Building resistance against plant pathogens

Transferring a single gene from a wild plant to disease-susceptible members of the tomato and potato family may make them resistant to a range of agricultural pathogens. If the results, published online this week in Nature Biotechnology, can be more generally duplicated, it would help in preventing massive crop losses while avoiding the environmental, health and financial costs associated with using pesticides.

Most plants possess both general and very specific mechanisms to combat the range of microbial pathogens encountered. However, the ability to resist a particular pathogen often varies from species to species. One approach to create pathogen resistant crops has involved making them express specific receptors that trigger a defense response once activated by molecules particular to the pest of interest. But this resistance usually breaks down in field-grown crops as the pathogen finds ways to outwit the plant.

Cyril Zipfel and colleagues focused on an immune receptor that is activated by a factor present in many bacterial pathogens. This pattern recognition receptor (PRR) ― from a wild species belonging to the mustard family ― is not found in the potato, tomato, or tobacco family. When Zipfel and colleagues express the gene in tomato and a close relative of the tobacco plant, the plants were more resistant to pathogens from four different families of bacteria which cause bacterial wilt, bacterial spot and crown gall disease. Since PRR targets are usually essential for pathogen viability, this methodology may make it more difficult for bacteria to circumvent crop resistance.

Field trials are needed to see whether the PRR strategy indeed provides more durable resistance than current methods.