The Distribution of Two Major Iridoids in Different Organs of <Emphasis Type="Italic">Antirrhinum majus</Emphasis> L. at Selected Stages of Development

Two iridoid glucosides isolated from leaves of Antirrhinum majus L. were identified as the known compounds antirrhinoside and antirrhide. Plants grown hydroponically demonstrated that antirrhinoside is present in all plant organs including the roots. In contrast, antirrhide is found only in leaves. Furthermore, both iridoids were identified in the main stem axillary leaves and leaves on the lateral branches. The highest concentrations of antirrhinoside were found in the main and lateral stems as well as the buds and flowers. As leaves age, for both cultivars, the levels of antirrhinoside drop significantly, and there is a corresponding increase in antirrhide. In spite of the different genetic backgrounds of the two cultivars, the overall distribution of the iridoids was similar during vegetative and flowering development. Radiolabeling of recently expanded axillary leaves with ¹⁴CO₂ showed that both antirrhinoside and antirrhide were prominently labeled in the laminar tissue. However, only ¹⁴C-antirrhinoside was recovered in the subtending petiole tissue, consistent with the suggestion that it is a phloem mobile compound.     

Sex pheromone biosynthesis of (E,E)-8,10-dodecadienol in codling mothCydia pomonella involvesE9 desaturation

Sex pheromone biosynthesis in the codling mothCydia pomonella (Lepidoptera; Tortricidae) was studied by topical application of deuterated fatty acids in DMSO to pheromone glands. The incorporation of deuterium label into fatty acids and alcohols in the pheromone gland was monitored by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. Dodecanol, (E)-9-dodecenol, (E,E)-8,10-dodecadienol, tetradecanol, and hexadecanol were found in gland extracts. The application of [12,12,12-²H₃]dodecanoic acid resulted in labeled dodecanol, (E)-9-dodecenol, and (E,E)-8,10-dodecadienol, as well as the corresponding labeled acids. No label was incorporated into tetradecanol or hexadecanol or any acid with more than 12 carbon atoms. The application of labeled tetradecanoic or hexadecanoic acid introduced label not only into the 12-carbon alcohols, but also into tetradecanol, or tetradecanol and hexadecanol, respectively. The application of (E)-[11, 11,12,12,12,-²H₅]9-dodecen-oic acid, whose facile synthesis is described, resulted in labeled (E)-9-do-decenol and (E,E)-8,10-dodecadienol. The (E,E)-8,10-dodecadienol so produced was characterized by an ion atm/z 186, equivalent to [M]⁺ of a dienol labeled with four deuterons. Thus, one deuterium label is lost when the labeled (E)-9-monoene is converted to the (E,E)-8,10-diene. We conclude that (E,E)-8,10-dodecadienol is synthesized by chain shortening (-oxidation) of palmitic acid to dodecanoic acid, followed by an unusualE9 desaturation and subsequent conversion of this intermediate into the conjugated precursor, which is finally reduced to the pheromone alcohol. The evolutionary significance ofE9 desaturation being responsible for pheromone production in an Olethreutinae species is discussed.     

Development of a bioassay to test phloem sap samples from lettuce for resistance toNasonovia ribisnigri (homoptera,aphididae)

TheNr-gene-based resistance of lettuce to the aphidNasonovia ribisnigri (Mosley) has previously been shown to be located in the phloem. Since chemical analyses of the phloem sap had shown no differences between resistant and susceptible lines, a bioassay was developed in order to test samples from resistant and susceptible plants on aphid feeding. For this, whole-plant extracts, honeydew, and EDTA-collected phloem extracts were obtained, and a sensitive bioassay was developed using EDTA samples. The EDTA was removed, and samples were added to a simple sucrose solution or to a complex artificial diet and presented in a choice situation comparing extracts from resistant and susceptible plants. EDTA-collected phloem sap samples from susceptible plants were preferred to those from resistant plants. The resistance is probably based on a feeding deterrent activity of the phloem sap in the resistant plant.     

Strong repellency of the root knot nematode,Meloidogyne incognita by specific inorganic ions

Simple inorganic salts of the ions K⁺, NH ₄ ⁺ , Cs⁺, NO ₃ ^– , and Cl^– are strongly repellent to infective second-stage larvae of the root knot nematode,Meloidogyne incognita. Some of these salts are known to be beneficial to plant growth. The results suggest a new means of plant protection.     

