Gibberellins in Higher Plants: The Biosynthetic Pathway Leading to GA1

1987 ◽  
pp. 25-43 ◽  
Author(s):  
C. R. Spray ◽  
B. O. Phinney
Keyword(s):  
Biosynthetic Pathway ◽  
Higher Plants

scholarly journals Dissection of the general two-step di-C-glycosylation pathway for the biosynthesis of (iso)schaftosides in higher plants

2020 ◽  
Vol 117 (48) ◽  
pp. 30816-30823
Author(s):  
Zi-Long Wang ◽  
Hao-Meng Gao ◽  
Shuang Wang ◽  
Meng Zhang ◽  
Kuan Chen ◽  
...  
Keyword(s):  
Defense Mechanisms ◽  
Biosynthetic Pathway ◽  
Higher Plants ◽  
Cereal Crops ◽  
High Homology ◽  
Efficient Synthesis ◽  
Bioactive Natural Products ◽  
Homologous Genes ◽  
Glycosylation Pathway

Schaftoside and isoschaftoside are bioactive natural products widely distributed in higher plants including cereal crops and medicinal herbs. Their biosynthesis may be related with plant defense. However, little is known on the glycosylation biosynthetic pathway of these flavonoid di-C-glycosides with different sugar residues. Herein, we report that the biosynthesis of (iso)schaftosides is sequentially catalyzed by twoC-glycosyltransferases (CGTs), i.e., CGTa forC-glucosylation of the 2-hydroxyflavanone aglycone and CGTb forC-arabinosylation of the mono-C-glucoside. The two enzymes of the same plant exhibit high homology but remarkably different sugar acceptor and donor selectivities. A total of 14 CGTa and CGTb enzymes were cloned and characterized from seven dicot and monocot plants, includingScutellaria baicalensis,Glycyrrhiza uralensis,Oryza sativassp.japonica, andZea mays, and the in vivo functions for three enzymes were verified by RNA interference and overexpression. Through transcriptome analysis, we found homologous genes in 119 other plants, indicating this pathway is general for the biosynthesis of (iso)schaftosides. Furthermore, we resolved the crystal structures of five CGTs and realized the functional switch of SbCGTb to SbCGTa by structural analysis and mutagenesis of key amino acids. The CGT enzymes discovered in this paper allow efficient synthesis of (iso)schaftosides, and the general glycosylation pathway presents a platform to study the chemical defense mechanisms of higher plants.

scholarly journals Investigation of the subcellular location of the tetrapyrrole-biosynthesis enzyme coproporphyrinogen oxidase in higher plants

1993 ◽  
Vol 292 (2) ◽  
pp. 503-508 ◽  
Author(s):  
A G Smith ◽  
O Marsh ◽  
G H Elder
Keyword(s):  
Biosynthetic Pathway ◽  
Higher Plants ◽  
Protoporphyrin Ix ◽  
Subcellular Location ◽  
Subcellular Fractionation ◽  
Radiochemical Method ◽  
Coproporphyrinogen Oxidase ◽  
Isotonic Buffer ◽  
Arum Maculatum ◽  
Cellular Organelles

The subcellular location of two enzymes in the biosynthetic pathway for protoporphyrin IX, coproporphyrinogen (coprogen) oxidase (EC 1.3.3.3) and protoporphyrinogen (protogen) oxidase (EC 1.3.3.4) has been investigated in etiolated pea (Pisum sativum) leaves and spadices of cuckoo-pint (Arum maculatum). Plant tissue homogenized in isotonic buffer was subjected to subcellular fractionation to prepare mitochondria and plastids essentially free of contamination by other cellular organelles, as determined by marker enzymes. Protogen oxidase activity measured fluorimetrically was reproducibly found in both mitochondria and etioplasts. In contrast, coprogen oxidase could be detected only in etioplasts, using either a coupled fluorimetric assay or a sensitive radiochemical method. The implications of these results for the synthesis of mitochondrial haem in plants is discussed.

