Zhao J, Williams C C, Last R L
Boyce Thompson Institute for Plant Research and Section of Genetics and Development, Cornell University, Tower Road, Ithaca, New York 14853-1801, USA.
Plant Cell. 1998 Mar;10(3):359-70. doi: 10.1105/tpc.10.3.359.
The tryptophan (Trp) biosynthetic pathway leads to the production of many secondary metabolites with diverse functions, and its regulation is predicted to respond to the needs for both protein synthesis and secondary metabolism. We have tested the response of the Trp pathway enzymes and three other amino acid biosynthetic enzymes to starvation for aromatic amino acids, branched-chain amino acids, or methionine. The Trp pathway enzymes and cytosolic glutamine synthetase were induced under all of the amino acid starvation test conditions, whereas methionine synthase and acetolactate synthase were not. The mRNAs for two stress-inducible enzymes unrelated to amino acid biosynthesis and accumulation of the indolic phytoalexin camalexin were also induced by amino acid starvation. These results suggest that regulation of the Trp pathway enzymes under amino acid deprivation conditions is largely a stress response to allow for increased biosynthesis of secondary metabolites. Consistent with this hypothesis, treatments with the oxidative stress-inducing herbicide acifluorfen and the abiotic elicitor alpha-amino butyric acid induced responses similar to those induced by the amino acid starvation treatments. The role of salicylic acid in herbicide-mediated Trp and camalexin induction was investigated.
色氨酸（Trp）生物合成途径可产生许多具有不同功能的次生代谢产物，预计其调控会响应蛋白质合成和次生代谢的需求。我们测试了Trp途径酶以及其他三种氨基酸生物合成酶对芳香族氨基酸、支链氨基酸或蛋氨酸饥饿的反应。在所有氨基酸饥饿测试条件下，Trp途径酶和胞质谷氨酰胺合成酶均被诱导，而蛋氨酸合成酶和乙酰乳酸合成酶则未被诱导。与氨基酸生物合成无关的两种应激诱导酶的mRNA以及吲哚类植物抗毒素camalexin的积累也受到氨基酸饥饿的诱导。这些结果表明，在氨基酸剥夺条件下，Trp途径酶的调控很大程度上是一种应激反应，以增加次生代谢产物的生物合成。与此假设一致，用氧化应激诱导除草剂三氟羧草醚和非生物激发子α-氨基丁酸处理诱导的反应与氨基酸饥饿处理诱导的反应相似。研究了水杨酸在除草剂介导的Trp和camalexin诱导中的作用。