Hydroxamic acid glucosides in honeydew of aphids feeding on wheat

DIMBOA glucoside (2-O-/gb-D-glucopyranosyl-4-hydroxy-7-meth-oxy-1,4-benzoxazin-3-one), the main hydroxamic acid (Hx) in intact wheat plants, was detected in the honey dew ofRhopalosiphum padi feeding on seedlings of six wheat cultivars that differed in their concentration of Hx, suggesting that the chemical circulates in the phloem. Neither the aglucone (DIMBOA) nor its main breakdown product were found in any of the honeydew samples. Honey dew production by aphids caged on seedlings of the wheat cultivars and DIMBOA glucoside concentrations in the honeydew followed biphasic curves when plotted against Hx concentration, suggesting passive ingestion of the chemical from the phloem at low Hx concentrations and limited ingestion due to feeding deterrency by Hx in mesophyll cells at high Hx concentrations. The presence of plant toxins such as Hx glucosides in the phloem sap, the main ingesta of aphids, and in the mesophyll cells, has major implications for plant defense, through a feeding deterrent effect during stylet penetration, and deterrency (antixenosis) along with antibiosis during feeding.     

Phenolic Chemistry of Coast Live Oak Response to <Emphasis Type="Italic">Phytophthora ramorum</Emphasis> Infection

Since the mid 1990s, Phytophthora ramorum has been responsible for the widespread mortality of tanoaks, as well as several oak species throughout California and Oregon forests. However, not all trees die, even in areas with high disease pressure, suggesting that some trees may be resistant to the pathogen. In this study, the chemical basis of host resistance was investigated. Three field experiments were carried out in California between December 2004 and September 2005. The levels of nine phenolic compounds (gallic acid, catechin, tyrosol, a tyrosol derivative, ellagic acid, and four ellagic acid derivatives) extracted from the phloem of trees that had been either artificially inoculated with P. ramorum or trees putatively infected with P. ramorum (based on canker symptoms) were quantified by high-performance liquid chromatography (HPLC). Significant differences in phenolic profiles were found between phloem sampled from the active margins of cankers, healthy phloem from asymptomatic trees, and phloem sampled 60 cm away from canker sites, although the magnitude and direction of the responses was not consistent across all experiments. Concentrations of gallic acid, tyrosol, and ellagic acid showed the greatest differences in these different tissues, but varied considerably across treatments. Gallic acid and tyrosol were tested in in vitro bioassays and showed strong dose-dependent inhibitory effects against P. ramorum, P. cinnamomi, P. citricola, and P. citrophthora. These results suggest that phloem chemistry varies in response to pathogen infection in California coast live oak populations and that changes in phloem chemistry may be related to apparently resistant phenotypes observed in the field. Frances S. Ockels and Alieta Eyles contributed equally to the paper     

Comparison between two controlled-release fertilizers on selected foliage plants in an artificial potting mix

A series of trials compared Osmocote^® and a recently available controlled-release fertilizer (CRF) product, Nutricote^®, at the same rates of N per container. Comparable formulations (e.i. 3–4 months) were compared on a variety of tropical foliage plants including:Impatiens, palms (Chamaedorea seifrizii, Chrysalidocarpus lutescens, Phoenix roebelinii, Rhapis excelsa andChamaedorea elegans) andSpathiphyllum; at 10 rates of N from 0 to 2–3 times the manufacture's recommended rate in a 1:1 (v:v) peat:perlite mix amended with dolomitic lime and a commercial micronutrient mixture. The plants were grown in a shade house, watered with overhead spray stakes and pest control measures used as required. Growth parameters used were plant height, growth index and top dry weight, along with tissue analysis and NO ₃ ^- concentrations. Overall plant height of the majority of plants tested was found to be comparable for the two CRF sources. However, there were some differences in top dry weight and leaf green color which were species specific. These results suggest that the release rate and availability of specific nutrients during the various plant growth phases may be more important for optimum plant growth and quality than the fertilizer formulation used. In general, both CRF products resulted in satisfactory plant growth and quality under the conditions of these trials.Additional studies are needed on the other factors affecting the use of these fertilizer products, such as water quality, media, media temperature, light, fertilizer placement, and economics. Once these factors are fully understood it will be possible to fully take advantage of this newer fertilizer technology and to customize the fertilizer to the plant species and its growing conditions.Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3905.     

