Anthocyanin3 negatively regulates anthocyanin synthesis in maize

Anthocyanins are colorful molecules receiving recent attention due to their numerous health benefits and applications as natural colorants and nutraceuticals. Purple corn in particular is being investigated as a more economical source of natural colorants. Anthocyanin3 (A3) is a known recessive intensifier of anthocyanin pigmentation in maize. Two genetic approaches were used to pinpoint the gene involved with the a3 intense purple plant phenotype. First, a large-scale transposon-tagging population was created with a Dissociation (Ds) insertion in the nearby Anthocyanin1 gene. A de novo a3-m1::Ds mutant generated pinpointed the transposon insertion in Mybr97, which has homology to R3-Myb-like repressor CAPRICE in Arabidopsis. Second, a bulk segregant RNA-sequencing population found expression differences between pools of green A3 plants and purple mutant a3 plants. Mybr97 was highly downregulated, confirming its role as the gene responsible for the a3 dark purple phenotype.

花青素（Anthocyanins）是一类色彩丰富的分子，近年来因其诸多健康益处，以及作为天然着色剂与营养保健食品的应用价值而受到广泛关注。其中紫玉米作为更具经济性的天然着色剂来源，正受到深入研究。花青素3（Anthocyanin3，A3）是已被证实的玉米花青素着色隐性增强因子。研究采用两种遗传学手段，精准定位了与a3植株深紫色表型相关的基因：其一，通过在邻近的花青素1（Anthocyanin1）基因中插入解离（Dissociation，Ds）元件，构建了大规模转座子标签（transposon-tagging）群体；通过诱导获得的全新a3-m1::Ds突变体，精准定位到Mybr97基因中存在转座子插入，该基因与拟南芥中R3-MYB类抑制因子CAPRICE具有同源性。其二，通过混合分组转录组测序（bulk segregant RNA-sequencing）群体，发现绿色表型A3植株池与紫色突变体a3植株池之间存在显著表达差异；Mybr97基因呈现高度下调表达，证实其正是调控a3植株深紫色表型的关键基因。