scholarly journals Two UGT84A Family Glycosyltransferases Regulate Phenol, Flavonoid, and Tannin Metabolism in Juglans regia (English Walnut)

2021 ◽  
Vol 12 ◽  
Author(s):  
Houston J. Saxe ◽  
Takanori Horibe ◽  
Bipin Balan ◽  
Timothy S. Butterfield ◽  
Noah G. Feinberg ◽  
...  
Keyword(s):  
Gallic Acid ◽  
Transgenic Tobacco ◽  
Phenolic Acids ◽  
Transcriptome Analysis ◽  
Shikimic Acid ◽  
Juglans Regia ◽  
Shikimate Dehydrogenase ◽  
Shikimic Acid Pathway ◽  
Acid Pathway

We showed previously that gallic acid is produced in walnut from 3-dehydroshikimate by a shikimate dehydrogenase (JrSkDH). This study focuses on the next step in the hydrolysable tannin pathway, the formation of 1-O-galloyl-β-D-glucose from the phenolic gallic acid and UDP glucose by a glycosyltransferase. JrGGT1 (UGT84A73) and JrGGT2 (UGT84A74) are predicted to be two such glycosyltransferases, which we expressed in tobacco plants. GC-MS analysis of the transgenic tobacco revealed moderate, yet significant alterations in plant secondary metabolism, such as depleted phenolic acids, including gallic acid. We postulate that these effects are due to JrGGT1 and JrGGT2 activity, as JrGGT orthologs glycosylate these phenolic compounds in vitro. Moreover, JrGGT expression in tobacco caused upregulation of shikimic acid pathway metabolites and differing responses in phenylpropanoids, such as phenolic acids and flavonoids. In transcriptome analysis of walnut pellicle tissues, both JrGGTs showed substantial and significant expression correlations with the gallic acid-producing JrSkDHs and were highly coexpressed with the genetic circuits constituting the shikimic acid and phenylpropanoid biosynthetic pathways. Verification of JrGGT gene expression by transcriptome analysis of 20 walnut tissues revealed striking similarities with that of the pellicle data, with the greatest expression in roots, wood, buds, and leaves of Juglans regia cv. Chandler: tissues that typically accumulate hydrolysable tannins. Like the transgenic tobacco, pellicle metabolomic analyses revealed that many phenylpropanoids correlated negatively with JrGGT expression, while shikimic acid pathway metabolites correlated positively with JrGGT expression. This research supports the hypothesis that JrGGT1 and JrGGT2 play non-trivial roles in metabolism of phenolic acids, flavonoids, and ostensibly, tannins.

Regulation of Chloramphenicol Synthesis in Streptomyces sp. 3022a. 3-Deoxy-D-arabino-heptulosonate 7-Phosphate Synthetase

1971 ◽  
Vol 49 (4) ◽  
pp. 448-455 ◽  
Author(s):  
D. A. Lowe ◽  
D. W. S. Westlake
Keyword(s):  
Enzyme Activity ◽  
Shikimic Acid ◽  
Aromatic Amino Acids ◽  
Product Inhibition ◽  
Enzyme Synthesis ◽  
Synthetase Activity ◽  
Shikimic Acid Pathway ◽  
Sugar Phosphates ◽  
Acid Pathway ◽  
Single Enzyme

The repression and end-product inhibition of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthetase were studied in a chloramphenicol-producing Streptomycetes. Synthesis of DAHP synthetase was repressed by p-hydroxybenzoate, and enzyme activity was inhibited competitively by sugar phosphates, especially D-ribose 5-phosphate. The presence of chloramphenicol, aromatic amino acids, or shikimic acid pathway intermediates did not repress enzyme synthesis nor inhibit enzyme activity. Chloramphenicol production by growing cultures was not affected by the intermediates or end products of the shikimic acid pathway nor by the repression of DAHP synthetase. Purification of DAHP synthetase activity indicated the presence of a single enzyme protein with a molecular weight of 88 000.

