Friendly fungi could revolutionize rice farming

By engineering a strain of symbiotic fungus, researchers have massively increased the growth rate of rice, and may help stave off the specter of global shortages of phosphates, which are essential minerals for plants.

Mycorrhiza fungi are those that live in a mutually beneficial arrangement with the roots of plants. Found in just about every piece of flora on the planet, they form a mutualistic bond with the host — in exchange for sugar, the fungi adds a much greater amount of surface area to the root, which allows for better water uptake and the higher absorption of phosphate, which can be hard for plants to access in certain forms.

Unfortunately, many major food source crops don't respond well to existing Mycorrhiza fungi, and don't take advantage of these benefits. Rice — food staple to the most of humanity — is one such plant. Ian Sanders of the University of Lausanne in Switzerland has found what seems to be a way to get around this problem.

He took Glomus intraradices — a fungal strain with no benefit towards rice crops — and found that it had a much greater variety of genetic variation in it than was usually seen in a clonal fungi. By tweaking the genes of G. intraradices, they created a strain that activates the capacity of the rice plants to form the bond.

With this symbiosis in place, the rice experienced a five-fold growth increase. The benefits aren't just limited to Syfy levels of gigantism, there are also major potential improvements for the plants mineral uptake. Mycorrhiza can allow plants to take up phosphate ions that are demineralized — which is usually inaccessible — like in soil that is particularly basic. Without the fungi, this phosphate would have to be provided externally, and this nutrient might be in short supply.

"Global reserves of phosphate are critically low, and because the demand for phosphate goes hand in hand with human population expansion, it is predicted that there will be major shortages in the next few decades," says Sanders. By inoculating the plant with G. intraradices, the pressure on phosphate supplies could potentially be significantly lowered.

Research published in the July 13 issue of Current Biology