Biosynthesis of Tiglic, Ethacrylic, and 2-Methylbutyric Acids in a Carabid Beetle, Pterostichus (Hypherpes) californicus

Tiglic, 2-methylbutyric, and ethacrylic acids are found in the pygidial gland defensive fluid of many carabid beetles. By injecting a deuterium-labeled precursor into the carabid beetle Pterostichus (Hypherpes) californicus, and analyzing the defensive fluid by gas chromatography/mass spectrometry, we were able to demonstrate that tiglic and ethacrylic acids are biosynthesized from isoleucine via 2-methylbutyric acid. Moreover, we observed that the injection of l-isoleucine induces an increased production of tiglic acid in P. californicus. A strong primary kinetic isotope effect was found to operate in the dehydrogenation step of 2-methylbutyric acid to tiglic and ethacrylic acids. Consequently, ethacrylic acid was found to preferentially accumulate the deuterium labeling from [2,3,4,4-²H₄]isoleucine during our biosynthetic experiments. This paper is dedicated to Prof. Jerrold Meinwald on the occasion of his 80th birthday.     

A New Perspective on the Role of Glutamine Synthetase in Nitrogen Remobilization in Wheat (Triticum aestivum L.)

Glutamine synthetase (GS), a key enzyme in plant nitrogen metabolism, is closely related to nitrogen remobilization. However, how GS isoforms participate in nitrogen remobilization remains unclear. Here, the spatiotemporal expression of the TaGS gene family after anthesis was investigated, and the results showed that TaGS1;1 was mainly encoded by TaGS1;1-6A, while the other isozymes were mainly encoded by TaGS localized on the A and D subgenomes. TaGS1;2-4A/4D had the highest expression level, especially in rachis and peduncle. Furthermore, immunofluorescence showed TaGS1;2 was located in the phloem of rachis and peduncle. GUS (β-glucuronidase) staining confirmed that ProTaGS1;2-4A/4D::GUS activity was mainly present in the vascular system of leaves, roots, and petal of Arabidopsis. Ureides, an important transport form of nitrogen, were mainly synthesized in flag leaves and transported to grains through the phloem of peduncle and rachis during grain filling. TaAAH, which encodes the enzyme that degrades ureides to release NH₄⁺, had a higher expression in rachis and peduncle and was synchronized with the increase in NH₄⁺ concentration in phloem, indicating that NH₄⁺ in phloem is from ureide degradation. Taking the above into account, TaGS1;2, which is highly expressed in the phloem of peduncle and rachis, may participate in N remobilization by assimilating NH₄⁺ released from ureide degradation.     

Feeding response of Ips paraconfusus to phloem and phloem metabolites of Heterobasidion annosum-inoculated ponderosa pine,Pinus ponderosa

In studies of feeding by the bark beetle, Ips paraconfusus, two pine stilbenes (pinosylvin and pinosylvin methyl ether), ferulic acid glucoside, and enantiomers of the four most common sugars present in ponderosa pine phloem (sucrose, glucose, fructose, and raffinose) did not stimulate or reduce male feeding when assayed on wet -cellulose with or without stimulatory phloem extractives present. When allowed to feed on wet -cellulose containing sequential extracts (hexane, methanol, and water) of ponderosa pine phloem, methanol and water extractives stimulated feeding, but hexane extractives did not. Males confined in wet -cellulose containing aqueous or organic extracts of culture broths derived from phloem tissue and containing the root pathogen, Heterobasidion annosum, ingested less substrate than beetles confined to control preparations. In an assay using logs from uninoculated ponderosa pines, the mean lengths of phloem in the digestive tracts increased as time spent feeding increased. Males confined to the phloem of basal logs cut from ponderosa pines artificially inoculated with H. annosum ingested significantly less phloem than beetles in logs cut from trees that were (combined) mock-inoculated or uninoculated and did not contain the pathogen. However, individual pathogen-containing treatments were not significantly different from uninoculated controls. It was concluded that altered feeding rates are not a major factor which may explain why diseased ponderosa pines are colonized by I. paraconfusus.     

