Viroids , the first known representatives of a new domain of `` sub-viral pathogens '' , were discovered , initially characterized , and named by Theodor Otto Diener , plant pathologist at the U.S Department of Agriculture 's Research Center in Beltsville , Maryland , in 1971 .
Viroids were the first `` sub-viral pathogens '' discovered and named by Theodor Otto Diener . He was a plant pathologist at the U.S Department of Agriculture 's Research Center in Beltsville , Maryland , in 1971 .