Immunological Studies on the Tuber-bearing Solanums: 1. Techniques and South American Species

Many improvements have been made in recent years in serologicaltechniques which give them a sounder basis and make them morelikely to provide information of taxonomic importance. The Ouchterlonydouble diffusion technique and immuno-electrophoretic analysisare here described, together with new ways of analysing theresults by characterization of the individual antigens. It was shown experimentally with two species that the normalrange of variation in temperature or light intensity duringstorage has no significant effect on the antigen content ofthe tubers. The antigenic proteins of Solanum tuberositm occurchiefly in the phloem and in the peripheral cortex of the tuber.By immuno-electrophoresis and zone electrophoresis, it was shownthat the antigens correspond to the major protein fractionsof the extracts. Organ specificity of antigens was demonstrated, in that withan antiserum to one organ of one species, extracts of otherorgans of the same species reacted weakly, whereas extractsof the same organ of other species reacted strongly. An investigation of the tuber antigens of some South Americanspecies showed a general uniformity, as reported by previousworkers. However some differences common to all clones of bothsubspecies of S.commersoniiybut not to any other species ofthe series Commersoniana, were found.