3种天然二萜的化感作用及机制的研究

以黑麦草（Lolium perenne L.）和莴苣（Lacutuca sativa L.）为受试植物,研究了3种对映—贝壳杉烷二萜wangzaozin A、leukamenin E和weisiensin B对受试植物种子萌发、幼苗生长、叶绿素和膜损伤的影响,旨在评估3种二萜的化感作用潜能。结果显示：不同浓度的3种二萜对黑麦草和莴苣种子的萌发稍有降低,但明显延迟种子萌发时间;较高浓度下,3种二萜对黑麦草和莴苣幼苗的根长、苗长、鲜质量和干质量均有显著的抑制作用,并显示了浓度依赖性;同时,3种二萜显著降低黑麦草和莴苣幼苗叶片叶绿素a和叶绿素b含量,显著升高丙二醛（MDA）含量和相对电导率,而相对含水量呈下降趋势。上述结果表明,3种二萜通过影响受试植物的光合作用能力,引起细胞膜氧化损伤,导致叶片保水性降低,抑制受试植物幼苗的生长。     

Calcium Antagonists Inhibit Sustained Gibberellic Acid-Induced Growth of Avena (Oat) Stem Segments

The elongation response of Avena sativa (oat) stem segments to gibberellic acid (GA3) is of large magnitude, with high hormonal sensitivity and specificity, but without cell division activity. This system is therefore an excellent model for mechanistic studies on higher plant cell elongation and the action of gibberellin. At millimolar concentrations, the calcium antagonists verapamil, D-600, nicardipine, diltiazem, bepridil, 8-(N,N,-diethylamino)-octyl-3,4,5-trimethoxybenzoate HCl, and lanthanum substantially inhibited the growth of GA3-treated segments but had no effect on the elongation of nonhormone-treated segments. Although verapamil reduced the maximum growth rate and caused premature cessation of growth, even preincubation of the segments with the drug prior to treatment with GA3 failed to inhibit the earliest measured stimulation of growth by the hormone. Inhibition by verapamil was not reversed by increased concentrations of GA3 or calcium. Neither the calcium ionophore A23187 nor agonist BAY K 8644 had any effect on growth. Light microscopic examination of epidermal peels from antagonist-treated internodal tissue revealed no obvious differences from the control except that the cells were not as elongated. Although these results may support a role for calcium ion movement in maintaining the GA3-induced growth of Avena stem segments, they do not support the involvement of calcium ion movement in the hormone-mediated initiation of growth.     

水稻水孔蛋白RWC3的分布及其受GA和蔗糖的调控(英文)

水孔蛋白能介导水分的跨膜运输,在植物的生长发育过程中起重要作用。对RWC3启动子-GUS转基因水稻的组织化学染色表明,水稻(Oryza sativa L.)水孔蛋白RWC3可能在包括营养和生殖器官在内的各部位中广泛表达。同时发现,赤霉素(GA)能提高转基因植物的愈伤组织、悬浮细胞和叶片中的GUS活性,而GA合成的抑制剂ancymidol降低了GUS活性。进一步研究发现,蔗糖能抑制GA对GUS活性的提高,说明GA和蔗糖在对RWC3的表达调控的信号传递过程中可能存在着相互作用。     

水稻水孔蛋白RWC3的分布及其受GA和蔗糖的调控

水扎蛋白能介导水分的跨膜运输,在植物的生长发育过程中起重要作用.对RWC3启动子-GUS转基因水稻的组织化学染色表明,水稻(Oryza sativa L.)水孔蛋白RWC3可能在包括营养和生殖器官在内的各部位中广泛表达.同是发现,赤霉素(GA)能提高转基因植物的愈伤组织、悬俘细胞和叶片中的GUS活必性,而GA合成的抑制ancymidol降低了GUS活性.进一步研究发现,蔗糖能抑制GA对GUS活性的提高,说明GA和蔗糖在对RWC3表达调控的信号传递过程中可能存在着相互作用.     

