Emission of Volatiles From Brown Boronia Flowers: Some Comparative Observations

Extensive research has focused on the concentration of aglyconeswithin brown boronia (Boronia megastigma) flowers, however emissionof volatiles into the headspace above these flowers is not welldocumented. Using solid-phase microextraction (SPME) to trapvolatiles and GCMS analysis, we observed 23 volatiles in theheadspace above buds and flowers throughout flower maturation,above dissected floral organs and above whole plants held for36 h under either continuous light, continuous dark or 12 hlight:12 h dark:12 h light treatments. Fully-opened flowersemitted the most complex mixture of volatiles and in the greatestquantity, with a rapid decline in senescent flowers. Caryophyllene,humulene and bicyclogermacrene declined as flower buds matured;ß-ionone increased. From the individual floral organs,emission from the petaline anthers comprised 38% of total emissionsfrom the (calculated) ‘whole flower’, with 27% contributedby the petals and 10.5% by the stigma. Monoterpenes dominatedthe headspace from the calyx; dodecyl acetate, methyl jasmonateand (Z)-n-heptadec-8-ene were relatively predominant in emissionsfrom the androecium. ß-Ionone, the major floral volatilein brown boronia, dominated volatiles emitted from the stigma(87%). However, the relatively tiny petaline anthers, activein pollen production and high in carotenoids, contributed thegreatest overall amount of ß-ionone to emission fromthe whole flower. There were three different patterns in emissionof volatiles from plants in response to different light conditions:(1) emission patterns identical irrespective of light environment,with maximum emission in the ‘endogenous’ dark period,i.e. when the plant would normally have been in the dark (-pinene);(2) similar emission in all treatments, with an increase anddecline over a period of 26 h (5-acetoxy linalool, cyclic ß-ionone,dodecyl acetate and (Z)-n-heptadec-8-ene); and (3) emissionin all treatments but enhanced in the dark, with a 27.5 h periodin some cases (cyclic ß-ionone endoperoxide, dihydroß-ionone, ß-ionone, and ‘total volatiles’).Preliminary evidence is presented for endogenous control ofemission of a number of volatiles such as -pinene, with perhapsdiurnal control of others such as ß-ionone. Copyright2000 Annals of Botany Company Boronia megastigma, brown boronia, SPME, headspace, floral volatiles, ß-ionone     

萜烯类与苯丙酸类花香挥发物的生物合成与调节

随着花香挥发物提取和检测技术的不断发展以及该技术与分子生物学研究的结合,花香挥发物的生物合成途径和调节机制的研究取得了较大进展,为花香的遗传控制和育种研究奠定了良好的基础。萜烯类和苯丙酸类/苯环型化合物是植物花香挥发物的重要化学成分,它们分别由甲羟戊酸-甲基赤藓醇磷酸途径、莽草酸途径等途径生成,调节机制较为复杂,但以前体物生物合成调节为主。两类花香物质在许多行业得到了应用广泛,但相关研究有待于进一步深入。     

连翘花蕾与花的挥发性成分研究

本文采用顶空固相微萃取和气相色谱质谱联用(HS-SPME-GC-MS)技术比较分析了连翘花蕾和花的挥发性成分。从连翘花蕾和花中共鉴定了83个化合物,其中40个化合物是共有的。连翘花蕾的挥发性成分以烃类(41.04%)为主,而连翘花的挥发性成分以醇、醛和酮类化合物(26.46%)为主;酯类化合物在花蕾中的含量为8.11%,在花中下降到2.12%;而酸类化合物则从3.56%上升到5.18%。结果表明,随着花蕾的开放,酯类成分逐渐被水解为酸。     

Effect of 2,5-Norbornadiene upon Ethylene Biosynthesis in Midclimacteric Carnation Flowers

The climacteric increase in ethylene production in carnation (Dianthus caryophyllus L. cv White Sim) flowers is known to be accompanied by an increase in 1-aminocyclopropane-1-carboxylate (ACC) synthase and ethylene forming enzyme (EFE) activities. When midclimacteric flowers were exposed to 2,5-norbornadiene, which blocks ethylene action, ethylene production began to decrease after 2 to 3 hours. ACC synthase activity was markedly reduced after 4 hours and the increase in EFE activity was blocked indicating that the autocatalytic signal associated with ethylene action stimulates both enzyme activities.     

