H. Fraenkel .Conrat and B. Singer demonstrated that RNA is a genetic material of TMV or tobacco mosaic virus by their experiments published in 1957.
They first developed the techniques for separating TMV · particles into RNA and proteins. Later by .using RNA and proteins separated in tests for infectivity, they demonstrated that RNA alone was able to cause infection. They developed techniques for forming reconstructed viruses containing the protein from one mutant strain of TMV. and RNA from another, or vice-versa. Such hybrid viruses or chimeras were allowed to infect tobacco leaves and the progeny were examined. In all cases the progeny were the parental RNA type and not the parental protein type.