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Takao Yokota - One of the best experts on this subject based on the ideXlab platform.
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The last reaction producing Brassinolide is catalyzed by cytochrome P-450s, CYP85A3 in tomato and CYP85A2 in Arabidopsis.
The Journal of biological chemistry, 2005Co-Authors: Takahito Nomura, Takao Yokota, Tetsuo Kushiro, Yuji Kamiya, Gerard J. Bishop, Shinjiro YamaguchiAbstract:Brassinosteroids are steroidal hormones essential for the growth and development of plants. Brassinolide, the most biologically active brassinosteroid, has a seven-membered lactone ring that is formed by a Baeyer-Villiger oxidation of its immediate precursor castasterone. Despite its potential key role in controlling plant development, Brassinolide synthase has not been identified. Previous work has shown that the formation of castasterone from 6-deoxocastasterone is catalyzed by members of the CYP85A family of cytochrome P-450 monooxygenases. A null mutation in the tomato Dwarf (CYP85A1) gene, extreme dwarf (d(x)), causes severe dwarfism due to brassinosteroid deficiency, but the d(x) mutant still produces fruits. Here, we show that d(x) fruits contain Brassinolide at a higher level than wild-type fruits and that a new CYP85A gene, CYP85A3, is preferentially expressed in tomato fruits. Tomato CYP85A3 catalyzed the Baeyer-Villiger oxidation to produce Brassinolide from castasterone in yeast, in addition to the conversion of 6-deoxocastasterone to castasterone. We also show that Arabidopsis CYP85A2, which was initially characterized as castasterone synthase, also has Brassinolide synthase activity. Exogenous application of castasterone and Brassinolide to the Arabidopsis cyp85a1/cyp85a2 double mutant suggests that castasterone can function as an active brassinosteroid but that its conversion into Brassinolide is necessary for normal vegetative development in Arabidopsis. We postulate that castasterone is the major active brassinosteroid during vegetative growth in tomato, whereas Brassinolide may play an organ-specific role in fruit development in this species.
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Molecular characterization of the brassinosteroid-deficient lkb mutant in pea
Plant Molecular Biology, 2001Co-Authors: Lee Schultz, Takao Yokota, L. Huub J. Kerckhoffs, Ulrich Klahre, James B. ReidAbstract:The brassinosteriod-deficient lkb mutant of garden pea ( Pisum sativum L.) is characterized by an erectoides phenotype (reduced internode length, thickened stems, epinastic leaves), which is rescued by application of exogenous Brassinolide. We show that the LKB gene is the Arabidopsis DIMINUTO/DWARF-1 ( DIM/DWF1 ) homologue of pea. The DIM/DWF1 homologue from lkb plants contains a mutation that may result in reduced enzyme function, thus resulting in the previously shown accumulation of 24-methylenecholesterol and a deficiency of its hydrogenated product, campesterol. This ultimately leads to a deficiency of the biologically active brassionolide. The mutation in the lkb sequence cosegregates with the lkb phenotype. Northern analyis of the LKB gene revealed that the gene is ubiquitously expressed around the plant and that there is no evidence for negative feedback regulation of the gene.
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Identification and quantification of Brassinolide-related steroids in the insect gall and healthy tissues of the chestnut plant
Phytochemistry, 2001Co-Authors: Masahiro Arima, Takao Yokota, Nobutaka TakahashiAbstract:Abstract Castasterone and 6-deoxocastasterone were identified by GC/MS and/or selected ion monitoring not only in the insect gall of chestnut but also in the healthy tissues, including the shoot, leaf and flower bud. In addition, the gall was found to contain a small amount of Brassinolide. Brassinone, which had been reported to be present in the gall, could not be detected in these tissues. The contents of castasterone, 6-deoxocastasterone and Brassinolide, which were determined by using selected ion monitoring, are discussed.
