平截独活的香豆素成分

从四川省汶川县产平截独活Heracleum vicinum根的乙醇提取物中分离鉴定了6个成分,分别为虎耳草素(pimpinellin)(1),异佛手柑内酯(2),6-甲氧基当归素(sphondin)(3)。佛手柑内酯(bergapten)(4),异虎耳草素(isopimpincllin)(5),falcarindi01)(6).     

CONSTRAINTS ON CHEMICAL COEVOLUTION: WILD PARSNIPS AND THE PARSNIP WEBWORM

The parsnip webworm (Depressaria pastinacella) and the wild parsnip (Pastinaca sativa) together represent a potentially “coevolved” system in that throughout their ranges the plant has relatively few other herbivores and the insect has virtually no other hosts. Individual wild parsnip plants within a central Illinois population vary in their content and composition of furanocoumarins, secondary compounds with insecticidal properties. Half-sib and parent-offspring regression estimates of the heritability of furanocoumarins demonstrate that this variation is genetically based. Wild parsnip plants also vary in their resistance to damage by the parsnip webworm, which feeds on flowers and developing seeds. In an experimental garden, seed production in the primary umbel ranged from 0 to 1,664 seeds among individuals, and mean seed production of half-sib families ranged from 3.7 seeds to 446.0 seeds. Approximately 75% of the variation in resistance among half-sib families to D. pastinacella was attributable to four furanocoumarin characteristics—resistance is positively related to the proportion of bergapten and the amount of sphondin in seeds, and negatively related to the amount of bergapten and the proportion of sphondin in leaves. Each of the four resistance factors had significant heritability. Thus, resistance in wild parsnip to the parsnip webworm is to a large extent chemically based and genetically controlled. Genetic correlations among fitness and resistance characters, however, tend to limit coevolutionary responses between herbivore and plant. In greenhouse plants protected from herbivory, several of the resistance factors have negative genetic correlations with potential seed production. Ostensibly, highly resistant plants in the absence of herbivory would be at a competitive disadvantage in the field. The selective impact of the herbivore is also limited in this population by a negative genetic correlation among resistance factors. Selection to increase one resistance factor (e.g., the proportion of bergapten in the seed) would at the same time decrease the amount of a second resistance factor (e.g., the amount of sphondin in the seed). The wild parsnip and the parsnip webworm, then, appear to have reached an evolutionary “stalemate” in the coevolutionary arms race.     

Germination Inhibitors in Fruit Extracts of Red Beet (Beta vulgaris cv. rubra

Germination inhibitors in methanol and water extracts of redbeet fruits (Beta vulgaris cv. rubra L.) have been studied usinglettuce and red beet seed germination as bioassays. The methanolextracts contained substances which inhibited lettuce seed germination,but had no effect on the germination of red beet seeds. Germinationof both lettuce seeds and of water-leached or sulphuric acid-treatedred beet seed balls were inhibited by the water extracts. Theconcentrations of ammonia, ferulic acid, and oxalate in thewater extracts were much lower than required for inhibitionof red beet seed germination. The water extracts contained,however, large amounts of inorganic ions, and the results clearlydemonstrated that the inhibitory effect of the water extractson red beet seed germination was mainly due to the content ofsuch inorganic ions.     

The fungitoxicities of plant furocoumarins

A mixture of the furocoumarins pimpinellin, isopimpinellin, isobergapten and sphondin isolated from Heracleum sphondylium root was toxic to Gloeosporium limetticola, Botryis cinerea, Sclerotinia fructigena and Stereum purpureum at 200 p.p.m. or less in nutrient medium. The extractive of the leaves of plants that contain furocoumarins suppressed in vivo growth of G. limetticola and B. cinerea at concentrations lower than the contents of the extractive in the leaves. Furocoumarins may form an important class of natural defensive agents against fungi; this possibility is discussed.     

Morphological and chemical variations in natural populations of Pituranthos triradiatus in the Negev Desert

Morphochemical variations among six populations of Pituranthos triradiatus have been studied in the Negev Desert, in areas located within an air distance of 80 km, with an aridity gradient from 150 to 50 mm of average annual rainfall. Based on morphological florisitic characters, as well as on the content of furanocoumarins in the shoots of the shrub, five different populations have been observed. Some of the morphological characters which are commonly used for classification in the species level were found useful for the subspecies level, e.g. number of rays per umbell or per umbellet. Others, such as the shape of petals or stylopodium, or petals color, were not efficient. In addition to the commonly used characters, average fruit weight was found useful. Seven different furanocoumarins were found in the examined populations of P. triradiatus. Four of them (isoimperatorin, imperatorin, bergapten and isopimpinellin) were in each of the populations studied. Three other furanocoumarins were found to be specific: cnidilin for the Revivim population; pimpinellin for Zin and isobergapten for the Marzeva and Neqarot populations. In addition to these specific furanocoumarins, the amount of bergapten in the shoots seems to be specific for each population and is suggested to be used as a chemical marker for further screening of chemotype differentiation in R. triradiatus. It is suggested that the differences in the floristic characters, as well as in the content of furanocoumarins are of genetic nature and not an artifact. To better establish this view and to evaluate the efficiency of furanocoumarins content as a chemotaxanomic marker, further work is needed. It is also suggested that levels of isolation among the investigated population account for the differences encountered. No association could be found between different levels of aridity and different levels of furanocoumarin content.     

Patterns of furanocoumarin production and insect herbivory in a population of wild parsnip (Pastinaca sativa L.)

Summary Seasonal changes in the distribution and abundance of furanocoumarins in wild parsnip, Pastinaca sativa (Umbelliferae), were examined in a population of plants in Tompkins County, New York. Xanthotoxin, imperatorin and bergapten (linear furanocoumarins) occur in all above-ground parts of the plant; in addition, angelicin and sphondin (angular furanocoumarins) occur in umbels of some individuals. Total furanocoumarin content, as measured by percent dry weight, is greatest in reproductive parts, particularly buds and seeds; variation in concentrations between plants is greatest in vegetative structures (e.g., leaves).Within the plant, the distribution of furanocoumarins is significantly correlated with nitrogen, as opposed to biomass, allocation. In that nitrogen is often a factor limiting the plant growth, furanocoumarins appear to be allocated in proportion to plant tissue value; reproductive structures, obvious contributors to plant fitness, contain over ten times the amount of nitrogen and furanocoumarin contained in vegetative structures such as senescent leaves.Stepwise multiple regression analysis revealed that generalized insect herbivores tend to feed on plants or plant parts low in furanocoumarin content and, correspondingly, low in nitrogen content. Parsnip specialists, notably Depressaria pastinacella (Lepidoptera: Oecophoridae), feed exclusively on umbels, plant parts rich in nitrogen and furanocoumarins; furanocoumarin number and content in fact account for over 60% of the variance in number of umbel feeders. These patterns conform with previous determinations of the toxicological properties of furanocoumarins. Nitrogen is known to affect growth rate, fecundity, longevity and survivorship of insect herbivores; by tolerating or detoxifying furanocoumarins, D. pastinacella can consume plant tissues containing significantly greater amounts of nitrogen than tissues consumed by generalist feeders. That the presence of D. pastinacella on individual plants is correlated with the number of furanocoumarins present is consistent with the hypothesis that parsnip specialists use angular furanocoumarins as host recognition cues.     

Inducible nitric oxide synthase inhibitors of Chinese herbs. Part 2: naturally occurring furanocoumarins

Inducible nitric oxide synthase (iNOS)-dependent production of nitric oxide (NO) plays an important role in inflammation. The effects of various naturally occurring furanocoumarins on NO production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage cells were evaluated in vitro. The results showed that angelicin, pimpinellin, sphondin, byakangelicol, oxypeucedanin, oxypeucedanin hydrate, xanthotoxin, and cnidilin are potential NO production inhibitors, and their IC50 values for inhibition of nitrite production were 19.5, 15.6, 9.8, 16.9, 16.8, 15.8, 16.6, and 17.7 microg/mL, respectively. Distinct structure-activity relationships were also revealed for the NO production inhibitory activities of these furanocoumarins. Activities of the angelicin type such as pimpinellin and sphondin were more potent than those of the psoralen type. Presence of a methoxy at the C6 position in the angelicin type seemed to be essential to augment the activity. Western blot analysis demonstrated that only sphondin dose-dependently inhibited the expression of the iNOS protein at 2.5-20 microg/mL. However, iNOS enzyme activity was stimulated with LPS for 12 h and sphondin was administered (20 microg/mL) for 24 h, which did not reasonably inhibit iNOS enzyme activity. L-NAME (100 microM), a known specific inhibitor of iNOS, was employed as a positive control with the same protocol and showed more than 50% inhibition activity. The results demonstrate that the NO production inhibitory activity of sphondin is due to the effect of iNOS expression, but not by direct inhibition of iNOS enzyme activity. Thus, sphondin may act as a potent inhibitor of NO production under tissue-damaging inflammatory conditions.     

