Article Figures & Data
Figures
- Fig. 1.
Proposed biosynthesis pathways for brassinolide from campesterol. Conversions marked with asterisks are hypothetical. Lesions in the BR biosynthesis of Arabidopsis mutantsdet2, dwf4, and cpd are shown.
- Fig. 2.
Effects of brassinolide and its biosynthetic precursors on the internode length of lkb plants of pea. The lengths of the fourth and fifth internodes were measured 3 d after the fourth internodes were treated. Results are means ±se (n = 5). Campesterol and campestanol were applied in lanolin paste.
- Fig. 3.
The sterol biosynthesis pathways. Lesions in the BR biosynthesis of the lkb mutant of pea are shown.
- Fig. 4.
Proposed synthetic pathway from [25,26,27-2H7]24-methylenecholesterol to [26,27-2H6] campesterol.
Tables
Genotype No. of Plants Plant Height-a No. of Expanded Leaves per Shoot-a Total Wt Averaged Wt per Shoot cm g WT 190 28.9 ± 0.9 7.80 ± 0.1 435 2.29 lka 192 20.0 ± 0.3 7.04 ± 0.1 395 2.06 lkb 218 19.8 ± 0.3 7.48 ± 0.1 481 2.21 These plant materials were used for analyses of endogenous BRs (TableII) and sterols (Table III).
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↵F0-a Data are means ± se of 25 plants randomly selected.
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BR BR Level WT lka lkb ng kg−1 fresh wt Brassinolide ND1-a ND ND Castasterone 491 ± 0.3 3005 ± 2.5 112 ± 0.2 Typhasterol 26 ± 0.1 39 ± 1.5 4 ± 0.0 3-Dehydroteasterone 20 ± 1.4 21 ± 1.9 15 ± 0.4 Teasterone 5 ± 0.1 5 ± 0.5 4 ± 0.2 6-Deoxocastasterone 2937 ± 22 4053 ± 73 208 ± 7.8 6-Deoxotyphasterol 835 ± 2.1 983 ± 17 245 ± 13 3-Dehydro-6-deoxoteasterone 182 ± 1.9 339 ± 4.2 101 ± 4.1 6-Deoxoteasterone 180 ± 2.8 197 ± 1.1 176 ± 2.9 The levels of BRs were determined by GC-SIM using 2H internal standards. Data are means ± se of duplicate determinations.
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↵F1-a ND, Not detected.
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- Table III.
Endogenous levels of sterols in 49-d-old shoots and mature seeds of WT, lka, and lkb of pea
Sterol Sterol Level WT lka lkb Shoot Seed Shoot Seed Shoot Seed μg g−1 fresh wt 24-Methylenecholesterol 0.7 ± 0.0 ND2-a 0.5 ± 0.0 ND 17.5 ± 0.2 14.5 ± 0.4 Campesterol/24-epicampesterol 21.1 ± 0.1 85.8 ± 1.0 25.0 ± 0.4 88.2 ± 2.0 2.3 ± 0.0 6.0 ± 0.0 Campestanol/24-epicampestanol 1.3 ± 0.0 5.3 ± 0.1 1.4 ± 0.0 5.7 ± 0.0 0.1 ± 0.0 0.5 ± 0.0 Isofucosterol 20.3 ± 0.2 6.8 ± 0.1 16.5 ± 0.3 6.1 ± 0.1 252.5 ± 2.0 1514.5 ± 20 Sitosterol 122.4 ± 0.8 872.0 ± 17 143.5 ± 0.8 943.2 ± 39 11.7 ± 0.1 21.7 ± 0.2 Stigmasterol 46.9 ± 0.2 42.0 ± 1.1 57.5 ± 0.4 60.4 ± 2.1 0.6 ± 0.0 4.4 ± 0.0 Sitostanol 5.8 ± 0.0 15.9 ± 0.3 6.3 ± 0.0 15.7 ± 0.1 ND ND Cholesterol 1.4 ± 0.0 1.4 ± 0.0 1.2 ± 0.0 2.2 ± 0.0 2.0 ± 0.0 1.9 ± 0.0 Total sterols 219.9 1029.2 251.9 1121.5 286.7 1563.5 End-pathway sterols2-b 191.8 1001.2 227.2 1094.0 16.6 34.0 - Table IV.
