The Effect of Uracil on the Germination and Growth of some leguminous Plants*

241 Abstract: All known pyrimidine and pyrimidine-derived secondary producs originate from uracil or its precursor, uracil-6-carboxylic acid. The biosynthesis of these products has been suggested to be uracil detoxication mechanisms. The possible toxic effects of uracil on the germination and growh of Pisum sativum L. cultivar Meteor, Lathyrus tingitanus L. in which pyrimidine-derived secondary products occur naturally, and of Phaseolus aureus Roxb. and Glycine max (L.) Merr., in which these compouns do not occur, were examined. The results show that the germination and growth of the P. aureus and G. max seeds under investigation were considerably inhibited by exogenous uracil. The effect of uracil was obvious on the non-producer group of experimental plants, especially on G. max. However, there was not any noticeable effect of uracil either on P. sativum, or on L. tingitanus in the experimental periods of germination and growth. These results show that uracil accumulation is most probably toxic to plants and that the production of these pyrimidine-derived secondary compounds from uracil is therefore a detoxication mechanism.