Ramsay Nicola A, Walker Amanda R, Mooney Mark, Gray John C
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
Plant Mol Biol. 2003 Jun;52(3):679-88. doi: 10.1023/a:1024852021124.
Basic helix-loop-helix (bHLH) proteins, similar to mammalian Myc transcription factors, regulate the anthocyanin biosynthetic pathway in both monocots and dicots. Two Arabidopsis bHLH genes, GLABRA3 (GL3) and MYC-146, encode proteins that are similar throughout the predicted amino acid sequence to R and DELILA, which regulate anthocyanin production in maize and snapdragon, respectively. Northern blot analysis indicates that MYC-146 is most highly expressed in flower buds and flowers. Expression of a MYC-146 cDNA from the CaMV 35S promoter was unable to complement the anthocyanin deficiency in a ttg1 mutant of Arabidopsis and resulted in no obvious phenotypic change in Columbia plants. However, transient expression of GL3 and MYC-146 upon microprojectile bombardment of petals of a white-flowered mutant of Matthiola incana was able to complement anthocyanin deficiency. The lack of anthocyanin-deficient Arabidopsis mutants mapping to the locations of GL3 and MYC-146 suggests that the two bHLH proteins may be partially redundant and overlap in function.
与哺乳动物的Myc转录因子相似，碱性螺旋-环-螺旋（bHLH）蛋白在单子叶植物和双子叶植物中均调控花青素生物合成途径。拟南芥的两个bHLH基因，即GLABRA3（GL3）和MYC-146，所编码的蛋白质在预测的氨基酸序列上与R和DELILA相似，它们分别调控玉米和金鱼草中的花青素生成。Northern杂交分析表明，MYC-146在花芽和花中表达量最高。来自CaMV 35S启动子的MYC-146 cDNA的表达无法弥补拟南芥ttg1突变体中的花青素缺陷，并且在哥伦比亚植株中未导致明显的表型变化。然而，对白花突变型紫罗兰花瓣进行微粒轰击时，GL3和MYC-146的瞬时表达能够弥补花青素缺陷。缺乏定位到GL3和MYC-146位置的花青素缺陷型拟南芥突变体，这表明这两种bHLH蛋白可能在功能上部分冗余且有重叠。