Distribution of Water Channel Protein RWC3 and Its Regulation by GA and Sucrose in Rice （Oryza sativa）

Water channel proteins facilitate water flux across cell membranes and play important roles in plant growth and development. By GUS histochemical assay in RWC3 promoter-GUS transgenic rice (Oryza sativa L. cv. Shenxiangjin 4), one of the members of water channel proteins in rice, RWC3, was found to distribute widely in variety of organs, from vegetative and reproductive organs. Further studies showed that gibberellin (GA) enhanced the GUS activity in the transgenic calli, suspension cells and leaves, whereas ancymidol (anc), an inhibitor of GA synthesis, reduced the GUS activity. Sucrose was found to inhibit the effects induced by addition of GA, suggesting a possible cross-talk between GA and sucrose signaling on regulation of the RWC3 gene expression.     

CYP701A8: a rice ent-kaurene oxidase paralog diverted to more specialized diterpenoid metabolism

All higher plants contain an ent-kaurene oxidase (KO), as such a cytochrome P450 (CYP) 701 family member is required for gibberellin (GA) phytohormone biosynthesis. While gene expansion and functional diversification of GA-biosynthesis-derived diterpene synthases into more specialized metabolism has been demonstrated, no functionally divergent KO/CYP701 homologs have been previously identified. Rice (Oryza sativa) contains five CYP701A subfamily members in its genome, despite the fact that only one (OsKO2/CYP701A6) is required for GA biosynthesis. Here we demonstrate that one of the other rice CYP701A subfamily members, OsKOL4/CYP701A8, does not catalyze the prototypical conversion of the ent-kaurene C4α-methyl to a carboxylic acid, but instead carries out hydroxylation at the nearby C3α position in a number of related diterpenes. In particular, under conditions where OsKO2 catalyzes the expected conversion of ent-kaurene to ent-kaurenoic acid required for GA biosynthesis, OsKOL4 instead efficiently reacts with ent-sandaracopimaradiene and ent-cassadiene to produce the corresponding C3α-hydroxylated diterpenoids. These compounds are expected intermediates in biosynthesis of the oryzalexin and phytocassane families of rice antifungal phytoalexins, respectively, and can be detected in rice plants under the appropriate conditions. Thus, it appears that OsKOL4 plays a role in the more specialized diterpenoid metabolism of rice, and our results provide evidence for divergence of a KO/CYP701 family member from GA biosynthesis. This further expands the range of enzymes recruited from the ancestral GA primary pathway to the more complex and specialized labdane-related diterpenoid metabolic network found in rice.     

Antisense inhibition of NADH glutamate synthase impairs carbon/nitrogen assimilation in nodules of alfalfa (Medicago sativa L.)

Legumes acquire significant amounts of nitrogen for growth from symbiotic nitrogen fixation. The glutamine synthetase (GS)/NADH-dependent glutamate synthase (NADH-GOGAT) cycle catalyzes initial nitrogen assimilation. This report describes the impact of specifically reducing nodule NADH-GOGAT activity on symbiotic performance of alfalfa (Medicago sativa L.). Four independent transgenic alfalfa lines, designated GA89, GA87, GA88, and GA82 (for GOGATantisense), containing an antisense NADH-GOGAT cDNA fragment under the control of the soybean leghemoglobin (lbc3) promoter were evaluated. The GA plants were fertile and showed normal growth in non-symbiotic conditions. The NADH-GOGAT antisense transgene was heritable and the T1 plants showed phenotypic alterations - similar to primary transformants. Clonally propagated plants were inoculated with Sinorhizobium meliloti after rooting and the symbiotic phenotype was analyzed 21 days post-inoculation. Nodules of each GA line had reduced NADH-GOGAT activity, ranging from 33 to 87% of control plants, that was accompanied by comparable decreases in RNA and protein. Plants from the GA89 line, with the lowest NADH-GOGAT activity (c. 30%), presented a strikingly altered symbiotic phenotype: concomitantly activities of key enzyme for carbon and nitrogen assimilation decreased; nodule amino acids and amides were reduced while sucrose accumulated. Antisense GOGAT plants were chlorotic, reduced in fresh weight, and had a lower N content than control plants. Photosynthesis was also impaired in antisense plants. Specifically, reducing NADH-GOGAT in nodules resulted in plants having impaired nitrogen assimilation and altered carbon/nitrogen metabolic flux.     

深水稻节间伸长生长的机制

淹水可促进深水稻节间快速伸长生长,其主要受内源赤霉素、乙烯、脱落酸等激素信号分子的调控。淹水能促进深水稻植物株体内乙烯、赤霉素的生物合成、抑制脱落酸的生物合成,外源乙烯、赤霉素会加速深水稻节间伸长,而外源脱落酸抑制淹水节间的伸长,其中赤霉素是直接作用因子,乙烯能降低内源脱落酸水平、增加节地赤霉素的敏感性;还与渗透调节、细胞壁组份如膨胀素等有关,淹水及赤霉素都大大增加了膨胀素基因的表达。并就深水稻的     

深水稻节间伸长生长的机制

淹水可促进深水稻节间快速伸长生长,其主要受内源赤霉素、乙烯、脱落酸等激素信号分子的调控。淹水能促进深水稻植株体内乙烯、赤霉素的生物合成、抑制脱落酸的生物合成,外源乙烯、赤霉素会加速深水稻节间伸长,而外源脱落酸抑制淹水节间的伸长,其中赤霉素是直接作用因子,乙烯能降低内源脱落酸水平、增加节间对赤霉素的敏感性;还与渗透调节、细胞壁组份如膨胀素等有关,淹水及赤霉素都大大增加了膨胀素基因的表达。并就深水稻的进一步研究进行了展望。     

Terpenes with antimicrobial activity from Cretan propolis

Five terpenes, the diterpenes: 14,15-dinor-13-oxo-8(17)-labden-19-oic acid and a mixture of labda-8(17),13E-dien-19-carboxy-15-yl oleate and palmitate as well as the triterpenes, 3,4-seco-cycloart-12-hydroxy-4(28),24-dien-3-oic acid and cycloart-3,7-dihydroxy-24-en-28-oic acid were isolated from Cretan propolis. Moreover, 18 known compounds were also isolated, seven of them for the first time as propolis components. All structures were established on the basis of spectroscopic analysis and chemical evidence. All isolated compounds were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria as well as against some human pathogenic fungi showing a broad spectrum of antimicrobial activity.     

Stimulation and Inhibition by Ethephon of Stem and Leaf Growth of Some Gramineae at Different Stages of Development

The effect of ethephon on the growth of leaves and stems ofP. pratensis, Agrostis sp., and A. sativa was investigated.The length of the leaves of all species as well as that of theinternodes of stems of vegetative tillers of Agrostis sp. andof stems of reproductive A. sativa plants was reduced. Epidermalcell length was unchanged or somewhat increased, indicatinga reduction in cell number. The rate of cell elongation maybe decreased, however. A reduction in cell length was observedin the internode of generative oat plants that just startedto elongate at the time of treatment. In vegetative tillers of P.pratensis and A. sativa ethephonpromoted growth of the internodes by increasing cell length.Cell number was little affected. GA3 also promoted internodegrowth, causing an increase in cell length as well as in cellnumber. Application of ethephon and GA3 together gave an additiveeffect on cell length but a reverse effect on cell number. Effects of ethephon were observed for 5 or more weeks aftertreatment. Ethylene production from plants of A sativa increased,but the extra production had already decreased by 90% after11 d. No stimulation of the ethylene production by the plantsother than from the breakdown of ethephon was observed.     

Effect of inhibitors of polyamine biosynthesis on gibberellin-induced internode growth in light-grown dwarf peas

When gibberellic acid (GA3) is sprayed on 9-day-old light-brown dwarf Progress pea (Pisum sativum) seedlings, arginine decarboxylase (ADC; EC 4.1.1.9) activity increases within 3 h and peaks at about 9 h after GA3 application. This is followed by a second lower peak at about 30 h; both peaks were higher than the corresponding peaks in the controls. In contrast, no appreciable effect of GA3 on internode length was observed until about 12 h, after which time a dramatic increase in growth rate occurred and persisted for about 12 h. Specific (DL-alpha-difluoromethylarginine) and non-specific (D-arginine and L-canavanine) inhibitors of ADC strongly inhibited ADC activity and to a lesser extent internode growth. The inhibition was reversed only slightly by the addition of polyamines. Actinomycin D and cycloheximide inhibited the rise in ADC activity induced by GA3. The half-life of the enzyme was increased by GA3 treatment. The results suggest that part of the GA3-induced increase in internode growth may result from enhanced polyamine biosynthesis through the ADC pathway. Furthermore, the GA3 induced increase in ADC activity probably requires de novo synthesis of both RNA and protein.     

