Rice is well-equipped with an effective immune system that enables it to detect and fend off disease-causing microbes but sometimes nature needs a hand.

A new study shows that rice immunity gets boosted when the plant receives a receptor protein from a completely different plant species, a result which may help increase health and productivity of rice, the staple food for half of the world's population, at least in countries that don't ban food science.

Immune receptors are specialized proteins that can recognize molecular patterns associated with disease-causing microbes, including bacteria and fungi, at the beginning of an infection. These receptors are found on the surface of plant cells, where they play a key role in the plant's early warning system.

Some of the receptors, however, occur only in certain groups of plant species. For example, the monocotyledon plant group, including rice and other grasses that sprout with a single seed leaf, contains different receptor proteins than does the dicotyledon group, including plants like beans, which germinate with two seed leaves. 

"Our results demonstrate that disease resistance in rice -- and possibly related crop species -- could very likely be enhanced by transferring genes responsible for specific immune receptors from dicotyledonous plants into rice, which is a monocotyledonous crop," said lead author Benjamin Schwessinger, a postdoctoral scholar in the UC Davis Department of Plant Pathology.

Schwessinger and colleagues Pamela Ronald in the UC Davis Department of Plant Pathology, Ofir Bahar at the Agricultural Research Organization's Volcani Center in Israel, and Cyril Zipfil from the Sainsbury Laboratory in the UK, successfully transferred the gene for an immune receptor from the model plant Arabidopsis, a member of the mustard family, into rice.

The rice plants that subsequently expressed this gene and produced the related immune receptor proteins were able to sense Xanthomonas oryzae pv. oryzae, an important bacterial disease of rice.

This demonstrated that receptors introduced to rice from the Arabidopsis plants via genetic engineering were able to make use of the rice plants' built-in immune signaling mechanisms and cause the rice plants to launch a stronger defensive immune response against the invading bacteria.

Funding for the study was provided by the European Molecular Biology Organization, headquartered in Germany; the Human Frontier Science Program Organization of France; the Gatsby Charitable Foundation, headquartered in London; the U.S. Department of Energy and the National Institutes of Health.

More papers involving the transfer of immune receptors between species: