State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, Shaanxi, China.
J Exp Bot. 2018 Apr 27;69(10):2555-2567. doi: 10.1093/jxb/ery101.
Purple pericarps of bread wheat (Triticum aestivum L.) are a useful source of dietary anthocyanins. Previous mapping results indicated that the purple pericarp trait is controlled by two complementary genes located on chromosomes 7D and 2A. However, the identity of the genes and the mechanisms by which they regulate the trait are unknown. In this study, two transcription factors were characterised as anthocyanin activators in purple pericarps: TaPpm1 (purple pericarp-MYB 1) and TaPpb1 (purple pericarp-bHLH 1). Three non-functional variants were detected in the coding sequence of TaPpm1 from non-purple seed lines, in which the function of TaPpm1 was destroyed either by insertion-induced frame shifts or truncated peptides. There were six 261-bp tandem repeats in the promoter region of TaPpb1 in the purple-grained varieties, while there was only one repeat unit present in the non-purple varieties. Furthermore, using yeast two-hybrid, dual luciferase, yeast one-hybrid, and transient assays, we were able to demonstrate that the interaction of TaPpm1 and TaPpb1 co-regulates the synthesis of anthocyanin. Overall, our results provide a better understanding of the molecular basis of anthocyanin synthesis in the wheat pericarp and indicate the existence of an integrated regulatory mechanism that controls production.
面包小麦（Triticum aestivum L.）的紫色果皮是膳食花青素的有用来源。先前的图谱结果表明，紫色果皮性状由位于 7D 和 2A 染色体上的两个互补基因控制。然而，这些基因的身份以及它们调节性状的机制尚不清楚。在这项研究中，两个转录因子被鉴定为紫色果皮中花青素的激活剂：TaPpm1（紫色果皮-MYB1）和 TaPpb1（紫色果皮-bHLH1）。在非紫色种子系的 TaPpm1 编码序列中检测到三个无功能变体，其中 TaPpm1 的功能要么被插入诱导的移码要么被截断肽破坏。在紫色粒品种的 TaPpb1 启动子区域有六个 261-bp 的串联重复，而在非紫色品种中只有一个重复单元。此外，通过酵母双杂交、双荧光素酶、酵母单杂交和瞬时测定，我们能够证明 TaPpm1 和 TaPpb1 的相互作用共同调节花青素的合成。总的来说，我们的结果提供了对小麦果皮中花青素合成分子基础的更好理解，并表明存在一个整合的调控机制来控制产量。