The Effect of Lodging and Time of Harvest on Deoxynivalenol Contamination in Barley and Oats

A split-split plot design was used to study the effect of lodging and time of harvest on the formation of the Fusarium toxin deoxynivalenol (DON). Altogether 19 experimental fields were included in the study, which was carried out over the period 1991–1993. There were two cultivars each of barley and oats tested. Half of each field was lodged artificially using a drum roller to flatten the crop about 3 weeks after ear emergence. The grain was harvested at the stage of mealy ripe and about 15 and 30 days after. The DON concentratioti in the grain was in descending order influenced by lodging, cultivar, experimental field, year and time of harvest. When paired plots were compared a distinct increase (more than 65%) in the DON concentration was found in samples from 49% of the plots with lodging compared with their pair plot. Both a decrease and an increase in the DON content were detected in the period from the first time of harvest to the second and third titne of harvest. The overall contamination level of DON was found to be higher in the samples of barley compared to oats.     

De Novo Biosynthesis of Volatiles Induced by Insect Herbivory in Cotton Plants

In response to insect feeding on the leaves, cotton (Gossypium hirsutum L.) plants release elevated levels of volatiles, which can serve as a chemical signal that attracts natural enemies of the herbivore to the damaged plant. Pulse-labeling experiments with [13C]CO2 demonstrated that many of the volatiles released, including the acyclic terpenes (E,E)-[alpha]-farnesene, (E)-[beta]-farnesene, (E)-[beta]-ocimene, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, and (E/E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, as well as the shikimate pathway product indole, are biosynthesized de novo following insect damage. However, other volatile constituents, including several cyclic terpenes, butyrates, and green leaf volatiles of the lipoxygenase pathway are released from storage or synthesized from stored intermediates. Analysis of volatiles from artificially damaged plants, with and without beet armyworm (Spodoptera exigua Hubner) oral secretions exogenously applied to the leaves, as well as volatiles from beet armyworm-damaged and -undamaged control plants, demonstrated that the application of caterpillar oral secretions increased both the production and release of several volatiles that are synthesized de novo in response to insect feeding. These results establish that the plant plays an active and dynamic role in mediating the interaction between herbivores and natural enemies of herbivores.     

Effect of Variations in Conditions of Incubation upon Inhibition of Staphylococcus aureus by Pediococcus cerevisiae and Streptococcus lactis

The effects of pH, temperature, proportion of Staphylococcus aureus in the inoculum, various strains of effector organism, and various strains of S. aureus were examined for their influence on interactions between staphylococci and effector organisms in associative culture. In general, small changes in pH had little effect upon either growth of S. aureus or production of enterotoxin in associative culture. Inhibition of growth of S. aureus caused by effector organisms was much greater at 25 than at 30 C. Proportion of S. aureus in the inoculum greatly affected both growth of the staphylococci and production of enterotoxin. Only slight differences were found between strains of either effector organism or S. aureus which affected the interactions in associative culture.     

Relative Time of Anthesis in Pistillate and Staminate Cucumber Flowers

Staminate (male) floral buds of cucumber plants reach anthesisat consecutive nodes of the main shoot at regular time intervals;however, pistillate (female) buds reach anthesis earlier thanmale ones, thus causing a marked deviation from the linear chronologicalsequence of male anthesia along the main shoot. Measured indays, this relative precedence of the female is greatest inwinter planting time, when short days and low temperatures causea shift towards femaleness in the whole plant, and it is smallestin late summer planting when environmental conditions favourmale tendency. There are also varietal differences in this respect—inone variety (Beth Alpha) the female precedes the male by a longerperiod of time than in another variety (Yorkstate Pickling).The position of the female flower on the main shoot does notseem to play an important role in this respect, but, as a rule,the precedence is greater for the first female than for thesecond or third female developing on the main shoot. It is suggested that the relative enhancement of one type ofsex organs (carpels) is a continuous process which determinesfirst the final sex type of the flower and later causes it toreach anthesis earlier.     

Generation of Phenylpropanoid Pathway-Derived Volatiles in Transgenic Plants: Rose Alcohol Acetyltransferase Produces Phenylethyl Acetate and Benzyl Acetate in Petunia Flowers

Esters are important contributors to the aroma of numerous flowers and fruits. Acetate esters such as geranyl acetate, phenylethyl acetate and benzyl acetate are generated as a result of the action of alcohol acetyltransferases (AATs). Numerous homologous AATs from various plants have been characterized using in-vitro assays. To study the function of rose alcohol acetyltransferase (RhAAT) in planta, we generated transgenic petunia plants expressing the rose gene under the control of a CaMV-35S promoter. Although the preferred substrate of RhAAT in vitro is geraniol, in transgenic petunia flowers, it used phenylethyl alcohol and benzyl alcohol to produce the corresponding acetate esters, not generated by control flowers. The level of benzyl alcohol emitted by the flowers of different transgenic lines was ca. three times higher than that of phenylethyl alcohol, which corresponded to the ratio between the respective products, i.e. ca. three times more benzyl acetate than phenylethyl acetate. Feeding of transgenic petunia tissues with geraniol or octanol led to the production of their respective acetates, suggesting the dependence of volatile production on substrate availability.     

