Influence of Genes Controlling Flower Color on Relative Quantities of Anthocyanins and Flavonols in Petals of Impatiens Balsamina.

N earlier studies concerned with the genetic regulation of pigmentation in the I garden balsam, Impatiens balsamina, the genes which determine the nature of anthocyanin pigmentation were found in individual cases to regulate also the structure of leucoanthocyanins (ALSTON and HAGEN 1958) and flavonols (CLEVENGER 1958). Thus the dominant gene H , while increasing the quantity of pelargonidin derivatives present in the flowers, also allows production of a leucopelargonidin, which does not occur when the recessive allele, h, is homozygous. At another locus, L governs production of anthocyanins derived from malvidin and at the same time introduces a polyhydroxy flavonol, apparently myricetin. The simplest interpretation of these observations would indicate that an intermediate made available for anthocyanin synthesis may also be exploited for leucoanthocyanin and flavonol synthesis and, therefore, that both L and H operate at an early stage in the elaboration of the flavonoid structure. Additional control of flower color in the balsams is provided by a series of alleles p, Pg and Pr. While slight anthocyanin pigmentation may occur with p , the principal influence of these genes seems to be an augmentation of anthocyanin production, p being the least effective of the series and P r the most effective. This effect is clear when the quantities of anthocyanin pigments produced in each genotype are determined, and the relation of the alleles at the p locus to flavonol synthesis can be assessed by taking advantage of certain features of the ultraviolet absorption by this group of compounds.