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Brassinolide and [26, 28-2H6]Brassinolide Are Differently Demethylated by Loss of C-26 and C-28, Respectively, in Marchantia polymorpha
Plant & cell physiology, 2000Co-Authors: Tae-wuk Kim, Suguru Takatsuto, Takao Yokota, Soo Chul Chang, Jongkil Choo, Tsuyoshi Watanabe, June Seung Lee, Soon Young Kim, Seong-ki KimAbstract:Metabolism of Brassinolide in Marchantia polymorpha was investigated by use of in vivo suspension cultured cells. GC-MS analysis of metabolites derived from non-labelled Brassinolide and [26, 28-2H6] Brassinolide revealed that Brassinolide was converted to 26-norBrassinolide while [26, 28-2H6]Brassinolide to [26-2H3]28-norBrassinolide. It seems that Marchantia cells recognized [26, 28-2H6]Brassinolide as a xenobiotic rather than Brassinolide and deteriums attached to C-28 significantly affect demethylation reaction due to isotopic effect. Thus, demethylation of Brassinolide in planta seems to proceed by loss of C-26 rather than C-28. The present finding is the first evidence for demethylation metabolism of brassinosteroids. The biological activity of 26-norBrassinolide was 10-fold reduced as shown by the rice lamina inclination test. However, because of its high biological activity, it remains difficult to conclude whether or not C-26 demethylation serves as an important deactivation process of Brassinolide.
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Transcription of the Arabidopsis CPD gene, encoding a steroidogenic cytochrome P450, is negatively controlled by brassinosteroids
The Plant journal : for cell and molecular biology, 1998Co-Authors: Jaideep Mathur, Gunter Adam, Shozo Fujioka, Suguru Takatsuto, Takao Yokota, Gergely Molnár, Akira Sakurai, Brunhilde Voigt, Ferenc Nagy, Christoph MaasAbstract:Summary The Arabidopsis CPD gene encodes a cytochrome P450 steroid side-chain hydroxylase (CYP90) that plays an essential role in the biosynthesis of the plant hormone Brassinolide. Expression of the CPD gene is confined to cotyledons and leaf primordia in etiolated seedlings and detectable in the adaxial parenchyma of expanding leaves in light-grown plants. Transcription of the CPD gene is not affected by the plant growth factors auxin, ethylene, gibberellin, cytokinin, jasmonic acid and salicylic acid, but is specifically down-regulated by Brassinolide in both dark and light. Steady-state mRNA levels of a CPD promoter-driven uidA reporter gene correlate with the expression of resident CPD gene in transgenic plants. Intermediates of the early and late C-6 oxidation pathways of Brassinolide, carrying C-22 and C-23 side-chain hydroxyls, efficiently inhibit the activity of the CPD promoter. Repression of CPD transcription by brassinosteroids is sensitive to the protein synthesis inhibitor cycloheximide, indicating a requirement for de novo synthesis of a regulatory factor.
Nobutaka Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Identification and quantification of Brassinolide-related steroids in the insect gall and healthy tissues of the chestnut plant
Phytochemistry, 2001Co-Authors: Masahiro Arima, Takao Yokota, Nobutaka TakahashiAbstract:Abstract Castasterone and 6-deoxocastasterone were identified by GC/MS and/or selected ion monitoring not only in the insect gall of chestnut but also in the healthy tissues, including the shoot, leaf and flower bud. In addition, the gall was found to contain a small amount of Brassinolide. Brassinone, which had been reported to be present in the gall, could not be detected in these tissues. The contents of castasterone, 6-deoxocastasterone and Brassinolide, which were determined by using selected ion monitoring, are discussed.
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Metabolism of castasterone and Brassinolide in mung bean explant
Phytochemistry, 1993Co-Authors: Hiroyuki Suzuki, Seong-ki Kim, Nobutaka Takahashi, Takao YokotaAbstract:Abstract Different metabolism of Brassinolide and its biosynthetic precursor castasterone in explants of mung bean ( Vigna radiata ) seedlings is described. Castasterone was not converted to Brassinolide, but to unknown water-soluble metabolites in which major components seemed to be non-glycosidic and minor ones to be glycosidic. It is likely that castasterone is biologically active in its own right without conversion to Brassinolide. In contrast, Brassinolide was largely converted to 23- O -β- d -glucopyranoside. It seems that 23- O -glycosylation is important in deactivation of brassinosteriods in bean plants.