Sequestration, Maintenance, and Tissue Distribution of Pyrrolizidine Alkaloid N-Oxides in Larvae of Two Oreina Species

Oreina cacaliae and O. speciosissima are leaf beetles that, as larvae and adults, sequester pyrrolizidine alkaloid N-oxides (PAs) as defensive compounds from their host plants Adenostyles alliariae and Senecio nemorensis. As in most Oreina species, O. speciosissima is also defended by autogenously produced cardenolides (mixed defensive strategy), whereas O. cacaliae does not synthesize cardenolides and is exclusively dependent on host-plant-acquired PAs (host-derived defense). Adults of the two Oreina species were found to have the same PA storage capacity. The larvae, however, differ; larvae of O. speciosissima possess a significantly lower capability to store PAs than O. cacaliae. The ability of Oreina larvae to sequester PAs was studied by using tracer techniques with ¹⁴C-labeled senecionine N-oxide. Larvae of the two species efficiently take up [¹⁴C]senecionine N-oxide from their food plants and store the alkaloid as N-oxide. In O. cacaliae, there is a slow but continuous loss of labeled senecionine N-oxide. This effect may reflect the equilibrium between continuous PA uptake and excretion, resulting in a time-dependent tracer dilution. No noticeable loss of labeled alkaloid is associated with molting. Senecionine N-oxide is detectable in all tissues. The hemolymph is, with ca. 50–60% of total PAs, the major storage compartment, followed by the integument, with ca 30%. The alkaloid concentration in the hemolymph is approximately sixfold higher than in the solid tissues. The selectivity of PA sequestration in larvae is comparable to PA sequestration in the bodies of adult beetles.     

Effects of benzoic and cinnamic acids on growth,mineral composition,and chlorophyll content of soybean

Organic acids are major water-soluble allelochemicals found in soil infested with quackgrass and are involved in several processes that are important in plant growth and development. This study was carried out to gain more information on the effects of benzoic acid (BEN) andtrans-cinnamic acid (CIN) on growth, mineral composition, and chlorophyll content of soybean [Glycine max (L.) Merr. cv. Maple Bell] grown in nutrient solution. The two allelochemicals reduced root and shoot dry biomass of soybean. Treated plants had fewer lateral roots and tended to grow more horizontally compared to the untreated plants. Lateral roots were stunted and less flexible. The amounts of P, K, Mg, Mn, Cl^–, and SO ₄ ^2– were lower, and Zn and Fe contents were higher in roots of plants grown with BEN or CIN as compared to untreated plants. Shoots of plants grown with the allelochemical showed greater accumulation of Ca, Mg, and Zn, whereas P and Fe contents were reduced. The BEN and CIN also caused reductions in leaf chlorophyll content. The BEN and CIN may be responsible for negative allelopathic effects of quackgrass on soybean by inhibiting root growth, by altering ion uptake and transport, and by reducing chlorophyll content.Contribution 493 of the Soils and Crop Research Center.     

Effects of Host Tree Species on Attractiveness of Tunneling Pine Engravers, Ips pini, to Conspecifics and Insect Predators

The effect of host tree species on the attractiveness of tunneling Ips pini to flying beetles and their insect predators in Wisconsin was investigated. Tree species influenced the flight response of both predators and prey in the same rank order. Ips pini and its major predators, Thanasimus dubius and Platysoma cylindrica, were more attracted to I. pini males boring into bark–phloem disks of Pinus strobus L. than Pinus banksiana Lamb, and least attracted to I. pini males boring into bark–phloem disks of Pinus resinosa. Sources of within-tree, between-tree, and between-species variation in the degree of attraction elicited by tunneling beetles were quantified. A bioassay for evaluating host tree effects on pheromone based communication among bark beetles under conditions of controlled beetle entry was developed. Possible mechanisms of host species effects on the dynamics of predator and prey interactions in bark beetle ecology are discussed.     