Investigating and modeling the combined effects of pH and osmotic pressure on seed germination for use in phytoactivity and allelopathic research

Phytoactivity and allelopathic studies are heavily dependent on germination bioassays of water solutions of allelochemical(s), which necessarily imply that pH and osmotic pressure vary among treatments and between treatments and controls and are therefore a confounding factor in the assessment of seed germination responses to allelochemical(s). When the contribution of pH and osmotic pressure to seed germination responses is considered in experimental designs their effects are almost without exceptions examined separately being assumed, without any evidences, that pH and osmotic pressure act independently on seed germination responses. The objectives of this work were to examine experimentally such assumption using wheat, lettuce, and subterranean clover cultivars to evaluate and model the combined effects on germination of pH and osmotic pressure in the range between 3.0–6.0 and 0–100 mOsmol kg^?1, respectively. Empirical equations are fitted, discussed, and the need to consider the simultaneous effects of pH and osmotic pressure firmly established. Finally, the use of the equations fitted and its impact on conclusions is exemplified in a dose-response bioassay of water extracts of Cistus ladanifer on seed germination using subterranean clover as target species where hormesis was found before allelochemical effects were corrected for pH and osmotic pressure values of control and extracts.     

Evaluation of in vitro shoots of <Emphasis Type="Italic">Artemisia judaica</Emphasis> for allelopathic potential

Allelopathic performance of in vitro fresh green shoot, green, and brown shoot extracts including dry shoot powders of Artemisia judaica was evaluated through bioassay-guided studies using lettuce under laboratory conditions. The dry powders caused strong germination and growth inhibition of the lettuce seed tested. The green and brown shoot crude extracts of A. judaica also produced a strong germination and growth inhibition. The magnitude of inhibition in experiments with the brown shoot extracts was higher than that with the green shoot extracts. The lettuce seed incubated together with the fresh green shoots showed that the growth of lettuce was stimulated, while the germination of seed was delayed. The results show that there are different allelochemicals present in the exudates and volatiles of A. judaica. The shoot extracts under assay conditions showed a dose-dependent free radical scavenging effect of DPHH and a dose-dependent reduction of chlorophyll content from lettuce leaves. The antioxidant potential and total chlorophyll content of the lettuce leaf declined in all the shoot extract treatments. These results clearly indicate that the in vitro shoot of A. judaica contains some strong biologically active allelochemicals that are involved in plant growth regulation.     

Alternating Dependency of Cytokinin Activity on the Number of Methylene Units in ω-Phenylalkyl Derivatives of Some Purine Cytokinins and 4-Substituted Pyrido[3,4-d]pyrimidine

ω-Phenylalkyl derivatives of N⁶-substituted adenine, N⁶-substituted adenosine and 6-alkoxy-purine with odd numbers of methylenes had relatively high activity, while the corresponding 2-methyl-4-substituted-aminopyrido[3,4-d]pyrimidines with even numbers of methylenes had high activity in an Amaranthus betacyanin test and lettuce seed germination test. These results suggest that the ω-phenyl groups of the cytokinins play a specific role for cytokinin-receptor binding and that the pyrido[3,4-d]pyrimidines interact with a receptor in a different binding mode.     

Cytokinin-agonistic and antagonistic activities of 4-substituted-2-methylpyrrolo[2,3-d] pyrimidines, 7-deaza analogs of cytokinin-active adenine derivatives

Sixteen 4-substituted-2-methylpyrrolo[2,3-d]pyrimidines were tested for their activities as cytokinin agonists and antagonists in three bioassay systems. With the systematic variation of the 4-substituent, the activity changed consecutively from agonistic to antagonistic in the tobacco callus test, and this agonist-antagonist relationship was analysed by a steric substituent parameter as a common quantitative measure. Two compounds were found to possess bud-forming activity in the absence of added cytokinins. Eight compounds promoted betacyanin synthesis'in Amaranthus and 4 promoted germination in lettuce seeds. The 4-hydroxyethyl derivative, which was inactive in the tobacco test, suppressed betacyanin synthesis at 100 μM against 100 μM 6-(3-methyl-2-butenylamino)- purine. The 4-phenyl derivative showed antagonist activity in the tobacco test, little activity in the Amaranthus bio- assay and significant agonist activity in the lettuce seed germination. The 4-cyclobutyl derivative exerted the strongest anticytokinin activity (I₅₀ at 0.06 μM against 0.05 μM kinetin) in the tobacco callus assay, while little activity was observed in the other two assay systems.     

Chemical barriers to adaptation by a specialist herbivore

Summary Depressaria pastinacella, the parsnip webworm (Lepidoptera: Oecophoridae), feeds throughout eastern North America on Pastinaca sativa (wild parsnip) and few other species. The assumption that specialist herbivores such as the parsnip webworm are adapted to hostplant chemistry, and are therefore unaffected by chemical variation in hostplants, was tested. Flower buds from plants grown first in the greenhouse and then in the field were fed to ultimate instar webworms. Plant phenotype had a significant effect on virtually all webworm food utilization parameters. While nutritional factors (i.e., nitrogen content) were correlated with approximate digestibility, two constituents of the flowers — bergapten and xanthotoxin, both linear furanocoumarins — independently accounted for a significant amount of variation in food utilization indicies. The physiological effects of these furanocoumarins were confirmed in artificial diet experiments. Despite the fact that the two most important furanocoumarins in parsnip flowers relative to webworm feeding and growth are isomers, differing only in the positioning of a methoxy substituent, they have different physiological effects; while xanthotoxin in general has no effect on growth, bergapten decreases growth and digestibility of the diet. These results underscore the need in studies of plant-animal interactions to examine individual chemical components rather than classes of compounds.     

Quantitative trait loci associated with seed and seedling traits in Lactuca

Seed and seedling traits related to germination and stand establishment are important in the production of cultivated lettuce (Lactuca sativa L.). Six seed and seedling traits segregating in a L. sativa cv. Salinas x L. serriola recombinant inbred line population consisting of 103 F8 families revealed a total of 17 significant quantitative trait loci (QTL) resulting from three seed production environments. Significant QTL were identified for germination in darkness, germination at 25 and 35°C, median maximum temperature of germination, hypocotyl length at 72 h post-imbibition, and plant (seedling) quality. Some QTL for germination and early seedling growth characteristics were co-located, suggestive of pleiotropic loci regulating these traits. A single QTL (Htg6.1) described 25 and 23% of the total phenotypic variation for high temperature germination in California- and Netherlands-grown populations, respectively, and was significant between 33 and 37°C. Additionally, Htg6.1 showed significant epistatic interactions with other Htg QTL and a consistent effect across all the three seed production environments. L. serriola alleles increased germination at these QTL. The estimate of narrow-sense heritability (h²) of Htg6.1 was 0.84, indicating potential for L. serriola as a source of germination thermotolerance for lettuce introgression programs.     

An examination of the growth substance activity of vitamin D3

The plant growth activity of vitamin D₃ has been examined using well-established bioassays. Vitamin D₃ was found to promote adventitious root formation in cuttings ofPopulus tremula and to promote the germination of lettuce (Lactuca sativa cv. Grand Rapids) seeds in the absence of light. No other effects were observed typical of plant growth substances.Presented at the Federation of European Societies of Plant Physiology IVth Congress, Strasbourg (1984).     

Comparison of the seed germination effects of synthetic analogs of strigol,gibberellic acid,cytokinins, and other plant growth regulators

Four synthetic multiring analogs of strigol, a naturally occurring sesquiterpene lactone that promotes germination of dormant seeds ofStriga (witchweed), were found to stimulate germination of dormantLactuca (lettuce) seeds. The effects on light-sensitive and light-insensitive lettuce seeds were concentration-dependent and exceeded those produced by equimolar (0.1 mM) solutions of gibberellic acid. Strigol and epistrigol promoted lettuce seed germination to a lesser degree than did the synthetic analogs. The strigol group compounds had minimal effect on the germination of monocot seeds. The results indicate that the synthetic strigol analogs have plant growth regulatory activity in dormant seeds of genera beyondStriga in which germination stimulation by strigol and the synthetic analogs was first demonstrated.Names of companies of commercial products are given solely for the purpose of providing specific information; their mention does not imply recommendation or endorsement by the U.S. Department of Agriculture over others not mentioned.     

