He Lu, Cheng Lu, Wang Junjie, Liu Jing, Cheng Jinjin, Yang Zhirong, Cao Rui, Han Yuanhuai, Li Hongying, Zhang Bin
College of Agriculture, Shanxi Agricultural University, Taigu 030801, China.
Maize Research Institute, Shanxi Agricultural University, Xinzhou 034000, China.
J Agric Food Chem. 2022 Aug 3;70(30):9283-9294. doi: 10.1021/acs.jafc.2c01951. Epub 2022 Jul 25.
Foxtail millet is a minor but economically important crop in certain regions of the world. Millet color is often used to judge grain quality, yet the molecular determinants of millet coloration remain unclear. Here, we explored the relationship between and millet coloration in yellow and white millet varieties. Carotenoid levels declined with grain maturation and were negatively correlated with expression, which was significantly higher in white millet as compared to yellow millet during the color development stage. Cloning of the promoter and CDS sequences from these different millet varieties revealed the presence of two additional -regulatory elements within the promoter in white millet varieties, including an enhancer-like GC motif element associated with anoxic specific inducibility and a GCN4-motif element associated with endosperm expression. Dual-luciferase reporter assays confirmed that promoter fragments containing these additional -acting elements derived from white millet varieties were significantly more active than those from yellow millet varieties, consistent with the observed expression patterns. Further in vitro enzyme detection assays confirmed that SiCCD1 primarily targets and degrades lutein. Together, these data suggest that promoter variation was a key factor associated with the observed differences in expression, which in turn led to the difference in millet coloration.
谷子是世界某些地区一种规模较小但具有重要经济意义的作物。谷粒颜色常被用于判断谷物品质，然而谷子着色的分子决定因素仍不清楚。在此，我们探究了黄谷和白谷品种中[相关基因]与谷子着色之间的关系。类胡萝卜素水平随谷粒成熟而下降，且与[相关基因]表达呈负相关，在颜色发育阶段，白谷中的[相关基因]表达显著高于黄谷。从这些不同谷子品种中克隆[相关基因]的启动子和编码序列，发现在白谷品种的[相关基因]启动子中存在另外两个[相关基因]调控元件，包括一个与缺氧特异性诱导相关的增强子样GC基序元件和一个与胚乳表达相关的GCN4基序元件。双荧光素酶报告基因检测证实，含有源自白谷品种的这些额外[相关基因]作用元件的[相关基因]启动子片段比源自黄谷品种的启动子片段活性显著更高，这与观察到的[相关基因]表达模式一致。进一步的体外酶检测证实，SiCCD1主要靶向并降解叶黄素。这些数据共同表明，[相关基因]启动子变异是与观察到的[相关基因]表达差异相关的关键因素，进而导致了谷子颜色的差异。
