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.     

利用花色素苷合成调节基因C1-R作为基因枪转化效果指示的研究

报道了玉米花色素苷合成调节基因Ｃ１－Ｒ在小麦幼胚、玉米愈伤组织、水稻愈伤组织、烟草叶片中的瞬时表达情况。由于调节基因Ｃ１－Ｒ激活了植物体细胞内花色素苷的合成,因此不需任何生色底物,即可活体观察到花色素苷的表达。结果表明,对于目前仍主要通过基因枪法转化的几类主要粮食作物──小麦、玉米、水稻、枪击４８ｈ后,放大２倍便清晰可见红色斑点,且其表达强度远高于ＧＵＳ的表达,证明Ｃ１－Ｒ可作为一个很好的衡量打枪效果的指示,同时还证明其在双子叶植物──烟草叶片的基因枪转化瞬时表达体系中也起同样的作用。