共查询到20条相似文献,搜索用时 15 毫秒
1.
A mutant R-9 of Gibberella fujikuroi has been isolated and shown to be blocked for GA 1 and GA 3 biosynthesis, but not for GA 4, G A7 and other gibberellins. Cultures of this mutant convert low concentrations of [1,2- 3H2]-GA 1 into GA 3 in a radiochemical yield of 2·7 %. 相似文献
2.
Methyl 6′, 6′-didemethyl abscisate ( 5) was synthesized and assayed to elucidate the physiological activity of methyl substituents on the cyclohexene ring of abscisic acid (ABA). During this study two new chiral stereoisomeric analogs 6 and 7 were synthesized from l-and d-carvone. The rice seedling assay and germination assay of garden radish showed that 6′-methyl groups of ABA were not important in biological activity and that 5′-isopropenyl analogs 6 and 7 were inactive. 相似文献
3.
The biotransformation of 7alpha-hydroxy-ent-kaur-16-ene (epi-candol A) by the fungus Gibberella fujikuroi gave 7alpha,16alpha,17-trihydroxy-ent-kaur-16-ene and a seco-ring B derivative, fujenoic acid, whilst the incubation of candicandiol (7alpha,18-dihydroxy-ent-kaur-16-ene) and canditriol (7alpha,15alpha,18-trihydroxy-ent-kaur-16-ene) afforded 7alpha,18,19-trihydroxy-ent-kaur-16-ene and 7alpha,11beta,15alpha,18-tetrahydroxy-ent-kaur-16-ene, respectively. The presence of a 7alpha-hydroxyl group in epi-candol A avoids its biotransformation along the biosynthetic pathway of gibberellins, and directs it to the seco-ring B acids route. The 15alpha-hydroxyl group in canditriol inhibits oxidation at C-19 and direct hydroxylation at C-11(beta). The formation of fujenoic acid, from 7alpha-hydroxy-ent-kaur-16-ene, probably occurs via 7alpha-hydroxykaurenoic acid and 7-oxokaurenoic acid, with subsequent hydroxylation at the C-6(beta) position. 相似文献
4.
Incubation of the diterpene 2beta-hydroxy-ent-13-epi-manoyl oxide with Gibberella fujikuroi afforded in good yield 2beta,6beta-dihydroxy-ent-13-epi-manoyl oxide, 2beta,12beta-dihydroxy-ent-13-epi-manoyl oxide and 2beta,20-dihydroxy-ent-13-epi-manoyl oxide, confirming that although ent-13-epi-manoyl oxide is a final metabolite of a biosynthetic branch in this fungus, more polar derivatives of this compound can be transformed by this micro-organism. 相似文献
5.
The best culture medium composition for the production of bikaverin by Gibberella fujikuroi in shake-flasks, i.e. 100 g glucose l –1; 1 g NH 4Cl l –1; 2 g rice flour l –1; 5 g KH 2PO 4 l –1 and 2.5 g MgSO 4 l –1, was obtained through a fractional factorial design and then scaled-up to a fluidized bioreactor. The effects of carbon and nitrogen concentrations, inoculum size, aeration, flow rate and bead sizes on batch bikaverin production using immobilized G. fujikuroi in a fluidized bioreactor were determined by an orthogonal experimental design. Concentrations of up to 6.83 g bikaverin l –1 were obtained when the medium contained 100 g glucose l –1 and 1 g NH 4Cl l –1 with an inoculum ratio of 10% v/v, an aeration rate of 3 volumes of air per volume of medium min –1, and a bead size of 3 mm. Based on dry weight, the bikaverin production was 30–100 times larger than found in submerged culture and approximately three times larger than reported for solid substrate fermentation. 相似文献
6.
