Metabolic profiling of tryptophan-overproducing rice calli that express a feedback-insensitive alpha subunit of anthranilate synthase.
The profile of aromatic metabolites in calli was compared between wild-type rice (Oryza sativa cv. Nipponbare) and tryptophan-overproducing transgenic rice lines that express a gene (OASA1D) for a feedback-insensitive alpha subunit of anthranilate synthase. Metabolic profiling by high-performance liquid chromatography coupled with photodiode array detection of ultraviolet absorbance revealed a total of 71 peaks in both wild-type and transgenic calli. Only a limited effect on the pattern of major aromatic compounds was observed in tryptophan-accumulating transgenic rice lines, with the exception of an approximately 80-fold increase in the amount of tryptophan. Expression of OASA1D induced relatively small changes in several minor metabolites. One of the minor metabolites whose abundance was increased by OASA1D expression was purified and identified as a previously unknown indole-alkaloid glucoside. The levels of free and conjugated forms of indole-3-acetic acid (IAA), a plant hormone derived from the tryptophan biosynthetic pathway, were determined separately by liquid chromatography and tandem mass spectrometry (LC-MS/MS). The amounts of both free IAA and its conjugates were increased in the transgenic calli, suggesting that the activity of anthranilate synthase or the concentration of tryptophan (or both) is an important determinant of IAA biosynthesis.
Morino
Keiko
K
Division of Applied Life Sciences, Department of Agriculture, Kyoto University, Kyoto, 606-8502 Japan.
Matsuda
Fumio
F
Miyazawa
Haruna
H
Sukegawa
Akiko
A
Miyagawa
Hisashi
H
Wakasa
Kyo
K
D000878:Anthranilate Synthase / Q000235:genetics / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D025461:Feedback, Physiological / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification; D007210:Indoleacetic Acids / Q000378:metabolism; D015394:Molecular Structure; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D014364:Tryptophan / Q000096:biosynthesis*
D005960:Glucosides; D007210:Indoleacetic Acids; D021122:Protein Subunits; C030737:indoleacetic acid; D014364:Tryptophan; D000878:Anthranilate Synthase