Plant Species and Plant Incubation Conditions Influence Variability in Epiphytic Bacterial Population Size

Abstract The influences of plant species and plant incubation conditions on the variability in bacterial population sizes among leaves were investigated in field and growth chamber studies. Pseudomonas syringae strains TLP2 and Cit7 were inoculated onto plants and population sizes were measured at intervals after inoculation. Total bacterial population sizes were also assessed in field studies. Levels of leaf-to-leaf variability in both P. syringae population size and bacterial community size differed significantly among plant species. For all plant species, variability among leaves in population sizes of inoculated bacteria was consistently greater than the leaf-to-leaf variability in numbers of total bacteria. Considering levels of variability in population size immediately prior to and following incubation under either wet or dry physical conditions, leaf-to-leaf variability in the population sizes of inoculated P. syringae strains increased significantly following incubation under dry, but not under wet, conditions. Measurements of leaf-to-leaf variability immediately prior to and following incubation were positively correlated regardless of whether the incubation was under wet or dry conditions, though the correlation was greater following dry incubation. These data provide insight into the biological and physical factors that may be important in generating variability in bacterial population sizes among leaves, and they have important implications for the design of appropriate strategies for sampling leaf surface microbial populations.     

除虫菊开花特性与适宜采摘期

除虫菊 (Pyrethrumcinerariifolium)是提取天然除虫菊酯的原料 ,植物体的各个部位均有除虫菊酯分布 ,最主要存在于头状花序 (简称花头 )的子房中 ,随着花蕾的孕育、开花直至种子 (瘦果 )成熟 ,子房壁导管的油腺也同时经历了发生、发展和分泌物转化的过程。直接反映在开花期的不同阶段所采摘的花头内菊酯含量的变化十分显著 ,为了进一步认识除虫菊开花期小花开放程度与菊酯含量变化的内在规律 ,把除虫菊开花期 (从孕蕾盛期到瘦果成熟 )划分成 8个阶段。通过样品测定 ,了解开花期花头中菊酯含量的变化状况和头状花序发育过程中小花子房的增长与干物质积累之间的关系 ,表明头状花序的小花开放至第 4至第 5阶段 ,即花头上管状小花开放初盛期至盛期时采摘 ,是获得最高生物产量和菊酯含量的最适宜采摘期。     

Sod1 Deficiency Reduces Incubation Time in Mouse Models of Prion Disease

Prion infections, causing neurodegenerative conditions such as Creutzfeldt-Jakob disease and kuru in humans, scrapie in sheep and BSE in cattle are characterised by prolonged and variable incubation periods that are faithfully reproduced in mouse models. Incubation time is partly determined by genetic factors including polymorphisms in the prion protein gene. Quantitative trait loci studies in mice and human genome-wide association studies have confirmed that multiple genes are involved. Candidate gene approaches have also been used and identified App, Il1-r1 and Sod1 as affecting incubation times. In this study we looked for an association between App, Il1-r1 and Sod1 representative SNPs and prion disease incubation time in the Northport heterogeneous stock of mice inoculated with the Chandler/RML prion strain. No association was seen with App, however, significant associations were seen with Il1-r1 (P = 0.02) and Sod1 (P<0.0001) suggesting that polymorphisms at these loci contribute to the natural variation observed in incubation time. Furthermore, following challenge with Chandler/RML, ME7 and MRC2 prion strains, Sod1 deficient mice showed highly significant reductions in incubation time of 20, 13 and 24%, respectively. No differences were detected in Sod1 expression or activity. Our data confirm the protective role of endogenous Sod1 in prion disease.     

Incubation Temperature and Time Effects on Life Stages of Bursaphelenchus xylophilus in Wood Chips

Wood chips of Pinus strobus inoculated with Bursaphelenchus xylophilus were incubated at 3, 12, 30, or 40 C during intervals of 47, 82, and 130 days to determine the effects of incubation temperature and time on total number of nematodes and occurrence of each life stage. Nematodes did not survive at 40 C; the greatest number of nematodes was maintained at 3 C. The number and percentage of juveniles in the propagative cycle were greatest at 3 C after 47 days, but the percentage was greatest at 30 C after 130 days. More third-stage dispersal larvae, with percentages as high as 85%, were extracted at 3 and 12 C than at 30 C by the end of the study. Dauer larvae were extracted from the chips, but percentages never exceeded 5%. The percentage of adults was greater at 30 C than at 3 and 12 C after 82 and 130 days. When a 1-week heat treatment at 30 C was applied to samples at 3 and 12 C,. numbers and percentages of adults increased. Percentages of dauer larvae increased very slightly when the heat treatment was applied after 47 days, but numbers and percentages of juveniles and dispersals were affected erratically.     

