THE PLANT CELL, Vol 2, Issue 2 115-127, Copyright © 1990 by American Society of Plant Biologists
Genetic Regulation and Photocontrol of Anthocyanin Accumulation in Maize Seedlings
L. P. Taylor and W. R. Briggs
Carnegie Institution of Washington, Department of Plant Biology, 290 Panama Street, Stanford, California 94305
The flavonoid pathway leading to anthocyanin biosynthesis in maize is
controlled by multiple regulatory genes and induced by various
developmental and environmental factors. We have investigated the effect of
the regulatory loci R, B, and PI on anthocyanin accumulation and on the
expression of four genes ( C2, A1, Bz1, and Bz2) in the biosynthetic
pathway during an inductive light treatment. The results show that
light-mediated anthocyanin biosynthesis is regulated solely by R; the
contributions of B and PI are negligible in young seedlings. Induction of
the A1 and Bz2 genes by high fluence-rate white light requires the
expression of a dominant R allele, whereas accumulation of C2 and Bz1 mRNA
occurs with either a dominant or recessive allele at R. A1 and Bz2 mRNA
accumulate only in response to high fluence-rate white light, but Bz1 is
fully expressed in dim red light. Some C2 mRNA is induced by dim red light,
but accumulation is far greater in high fluence-rate white light.
Furthermore, expression from both dominant and recessive alleles of the
regulatory gene R is enhanced by high fluence-rate white light. Seedlings
with a recessive allele at R produce functional chalcone synthase protein
(the C2 gene product) but accumulate no anthocyanins, suggesting that, in
contrast to the R-mediated coordinate regulation of C2 and Bz1 observed in
the aleurone, C2 expression in seedlings is independent of R and appears to
be regulated by a different light-sensitive pathway.