Effects of brassinolide on the growth and sterol levels of WT, lka, and lkb shoots of pea
Growth and Level WT lka lkb Control Brassinolide (100 ng) Control Brassinolide (100 ng) Control Brassinolide (100 ng) Profile Fourth internode length (mm ±se) 11.2 ± 0.4 17.2 ± 0.6 7.7 ± 0.2 11.5 ± 0.4 8.7 ± 0.2 21.4 ± 0.7 Averaged weight per apical segment (g) 0.18 0.22 0.19 0.22 0.19 0.27 Sterol (μg g−1 fresh wt) 24-Methylenecholesterol 1.2 ± 0.0 1.4 ± 0.0 1.5 ± 0.0 1.9 ± 0.1 43.7 ± 0.4 32.1 ± 0.3 Campesterol/24-epicampesterol 38.3 ± 0.2 39.0 ± 0.1 49.9 ± 0.1 46.0 ± 0.3 2.0 ± 0.1 1.3 ± 0.0 Campestanol/24-epicampestanol 0.9 ± 0.0 0.8 ± 0.0 1.3 ± 0.0 1.4 ± 0.0 0.1 ± 0.0 0.1 ± 0.0 Isofucosterol 32.2 ± 0.3 31.1 ± 0.1 21.4 ± 0.0 26.8 ± 0.3 311.8 ± 8.0 161.1 ± 2.5 Sitosterol 100.5 ± 0.4 100.2 ± 2.2 131.7 ± 1.4 121.1 ± 0.3 9.5 ± 0.0 6.5 ± 0.1 Stigmasterol 132.0 ± 0.0 132.5 ± 1.3 144.9 ± 0.3 137.8 ± 1.1 0.8 ± 0.0 0.5 ± 0.0 Sitostanol 3.3 ± 0.0 3.2 ± 0.0 4.7 ± 0.2 4.4 ± 0.0 ND3-a ND Cholesterol 7.2 ± 0.1 8.4 ± 0.1 16.9 ± 0.2 13.9 ± 0.1 7.7 ± 0.0 3.4 ± 0.0 Total sterols (μg g−1 fresh wt) 315.6 316.6 372.3 353.3 375.6 205.0 Total sterols (μg per segment) 56.9 69.6 70.8 77.7 71.4 55.5 Third leaves of 8-d-old seedlings (n = 20) were treated with brassinolide. After 2 d growth data and sterol levels were determined. The levels of sterols were determined by GC-SIM using [2H6]campestanol as an internal standard. Sterol levels are expressed as means ± se of duplicate determinations.
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↵F3-a ND, Not detected.
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- Table V.
Subcellular distribution of sterols in 23-d-old WT, lka, and lkb seedlings of pea
Sterol Sterol Composition Microsomal fraction Soluble fraction Whole shoot WT lka lkb WT lka lkb WT lka lkb % wt of total sterols 24-Methylenecholesterol ND4-a ND 3 ND ND ND ND ND 9 Campesterol/24-epicampesterol 9 10 4 11 11 11 11 12 1 Campestanol/24-epicampestanol 1 1 0.5 1 5 2 0.5 0.5 0.1 Isofucosterol 8 7 64 ND ND 2 14 10 88 Sitosterol 52 52 25 73 74 73 38 38 1 Stigmasterol 24 25 0.5 1 1 2 34 37 0.4 Sitostanol 3 3 1 1 1 1 2 2 ND Cholesterol 3 2 2 13 8 9 0.5 0.5 0.5 Sterols were quantified by GC-SIM using [2H6]campestanol as an internal standard. Data determined in duplicates were averaged and used to calculate sterol compositions.
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↵F4-a ND, Not detected.
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