A novel dark-inducible protein, LeDI-2, and its involvement in root-specific secondary metabolism in Lithospermum erythrorhizon.
A novel dark-inducible protein, LeDI-2, and its involvement in root-specific secondary metabolism in Lithospermum erythrorhizon.
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DOI：
10.1104/pp.125.4.1831
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发表时间：
2001-04
期刊：
影响因子：
7.4
通讯作者：
K. Yazaki;Hideaki Matsuoka;K. Shimomura;Andreas Bechthold;Fumihiko Sato
中科院分区：
文献类型：
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作者：
K. Yazaki;Hideaki Matsuoka;K. Shimomura;Andreas Bechthold;Fumihiko Sato
紫草产生的红色萘醌色素是紫草素的衍生物。它们只在这种植物的根部积累。尽管其它环境条件被优化，紫草素的生物合成仍被光强烈抑制。因此，L.为研究紫草色素生物合成的调控机制，分离了红根暗诱导基因（LeDI）。LeDI-2具有严格的暗特异性表达，并以细胞悬浮培养和毛状根培养为模型系统对其进行了进一步的表征。其mRNA积累模式与紫草素相似。LeDI-2在完整植株中只在根中表达，其mRNA的纵向分布也与紫草素一致。LeDI-2编码一个114个氨基酸的疏水性多肽，与玉米根特异性多肽ZRP 3和水稻根特异性多肽RcC 3具有显著的相似性。LeDI-2反义DNA抑制L.刺桐根减少了紫草素的积累，而催化关键生物合成步骤的其它生物合成酶，例如对羟基苯甲酸：香叶基转移酶，显示出与野生型克隆相似的活性。这是第一次报道该基因参与次级代谢产物的产生而不影响生物合成酶的活性。
Lithospermum erythrorhizon produces red naphthoquinone pigments that are shikonin derivatives. They are accumulated exclusively in the roots of this plant. The biosynthesis of shikonin is strongly inhibited by light, even though other environmental conditions are optimized. Thus, L. erythrorhizon dark-inducible genes (LeDIs) were isolated to investigate the regulatory mechanism of shikonin biosynthesis. LeDI-2, showing the strict dark-specific expression, was further characterized by use of cell suspension cultures and hairy root cultures as model systems. Its mRNA accumulation showed a similar pattern with that of shikonin. In the intact plants LeDI-2 expression was observed solely in the root, and the longitudinal distribution of its mRNA was also in accordance to that of shikonin. LeDI-2 encoded a very hydrophobic polypeptide of 114 amino acids that shared significant similarities with some root-specific polypeptides such as ZRP3 (maize) and RcC3 (rice). Reduction of LeDI-2 expression by its antisense DNA in hairy roots of L. erythrorhizon decreased the shikonin accumulation, whereas other biosynthetic enzymes, e.g. p-hydroxybenzoic acid:geranyltransferase, which catalyzed a critical biosynthetic step, showed similar activity as the wild-type clone. This is the first report of the gene that is involved in production of secondary metabolites without affecting biosynthetic enzyme activities.