A method for profiling classes of plant hormones and their metabolites using liquid chromatography-electrospray ionization tandem mass spectrometry: an analysis of hormone regulation of thermodormancy of lettuce (Lactuca sativa L.) seeds

A highly selective and sensitive method for the simultaneous analysis of several plant hormones and their metabolites is described. The method combines high-performance liquid chromatography (HPLC) with positive and negative electrospray ionization-tandem mass spectrometry (ESI-MS/MS) to quantify a broad range of chemically and structurally diverse compounds. The addition of deuterium-labeled analogs for these compounds prior to sample extraction permits accurate quantification by multiple reaction monitoring (MRM). Endogenous levels of abscisic acid (ABA), abscisic acid glucose ester (ABA-GE), 7'-hydroxy-abscisic acid (7'-OH-ABA), phaseic acid (PA), dihydrophaseic acid (DPA), indole-3-acetic acid (IAA), indole-3-aspartate (IAAsp), zeatin (Z), zeatin riboside (ZR), isopentenyladenine (2iP), isopentenyladenosine (IPA), and gibberellins (GA)1, GA3, GA4, and GA7 were determined simultaneously in a single run. Detection limits ranged from 0.682 fmol for Z to 1.53 pmol for ABA. The method was applied to the analysis of plant hormones and hormonal metabolites associated with seed dormancy and germination in lettuce (Lactuca sativa L. cv. Grand Rapids), using extracts from only 50 to 100 mg DW of seed. Thermodormancy was induced by incubating seeds at 33 degrees C instead of 23 degrees C. Germinating seeds transiently accumulated high levels of ABA-GE. In contrast, thermodormant seeds transiently accumulated high levels of DPA after 7 days at 33 degrees C. GA1 and GA3 were detected during germination, and levels of GA1 increased during early post-germinative growth. After several days of incubation, thermodormant seeds exhibited a striking transient accumulation of IAA, which did not occur in seeds germinating at 23 degrees C. We conclude that hormone metabolism in thermodormant seeds is surprisingly active and is significantly different from that of germinating seeds.     

Promotion of leaf sheath growth by gibberellic acid in a dwarf mutant of rice

The mechanism of gibberellin (GA)-induced leaf sheath growth was examined using a dwarf mutant of rice (Oryza sativa L. cv. Tan-ginbozu) treated in advance with an inhibitor of GA biosynthesis. Gibberellic acid (GA₃) enhanced the growth of the second leaf sheath, but auxins did not. Measurement of the mitotic index and cell size revealed that cell elongation rather than cell division is promoted by GA₃. Gibberellic acid increased the extensibility of cell walls in the elongation zone of the leaf sheath. It also increased the total amount of osmotic solutes including sugars in the leaf sheath, but did not increase the osmotic concentration of the cell sap, due to an accompanying increase in cell volume by water absorption. In the later stage of GA₃-induced growth, starch granules completely disappeared from leaf sheath cells, whereas dense granules remained in control plants. These findings indicate that GA enhances cell elongation by increasing wall extensibility, osmotic concentration being kept unchanged by starch degradation. Received: 28 August 1997 / Accepted: 16 October 1997     

Effects of indole amides on lettuce and onion germination and growth

Auxins, such as indole-3-acetic acid (IAA), are important in plant germination and growth, while physiological polyamines, such as putrescine, are involved in cell proliferation and differentiation, and their concentrations increase during germination. In this work, novel indole amides were synthesized in good yields by monoacylation of morpholine and unprotected symmetrical diamines with indole-3-carboxylic acid, a putative metabolite of IAA, possessing no auxin-like activity. These amides were tested for their effects on seed germination and growth of the radicles and shoots of Lactuca sativa (lettuce) and Allium cepa (onion) seedlings, at 100.0, 1.0, and 0.01 microM concentrations. Germination was generally stimulated, with the exception of amide 3, derived from morpholine, at 100 microM. On radicle and shoot growth, the effect of these compounds was predominantly inhibitory. Compound 3 was the best inhibitor of growth of lettuce and onion, at the highest concentration. Amides, such as propanil, among others, are described as having herbicidal activity.     

Inhibitory action of five tannins on growth induced by several gibberellins

The following tannins, Chinese gallotannin, 1,2,3,4,6-pentagalloyl glucose, chebulinic acid, procyanidin dimers, and procyanidin trimers were tested and found to be antagonists of seven gibberellins (GAs). Each tannin inhibited the growth induced by any of the gibberellins GA(1), GA(3), GA(4), GA(7), GA(9), GA(13), and GA(14) in the dwarf pea assay. Endogenous growth was not affected. The highest ratio of tannin to gibberellin tested (1000:1 by weight) inhibited from 60 to 95% of the induced growth for all tannins and all gibberellins tested. The tannins were particularly inhibitory against GA(4) and GA(14) where a ratio of 10:1 (tannins: GA by weight) resulted in up to 85% growth reduction. Inhibition could be completely reversed by increasing the amount of gibberellin in all combinations studied. The procyanidin dimers and trimers were the first purified components of condensed tannins to be tested in this system and were potent inhibitors particularly against growth induced by GA(4) and GA(14). Inhibition by these compounds along with similar inhibition by previously tested hydrolyzable tannins demonstrates that the effect is general to tannins of all classes.     

Restoration of gibberellin biosynthesis by 2,6-diisopropylphenoxyacetic acid in uniconazole-treated rice plants

2,6-Diisopropylphenoxyacetic acid (DIPA), a promoter of growth and flowering of Sagittaria species, was found to improve the shoot growth of rice plants treated with uniconazole, an inhibitor of gibberellin (GA) biosynthesis. In a modified micro-drop bioassay using semi-dwarf rice, Oryza sativa L. cv. Tan-ginbozu, in which uniconazole had been incorporated into the agar medium, a significant recovery from growth inhibition was observed for both the 3rd and the 4th leaf sheaths but not for the 2nd sheath. In greenhouse experiments, uniconazole-treated rice plants partially recovered from growth inhibition when DIPA was applied after uniconazole treatment, whereas DIPA applied with, or before, uniconazole treatment did not improve growth. The levels of GA₁ and GA₂₀ in the rice plants treated with uniconazole plus DIPA were almost equal to those of the untreated controls, indicating that the observed growth recovery is attributable to the restoration of GA biosynthesis by DIPA.     

Abscisic acid in the thermoinhibition of lettuce seed germination and enhancement of its catabolism by gibberellin

Germination of lettuce (Lactuca sativa L. cv. 'Grand Rapids') seeds was inhibited at high temperatures (thermoinhibition). Thermoinhibition at 28 degrees C was prevented by the application of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis. At 33 degrees C, the sensitivity of the seeds to ABA increased, and fluridone on its own was no longer effective. However, a combined application of fluridone and gibberellic acid (GA3) was able to restore the germination. Exogenous GA3 lowered endogenous ABA content in the seeds, enhancing catabolism of ABA and export of the catabolites from the intact seeds. The fluridone application also decreased the ABA content. Consequently, the combined application of fluridone and GA3 decreased the ABA content to a sufficiently low level to allow germination at 33 degrees C. There was no significant temperature-dependent change in endogenous GA1 contents. It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.     

Phytotoxic clerodane diterpenes from Salvia miniata Fernald (Lamiaceae)

Our ongoing research to identify natural growth inhibitors with diterpene and triterpene skeletons exuding from the surface of the aerial parts of Salvia species led us to study Salvia miniata Fernald. Ten clerodane diterpenoids were found, along with three known diterpenes. Most of the isolated compounds from S. miniata inhibited the germination of Papaver rhoeas L. and Avena sativa L. in Petri dish experiments. Parallel results have been obtained in experiments carried out to evaluate the subsequent growth of the seedlings of the target species in the presence of the tested compounds.