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Castasterone and Brassinolide in Raphanus sativus seeds
Phytochemistry, 1991Co-Authors: Jürgen Schmidt, Gunter Adam, Takao Yokota, Nobutaka TakahashiAbstract:Abstract Castasterone and Brassinolide have been identified from seeds of Raphanus sativus by GC-MS analysis. Comparative quantification experiments with seeds and germinated seeds carried out by GC-SIM indicated a remarkable difference in the ratio of brassinosteroids in favour of the formation of Brassinolide during germination.
Gunter Adam - One of the best experts on this subject based on the ideXlab platform.
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Transcription of the Arabidopsis CPD gene, encoding a steroidogenic cytochrome P450, is negatively controlled by brassinosteroids
The Plant journal : for cell and molecular biology, 1998Co-Authors: Jaideep Mathur, Gunter Adam, Shozo Fujioka, Suguru Takatsuto, Takao Yokota, Gergely Molnár, Akira Sakurai, Brunhilde Voigt, Ferenc Nagy, Christoph MaasAbstract:Summary The Arabidopsis CPD gene encodes a cytochrome P450 steroid side-chain hydroxylase (CYP90) that plays an essential role in the biosynthesis of the plant hormone Brassinolide. Expression of the CPD gene is confined to cotyledons and leaf primordia in etiolated seedlings and detectable in the adaxial parenchyma of expanding leaves in light-grown plants. Transcription of the CPD gene is not affected by the plant growth factors auxin, ethylene, gibberellin, cytokinin, jasmonic acid and salicylic acid, but is specifically down-regulated by Brassinolide in both dark and light. Steady-state mRNA levels of a CPD promoter-driven uidA reporter gene correlate with the expression of resident CPD gene in transgenic plants. Intermediates of the early and late C-6 oxidation pathways of Brassinolide, carrying C-22 and C-23 side-chain hydroxyls, efficiently inhibit the activity of the CPD promoter. Repression of CPD transcription by brassinosteroids is sensitive to the protein synthesis inhibitor cycloheximide, indicating a requirement for de novo synthesis of a regulatory factor.
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Role of a cytochrome P450-dependent monooxygenase in the hydroxylation of 24-epi-Brassinolide
Phytochemistry, 1997Co-Authors: Jochen Winter, Bernd Schneider, Dieter Strack, Gunter AdamAbstract:Abstract 24-epi-Brassinolide, exogenously applied to cell suspension cultures of Lycopersicon esculentum is hydroxylated at C-25 and C-26, respectively, followed by glucosylation of the newly formed hydroxyl group. Treatment of the cell cultures with the specific cytochrome P450 inhibitors, clotrimazole and ketoconazole, resulted in a strong decrease of only the C-25 hydroxylation, whereas hydroxylation at C-26 was not affected. The common cytochrome P450 inducers, ethanol, MnCl2, phenobarbital, pregnenolone 16α-carbonitrile or clofibrate, did not induce hydroxylation activity at C-25 or at C-26. In addition, substrate analogues (22S,23S-homoBrassinolide, 24-epi-castasterone, ecdysone, and 20-OH-ecdysone) were not accepted. Only application of 24-epi-Brassinolide and Brassinolide resulted in an increased activity of both the C-25- and C-26-hydroxylases. For further examination of the molecular level of this inducing effect, the influence of the protein biosynthesis inhibitor cycloheximide has been studied. Thus, increase of both hydroxylase activities is obviously based on gene expression by action of the substrates, 24-epi-Brassinolide and Brassinolide.
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Metabolic conversion of 24-epi-Brassinolide into pentahydroxylated brassinosteroid glucosides in tomato cell cultures
Phytochemistry, 1995Co-Authors: Tran Hai, Bernd Schneider, Gunter AdamAbstract:Abstract Two isomeric metabolites, 25-β- d -glucopyranosyloxy-24-epi-Brassinolide and 26-β- d -glucopyranosyloxy-24-epi-Brassinolide, have been formed in cell suspension cultures of Lycopersicon esculentum from exogenously applied 24-epi-Brassinolide. The two-step metabolic process involved hydroxylation of the side-chain at C-25 and C-26, respectively, followed by glucosidation of the newly formed hydroxyl groups. The ratio between both metabolites was significantly altered by in vivo treatment of the cell cultures with various cytochrome P-450-specific inhibitors, indicating the involvement of two different enzyme systems. Biosynthetically prepared 25-hydroxy-24-epi-Brassinolide, reapplied to cell cultures, was exclusively glucosylated at the 25-hydroxyl group, strongly suggesting regiospecificity of the corresponding glucosyltransferase.