Chemical Composition of Ambrosia trifida Essential Oil and Phytotoxic Effect on Other Plants

This study aimed to identify the main components of an essential oil produced from leaves of Ambrosia trifida and to evaluate its potential allelopathic effect on seed germination and seedling growth of lettuce, watermelon, cucumber and tomato. The essential oil was obtained by hydrodistillation and characterized chemically by gas chromatography (GC) coupled with both mass spectrometry (MS) and flame ionization detector (FID). Total 69 compounds were identified, with limonene (20.7 %), bornyl acetate (15.0 %), borneol (14.7 %) and germacrene D (11.6 %) as the major components. The working solutions of the essential oil emulsified with Tween 20 and dissolved in distilled water were prepared at four concentration levels (0.01, 0.1, 0.5 % and 1 %, v/v). The results obtained showed that increase in essential oil concentration leads to decrease in seed germination, as well as shoot and radical length of lettuce, watermelon, cucumber and tomato. The obtained data revealed a highly significant effect (p<0.05) between control and 1 % and 0.5 % oil concentrations in all treatments. The essential oil of A. trifida exhibited more powerful phytotoxic effects on lettuce, watermelon and tomato than on cucumber regarding germination and early seedling growth.     

Allelopathic Potential of <Emphasis Type="Italic">Pueraria thunbergiana</Emphasis>

The allelopathic potential of Pueraria thunbergiana was investigated under laboratory conditions. The powder of freeze-dried leaves of P. thunbergiana inhibited the germination and the growth of roots and shoots of cress, lettuce, timothy and ryegrass. Significant reductions in the germination and growth of roots and shoots were observed as the powder concentration increased in all bioassays. The putative compounds causing the inhibitory effect of the powder were isolated and determined by their spectral data as cis.trans- and trans,trans-xanthoxin This revised version was published online in July 2006 with corrections to the Cover Date.     

Improved germination bioassays for allelopathy research

A new method for germination bioassays in allelopathy was evaluated. Inspired by pharmacology, allelochemical quantity to test on different target seeds was calculated according to seeds biometry. The first step consisted in measuring volume, mass, surface and shape of Lactuca sativa and Raphanus sativus seeds. The radish seed mass, surface, volume and contact area biometric parameters were respectively 10, 2, 6 and 1.7 that of lettuce. Two germination bioassay sets were compared: (i) a conventional one, testing the same concentration of allelochemical (2-benzoxazolinone termed as “BOA”) on the two species and, (ii) a biometrics enhanced seed test (“BEST” method), employing quantities of the chemical that were calculated in proportion to seed biometry parameters. The conventional method indicated that 1 mM BOA slowed and decreased germination rate (radish 50 %, lettuce 10 %) whereas 10 and 0.1 μM did not induce any effect. The BEST method offered more differentiated results: applied BOA according to seed volume induced significant inhibition of radish germination (both quantities), while lettuce was only affected by the highest dose. The same occurred when considering grain surface and contact area. Thus, the BEST assay showed more clearly that radish was more sensitive to BOA than lettuce. Compared to a setup with identical test compound concentrations for all tested species, the BEST method provides more differentiated results contributing to a more realistic comparative susceptibility assessment.     

Molecular requirements for abscisic acid activity in two bioassay systems

Summary Twenty-two analogues of ABA have been tested in the Avena coleoptile and lettuce germination bioassays. Ten of these analogues were considerably more active than ABA itself as inhibitors of lettuce germination, but in the Avena coleoptile assay their activity never significantly exceeded that of ABA. The molecular requirements for activity also differ in the two assay systems, although the presence of the ring double bond is a requirement of both.     

Effects of Simulated Oilfield Produced Water on Early Seedling Growth After Treatment in a Pilot-Scale Constructed Wetland System

Seed germination and early seedling growth bioassays were used to evaluate phytotoxicity of simulated oilfield produced water (OPW) before and after treatment in a subsurface-flow, pilot-scale constructed wetland treatment system (CWTS). Responses to untreated and treated OPW were compared among seven plant species, including three monocotyledons: corn (Zea mays), millet (Panicum miliaceum), and sorghum (Sorghum bicolor); and four dicotyledons: lettuce (Lactuca sativa), okra (Abelmoschus esculents), watermelon (Citrullus lanatus), and soybean (Glycine max). Phytotoxicity was greater in untreated OPW than in treated OPW. Exposures to untreated and treated OPW enhanced growth in some plant species (sorghum, millet, okra, and corn) relative to a negative control and reduced growth in other plant species (lettuce, soybean, and watermelon). Early seedling growth parameters indicated that dicotyledons were more sensitive to test waters compared to monocotyledons, suggesting that morphological differences between plant species affected phytotoxicity. Results indicated the following sensitivity scale for plant species: lettuce > soybean > watermelon > corn> okra≈millet >sorghum. Phytotoxicity of the treated OPW to lettuce and soybean, although concentrations of COCs were less than irrigation guideline concentrations, suggests that chemical characterization and comparison to guideline concentrations alone may not be sufficient to evaluate water for use in growing crops.