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1.
Two-year old saplings grown from cuttings of Cryptomeria japonica D. Don initiate strobilus development following treatment with gibberellic acid under long-day photoperiods. At 25 °C with a 14-h photoperiod in a phytotron, male strobili initiated normally; however, they remained green and fell from the saplings prematurely. To examine the change in male strobilus development at the molecular level, three genes expressed specifically in male strobili were analyzed. Two were MADS box genes homologous to the B-function genes in angiosperms, CjMADS1 and CjMADS2, and the third was Cry j I, which encodes an allergen protein, and this gene is expressed mainly in microspores. Under phytotron growing conditions, the homeotic genes were expressed constantly, which reflected the extended early developmental stage of male strobili. On the other hand, Cry j I expression was detected after a long delay just before strobilus development ceased. These results indicate that the expression of the genes related to male reproductive development in C. japonica is regulated by a factor(s) that is sensitive to environmental signals.Abbreviation GA3 gibberellic acid 相似文献
2.
In flowering plants, flower organ identity is controlled by the ABC genes, including several MADS box genes. We present two MADS box genes of a conifer, Cryptomeria japonica D. Don. The genes, CjMADS1 and CjMADS2, were related to the angiosperm B function genes which determine the identities of petals and stamens. A phylogenetic analysis showed that these genes form a new clade outside the angiosperm B group, that is, PISTILLATA (PI) and APETALA3 (AP3) lineages. CjMADS1 had a PI-group specific motif and CjMADS2 had AP3-group specific motifs at the C terminal end, respectively. CjMADS1 was expressed in male strobili (or cones) throughout its development, while CjMADS2 was transiently expressed during male strobilus development. The specific expression in the male reproductive organ indicated that the B function is maintained in gymnosperms. Our cladistic analysis suggests that the gene duplication event which generated B function gene lineages predates the divergence of angiosperms and gymnosperms and that the gene duplication which produced the two genes of C. japonica occurred in an ancestral conifer species. 相似文献
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5.
cDNA
corresponding to the GA4 gene of
Arabidopsis thaliana L. (Heynh.) was
expressed in Escherichia coli, from which cell lysates
converted [14C]gibberellin (GA)9 and
[14C]GA20 to radiolabeled GA4 and
GA1, respectively, thereby confirming that
GA4 encodes a GA 3β-hydroxylase. GA9 was
the preferred substrate, with a Michaelis value of 1 μm
compared with 15 μm for GA20. Hydroxylation
of these GAs was regiospecific, with no indication of
2β-hydroxylation or 2,3-desaturation. The capacity of the recombinant
enzyme to hydroxylate a range of other GA substrates was investigated.
In general, the preferred substrates contained a polar bridge between
C-4 and C-10, and 13-deoxy GAs were preferred to their 13-hydroxylated
analogs. Therefore, no activity was detected using
GA12-aldehyde, GA12, GA19,
GA25, GA53, or GA44 as the open
lactone (20-hydroxy-GA53), whereas GA15,
GA24, and GA44 were hydroxylated to
GA37, GA36, and GA38, respectively.