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A Metabolite of 24-Epi-Brassinolide in Cell-Suspension Cultures of Lycopersicon Esculentum
Phytochemistry, 1994Co-Authors: Bernd Schneider, Adelheid Kolbe, Andrea Porzel, Gunter AdamAbstract:Abstract Exogenously applied 24- epi -Brassinolide is converted into 25-β- d -glucosyloxy-24- epi -Brassinolide by cell suspension cultures of Lycopersicon esculentum . The structure was fully elucidated by FAB-MS and NMR analysis.
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Castasterone and Brassinolide in Raphanus sativus seeds
Phytochemistry, 1991Co-Authors: Jürgen Schmidt, Gunter Adam, Takao Yokota, Nobutaka TakahashiAbstract:Abstract Castasterone and Brassinolide have been identified from seeds of Raphanus sativus by GC-MS analysis. Comparative quantification experiments with seeds and germinated seeds carried out by GC-SIM indicated a remarkable difference in the ratio of brassinosteroids in favour of the formation of Brassinolide during germination.
Thomas G. Back - One of the best experts on this subject based on the ideXlab platform.
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Interaction of Brassinosteroids with Light Quality and Plant Hormones in Regulating Shoot Growth of Young Sunflower and Arabidopsis Seedlings
Journal of Plant Growth Regulation, 2012Co-Authors: Leonid V. Kurepin, Seong-ki Kim, Richard P. Pharis, Se-hwan Joo, Thomas G. BackAbstract:Sunflower hypocotyls elongate as light quality changes from the normal red to far-red (R/FR) ratio of sunlight to a lower R/FR ratio. This low R/FR ratio-induced elongation significantly increases endogenous concentrations of indole-3-acetic acid (IAA) and also of three gibberellins (GAs): GA_20, GA_1, and GA_8. Of these, it is likely GA_1 that drives low R/FR-induced growth. Brassinosteroids are also involved in shoot growth. Here we tested three R/FR ratios: high, normal, and low. Significant hypocotyl elongation occurred with this stepwise reduction in R/FR ratio, but endogenous castasterone concentrations in the hypocotyls remained unchanged. Brassinolide was also applied to the seedlings and significantly increased hypocotyl growth, though one that was uniform across all three R/FR ratios. Applied Brassinolide increased hypocotyl elongation while significantly reducing (usually) levels of IAA, GA_20, and GA_8, but not that of GA_1, which remained constant. Given the above, we conclude that endogenous castasterone does not mediate the hypocotyl growth that is induced by enriching FR light, relative to R light. Similarly, we conclude that the hypocotyl growth that is induced by applied Brassinolide does not result from an interaction of Brassinolide with changes in light quality. The ability of applied Brassinolide to influence IAA, GA_20, and GA_8 content, yet have no significant effect on GA_1, is hard to explain. One speculative hypothesis, though, could involve the Brassinolide-induced reductions that occurred for endogenous IAA, given IAA’s known ability to differentially influence the expression levels of GA20ox , GA3ox , and GA2ox , key genes in GA biosynthesis.