Effect of Incubation Conditions on the Enrichment of Pyrene-degrading Bacteria Identified by Stable-isotope Probing in an Aged,PAH-contaminated Soil

To determine whether the diversity of pyrene-degrading bacteria in an aged polycyclic aromatic hydrocarbon-contaminated soil is affected by the addition of inorganic nutrients or by slurrying the soil, various incubation conditions (all including phosphate buffer) were examined by mineralization studies and stable-isotope probing (SIP). The addition of nitrogen to either continuously mixed slurry or static field-wet soil incubations increased the rate and extent of mineralization of [(14)C]pyrene, with the most rapid mineralization observed in slurried, nitrogen-amended soil. Microcosms of slurry and static field-wet soil amended with nitrogen were also examined by SIP with [U-(13)C]pyrene. Recovered (13)C-enriched deoxyribonucleic acid (DNA) was analyzed by denaturing-gradient gel electrophoresis (DGGE) and 16S ribosomal ribonucleic acid (rRNA) gene clone libraries. DGGE profiles of (13)C-enriched DNA fractions from both incubation conditions were similar, suggesting that pyrene-degrading bacterial community diversity may be independent of treatment method. The vast majority (67 of 71) of the partial sequences recovered from clone libraries were greater than or equal to 97% similar to one another, 98% similar to sequences of pyrene-degrading bacteria previously detected by SIP with pyrene in different soil, and only 89% similar to the closest cultivated genus. All of the sequences recovered from the field-wet incubation and most of the sequences recovered from the slurry incubation were in this clade. Of the four sequences from slurry incubations not within this clade, three possessed greater than 99% similarity to the 16S rRNA gene sequences of phylogenetically dissimilar Caulobacter spp.     

Effect of Combined Changes in Culture Medium and Incubation Conditions on the Regeneration from Immature Embryos of Elite Varieties of Winter Wheat

In this study, tissue culture method for plant regeneration from immature embryos of elite Hungarian winter wheat varieties was established. The influence of the growth regulators and the concentration of macroelements in the regeneration medium and of the incubation temperature and light intensity on regeneration frequency were investigated. The most noticeable effect on regeneration frequency was achieved by simultaneously reducing both the incubation temperature to 23 °C and the concentration of macroelements in the regeneration medium to half-strength. This modification increased the average regeneration frequency from about 10–78%. Changes in the light intensity and temperature gave an average plant regeneration frequency of 83%.     

Autogamy in Boronia falcifolia: consequences for inbreeding and persistence in fragmented coastal heaths

Coastal heath is becoming increasingly fragmented, resulting in reduced pollinator abundance affecting species viability. The reproductive ecology and inbreeding of a common coastal heath species, Boronia falcifolia (Rutaceae), was investigated. Pollination observations and experiments were carried out at one site, and inbreeding was assessed using genetic markers at eight populations. Four pollination treatments were assessed: cross-pollination, self-pollination, autogamous pollination and open (insect) pollination. Boronia falcifolia was found to be highly self-compatible, frequently setting seeds from autogamous pollination. There were no significant differences between the autogamous, self and cross pollen treatments for any measures of reproductive success (pollen tube growth, fruit set, swollen locules and seed production). Insect activity resulted in fewer seeds per fruit than hand cross pollination, although pollinator visits were few. All populations studied were highly inbred. Autogamous self-pollination is widespread in B. falcifolia and this combined with its ability to vegetatively regenerate enhances its potential for survival when pollinators are few.     

Transient Water Stress in Carnation Flowers: Effect of Amino-oxyacetic Acid

A short and temporary water stress imposed on cut carnationflowers (Dianthus caryophyllus L., cv. White Sim) flowers advancedsenescence symptoms, including ethylene production and wilting.Pretreatment with amino-oxyacetic acid (AOA) resulted in anincrease of the resistance of the flowers to water stress: waterloss during stress was reduced, recovery was more rapid andwilting was delayed. Water stress accelerated the decrease inlevel of membrane phospholipids, but pretreatment with AOA counteractedthis effect. Since the content of membrane sterols was not affectedby the treatments, the mole ratio of sterol to phospholipidincreased in water-stressed flower petals but not in stressedflowers pretreated with AOA. Membrane permeability and fluiditywere also adversely affected by water stress and AOA: waterstress alone resulted in an increase in permeability and a decreasein fluidity, but in AOA-pretreated stressed flower petals theseparameters were similar to those of nonstressed control flowerpetals. On the basis of these results two main conclusions can be drawn:(a) Water stress induces alterations in the physical and compositionalproperties of carnation petal membranes, (b) Pretreatment ofthe flowers with AOA influences petal membrane traits, mostprobably via modifications in phospholipid turnover, in a waywhich counteracts the effects of water stress. Key words: Amino-oxyacetic acid, Water stress, Carnation flowers