Inheritance of a Gene Conditioning Blotchy Root Color in Table Beet (Beta vulgaris L.)

Abstract

The primary pigments in red beet are the betalains, which include the red-violet betacyanins and the yellow betaxanthins. The recent adoption of betalain pigments from red beet as an alternative to synthetic food dyes has heightened interest in genetic modification of pigment production. Dominant alleles at two tightly linked loci (R and Y) condition production of betalain pigment in the beet plant, however several alleles at the R locus influence pigment amount and distribution. In addition, recurrent selection for pigment concentration has been effective at increasing pigment concentration, suggesting other modifying genes play an important role in betalain synthesis. A mutant phenotype, characterized by irregular sectors of blotchy red and white root color, was observed in a breeding line in the beet breeding nursery at the University of Wisconsin-Madison. The blotchy mutant plant was used in crosses with nonblotchy inbred lines to characterize its inheritance. Chi-square goodness-of-fit tests of segregation data in backcross and F2 generations for several genetic backgrounds did not deviate from the hypothesis that a single recessive gene controls the blotchy phenotype. We propose the symbol bl to describe the genetic control of this blotchy phenotype.