GENETIC-REGULATION OF ANTHOCYANIN BIOSYNTHESIS IN EMBRYOGENIC MAIZE CALLUS

Anthocyanin pigment accumulation in friable, Type II embryogenic maize callus was analyzed in a set of genotypes constructed in the inbred l ine A188. As in intact tissues, anthocyanin biosynthesis in embryogeni c callus is under genetic and environmental control. Embryogenic calli that were homozygous recessive for the enzyme-encoding structural gen es a1, a2, bz1, or bz2 were all colorless. Calli differing in their re gulatory genotypes demonstrated the need for both an R gene-family mem ber and a C1 gene-family member. The R alleles R-nj, R(S), and R(P) we re each found to be functional in embryogenic callus; in planta R(S) a nd R(P) act in mutually exclusive seed and vegetative tissues, while R -nj acts in both. The requirement for a C1 gene-family member resemble d that of mature vegetative tissues: either PI, or pl plus prolonged l ight treatment, but not C1, were functional in callus. The regulation in these callus cultures does not reflect any one specific tissue type in the intact plant. These observations and the constructed maize lin es may aid in the use of anthocyanin genes as plant-derived markers fo r the production of transgenic maize.