scholarly journals The Evolution of Capsaicinoids during Fruit Development of Three Varieties of Hot Peppers

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 488B-488
Author(s):  
Margarita Contreras-Padilla ◽  
Elhadi M. Yahia
Keyword(s):  
Fruit Development ◽  
Fruit Set ◽  
Shikimic Acid ◽  
Maximum Activity ◽  
Main Element ◽  
Shikimic Acid Pathway ◽  
The Past ◽  
Hot Peppers ◽  
Acid Pathway ◽  
Chile Peppers

Hot chile peppers are the main element that characterizes the Mexican cuisine and culture for at least the past 8 centuries. The components responsible for chile hot flavor, capsaicinoids, are synthesized through the shikimic acid pathway. Their degradation is thought to be aided by the action of peroxidases. This work describes the evolution of capsaicinoids during the development of the fruit in three varieties of hot chile widely used in Mexico: `Habanero', `Arbol', and `Piquin', and its relation with the activity of peroxidases in these fruits. Plants were seeded and transplanted in a greenhouse and fruit were harvested after 10, 20, 30, 40, 50, and 60 days from fruit set. At 60 days from fruit set fruit were completely red and senescent. Total capsaicinoids, capsaicin, and dihidrocapsaicin were detected and quantified using HPLC. The activity of peroxidases was followed using spectrophotometry. Capsaicinoids were higher in the fruit of `Habanero', followed by `Arbol', and then by `Piquin'. Capsaicin was higher than dihidrocapsaicin in the three varieties. Capsaicinoids, capsaicin, and dihidrocapsaicin increased continuously and reached a peak at 50 days after fruit set in the varieties `Habanero' and `Arbol' and after 40 days in `Piquin', and then started to decline. Peroxidases had a maximum activity at pH 6.0, ≈1.0 mM of capsaicin, and 1.0–1.5 mM of H2O2. The activity of peroxidases was slightly high after 10 days from fruit set, decreased, and started to increase again after 50 days from fruit set, which might be related to the evolution of the capsaicinoids.

ʟ-Tyrosine as a Precursor of Flavonoids in Buckwheat Cotyledons

1985 ◽  
Vol 40 (3-4) ◽  
pp. 154-159 ◽  
Author(s):  
U. Margna ◽  
L. Laanest ◽  
E. Margna ◽  
T. Vainjärv
Keyword(s):  
Shikimic Acid ◽  
Incorporation Rate ◽  
Simultaneous Administration ◽  
Shikimic Acid Pathway ◽  
Acid Pathway ◽  
High Doses ◽  
Similar Decrease ◽  
Natural Precursor

Abstract Exogenous ʟ-tyrosine was incorporated 13 -14 times less effectively than exogenous L-phenylalanine into flavonoids in excised cotyledons of 3 days old buckwheat seedlings but proved to be an only 5 times poorer precursor when the experiments were carried out with 5 days old material. Simultaneous administration of ʟ-phenylalanine markedly reduced incorporation of ʟ-tyrosine into flavonoids. A similar decrease in the utilization of exogenous ʟ-tyrosine for flavonoid bio­ synthesis occurred in kinetin-treated cotyledons. However, in cotyledons treated with high doses of glyphosate, an inhibitor of the shikimic acid pathway, an increase in the formation of flavonoids from exogenously supplied ʟ-tyrosine was observed. Under all conditions the relative incorporation rate of exogenous L-tyrosine was highest for anthocyanins and lowest for C-glycosylflavones while within the latter class of compounds the luteolinic derivatives orientin and isoorientin incorporated more label than their apigeninic analogues vitexin and isovitexin. PAL and TAL activities were found to be present in the cotyledons in a ratio of 50:1. The possible role of ʟ-tyrosine as an alternative natural precursor for the biosynthesis of flavonoids and other related polyphenols is discussed.

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