The open lactone of GA15 (20-hydroxy-GA12) was
hydroxylated but less efficiently than GA15. In contrast to
the free acid, GA25 19,20-anhydride was 3β-hydroxylated
to give GA13. 2,3-Didehydro-GA9 and
GA5 were converted by recombinant GA4 to the corresponding
epoxides 2,3-oxido-GA9 and GA6.Dwarf mutants with reduced biosynthesis of the GA plant hormones
have been valuable tools in studies of the function of these compounds
(Ross, 1994). In Arabidopsis thaliana, mutations
at six loci (GA1-GA6) that result in reduced GA
biosynthesis have been identified (Koorneef and van der Veen, 1980;
Sponsel et al., 1997), and three of these loci have recently been
cloned. The GA1 locus was isolated by genomic subtraction
(Sun et al., 1992) and shown by heterologous expression in
Escherichia coli to encode the enzyme that cyclizes
geranylgeranyl diphosphate to copalyl diphosphate (Sun and Kamiya,
1994). This enzyme was formerly referred to as ent-kaurene
synthase A but has been renamed copalyl diphosphate synthase
(Hedden and Kamiya, 1997; MacMillan, 1997). The GA5
locus was shown to correspond to one of the GA 20-oxidase genes (Xu et
al., 1995), the products of which catalyze the conversion of
GA12 to GA9 and
GA53 to GA20 (Phillips et
al., 1995; Xu et al., 1995). GA 20-oxidases are
2-oxoglutarate-dependent dioxygenases that are encoded by small
multigene families, members of which are differentially expressed in
plant tissues (Phillips et al., 1995; Garcia-Martinez et al., 1997).The GA4 locus was isolated by T-DNA tagging and, on the
basis of the derived amino acid sequence, was also shown to encode a
dioxygenase (Chiang et al., 1995). Several lines of evidence indicate
that the GA4 gene encodes a GA 3β-hydroxylase. Shoots of a
ga4 mutant, all alleles of which are semidwarf, contained
reduced concentrations of the 3β-hydroxy GAs
GA1, GA4, and
GA8 compared with the Landsberg erecta
wild type, whereas levels of immediate precursors to these GAs were
elevated (Talon et al., 1990). Furthermore, metabolism of
[13C]GA20 to
[13C]GA1 was
substantially less in the mutant than in the wild type (Kobayashi et
al., 1994). In the present paper we confirm by functional expression of
its cDNA in E. coli that GA4 encodes a GA
3β-hydroxylase. In addition, we determine the substrate specificity
of recombinant GA4 using a number of C20- and
C19-GAs and show by kinetic analysis that the enzyme
has a higher affinity for GA9 than for
GA20, which is consistent with the
non-13-hydroxylation pathway predominating in Arabidopsis (Talon et
al., 1990). 相似文献
6.
Metabolism of gibberellin a(12)-7-aldehyde by soybean cotyledons and its use in identifying gibberellin a(7) as an endogenous gibberellin 总被引:2,自引:1,他引:1
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The level of gibberellin(GA)-like material in cotyledons of soybean (Glycine max L.) was highest at mid-pod fill—about 10 nanograms GA3 equivalents per gram fresh weight of tissue, assayed in the immersion dwarf rice bioassay. This amount is about 1000-fold less than levels in Pisum and Phaseolus seed, other legume species whose spectrum of endogenous gibberellins (GAs) is well known. The metabolism of [14C]-GA12-7-aldehyde (GA12ald)—the universal GA precursor—by intact, mid-pod-fill, soybean cotyledons and their cell-free extracts was investigated. In 4 hours, extracts converted GA12ald to two products—[14C]GA12 (42% yield) and [14C]GA15 (7%). Within 5 minutes, intact embryos converted GA12ald to [14C]GA12 and [14C]GA15 in 15% yield; 4 hour incubations afforded at least 22 products (96% total yield). The putative [14C]GA12 was identified as a product of [14C]GA12ald metabolism on the basis of co-chromatography with authentic GA12 on a series of reversed and normal phase high pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) systems, and by a dual feed of the putative [14C]GA12 and authentic [14C]GA12 to cotyledons of both peas and soybeans. The [14C]GA15 was identified as a metabolite of [14C]GA12ald by capillary gas chromatography (GC)-mass-spectrometry-selected ion monitoring, GC-radiocounting, HPLC, and TLC. By adding the [14C] metabolites of [14C]GA12ald to a different and larger extract (about 0.2 kg fresh weight of soybean reproductive tissue) and purifying endogenous substances co-chromatographing with these metabolites, at least two GA-like substances were obtained and one identified as GA7 by GC-mass spectrometry. Since [14C]GA9 was not found as a [14C]metabolite of [14C]GA12ald, soybean embryos might have a pathway for biosynthesis of active, C-19 gibberellins like that of the cucurbits; GA12ald → GA12 → GA15 → GA24 → GA36 → GA4 → GA7. 相似文献
7.