Environmental factors often affect plant growth bymodifying the levels of endogenous gibberellins (GAs).In this study, the involvement of GAs in theregulation of enhanced shoot growth in tomato ( Lycopersicon esculentum Mill.) plants grown in soiltreated by solarization (a soil disinfestation method)was investigated. Seedlings at the cotyledonary stagewere transplanted into either solarized or untreatedcontrol soil. Plants in both soils grew free of anydisease symptoms. As soon as four days after planting,seedlings in solarized soil had a higher dry weightcompared to the control. Throughout most of theexperimental period of 18 days, leaf weight ratio washigher in the solarized vs. the control soil. Treatingshoot tips of control plants with 0.1 mg .L -1GA 3 resulted in enhanced leaf and stem growth,thus reaching values similar to those of plants grownin solarized soil. The opposite effect was obtained bytreating plants grown in solarized soil with1 mg .L -1 uniconazole, a GA biosynthesisinhibitor. Quantitative GC-MS analyses revealed thatGA 1 content in one and two-weeks old transplantsgrown in various solarized soils was up to 1.8 fold,and that GA 3 content in two-weeks old plants wasup to five fold the values in the control. Theseincreases were linearly correlated with the increasein leaf dry weight. It was concluded that theincreased quantities of GA 1, and eventuallyGA 3, play a role in the increased growth oftomato shoots in solarized soil as early as seven daysafter transplanting.deceased 相似文献
7.
An endophytic fungus, Gibberella pulicaris, produced an amylase which degraded raw starches from cereals and other crops including raw potato, sago, tapioca, corn, wheat and rice starch. In each case, glucose was the main product. Among the raw starches used, raw potato starch gave the highest enzyme activity (85 units mg –1 protein) and raw wheat starch the lowest (49 units mg –1 protein). The highest amylase production (260 units mg –1 protein) was achieved when the concentration of raw potato starch was increased to 60 g l –1. Optimum hydrolysis was at 40°C and pH 5.5. 相似文献
8.
Summary A transformation system for Gibberella fujikuroi based on the Aspergillus niger nitrate reductase gene ( niaD) was developed. A strain (designated SG140) carrying a non-reverting niaD mutation ( niaD11) was generated by screening mutagenised cells for non-growth on nitrate as sole nitrogen source. Transformation frequencies of 1–2 transformants per g DNA were observed when strain SG140 was transformed to nitrate utilisation. Southern blot analyses of niaD + transformants showed that the vector DNA sequences were integrated into the chromosomal DNA. The results demonstrate that the A. niger niaD gene is expressed in G. fujikuroi. 相似文献
9.
Gibberella fujikuroi is a species-rich monophyletic complex of at least nine sexually fertile biological species (mating populations, MP-A to MP-I) and more than 30 anamorphs in the genus Fusarium. They produce a variety of secondary metabolites, such as fumonisins, fusaproliferin, moniliformin, beauvericin, fusaric acid, and gibberellins (GAs), a group of plant hormones. In this study, we examined for the first time all nine sexually fertile species (MPs) and additional anamorphs within and outside the G. fujikuroi species complex for the presence of GA biosynthetic genes. So far, the ability to produce GAs was described only for Fusarium fujikuroi (G. fujikuroi MP-C), which contains seven clustered genes in the genome all participating in GA biosynthesis. We show that six other MPs (MPs B, D, E, F, G, and I) and most of the anamorphs within the species complex also contain the entire gene cluster, except for F. verticillioides (MP-A), and F. circinatum (MP-H), containing only parts of it. Despite the presence of the entire gene cluster in most of the species within the G. fujikuroi species complex, expression of GA biosynthetic genes and GA production were detected only in F. fujikuroi (MP-C) and one isolate of F. konzum (MP-I). We used two new molecular marker genes, P450-4 from the GA gene cluster, and cpr, encoding the highly conserved NADPH cytochrome P450 reductase to study phylogenetic relationships within the G. fujikuroi species complex. The molecular phylogenetic studies for both genes have revealed good agreement with phylogenetic trees inferred from other genes. Furthermore, we discuss the role and evolutionary origin of the GA biosynthetic gene cluster. 相似文献
10.
Morphological studies were carried out with peach flower buds collected monthly in 1989 and 1990, from two months before leaf fall (7 March) until two to three weeks before bloom (7/8 August). Chilled (2–4°C for 30 days) and unchilled buds were exposed to 20 to 25°C, 100% RH and continuous light. Gibberellin A 3 (3 ng or 30 ng) was applied to some of the non-chilled cuttings at three days intervals. Then, 12, 19, and 26 days after they were planted, the buds were sampled and processed for histological studies. Cultured flower buds (chilled or unchilled) had accelerated anther and gynoecium morphogenesis after 12 days under controlled conditions, compared to buds processed immediately after collection from the field. Chilling treatment augmented the bud culture effect, while Gibberellin A 3 applications to the excised buds retarded bud morphogenesis to a stage comparable to that of buds collected directly from the field. This, suggests that the comparatively high levels of Gibberellin A 1/3 we previously found in mid winter [15, 18] could be at least one of the factors that controls floral bud dormancy by retarding anther and gynoecium development. 相似文献
11.
