Distinct cell-specific expression patterns of early and late gibberellin biosynthetic genes during Arabidopsis seed germination
Distinct cell-specific expression patterns of early and late gibberellin biosynthetic genes during Arabidopsis seed germination
复制标题
拟南芥种子萌发过程中早期和晚期赤霉素生物合成基因不同细胞特异性的表达模式
DOI：
10.1046/j.1365-313x.2001.01168.x
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发表时间：
2001-11-01
期刊：
影响因子：
7.2
通讯作者：
Sun, TP
中科院分区：
文献类型：
--
作者：
Yamaguchi, S;Kamiya, Y;Sun, TP
赤霉素（GAs）是通过涉及几类酶的复杂途径生物合成的。为了预测单个GA生物合成步骤的位点，我们研究了萌发的拟南芥种子中编码早期和晚期GA生物合成酶的基因的细胞类型特异性表达。我们发现，表达的两个基因，AtGA 3 ox 1和AtGA 3 ox 2，编码GA 3-氧化酶，催化终端的生物合成步骤，主要定位于皮层和内皮层的胚轴在萌发的种子。由于另一个GA生物合成基因，AtKO 1，编码对映贝壳杉烯氧化酶，表现出类似的细胞特异性表达模式，我们预测，生物活性的GA的合成从对映贝壳杉烯氧化发生在种子萌发过程中相同的细胞类型。我们还表明，皮层细胞在萌发过程中扩大，这表明GA生产和响应之间的空间相关性。然而，启动子活性的AtCPS 1基因，负责GA生物合成的第一个承诺的步骤，只检测到在萌发种子的胚provasculature。当AtCPS 1的cDNA只在皮层和内皮层的非发芽的GA 1 -3种子（缺乏AtCPS 1）使用AtGA 3 ox 2启动子，发芽不耐GA生物合成抑制剂中的provasculature的表达。这些结果表明，在种子萌发过程中的GAs的生物合成发生在两个不同的位置与早期的步骤发生在provasculature和皮层和内皮层的后期步骤。这意味着GA生物合成途径的中间体的细胞间运输是产生生物活性GA所必需的。
Gibberellins (GAs) are biosynthesized through a complex pathway that involves several classes of enzymes. To predict sites of individual GA biosynthetic steps, we studied cell type-specific expression of genes encoding early and late GA biosynthetic enzymes in germinating Arabidopsis seeds. We showed that expression of two genes, AtGA3ox1 and AtGA3ox2, encoding GA 3-oxidase, which catalyzes the terminal biosynthetic step, was mainly localized in the cortex and endodermis of embryo axes in germinating seeds. Because another GA biosynthetic gene, AtKO1, coding for ent-kaurene oxidase, exhibited a similar cell-specific expression pattern, we predicted that the synthesis of bioactive GAs from ent-kaurene oxidation occurs in the same cell types during seed germination. We also showed that the cortical cells expand during germination, suggesting a spatial correlation between GA production and response. However, promoter activity of the AtCPS1 gene, responsible for the first committed step in GA biosynthesis, was detected exclusively in the embryo provasculature in germinating seeds. When the AtCPS1 cDNA was expressed only in the cortex and endodermis of non-germinating ga1-3 seeds (deficient in AtCPS1) using the AtGA3ox2 promoter, germination was not as resistant to a GA biosynthesis inhibitor as expression in the provasculature. These results suggest that the biosynthesis of GAs during seed germination takes place in two separate locations with the early step occurring in the provasculature and the later steps in the cortex and endodermis. This implies that intercellular transport of an intermediate of the GA biosynthetic pathway is required to produce bioactive GAs.