Identification of Two Brassinosteroids from the Cambial Region of Scots Pine (<i>Pinus silverstris</i>) by Gas Chromatography-Mass Spectrometry, after Detection Using a Dwarf Rice Lamina Inclination Bioassay

Kim, S. K.; H, Abe; Little, C. H. A.; Pharis, Richard P.

doi:10.1104/pp.94.4.1709

Cited by 67 publications

(26 citation statements)

References 17 publications

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“…And typhasterol was about one-tenth as active as castasterone. These relative values for inclination activity are almost the same as those reported by a rice lamina inclination assay using a cultivar Koshihikari used as the most common rice cuitivar for detecting brassinosteroids (Kim et al, 1990). Thus our rice lamina inclination assay using a cultivar Tongjin is also useful for examination of brassinosteroids structure-activity relationship.…”

Section: Selection Of a Korean Rice Cultivar For A Rice Lamina Inclinsupporting

confidence: 76%

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

Han

Nam

et al. 1997

J. Plant Biol.

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Effect of ABA, GA3, zeatin (Zea) and IAA on the inclination activity was examined by a rice lamina inclination assay using a Korean cultivar, Tongjin. Treatment with ABA, GA3, Zea or IAA alone failed to increase the inclination response significantly at the concentration tested from 0.1 ppm to 10 ppm. However, treatment with 0.1 and 1 ppm ABA in the presence of brassinolide inhibited the inclination activity induced by treatment with brassinolide alone. And treatment with 0.1 and 1 ppm GA~ or Zea in the presence of brassinolide strongly inhibited the inclination activity induced by treatment with brassinolide alone. On the other hand, the inclination activity by treatment with brassinolide alone was clearly promoted by treatment with 0.1 and 1 ppm IAA in the presence of brassinolide. Based on the synergistic effect induced by treatment with BR and IAA, we could develope an improved rice lamina inclination assay whose minimum detectable concentration of brassinolide is 0.00001 ppm/petri dish. The minimum detectable concentration in our assay was five times as low as that of the previous rice lamina inclination assay.

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Section: Selection Of a Korean Rice Cultivar For A Rice Lamina Inclinsupporting

confidence: 76%

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

Han

Nam

et al. 1997

J. Plant Biol.

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“…Furthermore, previous studies on the effects of BRs on vascular development indicated that BRs play a role in tracheary element formation (Clouse and Zurek, 1991;Iwasaki and Shibaoka, 1991). Because BRs also have been found in the cambial region of pine, indicative of an important role in this tissue (Kim et al, 1990), we hypothesize that the deficiency of BRs in dwarf mutants caused changes in cell fate in vascular cambial cells through yet unknown mechanisms. Accumulation of episterol with a simultaneous decrease of downstream intermediates, including 24-MC and CR, predicts that the C-5 desaturation step is blocked in dwf7-1 plants.…”

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confidence: 93%

The Arabidopsis dwf7/ste1 Mutant Is Defective in the Δ⁷ Sterol C-5 Desaturation Step Leading to Brassinosteroid Biosynthesis