Natalia Mu?oz-Fambuena Carlos Mesejo M. Carmen González-Mas Domingo J. Iglesias Eduardo Primo-Millo Manuel Agustí 《Journal of Plant Growth Regulation》2012,31(4):529-536
In Citrus, gibberellic acid (GA3) applied at the floral bud inductive period significantly reduces flowering intensity. This effect is being used to improve the fruit set of parthenocarpic cultivars that tend to flower profusely. However, the molecular mechanisms involved in the process remain unclear. To contribute to the knowledge of this phenomenon, adult trees of ‘Salustiana’ sweet orange were sprayed at the floral bud inductive period with 40?mg?L?1 of GA3 and the expression pattern of flowering genes was examined up to the onset of bud sprouting. Trees sprayed with paclobutrazol (PBZ, 2,000?mg L?1), a gibberellin biosynthesis inhibitor, were used to confirm the effects, and untreated trees served as control. Bud sprouting, flowering intensity, and developed shoots were evaluated in the spring. GA3 significantly reduced the number of flowers per 100 nodes by 72% compared to the control, whereas PBZ increased the number by 123%. Data of the expression pattern of flowering genes in leaves of GA3-treated trees revealed that this plant growth regulator inhibited flowering by repressing relative expression of the homolog of FLOWERING LOCUS T, CiFT, whereas PBZ increased flowering by boosting its expression. The activity of the homologs TERMINAL FLOWER 1, FLOWERING LOCUS C, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1, and APETALA1 was not affected by the treatments. The number of flowers per inflorescence, in both leafy and leafless inflorescences, was not altered by GA3 but increased with PBZ; the latter paralleled LEAFY relative expression. These results suggest that GA3 inhibits flowering in Citrus by repressing CiFT expression in leaves. 相似文献
8.
Identification of Ten Gibberellins from Sporophytes of the Tree fern, Cyathea australis 总被引:2,自引:1,他引:1
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Yamane H Yamaguchi I Kobayashi M Takahashi M Sato Y Takahashi N Iwatsuki K Phinney BO Spray CR Gaskin P Macmillan J 《Plant physiology》1985,78(4):899-903
Ten gibberellins (GAs) have been identified by Kovats retention indices and full mass spectra from GC-MS analysis of purified extracts of sporophytes of the tree-fern, Cyathea australis. These include the known GA1, GA4, GA9, GA15, GA24, GA35, and GA58 and three new GAs, 12β-hydroxyGA9 (GA69), 12α-hydroxyGA9 (GA70) and 12β-hydroxyGA4 (GA71). The structure of GA71 was established by the preparation and characterization of its methyl ester (as a metabolite of GA4 methyl ester in a culture of prothallia of Lygodium japonicum). 相似文献
9.
Benjamin Ewa Ubi Takanori Saito Songling Bai Chikako Nishitani Yusuke Ban Kazuo Ikeda Akiko Ito Takaya Moriguchi 《Gene》2013
We cloned 10 Japanese pear (Pyrus pyrifolia) MIKC-type II MADS-box genes, and analyzed their expression during fruit development and ripening. PpMADS2-1 was APETALA (AP)1-like; PpMADS3-1 was FRUITFULL (FUL)/SQUAMOSA (SQUA)-like; PpMADS4-1 was AGAMOUS-like (AGL)6; PpMADS5-1 and PpMADS8-1 were SUPPRESSOR OF OVEREXPRESSION OF CONSTANS (SOC)-like; PpMADS9-1, PpMADS12-1, PpMADS14-1 and PpMADS16-1 were SEPALLATA (SEP)-like; while PpMADS15-1 was AGL/SHATTERPROOF (SHP)-like. Phylogenetic analysis showed their grouping into five major clades (and 10 sub-clades) that was consistent with their diverse functional types. Expression analysis in flower tissue revealed their distinct putative homeotic functional classes: A-class (PpMADS2-1, PpMADS3-1, PpMADS4-1, and PpMADS14-1), C-class (PpMADS15-1), E-class (PpMADS9-1, PpMADS12-1, and PpMADS16-1) and E (F)-class (PpMADS5-1 and PpMADS8-1). Differential gene expression was observed in different fruit tissues (skin, cortex and core) as well as in the cortex during the course of fruit development and ripening. Collectively, our results suggest their involvement in the diverse aspects of plant development including flower development and the course of fruit development and ripening. 相似文献
10.