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Structure–Activity Studies of Brassinosteroids and the Search for Novel Analogues and Mimetics with Improved Bioactivity
Journal of Plant Growth Regulation, 2003Co-Authors: Thomas G. Back, Richard P. PharisAbstract:A number of novel brassinosteroid analogues were synthesized and subjected to the rice leaf lamina inclination bioassay. Modified B-ring analogues included lactam, thiolactone, cyclic ether, ketone, hydroxyl, and exocyclic methylene derivatives of Brassinolide. Those derivatives containing polar functional groups retained considerable bioactivity, whereas the exocyclic methylene compounds were devoid of activity. Analogues containing normal alkyl and cycloalkyl substituents at C-24 (in place of the isopropyl group of Brassinolide) showed an inverse relationship between activity and chain length or ring size, respectively. The corresponding cyclopropyl and cyclobutyl derivatives were significantly more active than Brassinolide and appear to be the most potent brassinosteroids reported to date. When synergized with the auxin indole-3-acetic acid (IAA), their bioactivity can be further enhanced by 1–2 orders of magnitude. The cyclopropyl derivative, when coapplied with the auxin naphthaleneacetic acid, gave a significant increase in yield of wheat in a field trial. Certain 25- and 26-hydroxy derivatives are known metabolites of brassinosteroids. All of the C-25 stereoisomers of 25-hydroxy, 26-hydroxy, and 25,26-dihydroxy derivatives of Brassinolide were prepared and shown to be much less active than Brassinolide. This indicates that they are likely metabolic deactivation products of the parent phytohormone. A series of methyl ethers of Brassinolide was synthesized to block deactivation by glucosylation of the free hydroxyl groups. The most significant finding was that the compound where three of the four hydroxyl groups (at C-3, C-22, and C-23) had been converted to methyl ethers retained substantial bioactivity. This type of modification could, in theory, allow Brassinolide or 24-epiBrassinolide to resist deactivation and thus offer greater persistence in field applications. A series of nonsteroidal mimetics of Brassinolide was designed and synthesized. Two of the mimetics showed significant bioactivity and one had bioactivity comparable to Brassinolide, but only when formulated and coapplied with IAA. They thus represent the first nonsteroidal analogues possessing brassinosteroid activity.
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Structure–activity studies of Brassinolide B-ring analogues
Phytochemistry, 1998Co-Authors: Denise L. Baron, Richard P. Pharis, Weide Luo, Loeke Janzen, Thomas G. BackAbstract:Abstract Six new analogues of Brassinolide were prepared in order to investigate their structure–activity relationship: 7-azaBrassinolide, 7-thiaBrassinolide, 6-deoxyBrassinolide, B-homocastasterone, 6-methylidenecastasterone and 6-methylidene-B-homocastasterone. These compounds were subjected to the rice leaf lamina inclination assay, in comparison with Brassinolide and 24-epiBrassinolide and/or castasterone to test for brassinosteroid activity. The activity of 7-azaBrassinolide, 7-thiaBrassinolide and 6-deoxyBrassinolide was comparable to that of 24-epiBrassinolide, but lower than that of Brassinolide. B-Homocastasterone was less active than either Brassinolide or castasterone. The B-ring carbocycles 6-methylidenecastasterone and 6-methylidene-B-homocastasterone were essentially inactive. These results indicate that neither the oxygen atom at the 7-position of Brassinolide, nor its carbonyl group, is essential for activity. However, the complete absence of a polar functional group from the B-ring, as in 6-methylidenecastasterone and 6-methylidene-B-homocastasterone, results in a total loss of bioactivity. This inactivity persists even in the presence of an exocyclic methylidene group that flattens the B-ring to resemble that of Brassinolide or castasterone by virtue of the sp 2 -hybridized carbon atom at C-6. Finally, the bioactivity of several, but not all, of the brassinosteroids, was significantly and synergistically increased by the simultaneous application of the auxin, indole-3-acetic acid.
Dl Bagdi - One of the best experts on this subject based on the ideXlab platform.
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Role of Brassinolide on physio-biochemical traits of barley under salt stress
International Journal of Chemical Studies, 2019Co-Authors: Sanjay Dabariya, Dl BagdiAbstract:The study entitled “Role of Brassinolide on Physio-biochemical Traits of barley (Hordeum vulgare L.) Under Salinity’’ was conducted in the cage house at Department of Plant Physiology, S.K.N. College of Agriculture Jobner during rabi season of 2015-2016 under pot culture experiments. Two barley cultivars namely RD 2035 (salinity susceptible) and RD 2794 (Salinity tolerant) were grown in cemented pots under salinity (0, 3, 6, 9 and 12 dSm-1). Different concentrations of Brassinolide (0.0, 0.5, 1.0 and 1.5 ppm) were sprayed at 45 and 75 days after sowing. Control plants were provided normal water. Physio-biochemical observations were recorded at 52 and 82 days after sowing in pot conditions. A significant decrease were recorded in Chlorophyll, protein, relative water content, cell membrane stability, with increase in salt stress up to EC 12 dSm-1.Whereas the foliar spray treatment with Brassinolide up to 1.5 ppm significantly increased chlorophyll, proline, protein, reducing sugar, relative water content, cell membrane stability in both the cultivars at 52 and 82 DAS under salt stress as well as non stress conditions. The 1.5 ppm concentration of Brassinolide was found most effective under salt stress and non stress conditions. RD 2794 observed superior over RD 2035 on the basis of physio-biochemical analysis.