Long-term stability of the V2O5/Al2O3 catalyst for the selective reduction of nitrogen oxides

Changes of the V₂O₅/Al₃O₃ catalyst aged for up to 10 years under real conditions of the selective catalytic reduction of NO _x by ammonia (SCR) at the tail gases of the nitric acid plant were characterized by⁵¹V NMR spectroscopy, porosimetry, temperature programmed reduction (TPR) and catalytic activity measurements. The catalytic activity and the redox properties of the catalyst were found intact. Only small variations of the ratio of the octahedral and tetrahedral vanadia species were documented by⁵¹V NMR on aged catalyst.     

An Antiaphrodisiac in Heliconius melpomene Butterflies

Gilbert (1976) suggested that male-contributed odors of mated females of Heliconius erato could enforce monogamy. We investigated the pheromone system of a relative, Heliconius melpomene, using chemical analysis, behavioral experiments, and feeding experiments with labeled biosynthetic pheromone precursors. The abdominal scent glands of males contained a complex odor bouquet, consisting of the volatile compound (E)-β-ocimene together with some trace components and a less volatile matrix made up predominately of esters of common C₁₆- and C₁₈-fatty acids with the alcohols ethanol, 2-propanol, 1-butanol, isobutanol, 1-hexanol, and (Z)-3-hexenol. This bouquet is formed during the first days after eclosion, and transferred during copulation to the females. Virgin female scent glands do not contain these compounds. The transfer of ocimene and the esters was shown by analysis of butterflies of both sexes before and after copulation. Additional proof was obtained by males fed with labeled D-¹³C₆– glucose. They produced ¹³C-labeled ocimene and transferred it to females during copulation. Behavioral tests with ocimene applied to unmated females showed its repellency to males. The esters did not show such activity, but they moderated the evaporation rate of ocimene. Our investigation showed that β-ocimene is an antiaphrodisiac pheromone of H. melpomene.     

1-Cyano-2-Hydroxy-3-Butene, A Phytotoxin From Crambe (Crambe abyssinica) Seedmeal

Crambe (Crambe abyssinica) seedmeal was found to suppress seedling emergence and biomass accumulation when added to a sandy loam soil containing wheat (Triticum aestivum Cardinal) and hemp sesbania (Sesbania exahata) seeds. Hexane, CH₂Cl₂, MeOH, and water extracts of the seedmeal were prepared and bioassayed against wheat and velvetleaf (Abutilon theophrasti) radicle elongation. The CH₂Cl₂ extract was the most inhibitory, while the other extracts inhibited the bioassay species only slightly (MeOH) or not at all (hexane, water). Fractionation of the CH₂Cl₂ extract identified the major phytotoxin as l-cyano-2-hydroxy-3-butene (CHB), comprising 96.1% of the active CH₂Cl₂ fraction. Radicle elongation of wheat and velvetleaf were inhibited by CHB with I₅₀ values of 2.1 × 10^–4 M for wheat and 2.7 × l0^–3 M for velvetleaf.     

Within-plant variation in concentrations of amino acids,sugar, and sinigrin in phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae)

Although within-plant variation in the nutrient and allelochemical composition of phloem sap has been invoked to explain patterns of host use by phloem-feeding insects, little is known about within-plant variation in phloem chemistry. Here I describe a new technique in which I use the green peach aphid,Myzus persicae Sulz., to investigate within-plant variation in the concentrations of chemicals in the phloem sap of black mustard,Brassica nigra (L.) Koch (Cruciferae). Relationships between the concentrations of chemicals in aphid diets and honeydew were established using honeydew from aphids fed on artificial diets with known concentrations of amino acids, sucrose, and sinigrin. These relationships were applied to honeydew from aphids fed on different aged leaves of black mustard to estimate the concentrations of the chemicals in phloem sap. Sinigrin concentration was estimated to be high (>10 mM) in phloem sap in young leaves, calling into question the prevailing opinion that phloem sap contains only low concentrations of allelochemicals. High concentrations may function as defenses against sap-feeding herbivores. Within-plant variation in phloem sap composition was high: (1) young leaves had high concentrations of nutrients (216 mM amino acids, 26% sugar) and sinigrin (>10 mM); (2) mature and presenescent leaves had lower concentrations of nutrients (77–83 mM amino acids, 19–20% sugar) and low concentrations of sinigrin (1–2 mM); and (3) senescing leaves had high concentrations of nutrients (199 mM amino acids, 25% sugar) and low concentrations of sinigrin (3 mM).     

