Liu Touming, Zhu Siyuan, Tang Qingming, Tang Shouwei
Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China.
Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, China.
Gene. 2015 Apr 10;560(1):63-70. doi: 10.1016/j.gene.2015.01.045. Epub 2015 Jan 24.
Ramie is an important natural fiber and forage crop in China. Breeding of late- or non-flowering varieties, with higher vegetative yields, is an important goal in ramie improvement. However, the ramie genes involved in flowering regulation have not previously been identified. In model plants, such as rice and Arabidopsis, the CONSTANS (CO) and CONSTANS-like (COL) genes play key roles in flowering regulation. In the present study, six ramie COL genes (BnCOL1-BnCOL6) with a full-length open reading frame (ORF) were identified. Sequence alignment revealed that all six BnCOL proteins contained conserved CCT (CO, COL, TOC1) and B-box I domains, but that only four of these proteins contained the B-box II domain. Expression pattern analysis showed that BnCOL1-BnCOL6 were mainly expressed in the stem xylem, flowers, and leaves. Phylogenetic analysis classified the six newly identified BnCOL proteins, and also 16 COL proteins with known functions in other species, into three groups. The BnCOL2-encoded protein was assigned to the same group as the CO- and Hd1-encoded proteins, suggesting that this BnCOL2-encoded protein showed the highest level of homology with the CO/Hd1-encoded proteins. Photoperiodic experiments showed that BnCOL2 exhibited a diurnal expression pattern under long- and short-day conditions. Subcellular localization examination revealed that the BnCOL2 protein fused with YFP was localized in the nucleus. Because the homologous sequence and similar expression pattern between BnCOL2 and CO/Hd1, the BnCOL2 possibly has a role in flowering modulation, and can be used as a candidate gene for research in the flowering regulation of ramie.
苎麻是中国一种重要的天然纤维和饲料作物。培育营养产量更高的晚花或无花品种是苎麻改良的一个重要目标。然而，此前尚未鉴定出参与苎麻开花调控的基因。在水稻和拟南芥等模式植物中，CONSTANS（CO）和CONSTANS-like（COL）基因在开花调控中起关键作用。在本研究中，鉴定出了六个具有全长开放阅读框（ORF）的苎麻COL基因（BnCOL1-BnCOL6）。序列比对显示，所有六个BnCOL蛋白都含有保守的CCT（CO、COL、TOC1）和B-box I结构域，但其中只有四个蛋白含有B-box II结构域。表达模式分析表明，BnCOL1-BnCOL6主要在茎木质部、花和叶中表达。系统发育分析将新鉴定的六个BnCOL蛋白以及其他物种中16个具有已知功能的COL蛋白分为三组。BnCOL2编码的蛋白与CO和Hd1编码的蛋白归为同一组，这表明该BnCOL2编码的蛋白与CO/Hd1编码的蛋白具有最高水平的同源性。光周期实验表明，BnCOL2在长日照和短日照条件下均呈现昼夜表达模式。亚细胞定位检查显示，与YFP融合的BnCOL2蛋白定位于细胞核。由于BnCOL2与CO/Hd1之间存在同源序列和相似的表达模式，BnCOL2可能在开花调控中发挥作用，可作为苎麻开花调控研究的候选基因。