The evolution of volatile compounds produced during solid substrate cultivation (SSC) of Gibberella fujikuroi on wheat bran was tracked looking for volatile metabolites related with GA 3 production. Ethyl acetate and isoamyl acetate gave identical profiles and sharp increases that abated as the production of GA 3 began, while ent-kaurene displayed a profile matching that of the development of GA 3. ent-Kaurene is a precursor in the synthesis of gibberellins and was the most abundant compound found. 相似文献
12.
Effects of camptothecin, a naturally occurring alkaloid, on seed germination varied from promotive to inhibitory, depending on the species used. It markedly inhibited seedling root growth but its inhibition of hypocotyl growth varied among species. Camptothecin inhibited GA 3-induced dark germination of lettuce ( Lactuca sativa L.) seeds and hypocotyl elongation of seedlings. In contrast to ABA, the camptothecin inhibition of GA 3-induced germination could not be overcome by cytokinin. When seeds were germinated at 29C with a 0.5 h light treatment, little or no germination occurred in the camptothecin treatment, but addition of cytokinin overcame this inhibition. 相似文献
13.
Intact cells of a biotin-producing bacterium, KY–21–1–25, were found to synthesize biotin from dethiobiotin. Optimal conditions for the biosynthesis of biotin from dethiobiotin by intact cells were investigated. Intact cells harvested from adenine-supplemented medium showed intensive biosynthesis. However, the biosynthesis of biotin by intact cells was strongly inhibited by the addition of adenine or adenosine. The inhibitory activity of adenine was about 10-fold greater than that of adenosine. Formation of several unidentified biotin-vitamers was observed in both reaction mixtures incubated with and/or without addition of adenine. 相似文献
14.
The persistence of gibberellin A 3 on plant surfaces was examined using fruit of Marsh seedless grapefruit ( Citrus paradisi Macf.) and an inert glass model system. 14C-gibberellin A 3 was applied to surfaces in aqueous treatment solutions or in waxing solutions. Dried-out treatment residues were removed by washing and analyzed for total and GA 3-like radioactivity. Gibberellin A 3 persisted without significant loss for at least 7 d in aqueous treatment solutions (pH 4.0 or 6.2) but was less persistent in the pH 10.4 waxing solution ( t1/2=7 d).Loss of total peel surface radioactivity was fast during the first 3 days, slowing down afterwards. After 14 days 73% of the initial radioactivity could still be recovered from fruit peel surface and 70% of the recovered radioactivity was still in the form of gibberellin A 3. Gibberellin A 3 was somewhat more persistent in residues from pH 4 than pH 7 treatment solutions. Light had a slight enhancing effect on gibberellin A 3 decomposition on fruit peel under growth chamber conditions. After 12 d at 100% relative humidity, 88% of the radioactivity on glass surfaces was still in the form of gibberellin A 3, as against 45% at a relative humidity of 50%. Simulated field conditions, combining daily fluctuations in light, temperature and relative humidity, markedly enhanced gibberellin A 3 decomposition on glass surfaces ( t1/2=2 d). Gibberellin A 3 was very persistent (90% after 9 d) in the waxing residues on fruit peel surface.Abbreviations GA 3
gibberellin A 3
- RH
relative humidity 相似文献
15.
