Light-dependent induction of proline biosynthesis by abscisic acid and salt stress is inhibited by brassinosteroid in Arabidopsis
Light-dependent induction of proline biosynthesis by abscisic acid and salt stress is inhibited by brassinosteroid in Arabidopsis
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DOI：
10.1023/a:1022043000516
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发表时间：
2003-02-01
影响因子：
5.1
通讯作者：
Szabados, L
中科院分区：
文献类型：
--
作者：
Abrahám, E;Rigó, G;Szabados, L
脯氨酸是高等植物中重要的保护性渗透剂，渗透胁迫诱导的脯氨酸积累依赖于分别催化脯氨酸生物合成和降解限速步骤的 Delta(1)-吡咯啉-5-羧酸合酶 (P5CS) 和脯氨酸脱氢酶 (PDH) 的表达。拟南芥中脯氨酸代谢是通过 PDH 和重复 P5CS 基因的器官特异性表达的差异调节来调节的。脱落酸 (ABA) 和盐胁迫刺激脯氨酸合成与 P5CS1 表达的显着激活相关。相比之下，在光生长植物的芽和根中，P5CS2仅受到微弱的诱导，而PDH则受到ABA和盐胁迫的不同程度的抑制。在暗适应植物中，脯氨酸的积累以及 ABA 和盐胁迫对 P5CS1 的光依赖性诱导受到抑制。在暗适应过程中，P5CS2 也会下调，而枝条中的 PDH 表达显着增强。类固醇激素芸苔素内酯可模拟暗适应对 P5CS1 的抑制作用。然而，油菜素内酯不能刺激PDH，并且仅抑制芽中的P5CS2。在 ABA 过敏的 prl1 和油菜素类固醇缺陷的 det2 突变体中，脯氨酸积累和 P5CS1 转录的诱导同时增强，而 P5CS2 仅在 det2 突变体中表现出 ABA 和盐诱导的增强。相比之下，prl1突变降低了PDH表达的基础水平，而det2突变增强了ABA对PDH的抑制。因此，P5CS1 表达的调节似乎在控制拟南芥中 ABA 和盐胁迫刺激的脯氨酸积累方面发挥着主要作用。
Osmotic stress-induced accumulation of proline, an important protective osmolyte in higher plants, is dependent on the expression of Delta(1)-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (PDH) enzymes that catalyze the rate-limiting steps of proline biosynthesis and degradation, respectively. Proline metabolism is modulated by differential regulation of organ specific expression of PDH and duplicated P5CS genes in Arabidopsis. Stimulation of proline synthesis by abscisic acid (ABA) and salt stress correlates with a striking activation of P5CS1 expression. By contrast, P5CS2 is only weakly induced, whereas PDH is inhibited to different extent by ABA and salt stress in shoots and roots of light-grown plants. Proline accumulation and light-dependent induction of P5CS1 by ABA and salt stress is inhibited in dark-adapted plants. During dark adaptation P5CS2 is also down-regulated, whereas PDH expression is significantly enhanced in shoots. The inhibitory effect of dark adaptation on P5CS1 is mimicked by the steroid hormone brassinolide. However, brassinolide fails to stimulate PDH, and inhibits P5CS2 only in shoots. Proline accumulation and induction of P5CS1 transcription are simultaneously enhanced in the ABA-hypersensitive prl1 and brassinosteroid-deficient det2 mutants, whereas P5CS2 shows enhanced induction by ABA and salt only in the det2 mutant. In comparison, the prl1 mutation reduces the basal level of PDH expression, whereas the det2 mutation enhances the inhibition of PDH by ABA. Regulation of P5CS1 expression thus appears to play a principal role in controlling proline accumulation stimulated by ABA and salt stress in Arabidopsis.