Contribution of the mevalonate and methylerythritol phosphate pathways to the biosynthesis of gibberellins in Arabidopsis
Contribution of the mevalonate and methylerythritol phosphate pathways to the biosynthesis of gibberellins in Arabidopsis
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DOI：
10.1074/jbc.m208659200
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发表时间：
2002-11-22
影响因子：
4.8
通讯作者：
Yamaguchi, S
中科院分区：
文献类型：
--
作者：
Kasahara, H;Hanada, A;Yamaguchi, S
赤霉素(GAs)是一种二萜植物激素，在许多发育过程中都是必不可少的。虽然GA生物合成途径已经得到了很好的研究，但我们对其早期阶段的了解仍然有限。异戊二烯类化合物的生物合成有两条可能的途径，一条是胞质中的甲氧戊酸(MVA)途径，另一条是质体内的甲基赤藓糖醇磷酸(MEP)途径。为了区分这些可能性，在拟南芥幼苗中，每个类异戊二烯途径的代谢物被选择性地用C-13标记。有效的C-13标记是通过在MVA或MEP途径特异性的C-13标记前体的喂养过程中从化学或遗传上阻断内源途径来实现的。气相色谱-质谱联用分析表明，MVA和MEP途径均可促进拟南芥幼苗GAS和油菜籽甾醇(一种胞质甾醇)的生物合成。虽然GAs主要通过MEP途径合成，但MVA途径在油菜籽甾醇的生物合成中起着重要作用。与两条通路之间的某些交叉一致，MVA和MEP通路受阻导致的表型缺陷分别被外源MEP和MVA前体应用部分挽救。我们还提供了证据表明，当MVA途径是有限的时，该途径仍然有助于GA的生物合成。
Gibberellins (GAs) are diterpene plant hormones essential for many developmental processes. Although the GA biosynthesis pathway has been well studied, our knowledge on its early stage is still limited. There are two possible routes for the biosynthesis of isoprenoids leading to GAs, the mevalonate (MVA) pathway in the cytosol and the methylerythritol phosphate (MEP) pathway in plastids. To distinguish these possibilities, metabolites from each isoprenoid pathway were selectively labeled with C-13 in Arabidopsis seedlings. Efficient C-13-labeling was achieved by blocking the endogenous pathway chemically or genetically during the feed of a C-13-labeled precursor specific to the MVA or MEP pathways. Gas chromatography-mass spectrometry analyses demonstrated that both MVA and MEP pathways can contribute to the biosyntheses of GAs and campesterol, a cytosolic sterol, in Arabidopsis seedlings. While GAs are predominantly synthesized through the MEP pathway, the MVA pathway plays a major role in the biosynthesis of campesterol. Consistent with some crossover between the two pathways, phenotypic defects caused by the block of the MVA and MEP pathways were partially rescued by exogenous application of the MEP and MVA precursors, respectively. We also provide evidence to suggest that the MVA pathway still contributes to GA biosynthesis when this pathway is limiting.