The steps involved in kaurenolide and fujenoic acids biosynthesis, from ent-kauradienoic acid and ent-6alpha,7alpha-dihydroxykaurenoic acid, respectively, are demonstrated in the gibberellin (GA)-deficient Gibberella fujikuroi mutant SG139, which lacks the entire GA-biosynthesis gene cluster, complemented with the P450-1 gene of GA biosynthesis (SG139-P450-1). ent-[2H]Kauradienoic acid was efficiently converted into 7beta-hydroxy[2H]kaurenolide and 7beta,18-dihydroxy[2H]kaurenolide by the cultures while 7beta-hydroxy[2H]kaurenolide was transformed into 7beta,18-dihydroxy[2H]kaurenolide. The limiting step was found to be hydroxylation at C-18. In addition, SG139-P450-1 transformed ent-6alpha,7alpha-dihydroxy[14C4]kaurenoic acid into [14C4]fujenoic acid and [14C4]fujenoic triacid. Fujenal was also converted into the same products but was demonstrated not to be an intermediate in this sequence. All the above reactions were absent in the mutant SG139 and were suppressed in the wild-type strain ACC917 by disruption of the P450-1 gene. Kaurenolide and fujenoic acids synthesis were associated with the microsomal fraction and showed an absolute requirement for NADPH or NADH, all properties of cytochrome P450 monooxygenases. Only 7beta-hydroxy[14C4]kaurenolide synthesis and not further 18-hydroxylation was detected in the microsomal fraction. The substrates for the P450-1 monooxygenase, ent-kaurenoic acid and [2H]GA12, efficiently inhibited kaurenolide synthesis with I50 values of 3 and 6 microM, respectively. Both substrates also inhibited ent-6alpha,7alpha-dihydroxy[14C4]kaurenoic acid metabolism by SG139-P450-1. Conversely, [14C4]GA14 synthesis from [14C4]GA12-aldehyde was inhibited by ent-[2H]kauradienoic acid and fujenal with I50 values of 10 and 30 microM, respectively. These results demonstrate that kaurenolides and seco-ring B kaurenoids are formed by the P450-1 monooxygenase (GA14 synthase) of G. fujikuroi and are thus side products that probably result from stabilization of radical intermediates involved in GA14 synthesis. 相似文献
16.
The multifunctional cytochrome P450 monooxygenases P450-1 and P450-2 from Fusarium fujikuroi catalyze the formation of GA14 and GA4, respectively, in the gibberellin (GA)-biosynthetic pathway. However, the activity of these enzymes is qualitatively and quantitatively different in mutants lacking the NADPH:cytochrome P450 oxidoreductase (CPR) compared to CPR-containing strains. 3beta-Hydroxylation, a major P450-1 activity in wild-type strains, was strongly decreased in the mutants relative to oxidation at C-6 and C-7, while synthesis of C19-GAs as a result of oxidative cleavage of C-20 by P450-2 was almost absent whereas the C-20 alcohol, aldehyde and carboxylic acid derivatives accumulated. Interaction of the monooxygenases with alternative electron transport proteins could account for these different product distributions. In the absence of CPR, P450-1 activities were NADH-dependent, and stimulated by cytochrome b5 or by added FAD. These properties as well as the decreased efficiency of P450-1 and P450-2 in the mutants are consistent with the participation of cytochrome b5:NADH cytochrome b5 reductase as redox partner of the gibberellin monooxygenases in the absence of CPR. We provide evidence, from either incubations of GA12 (C-20 methyl) with cultures of the mutant suspended in [18O]H2O or maintained under an atmosphere of [18O]O2:N2 (20:80), that GA15 (C-20 alcohol) and GA24 (C-20 aldehyde) are formed directly from dioxygen and not from hydrolysis of covalently enzyme-bound intermediates. Thus these partially oxidized GAs correspond to intermediates of the sequential oxidation of C-20 catalyzed by P450-2. 相似文献
17.
Cuttings of potato shoots treated with the plant growth retardant 2-chloroethyltrimethyl ammonium chloride (CCC) form tubers earlier and have less biologically-active gibberellin (GA)-like substances in the roots than control cuttings. The major GA-like substance in roots of potato cuttings was identified as GA 3 by gas-chromatography-mass spectrometry (GC-MS). The content of GA 3 in roots of control cuttings, estimated by GC-MS-selected ion monitoring (SIM) using [17, 17- 2H]GA 3 as a quantitative internal standard, was 38.8 ng per g fresh weight (fw), and in roots of CCC-treated cuttings, in which tuberization was promoted, was 0.6 ng per g fw. Gibberellin A 1, GA 8 and GA 20 were also indicated as minor components of roots from both control and CCC-treated cuttings. The comparatively high GA 3 content in roots of control cuttings might be the root factor responsible for delaying tuberization in potato.Abbreviations CCC
2-chloroethyltrimethyl ammonium chloride
- dw
dry weight
- EtOAc
ethyl acetate
- GA
gibberellin
- GC-MS-SIM
gas chromatography-mass spectrometry-selected ion monitoring
- HPLC
high performance liquid chromatography
- IAA
indole-3-acetic acid
- KRI
Kovats' retention index
- MeOH
methanol
- MeTMSi
methyl ester trimethylsilyl ether
- NAA
naphthalene acetic acid
- SD
short day(s)
- 2,4-D
2,4-dichlorophenoxy acetic acid 相似文献
18.