Gibberellins and the Legume-Rhizobium Symbiosis : III. Quantification of Gibberellins from Stems and Nodules of Lima Bean and Cowpea
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Lima bean (Phaseolus lunatus L.) plants inoculated with Bradyrhizobium sp. strain 127E14 displayed a period of marked internode elongation that was not observed in plants inoculated with other compatible bradyrhizobia, including strain 127E15. When strain 127E14 nodulated an alternate host, cowpea (Vigna unguiculata L. Walp), a similar, although less dramatic growth response induced by the bacteria was observed. It has been speculated that the elongative growth promotion brought about by inoculation with strain 127E14 is mediated by gibberellins (GAs). Using deuterated internal standards and gas chromatography-mass spectroscopy analysis, we have quantified the levels of GA1, GA20, GA19, and GA44 in nodules and stems of two varieties of lima bean (bush and pole) and one variety of cowpea that were inoculated with either strain 127E14 or 127E15. In nodules formed by strain 127E14 on lima bean, endogenous levels of GA20 and GA19 were 10 to 40 times higher (35-88 ng/g dry weight) than amounts found in nodules formed by strain 127E15 (2.2-3.9 ng/g dry weight). Relative amounts of GA44 were also higher (4- to 11-fold) in 127E14 nodules, but this increase was less pronounced. The rhizobial-induced increase of these GAs in the nodule occurred in both pole and bush varieties and seemed to be independent of host morphology. Regardless of rhizobial inoculum, levels of the “bioactive” GA1 in the nodule (0.3-1.1 ng/g dry weight) were similar. In cowpea nodules, a similar, although smaller, difference in GA content due to rhizobial strain was observed. The concentration of GA1 in lima bean stems was generally higher than that observed in the nodule, whereas concentrations of the other GAs measured were lower. In contrast with the nodule, GA concentrations in lima bean stems were not greater in plants inoculated with strain 127E14, and in some cases the slower growing plants inoculated with strain 127E15 actually had higher levels of GA20, GA19, and GA44. Thus, there were major differences in concentrations of the precursors to GA1 in nodules formed by the two bacterial strains, which were positively correlated with the observed elongation growth. These results support the hypothesis that the rhizobial strain modifies the endogenous GA status of the symbiotic system. This alteration in GA balance within the plant, presumably, underlies the observed growth response. 相似文献
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12.
Tomoya Ogawa Satoru Nakabayashi Seiichi Shibata 《Bioscience, biotechnology, and biochemistry》2013,77(6):1353-1356
Gibberellins (GAs) A9, A15, A19, A20, A29, A35, A44, A50 and A61 were identified by capillary gas chromatography/selected ion monitoring (GC/SIM) in immature seeds of loquat (Eriobotrya japonica Lindl). Furthermore, five unknown GA-like compounds with apparent parent ions of m/z 418, 504 or 506 (as methyl ester trimethylsilyl ether derivatives) were found by GC/mass spectrometry (GC/MS) in the biologically active fractions. The m/z 418 and 504 compounds may have been C-11β hydroxylated GA9 and dehydro-GA35, respectively. The bioassay and GC/MS results suggest that the major GAs were GA50 and the five unknown GA-like compounds. In the immature seeds, at least two GA metabolic pathways may thus exist, one being the non-hydroxylation pathway of GA15→GA24→GA9, and the other, the early C-13 hydroxylation pathway of GA44→GA19→GA20→GA29. A late C-11β hydroxylation pathway is also possible. 相似文献
13.
Rengasamy Ramamoorthy Edwin Ek-Kian Phua Saw-Hoon Lim Hugh Tiang-Wah Tan Prakash P. Kumar 《PloS one》2013,8(6)
Rafflesia, a holoparasitic genus that produces the largest flower in the world is characterized by the absence of leaves, stem and other macroscopic organs. To better understand the molecular regulation of flower development in this genus we isolated and characterized a floral MADS-box gene, namely, RcMADS1 from Rafflesia cantleyi. Heterologous expression analysis in Arabidopsis was chosen because Rafflesia is not amenable to genetic manipulations. RcMADS1 shares sequence similarity with AGAMOUS-LIKE 24 (AGL24) and SHORT VEGETATIVE PHASE (SVP) of Arabidopsis. Ectopic expression of RcMADS1 in Arabidopsis caused early flowering and conversion of sepals and petals into leaf-like structures, and carpels into inflorescences. In 35S::RcMADS1 plants SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), a downstream target gene of AGL24, was upregulated. 35S::RcMADS1 plants exhibit early flowering and conversion of the floral meristem into inflorescence meristem, as in 35S::AGL24 plants. Similar to AGL24, RcMADS1 could rescue the late flowering phenotypes of agl24-1 and FRIGIDA, but not the early flowering of svp-41. Based on these results, we propose that RcMADS1 is a functional ortholog of Arabidopsis AGL24. 相似文献
14.