An Oviposition Stimulant for Spicebush Swallowtail Butterfly, Papilio troilus, from Leaves of Sassafras albidum

Female butterflies of the spicebush swallowtail, Papilio troilus, are specialists, ovipositing on plants in the family Lauraceae. Column chromatography and HPLC were used to isolate an oviposition stimulant from the leaves of one of its hosts, Sassafras albidum. The stimulant was identified as 3-trans-caffeoyl-muco-quinic acid on the basis of FAB-MS and ¹H NMR spectra as compared to a compound previously isolated from another plant. It was not active alone, but it increased the oviposition activity of butterflies when combined with other stimulant(s) at a concentration of 7 ng/mm² leaf surface area. Other caffeoylquinic acid isomers tested did not have this effect. This is the first report of a swallowtail contact oviposition stimulant from a plant in the family Lauraceae.     

Honeydew analysis for detecting phloem transport of plant natural products

Analysis of honeydew excreted by various sap-sucking insects indicated the presence of certain plant secondary constituents in the phloem of their host plants. Honeydew excreted by mealybugs (Pseudococcus longispinus), living onCastanospermum australe, contained the indolizidine alkaloid castanospermine, a potent -glucosidase inhibitor. Similarly, honeydew from green peach aphids (Myzus persicae), feeding onSenecio vulgaris flower buds, contained the pyrrolizidine alkaloid senecionine, itsN-oxide, and hydrolytic products including retronecine. Cardenolides were detected in the honeydew of oleander aphids (Aphis nerii) feeding on oleander (Nerium oleander), indicating that these compounds are translocated in the phloem. On the other hand, honeydew from greenbugs (Schizaphis graminum), feeding on barley, lacked gramine or related indole metabolites. Similarly MBOA, the breakdown product of DIMBOA, was not detected in the honeydew of greenbugs living on DIMBOA-containing wheat.     

Sequestration of ingested [14C]senecionineN-oxide in the exocrine defensive secretions of chrysomelid beetles

Oreina cacaliae (Chrysomelidae) sequesters in its elytral and pronotal defensive secretion theN-oxides of pyrrolizidine alkaloids (PAN-oxides) from its food plantAdenostyles alliariae (Asteraceae). [¹⁴C]SenecionineN-oxide was applied for detailed studies of PAN-oxide sequestration. An average of 11.4% of total radioactivity is taken up by individual beetles which had received [¹⁴C]senecionineN-oxide with their food leaves 8 days before. An average of 28.9% of the ingested radioactivity could be recovered from the defensive secretions collected twice, i.e., 5 and 8 days after tracer feeding. The tracer transfer into the secretion seems to be a slow but progressive process as indicated by the high percentage of tracer still recovered from the secretion sampled after 8 days. Chromatographic analysis revealed that [¹⁴C]senecionineN-oxide is the only labeled compound in the defensive secretion. Beetles that fed on tertiary [¹⁴C]senecionine sequestered only trace amounts of radioactivity (exclusively present as labeled IV-oxide) in their secretions.O. speciosissima, a species also adapted to PA containing food plants, was shown to sequester [¹⁴C]senecionineN-oxide with the same efficiency asO. cacaliae. O. bifrons, a specialist feeding onChaerophyllum hirsutum (Apiaceae), rejected PA treated leaf samples already at very low PA concentrations (10 nmol/leaf piece). In bothO. cacaliae andO. speciosissima, [¹⁴C]senecionineN-oxide applied by injection into the hemolymph is rapidly transferred into the glands.O. bifrons, not adapted to pyrrolizidine alkaloid containing plants was unable to sequester [¹⁴C]-senecionineN- oxide in the secretion but rapidly eliminated the tracer with the frass. Again, only traces of labeled [¹⁴C]senecionineN-oxide were found in the defensive secretions of the two PA adapted species if labeled senecionine was injected. It is suggested that the beetles are adapted to theN-oxide form of PAs, similarly as their food plants, and that they lack the ability to efficientlyN-oxidize tertiary PAs. No indication forde novo PA synthesis by the beetles was found in tracer feeding experiments with the biogenetic PA precursor putrescine.