Procedures are described for the isolation of the individual components A 1, A 2, and A 3 of native R-ovalbumin from freshly laid domestic hen eggs. Because heavy metal ion contaminants result in spurious irreproducible kinetics, particularly at high pH, considerable care is taken to avoid their presence. Kinetics studies are made of the behavior of whole R-ovalbumin and its individual components in urea solution over the pH range 3.7–9.6 following the reaction by determining absorbance differences at 233, 287, and 293 nm and ORD and CD changes at 350 and 221 nm, respectively. Reaction is rapid at low pH, slowing with increasing pH. Except under limited conditions, the reaction is not simple first order. Equations are presented for describing the reactions, and the nature of the reaction products is considered. Unfolding equilibrium profiles were also determined by ORD at several wavelengths and were not stigmoidal in shape and the normalized curves were not superimposed.Deceased December 8, 2001 相似文献
19.
Gibberellin A 4 (GA 4) was identified for the first time in the garden pea ( Pisum sativum) L.), by gas chromatography-mass spectrometry. However, in wild-type shoots the level of GA 4 was only about 6% of the level of GA 1, and it is therefore unlikely that GA 4 plays a major role per se in the control of pea stem elongation. In shoots of the le mutant, GA 4 was not detected, while the level of GA 9 was approximately twice that found in the wild-type. The le mutation also markedly reduced the elongation response to applied GA 9. It appears, therefore, that in Pisum the le mutation blocks the 3-hydroxylation of GA 9 to GA 4, in addition to the 3-hydroxylation of GA 20 to GA 1. In contrast, the le mutation did not reduce the response to applied GA 5, suggesting the step GA 5 to GA 3 is not catalysed by the enzyme controlled by the Le gene. The step GA 5 to GA 3 was confirmed in peas by metabolite analysis after treatment with deuterated GA 5. 相似文献
20.
6-Hydroxydopamine (6-OHDA) is the most used toxin in experimental Parkinson’s disease (PD) models. 6-OHDA shows high affinity for the dopamine transporter and once inside the neuron, it accumulates and undergoes non-enzymatic auto-oxidation, promoting reactive oxygen species (ROS) formation and selective damage of catecholaminergic neurons. In this way, our group has established a 6-OHDA in vitro protocol with rat striatal slices as a rapid and effective model for screening of new drugs with protective effects against PD. We have shown that co-incubation with guanosine (GUO, 100 μM) prevented the 6-OHDA-induced damage in striatal slices. As the exact GUO mechanism of action remains unknown, the aim of this study was to investigate if adenosine A1 (A1R) and/or A2A receptors (A2AR) are involved on GUO protective effects on striatal slices. Pre-incubation with DPCPX, an A1R antagonist prevented guanosine effects on 6-OHDA-induced ROS formation and mitochondrial membrane potential depolarization, while CCPA, an A1R agonist, did not alter GUO effects. Regarding A2AR, the antagonist SCH58261 had similar protective effect as GUO in ROS formation and mitochondrial membrane potential. Additionally, SCH58261 did not affect GUO protective effects. The A2AR agonist CGS21680, although, completely blocked GUO effects. Finally, the A1R antagonist DPCPX, and the A2AR agonist CGS21680 also abolished the preventive guanosine effect on 6-OHDA-induced ATP levels decrease. These results reinforce previous evidence for a putative interaction of GUO with A1R-A2AR heteromer as its molecular target and clearly indicate a dependence on adenosine receptors modulation to GUO protective effect. 相似文献
|