By reflecting light differently, the leaves of virus-infected plants entice insects, a new study has suggested.

It is common knowledge that insects can identify regions of polarized light, but the discovery of University of Bristol scientists shows that a viral infection influences the percentage of light polarization reflected from the leaves. This polarization of light allows sap-sucking aphids or greenfly to identify the infected plants and spread the virus to other plants.

Past studies have tackled that viruses alter the smell of the plants upon infection, but little is known how bugs are visually enticed by infected plants.

Using a series of photographs captured with polarizing filters, the scientists were able to identify that virus-infected plants have leaves that are less polarizing compared to healthy ones. Reduction in polarization is due to the waxy layer of the leaf cuticle.

Scientists noted that aphid-borne viral infection have a different gene expression from other plant viruses not transmitted by insects.

Spread of plant pathogens significantly reduce crop yields and contribute to the growing threat on food safety. Knowing the mechanism of how the virus is spread, plant scientists can formulate ways on how it can be minimized and prevented.

"Transmission of plant viruses by insects is of huge importance to agriculture and the environment," said Professor Gary Foster at the university's School of Biological Sciences.

The findings of the study are expected to encourage plant scientists to conduct further studies to help alleviate problems in global food security.

This discovery can be used to complement an earlier research that revealed plant leaves are able to detect light waves and adjust their growth rate accordingly, as they compete with their neighboring plants. When growth rate is improved and viral infection is reduced, crop yield can increase significantly.

The research was funded by the European Union (EU) and the Natural Environment Research Council (NERC) and was published in PLOS ONE on April 21.

Photo: Alan Goudy | Flickr