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Plant Defense Strategy

Researchers from a U.K. plant research institute have found a way to provide plants with an antibody-based defense for a specific threat, potentially speeding the creation of crops resistant to any kind of emerging virus, or bacterium (细菌). The strategy is to inoculate a protein from the plant pathogen (病原体) to be targeted to a camel or other camel relatives, purify the unusually small antibodies the camels produce, and engineer the corresponding gene section for them into a plant’s own immune gene.

Farmers lose many billions of dollars to plant diseases each year, and emerging pathogens pose new threats to food security in the developing world. Plants have evolved their own immune system, kick-started by cell receptors that recognize general pathogen features, such as a bacterial cell wall, as well as intracellular receptors for molecules (分子) produced by specific pathogens. If a plant cell detects these molecules, it may trigger its own death to save the rest of the plant. But plant pathogens often evolve and escape from those receptors.

A long-standing dream in plant biotechnology is to create designer disease resistance genes that could be produced as fast as pathogens emerge. One approach is to edit the gene for a plant immune receptor, changing the protein’s shape to recognize a particular pathogenic molecule.

Instead, Sophien Kamoun, a molecular biologist at the Sainsbury Laboratory, and his colleagues used an animal immune system to help make the receptor adjustments. During an infection with a new pathogen, animals produce billions of slightly different antibodies, ultimately selecting and mass-producing those that best target the virus.

Camelids, which include camels, are workhorses for antibody design because their immune systems create unusually small versions, called nano-bodies. As a proof of principle of the new plant defense strategy, Kamoun’s group turned to two standard camelid nano-bodies that recognize two different molecules, including one called green fluorescent protein (GFP), to detect test viruses, in this case a potato virus, engineered to make the fluorescent proteins. They investigated how well plants with the nano-body-enhanced receptors detected the changed potato viruses. It was found that the plants increased an active immune response and experienced almost no viral reproduction.

“The exciting part about this technology is that we have the potential of made-to-order resistance genes and keeping up with a pathogen,” Kamoun says. “This technology is a potential game changer,” says Jeff Dangl, a plant researcher at the University of North Carolina. Ksenia Krasileva, a scientist at the University of California, Berkeley, says the mixture of nano-bodies with plant immune receptors opens up a vast body of biomedical knowledge for plant scientists. “We can now dig into all of that research and translate it to save crops.”