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Effect of Brassinolide on physio-biochemical traits of wheat under salt stress
Journal of Pharmacognosy and Phytochemistry, 2019Co-Authors: Bhanwar Lal, Dl BagdiAbstract:The study entitled ‘’Effect of Brassinolide on Physio-biochemical Traits of Wheat (Triticum aestivum L.) Under Salinity’’ was conducted in the cage house at Department of Plant Physiology, S.K.N. College of Agriculture Jobner during rabi season of 2015-2016 under pot culture experiments. Two wheat cultivars namely Raj-1482 (salinity susceptible) and Raj-3077 (Salinity tolerant) were grown in cemented pots under salinity (0, 5 and 10 dSm-1). Different concentrations of Brassinolide (0.0, 1.0 and 1.5 ppm) were sprayed at 45 and 75 days after sowing. Control plants were provided normal water. Physio-biochemical observations were recorded at 52 and 82 days after sowing in pot conditions. A significant decrease were recorded in Chlorophyll, protein, relative water content, cell membrane stability, with increase in salt stress up to EC 10 dSm-1.Whereas the foliar spray treatment with Brassinolide up to 1.5 ppm significantly increased chlorophyll, proline, protein, reducing sugar, relative water content, cell membrane stability, potassium and calcium content in both the cultivars at 52 and 82 DAS under salt stress as well as non stress conditions. The 1.5 ppm concentration of Brassinolide was found most effective under salt stress and non stress conditions. Raj-3077 observed superior over Raj 1482 on the basis of physio-biochemical analysis.
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Effect of Brassinolide in amelioration of salinity adverse effects on growth and yield of wheat
Journal of Pharmacognosy and Phytochemistry, 2017Co-Authors: Kamlesh Jangid, Kanchan Kanwar, Paru Panwar, Rc Asiwal, Mamta Bajya, Dl BagdiAbstract:The present research was aimed to study the effect of Brassinolide in amelioration of salinity adverse effects on growth and yield of wheat at Department of Plant Physiology, S.K.N. College of Agriculture, Jobner, Rajasthan during rabi, 2013. Two wheat cultivars namely HD-2687 (salinity susceptible) and Raj-3777 (Salinity tolerant) were raised in petri-dishes and in cemented pots under salinity conditions (0, 4 and 8 dSm-1) Brassinolide (0.0, 0.25, 0.50 and 1.0 ppm) were also added in the saline set of petri-dishes and pots. Spray treatment with Brassinolide up to 1.0 ppm significantly increased Number of spikes per plant, grain yield, biological yield per plant. The maximum increase in number of spikes per plant, grain yield, and biological yield per plant was found under non stress conditions with 1.0 ppm concentration of Brassinolide in both genotypes. It may be concluded that among both the genotype Raj-3777 observed salinity tolerant and the tolerance was mediated by morphological characteristics. The experiment again reflects the significant role of Brassinolide in increasing productivity of wheat by improving germination, seedling growth, yield and yield attributes under non stress and salt stress conditions.
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Mitigation of salinity induced effects by using Brassinolide in cluster bean
Bhartiya Krishi Anusandhan Patrika, 2012Co-Authors: Gograj Jat, Dl Bagdi, B. L. KakralyaAbstract:A pot experiment was conducted to study the harmful effect of salinity and their amelioration by the application of Brassinolide on physiological, biochemical traits, growth and yield of cluster bean cultuvars namely ROC-1038 (salinity tolerant) and RGC-936 (salinity susceptible). These varieties were grown in cemented pots under different levels of salinity (0, 8, 12, dSm-1). Plants were sprayed at vegetative and flowering stage with Brassinolide solution (0,0,1, 0.5 and 1.0 ppm). Normal water was applied to control plants. Salinity was found to decrease significantly the photosynthesis rate, transpiration rate, stomatal conductance, relative water content, chlorophyll stability index, number of pods per plant, number of seeds per pod, plant height, pod length, test weight, grain yield. The use of Brassinolide up to, 1.0 ppm was observed to increase significantly in these parameters.