds of pollution and drought are all expected to have a growing impact on agricultural resources due to climate change.

"During the last 40 years of climate change, increased minimum air temperatures during growing seasons have resulted in a substantial decrease in rice yields in China and the Philippines and are predicted to continue," the USGS report says. "Collectively, these events along with increasing world-population, have contributed to shortages and increased prices of rice exacerbating hunger and famine issues globally."

Every protective fungus the USGS team worked with has been transferable to agricultural crops. Many have also been tested on plants outside the greenhouse in their natural habitats. The experiment applies only native fungi to a rice variety, to avoid introducing foreign species.

The next step, says Rodriguez, is to work with crops in different parts of the world in order to test how rice and other fungi react. USGS has already been in contact with researchers in South Korea and Kenya, and the experiment is not far off from broad-based application.

"We actually patented a couple of these fungi, and we're working with a seed company now to move forward with commercialization," said Rodriguez. "There's testing going on this year, and within two to three years, we should see large-scale implementation; that's the hope, anyway."

"In much of the continent of Africa, India and any area that is suffering from poor water availability or poor water quality, this could have a tremendous impact."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500

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