Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, No. 1 Qianhu Houcun, Nanjing, 210014, Jiangsu, China.
Planta. 2017 Oct;246(4):763-778. doi: 10.1007/s00425-017-2731-7. Epub 2017 Jul 3.
The contribution of variations in coding regions or promoters to the changes in FAE1 expression levels have be quantified and compared in parallel by specifically designed swapping constructs. FATTY ACID ELONGATION1 (FAE1) is a key gene in control of erucic acid synthesis in plant seeds. The expression of FAE1 genes in Brassica oleracea and Capsella rubella, representatives of high and low erucic acid species, respectively, was characterized to provide insight into the regulation of very long-chain fatty-acid biosynthesis in seeds. Virtually, no methylation was detected either in B. oleracea or in C. rubella, suggesting that modification of promoter methylation might not be a predominant mechanism. Swapping constructs were specifically designed to quantify and compare the contribution of variations in coding regions or promoters to the changes in FAE1 expression levels in parallel. A significantly higher fold change in erucic acid content was observed when swapping coding regions rather than when swapping promoters, indicating that the coding region is a major determinant of the catalytic power of β-ketoacyl-CoA synthase proteins. Common motifs have been proposed as essential for the preservation of basic gene expression patterns, such as seed-specific expression. However, the occurrence of variation in common cis-elements or the presence of species-specific cis-elements might be plausible mechanisms for changes in the expression levels in different organisms. In addition, conflicting observations in previous reports associated with FAE1 expression are discussed, and we suggest that caution should be taken when selecting a plant transformation vector and in interpreting the results obtained from vectors carrying the CaMV 35S promoter.
通过专门设计的交换构建体，已经定量并平行比较了编码区或启动子中的变异对 FAE1 表达水平变化的贡献。脂肪酸延长酶 1（FAE1）是控制植物种子中芥酸合成的关键基因。分别对甘蓝型油菜和毛蕊花，高和低芥酸物种的代表，的 FAE1 基因的表达进行了表征，以深入了解种子中非常长链脂肪酸生物合成的调控。实际上，在甘蓝型油菜或毛蕊花中几乎没有检测到甲基化，这表明启动子甲基化的修饰可能不是主要机制。专门设计了交换构建体来定量并平行比较编码区或启动子中的变异对 FAE1 表达水平变化的贡献。当交换编码区而不是交换启动子时，观察到芥酸含量的折叠变化明显更高，这表明编码区是β-酮酰基辅酶 A 合酶蛋白催化能力的主要决定因素。已经提出了共同基序作为保留基本基因表达模式（如种子特异性表达）的必需条件。然而，在不同生物体中，共同顺式元件的变异或特定物种顺式元件的存在可能是表达水平变化的合理机制。此外，还讨论了与 FAE1 表达相关的先前报告中的矛盾观察结果，并建议在选择植物转化载体时应谨慎，并在解释携带 CaMV 35S 启动子的载体获得的结果时应谨慎。
