New, virus-resistant snap beans may be available soon, thanks to genetic work done by Agricultural Research Service (ARS) scientists in Prosser, WA. The scientist are investigating a strain of the clover yellow vein virus, which is the culprit behind chocolate pod, a disease that causes defects on snap bean pods.
Soybean aphids transmit the virus while feeding on bean plants. Spraying insecticides to prevent such feeding, however, isn’t always effective or economically feasible. Incorporating genes for resistance into the crop offers a better approach, explains ARS plant pathologist Richard Larsen.
Larsen and ARS geneticist Phil Miklas developed a polymerase chain reaction-based test to detect the chocolate pod virus and distinguish it from other bean pathogens.
They were able to do this by identifying the sequence of amino acids that make up the virus’ coat protein, explains Larsen, who, along with Miklas, works in the ARS Vegetable and Forage Crops Research Laboratory at Prosser. The research was published in the journal Plant Disease.
The test, which yields results in less than a day versus weeks by traditional methods, has become a critical screening tool in the search for resistant bean germplasm. Only one snap bean variety out of 63 the researchers screened showed some resistance to chocolate pod.
Fortunately, a gene found in dry edible beans conferred stronger resistance. Even better, the gene “coexists” with another, dubbed bc-3, which confers resistance to other bean pathogens, including bean common mosaic virus and bean yellow mosaic virus.
For more information, go to www.ars.usda.gov/is/AR/archive/aug09/beans0809.htm.