The biosynthetic pathway of vitamin C in higher plants

Nature ◽  
10.1038/30728 ◽  
1998 ◽  
Vol 393 (6683) ◽  
pp. 365-369 ◽  
Author(s):  
Glen L. Wheeler ◽  
Mark A. Jones ◽  
Nicholas Smirnoff
Keyword(s):  
Vitamin C ◽  
Biosynthetic Pathway ◽  
Higher Plants

The biosynthesis of δ-aminolaevulinic acid in plants

1976 ◽  
Vol 273 (924) ◽  
pp. 99-108 ◽  
Keyword(s):  
Biosynthetic Pathway ◽  
Higher Plants ◽  
Condensation Reaction ◽  
Chemical Degradation ◽  
Plant Tissues ◽  
Bacterial Cells ◽  
Blue Green Algae ◽  
Aminolaevulinic Acid ◽  
Ala Biosynthesis

In animal and bacterial cells the first enzymic step unique to the tetrapyrrole biosynthetic pathway is the condensation of succinyl-CoA and glycine to yield δ-aminolaevulinic acid (ALA). The enzyme catalysing this reaction could not be detected in extracts from higher plants, or green or blue-green algae. Through the use of laevulinic acid, which competitively inhibits ALA dehydrase, and causes the accumulation of ALA in vivo , the ability of a number of specifically labelled 14 C radioactive compounds to label this ALA has been studied. Glycine and succinate are poor label donors, whereas α-ketoglutarate, glutamate and glutamine are able to donate 14 C to the ALA. Chemical degradation of the [ 14 C]ALA indicates that C 5 arises from C 1 of glutamate and the remaining four carbon atoms of the ALA arise from the remaining four carbon atoms of glutamate. This labelling pattern is incompatible with the succinyl-CoA-glycine condensation reaction and indicates a new pathway for ALA biosynthesis from the intact carbon skeleton of glutamate in greening plant tissues.

Herbicidal Inhibition of Carotenogenesis Detected by HPLC

1990 ◽  
Vol 45 (5) ◽  
pp. 492-497 ◽  
Author(s):  
Paul Barry ◽  
Ken E. Pallett
Keyword(s):  
Cell Suspension ◽  
Hplc Analysis ◽  
Biosynthetic Pathway ◽  
Higher Plants ◽  
Cell Suspension Cultures ◽  
Carotenoid Biosynthesis ◽  
Higher Plant ◽  
Target Sites ◽  
Carrot Cell ◽  
Carrot Cell Suspension

The target sites of three herbicides which inhibit carotenoid biosynthesis have been characterized using HPLC analysis of pigment extracts from two higher plant systems, carrot cell suspension cultures and barley seedlings. Diflufenican causes an accumulation of phytoene and phytofluene. Dichlormate causes accumulation of phytoene, phytofluene, ξ-carotene, neurosporene and β-zeacarotene. Amitrole causes accumulation of phytoene, phytofluene, β- γ- and δ-carotenes and lycopene. Significant differences in the geometric and hydroxylated natures of the accumulated precursors occurred between the carrot cell and dark- and light-grown barley. These differences are discussed with respect to both the target sites of the three carotenogenic herbicides and the biosynthetic pathway leading to carotenoid biosynthesis in higher plants.

Enzymatic synthesis of C40 carotenes by cell-free preparation from Halobacterium cutirubrum

1976 ◽  
Vol 54 (9) ◽  
pp. 816-823 ◽  
Author(s):  
Santosh C. Kushwaham ◽  
M. Kates ◽  
John W. Porter
Keyword(s):  
Enzymatic Synthesis ◽  
Biosynthetic Pathway ◽  
Higher Plants ◽  
Enzyme System ◽  
Glass Beads ◽  
Supernatant Fraction ◽  
Isopentenyl Pyrophosphate ◽  
Main Pathway ◽  
A Cell ◽  
Β Carotene

[14C]Mevalonate or [14C]isopentenyl pyrophosphate was found to be converted to trans-phytoene, trans-phytofluene, lycopene, and β-carotene by a cell-free 270 000 × g supernatant fraction prepared from Halobacterium cutirubrum cells that were broken by manual grinding with glass beads. Incubations were done under N2 in the dark at 37 °C in 4 M NaCl in presence of FAD, NADP, and MgCl2; ATP was also added when mevalonate was the substrate. This system was also capable of converting trans-[14C]phytoene to β-carotene via the intermediates trans-phytofluene, ζ-carotene, neurosporene, lycopene, and γ-carotene. Each of these labelled intermediates on incubation separately with the same enzyme system was shown to be converted to the intermediates farther down the pathway. The results of this study show that the biosynthetic pathway for the formation of C40 carotenes in H. cutirubrum proceeds as follows: isopentenyl pyrophosphate [Formula: see text] trans-phytoene → trans-phytofluene → ζ-carotene → neurosporene → lycopene → γ-carotene → β-carotene. This pathway differs from that in higher plants in that the cis isomers of phytoene and phytofluene are not on the main pathway of carotene biosynthesis, as they are in higher plants. Furthermore, trans-phytoene, which has not been reported to have any role in higher plants, appears to be the main intermediate in carotene biosynthesis in H. cutirubrum.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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