Carotenoid Cleavage Dioxygenase 1 Catalyzes Lutein Degradation To Influence Carotenoid Accumulation and Color Development in Foxtail Millet Grains
Carotenoid Cleavage Dioxygenase 1 Catalyzes Lutein Degradation To Influence Carotenoid Accumulation and Color Development in Foxtail Millet Grains
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DOI：
10.1021/acs.jafc.2c01951
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发表时间：
2022-07-25
影响因子：
6.1
通讯作者：
Zhang, Bin
中科院分区：
文献类型：
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作者：
He, Lu;Cheng, Lu;Zhang, Bin
小米是世界上某些地区的一种次要但经济上重要的作物。小米颜色常被用来判断谷物品质，但小米颜色的分子决定因素仍不清楚。本研究探讨了SiCCD 1基因与黄粟和白色粟籽粒着色的关系。类胡萝卜素水平随着籽粒成熟而下降，并与SiCCD 1表达呈负相关，在颜色发育阶段，白色小米中SiCCD 1的表达显著高于黄色小米。从这些不同的小米品种的SiCCD 1启动子和CDS序列的克隆揭示了在白色小米品种的SiCCD 1启动子内存在两个额外的顺式调节元件，包括与缺氧特异性诱导相关的增强子样GC基序元件和与胚乳表达相关的GCN 4基序元件。双荧光素酶报告基因测定证实，来自白色小米品种的含有这些额外顺式作用元件的SiCCD 1启动子片段比来自黄色小米品种的SiCCD 1启动子片段显着更活跃，这与观察到的SiCCD 1表达模式一致。进一步的体外酶检测试验证实SiCCD 1主要靶向并降解叶黄素。总之，这些数据表明SiCCD 1启动子变异是与观察到的SiCCD 1表达差异相关的关键因素，这反过来又导致了小米着色的差异。
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 SiCCD1 and millet coloration in yellow and white millet varieties. Carotenoid levels declined with grain maturation and were negatively correlated with SiCCD1 expression, which was significantly higher in white millet as compared to yellow millet during the color development stage. Cloning of the SiCCD1 promoter and CDS sequences from these different millet varieties revealed the presence of two additional cis-regulatory elements within the SiCCD1 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 SiCCD1 promoter fragments containing these additional cis-acting elements derived from white millet varieties were significantly more active than those from yellow millet varieties, consistent with the observed SiCCD1 expression patterns. Further in vitro enzyme detection assays confirmed that SiCCD1 primarily targets and degrades lutein. Together, these data suggest that SiCCD1 promoter variation was a key factor associated with the observed differences in SiCCD1 expression, which in turn led to the difference in millet coloration.