Integrated metabolomic and transcriptomic analyses of high-tryptophan rice expressing a mutant anthranilate synthase alpha subunit
Integrated metabolomic and transcriptomic analyses of high-tryptophan rice expressing a mutant anthranilate synthase alpha subunit
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DOI：
10.1093/jxb/erm179
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发表时间：
2007-10-01
影响因子：
6.9
通讯作者：
Wakasa, Kyo
中科院分区：
文献类型：
--
作者：
Dubouzet, Joseph G.;Ishihara, Atsushi;Wakasa, Kyo
过度表达邻氨基苯甲酸合酶α亚基突变水稻基因（OASA1D）的转基因水稻植物积累大量游离色氨酸（Trp），除了发芽不良和幼苗生长弱外，对表型几乎没有不利影响。代谢专业人士。通过高效液相色谱-光电二极管阵列 (HPLC-PDA) 对日本晴的 8 日龄幼苗和两个高色氨酸品系 HW1 和 HW5 进行分析，证实相对于日本晴，OASA1D 品系的谱中只有色氨酸峰发生了显着变化。使用 HPLC 结合串联质谱进行更详细和有针对性的分析表明，OASA1D 品系的邻氨基苯甲酸、色胺和血清素水平高于日本晴，但这些代谢物的水平远低于游离色氨酸。苯丙氨酸（Phe）和酪氨酸（Tyr）的水平不受色氨酸过量产生的影响。通过定量实时 PCR (qRT-PCR) 验证的微阵列转录组分析表明，21 500 个基因中至少有 12 个在基因型之间表现出显着差异表达。除了 OASA1D 转基因和推定的 IAA β-葡萄糖基转移酶外，这些都与色氨酸代谢无关。最重要的是，OASA1D 的过度表达以及随后的色氨酸在这些细胞系中的积累对整体转录组几乎没有影响，这与对生长和代谢组的最小影响一致。对这些 OASA1D 转基因株系的代谢组和转录组的综合分析表明，游离色氨酸的过度积累可能部分是由于色氨酸脱羧酶或直接利用色氨酸作为底物的其他代谢基因的低活性所致。
Transgenic rice plants overexpressing a mutant rice gene for anthranilate synthase alpha subunit (OASA1D) accumulate large amounts of free tryptophan (Trp) with few adverse effects on the phenotype, except for poor germination and weak seedling growth. Metabolic pro. ling of 8-d-old seedlings of Nipponbare and two high-Trp lines, HW1 and HW5, by high performance liquid chromatography-photo diode array (HPLC-PDA) confirmed that, relative to Nipponbare, only the peak attributed to Trp was significantly changed in the profiles of the OASA1D lines. More detailed and targeted analysis using HPLC coupled with tandem mass spectrometry revealed that the OASA1D lines had higher levels of anthranilate, tryptamine, and serotonin than Nipponbare, but these metabolites were at much lower levels than free Trp. The levels of phenylalanine (Phe) and tyrosine (Tyr) were not affected by the overproduction of Trp. Transcriptomic analysis by microarray validated by quantitative Real-Time PCR (qRT-PCR) revealed that at least 12 out of 21 500 genes showed significant differential expression among genotypes. Except for the OASA1D transgene and a putative IAA beta-glucosyltransferase, these were not related to Trp metabolism. Most importantly, the overexpression of the OASA1D and the consequent accumulation of Trp in these lines had little effect on the overall transcriptome, consistent with the minimal effects on growth and the metabolome. Integrated analysis of the metabolome and transcriptome of these OASA1D transgenic lines indicates that the over-accumulation of free Trp may be partly due to the low activity of Trp decarboxylase or other metabolic genes that directly utilize Trp as a substrate.