A mutation in the pale aleurone color1 gene identifies a novel regulator of the maize anthocyanin pathway.
By screening for new seed color mutations, we have identified a new gene, pale aleurone color1 (pac1), which when mutated causes a reduction in anthocyanin pigmentation. The pac1 gene is not allelic to any known anthocyanin biosynthetic or regulatory gene. The pac1-ref allele is recessive, nonlethal, and only reduces pigment in kernels, not in vegetative tissues. Genetic and molecular evidence shows that the pac1-ref allele reduces pigmentation by reducing RNA levels of the biosynthetic genes in the pathway. The mutant does not reduce the RNA levels of either of the two regulatory genes, b and c1. Introduction of an anthocyanin structural gene promoter (a1) driving a reporter gene into maize aleurones shows that pac1-ref kernels have reduced expression resulting from the action of the a1 promoter. Introduction of the reporter gene with constructs that express the regulatory genes b and c1 or the phlobaphene pathway regulator p shows that this reduction in a1-driven expression occurs in both the presence and absence of these regulators. Our results imply that pac1 is required for either b/c1 or p activation of anthocyanin biosynthetic gene expression and that pac1 acts independently of these regulatory genes.
Selinger
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DA
Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, USA.
Chandler
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VL
D000483:Alleles; D000872:Anthocyanins / Q000096:biosynthesis / Q000235:genetics*; D002874:Chromosome Mapping; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D009154:Mutation; D010858:Pigmentation / Q000235:genetics; D011401:Promoter Regions, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism
D000872:Anthocyanins