The Distribution of Gibberellins in Vegetative Tissues of Pisum sativum L. : I. Biological and Biochemical Consequences of the le Mutation 总被引:3,自引:2,他引:1
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The concentrations of endogenous gibberellin (GA) 1, 5, 8, 19, 20, and 29 in the component tissues of maturing tall (Le) and dwarf (le) pea (Pisum sativum) plants have been determined. The following conclusions were drawn from the data obtained: (a) GA20 and its metabolites accumulate only in the growing regions of Le and le plants; (b) the le mutation is biochemically expressed in all immature tissues of the dwarf plants; (c) the quantitative composition of the GA metabolites in the various immature tissues is variable; (d) the total GA concentration in apical buds, unexpanded leaves, and tendrils is considerably higher than in GA1-responsive stem tissue; and (e) there is very little GA accumulation of the inactive 2β-hydroxylated GAs (GA8 and GA29) in either the mature vegetative tissues or the roots of pea plants. 相似文献
15.
Jocelyn A. Ozga Dennis M. Reinecke Belay T. Ayele Phuong Ngo Courtney Nadeau Aruna D. Wickramarathna 《Plant physiology》2009,150(1):448-462
In pea (Pisum sativum), normal fruit growth requires the presence of the seeds. The coordination of growth between the seed and ovary tissues involves phytohormones; however, the specific mechanisms remain speculative. This study further explores the roles of the gibberellin (GA) biosynthesis and catabolism genes during pollination and fruit development and in seed and auxin regulation of pericarp growth. Pollination and fertilization events not only increase pericarp PsGA3ox1 message levels (codes for GA 3-oxidase that converts GA20 to bioactive GA1) but also reduce pericarp PsGA2ox1 mRNA levels (codes for GA 2-oxidase that mainly catabolizes GA20 to GA29), suggesting a concerted regulation to increase levels of bioactive GA1 following these events. 4-Chloroindole-3-acetic acid (4-Cl-IAA) was found to mimic the seeds in the stimulation of PsGA3ox1 and the repression of PsGA2ox1 mRNA levels as well as the stimulation of PsGA2ox2 mRNA levels (codes for GA 2-oxidase that mainly catabolizes GA1 to GA8) in pericarp at 2 to 3 d after anthesis, while the other endogenous pea auxin, IAA, did not. This GA gene expression profile suggests that both seeds and 4-Cl-IAA can stimulate the production, as well as modulate the half-life, of bioactive GA1, leading to initial fruit set and subsequent growth and development of the ovary. Consistent with these gene expression profiles, deseeded pericarps converted [14C]GA12 to [14C]GA1 only if treated with 4-Cl-IAA. These data further support the hypothesis that 4-Cl-IAA produced in the seeds is transported to the pericarp, where it differentially regulates the expression of pericarp GA biosynthesis and catabolism genes to modulate the level of bioactive GA1 required for initial fruit set and growth. 相似文献
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Significant female flowering of 6- to 11-year-old seedlings and grafted ramets of sexually mature scions of lodgepole pine (Pinus contorta Dougl.) was promoted by both topical and spray applications of a gibberellin (GA) A4/7 mixture (1.6 to c. 5 mg per plant in total) during that period (June to September) when sexual differentiation of lateral primordia would be expected to take place. Girdling was used in most experiments to enhance the GA4/7 effect, as was the auxin, naphthaleneacetic acid (NAA). Average frequency of flowering branches on treated plants over all experiments ranged from 27 to 59% (control ranged from 0 to 36%) and average number of female strobili was increased from 2- to 6-fold by growth regulator treatment, relative to controls. Within an experiment, clonal or family frequency of flowering for treated plants ranged from 11 to 67% (controls were 0 to 28%), and number of female strobili was increased from 2- to 14-fold by growth regulator treatment, relative to controls. Movement of the flowering stimulus from the point of application was apparent in several experiments, the response in adjacent branches being correlated positively with increasing dosage of GA4/7. Significant male flowering occurred only in one experiment, girdling and GA4/7 treatment being promotive factors. The use of spray applications of GA4/7+ NAA is warranted to induce early and enhanced flowering in lodgepole pine seedlings and vegetative propagules for genetic improvement programs. 相似文献
19.
