(PhysOrg.com) -- In 752, Japanese Empress Koken wrote a short poem about the summertime yellowing of a field in what is thought to be the first account of a viral plant disease. More than 1,250 years later, scientists concluded that the virus Koken described was part of the particularly insidious geminivirus family that continues to decimate tomato, tobacco and cotton crops worldwide. Now, new research shows how cunning an enemy one of these ancient viruses can be, manufacturing a protein that deforms and sterilizes plants and at the same time wrecks their defenses against the pests that spread the disease to others.