Lettuce Fights Back Arch Enemies

Iceberg lettuce is the unfortunate target of barrage of an impressive array of microbes. Some of these microbes are transmitted to lettuce fields by piercing and sucking insects such as aphids and whiteflies, while others team up microbes in invading susceptible lettuces. To help iceberg lettuce and its relatives counter the attacks of stealthy microbes, scientists at the United States Department of Agriculture Agricultural Research Service (ARS) have developed parent lettuces with resistance to two major diseases – lettuce mosaic and big vein.

Lettuce big vein gets its name from the unhealthy, enlarged appearance of veins in infected lettuce leaves. It is caused by the Mirafiori lettuce big vein virus, which makes its way to lettuce roots via a soil-dwelling, fungus-like microbe. Lettuce mosaic, on the other hand, is caused by a virus of the same name. Green peach aphids can spread the virus from an infected plant to an uninfected one as they move about a lettuce field. The scientists are expanding on this work by pursuing other genes that would provide superior resistance to these diseases or to any of about a half-dozen other microbes that the researchers are scrutinizing.
The complete article can be accessed at http://www.ars.usda.gov/is/AR/archive/feb07/lettuce0207.htm.