et al. 1999

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Lesions in brassinosteroid (BR) biosynthetic genes result in characteristic dwarf phenotypes in plants.Understanding the regulation of BR biosynthesis demands continued isolation and characterization of mutants corresponding to the genes involved in BR biosynthesis. Here, we present analysis of a novel BR biosynthetic locus, dwarf7 ( dwf7 ). Feeding studies with BR biosynthetic intermediates and analysis of endogenous levels of BR and sterol biosynthetic intermediates indicate that the defective step in dwf7-1 resides before the production of 24-methylenecholesterol in the sterol biosynthetic pathway. Furthermore, results from feeding studies with 13 C-labeled mevalonic acid and compactin show that the defective step is specifically the ⌬ 7 sterol C-5 desaturation, suggesting that dwf7 is an allele of the previously cloned STEROL1 ( STE1 ) gene. Sequencing of the STE1 locus in two dwf7 mutants revealed premature stop codons in the first ( dwf7-2 ) and the third ( dwf7-1 ) exons. Thus, the reduction of BRs in dwf7 is due to a shortage of substrate sterols and is the direct cause of the dwarf phenotype in dwf7. INTRODUCTIONSterols are known to play at least two critical roles in plants: as bulk components of membranes regulating stability and permeability (Bach and Benveniste, 1997) and as precursors of growth-promoting brassinosteroids (BRs; . Sterol biosynthesis in plants has been studied extensively through enzyme purification or gene cloning (Grunwald, 1975;Goodwin, 1979; Benveniste, 1986; Bach and Benveniste, 1997). Figure 1 shows the proposed biosynthetic pathway from squalene to brassinolide (BL). A major difference between photosynthetic and nonphotosynthetic organisms is that cyclization of squalene 2,3-oxide is bifurcated to a different route for each system (Benveniste, 1986). In animals and yeast, squalene 2,3-oxide is cyclized to lanosterol, whereas in photosynthetic organisms it is cyclized to cycloartenol (Nes and McKean, 1977). Accordingly, photosynthetic organisms require somewhat different biosynthetic enzymes, such as cycloartenol synthase (Corey et al., 1993) and cycloeucalenol-obtusifoliol isomerase, which are required to open the cyclopropane ring in cycloartenol ( Figure 1). However, most of the enzymatic steps are shared between the two different pathways.In plants, sterols are subject to a series of modifications before conversion to BL. Different sterols, such as 24-methylenecholesterol (24-MC), campesterol (CR), isofucosterol, and sitosterol, are converted to the BL congeners dolicholide, BL, 28-homodolicholide, and 28-homoBL, respectively, in a species-specific manner (Fujioka et al., 1995;Sasse, 1997). The BR-specific pathway diverges into the early and the late C-6 oxidation pathways. In the early C-6 oxidation pathway, introduction of a 6-oxo group occurs before the vicinal hydroxylation reactions at the side chain, whereas it occurs after these hydroxylations in the late C-6 oxidation pathway (Figure 1; Choi et al., 1997).Several mutants, such as constitutive photomorphogenesis a...

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“…Although, the existence of BRs in vascular cells of pine tree has been reported (Kim et al, 1990), it is still unknown if BRs are biosynthesized in the vascular tissues themselves. Mathur and others indicated that a chimeric CPD promoter-uid gene is strongly expressed in palisade cells, suggesting that a key enzyme for synthesizing BRs is expressed in mesophyll cells (Mathur et al, 1998).…”

Section: Brs Rapidly Increase Before Entry Into the Final Stagementioning

confidence: 99%

Brassinosteroid Levels Increase Drastically Prior to Morphogenesis of Tracheary Elements

et al. 2001

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As the first step toward understanding the involvement of endogenous brassinosteroids (BRs) in cytodifferentiation, we analyzed biosynthetic activities of BRs in zinnia (Zinnia elegans L. cv Canary Bird) cells differentiating into tracheary elements. The results of feeding experiments suggested that both the early and late C6-oxidation pathways occur during tracheary element differentiation. Gas chromatography-mass spectrometry analysis revealed that five BRs, castasterone, typhasterol, 6-deoxocastasterone, 6-deoxotyphasterol, and 6-deoxoteasterone, actually existed in cultured zinnia cells and culture medium. Quantification of endogenous BRs in each stage of tracheary element differentiation by gas chromatography-mass spectrometry exhibited that they increased dramatically prior to the morphogenesis, which was consistent with the idea that BRs are necessary for the initiation of the final stage of tracheary element differentiation. Moreover, the proportion of each BR in culture medium was quite different from that in cells, suggesting that specific BRs are selectively secreted into medium and may function outside the cells.

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Identification of Two Brassinosteroids from the Cambial Region of Scots Pine (Pinus silverstris) by Gas Chromatography-Mass Spectrometry, after Detection Using a Dwarf Rice Lamina Inclination Bioassay

Cited by 67 publications

References 17 publications

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

The Arabidopsis dwf7/ste1 Mutant Is Defective in the Δ⁷ Sterol C-5 Desaturation Step Leading to Brassinosteroid Biosynthesis

Brassinosteroid Levels Increase Drastically Prior to Morphogenesis of Tracheary Elements

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Identification of Two Brassinosteroids from the Cambial Region of Scots Pine (Pinus silverstris) by Gas Chromatography-Mass Spectrometry, after Detection Using a Dwarf Rice Lamina Inclination Bioassay

Cited by 67 publications

References 17 publications

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

Optimization of a rice lamina inclination assay for detection of brassinosteroids: I. effect of phytohormones on the inclination activity

The Arabidopsis dwf7/ste1 Mutant Is Defective in the Δ7 Sterol C-5 Desaturation Step Leading to Brassinosteroid Biosynthesis

Brassinosteroid Levels Increase Drastically Prior to Morphogenesis of Tracheary Elements

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The Arabidopsis dwf7/ste1 Mutant Is Defective in the Δ⁷ Sterol C-5 Desaturation Step Leading to Brassinosteroid Biosynthesis