The Roles of Riboflavin and Inhibitors in Conidial Germination in Peronospora Tabacina Adam

Abstract

Shepherd (1962) reported results suggesting that conidia of Peronospora tabacina Adam required an exogenous source of riboflavin for germination, but noted that the technique used was open to the objection that material might be leached from the spores during the washing process. Washing was found to be obligatory by Shepherd and Mandryk (1962) in order to obtain good germination and it was suggested that conidia contained a water-soluble auto-inhibitor of germination. Subsequently, Shepherd and Mandryk (1963) showed that washing removed materials inhibitory to spore germination from the surfaces of tobacco leaves. It was of interest, therefore, to determine whether the postulated auto-inhibitory materials were, in fact, picked up from the leaf surface during spore removal or were endogenous to conidia and also to examine further the riboflavin requirement of conidia removed from the leaf under more natural conditions than were used previously.