A short history of plant virology. II. The twenties

Plant virology, born at the end of the last century, consolidated during the Twenties. Important new viral diseases were described and their causal agents partially purified and characterized not least because of the development of methods and techniques. An interesting debate concerned the so called "intracellular bodies", which were finally demonstrated to be aggregates of virus particles. Discoveries mainly arrived from experimental investigations on tobacco mosaic virus, and concerned the identification of strains, the demonstration of antigenic property, and the protein nature of viruses. A new concept of virus drew great advantage from the first attempts of classification and nomenclature, and a debate on the living or non-living nature of viruses, universally accepted as a new class of pathogens, was opened. The idea of viruses as self-reproducing particles was first advanced, although on a controversial basis. On the contrary, there was only erratic investigations on the physiological alterations produced by viral diseases in plants and on the relationships between viruses and vectors. In spite of this gaps, the Twenties must be mentioned as the years of the turning-point towards a biochemical concept of viruses, which will be achieved in the next decade.