Enhancement of [C]Sucrose Export from Source Leaves of Vicia faba by Gibberellic Acid 总被引:2,自引:0,他引:2
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The effect of gibberellic acid (GA3) on sucrose export from source leaves was studied in broad bean (Vicia faba L.) plants trimmed of all but one source and one sink leaf. GA3 (10 micromolar) applied to the source leaf, enhanced export of [14C]sucrose (generated by 14CO2 fixation) to the root and to the sink leaf. Enhanced export was observed with GA treatments as short as 35 minutes. When GA3 was applied 24 hours prior to the 14CO2 pulse, the enhancement of sucrose transport toward the root was abolished but transport toward the upper sink leaf was unchanged. The enhanced sucrose export was not due to increased photosynthetic rate or to changes in the starch/sucrose ratio within the source leaf; rather, GA3 increased the proportion of sucrose exported. After a 10-min exposure to [14C]GA3, radioactivity was found only in the source leaf. Following a 2 hour exposure to [14C]GA3, radioactivity was distributed along the entire stem and was present in both the roots and sink leaf. Extraction and partitioning of GA metabolites by thin layer chromatography indicated that there was a decline in [14C]GA3 in the lower stem and root, but not in the upper stem. This pattern of metabolism is consistent with the disappearance of the GA3 effect in the lower stem with time after treatment. We conclude that in the short term, GA3 enhances assimilate export from source leaves by increasing phloem loading. In the long term (24 hours), the effect of GA3 is outside the source leaf. GA3 accumulates in the apical region resulting in enhanced growth and thus greater sink strength. Conversely, GA3 is rapidly metabolized in the lower stem thus attenuating any GA effect. 相似文献
20.
Gibberellins and Gravitropism in Maize Shoots : Endogenous Gibberellin-Like Substances and Movement and Metabolism of [3H]Gibberellin A20 总被引:4,自引:2,他引:2
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[3H]Gibberellin A20 (GA20) of high specific radioactivity (49.9 gigabecquerel per millimole) was applied equilaterally in a ring of microdrops to the internodal pulvinus of shoots of 3-week-old gravistimulated and vertical normal maize (Zea mays L.), and to a pleiogravitropic (prostrate) maize mutant, lazy (la). All plants converted the [3H]GA20 to [3H]GA1− and [3H]GA29-like metabolites as well as to several metabolites with the partitioning and chromatographic behavior of glucosyl conjugates of [3H]GA1, [3H]GA29, and [3H]GA8. The tentative identification of these putative [3H]GA glucosyl conjugates was further supported by the release of the free [3H]GA moiety after cleavage with cellulase. Within 12 hours of the [3H]GA20 feed, there was a significantly higher proportion of total radioactivity in lower than in upper halves of internode and leaf sheath pulvini in gravistimulated normal maize. Further, there was a significantly higher proportion of putative free GA metabolites of [3H]GA20, especially [3H]GA1, in the lower halves of normal maize relative to upper halves. The differential localization of the metabolites between upper and lower halves was not apparent in the pleiogravitropic mutant, la. Endogenous GA-like substances were also examined in gravistimulated maize shoots. Forty-eight hours after gravistimulation of 3-week-old maize seedlings, endogenous free GA-like substances in upper and lower leaf sheath and internode pulvini halves were extracted, chromatographed, and bioassayed using the `Tanginbozu' dwarf rice microdrop assay. Lower halves contained consistently higher total levels of GA-like activity. The qualitative elution profile of GA-like substances differed consistently, upper halves containing principally a GA20-like substance and lower halves containing mainly GA1-like and GA19-like substances. Gibberellins A1 (10 nanograms per gram) and A20 (5 nanograms per gram) were identified from these lower leaf sheath pulvini by capillary gas chromatography-selected ion monitoring. Results from all of these experiments are consistent with a role for GAs in the differential shoot growth that follows gravitropism, although the results do not eliminate the possibility that the redistribution of GAs results from the gravitropic response. 相似文献