Transcriptional regulation of proline biosynthesis in Medicago truncatula reveals developmental and environmental specific features
Transcriptional regulation of proline biosynthesis in Medicago truncatula reveals developmental and environmental specific features
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DOI：
10.1111/j.0031-9317.2004.00251.x
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发表时间：
2004-03-01
影响因子：
6.4
通讯作者：
Savouré, A
中科院分区：
文献类型：
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作者：
Armengaud, P;Thiery, L;Savouré, A
与许多其他生物体一样，模式豆科植物蒺藜苜蓿（Medicago truncatula）会积累游离脯氨酸以应对高渗胁迫。为了分析M. truncatula脯氨酸生物合成的转录调控，分离了编码Delta(1)-吡咯啉-5-羧酸合成酶（P5CS1、P5CS2；EC未分配）和鸟氨酸δ-转氨酶（OAT；EC 2.6.1.13）的三个cDNA。 cDNA 与其他植物序列具有高度同源性，基因组组织分析表明存在两个 P5CS 和两个推定的 OAT 基因。两个 P5CS 基因根据器官和对渗透压的反应表现出不同的转录水平调节。不同植物器官中的 MtP5CS1 稳态转录物水平与脯氨酸水平相关，但转录物丰度不受渗透胁迫的影响。 MtP5CS2 转录本在所有器官中均检测不到，但在盐胁迫植物的芽中大量积累。我们建议将 MtP5CS1 和 MtP5CS2 的特异性分别作为管家产品和应激特异性亚型。 MtOAT 转录物主要在未受胁迫的植物的根和芽中检测到。无论处于哪个发育阶段，盐胁迫处理都会诱导整个植物中 MtOAT 转录本的积累。在盐胁迫根中，发现脯氨酸和 MtOAT 转录物积累之间呈正相关。这些结果表明，鸟氨酸和谷氨酸生物合成途径均有助于渗透胁迫诱导的蒺蒺藜中脯氨酸的积累。
The model legume plant Medicago truncatula accumulates free proline in response to hyperosmotic stress as do many other organisms. In order to analyse the transcriptional regulation of proline biosynthesis in M. truncatula, three cDNAs encoding Delta(1)-pyrroline-5-carboxylate synthetase (P5CS1, P5CS2; EC not assigned) and ornithine delta-aminotransferase (OAT; EC 2.6.1.13) were isolated. The cDNAs shared high homologies with the other plant sequences and genomic organization analysis indicated the presence of two P5CS and two putative OAT genes. The two P5CS genes showed differing transcript level regulation according to organs and in response to osmotic stress. MtP5CS1 steady-state transcript levels in the different plant organs were correlated with proline levels but transcript abundance was unaffected by osmotic stresses. MtP5CS2 transcripts were poorly detected in all organs but were strongly accumulated in shoots of salt-stressed plants. We suggest a specific of MtP5CS1 and MtP5CS2 as a housekeeping product and as a stress specific isoform, respectively. MtOAT transcripts were predominantly detected in roots and shoots of unstressed plants. Salt-stress treatment induced the accumulation of MtOAT transcripts in the whole plant whatever the developmental stage. In salt-stressed roots, a positive correlation was found between proline and MtOAT transcript accumulation. These results suggest that both ornithine and glutamate biosynthesis pathways contribute to the osmotic stress-induced proline accumulation in M. truncatula.