杏树挥发物成分的鉴定及其对杏树皱小蠹的触角电位的测定

田间观察发现,伐倒木对杏树皱小蠹Lcolytus rugulosus Ratzeburg有很强的引诱作用。采用顶空吸附采样方法林间采集杏树不同部位的挥发性成分,经热脱附吹扫捕集-气相色谱-质谱联用仪(TCT-GC-MS)分析、鉴定杏树挥发物的组成成分。发现杏树释放的挥发性成分主要由脂肪族的绿叶成分和醛类物质组成,且不同部位的挥发物种类含量有一定差异。从已分析出的化合物中选取10种于室内进行杏树皱小蠹的触角电位试验,试验中以玻璃电极配合Kassiling’s电生理盐水作为导电电极,反-2-己烯-1-醛作为测定值的参照物,对试验结果进行处理得到相对反应值。研究表明,皱小蠹的触角对醛类化合物正庚醛、2-乙基丁醛、壬醛等有较强的触角电位反应,其中对正庚醛相对反应值最大,是对标样反应值的4.29倍;对挥发性绿叶成分2-乙基-1-己醇触角电位也有一定的反应;对单萜烯类化合物α-派烯的触角电位反应较弱。     

Volatiles emitted from in vitro grown tomato shoots during abiotic and biotic stress

Different stress factors were applied to in vitro grown tomato shoots (Lycopersicon esculentum Mill. `Moneymaker') to investigate the volatiles released in the headspace. Solid phase microextraction was used for the experiments with an abiotic stress factor (constant light) and automated dynamic sampling was used for the experiments with a biotic stress factor (Spodoptera littoralis caterpillar). Continuous light as stress factor induced constant emission of the sesquiterpene a-copaene. Constant emission was not found with any other sesquiterpene or with monoterpenes. Therefore, we hypothesize that this compound needs light for its biosynthesis and/ or emission. An attack by caterpillars caused an immediate higher emission of the constitutive compounds (mono-and sesquiterpenes) and the induced compounds (linalool and indole); the latter were emitted approximately 1 day after the attack and linalool was even emitted 2 days after removal of the caterpillar.     

Electronic nose evaluation of onion headspace volatiles and bulb quality as affected by nitrogen, sulphur and soil type

Edaphic factors affect the quality of onions (Allium cepa). Two experiments were carried out in the field and glasshouse to investigate the effects of N (field: 0,120 kg ha⁻¹; glasshouse: 0,108 kg ha⁻¹), S (field: 0, 20 kg ha⁻¹; glasshouse: 0, 4.35 kg ha⁻¹) and soil type (clay, sandy loam) on onion quality. A conducting polymer sensor electronic nose (E-nose) was used to classify onion headspace volatiles. Relative changes in the E-nose sensor resistance ratio (%dR/R) were reduced following N and S fertilisation. A 2D Principal Component Analysis (PCA) of the E-nose data sets accounted for c. 100% of the variations in onion headspace volatiles in both experiments. For the field experiment, E-nose data set clusters for headspace volatiles for no N-added onions overlapped (D²= 1.0) irrespective of S treatment. Headspace volatiles of N-fertilised onions for the glasshouse sandy loam also overlapped (D²=1.1) irrespective of S treatment as compared with distinct separations among clusters for the clay soil. N fertilisation significantly (P < 0.01) reduced onion bulb pyruvic acid concentration (flavour) in both experiments. S fertilisation increased pyruvic acid concentration significantly (P < 0.01) in the glasshouse experiment, especially for the clay soil, but had no effect on pyruvic acid concentration in the field. N and S fertilisation significantly (P < 0.01) increased lachrymatory potency (pungency), but reduced total soluble solids (TSS) content in the field experiment. In the glasshouse experiment, N and S had no effect on TSS. TSS content was increased on the clay by 1.2-fold as compared with the sandy loam. Onion tissue N: water-soluble SO₄²⁻ ratios of between five and eight were associated with greater %dR/R and pyruvic acid concentration values. N did not affect inner bulb tissue microbial load. In contrast, S fertilisation reduced inner bulb tissue microbial load by 80% in the field experiment and between 27% (sandy loam) and 92% (clay) in the glasshouse experiment. Overall, onion bulb quality discriminated by the E-nose responded to N, S and soil type treatments, and reflected their interactions. However, the conventional analytical and sensory measures of onion quality did not correlate with %dR/R.     

Involvement of ethylene on growth and plant regeneration in callus cultures of Heliconia psittacorum L.f.

The level of ethylene accumulated in morphogenic callus cultures of Heliconia psittacorum L.f. was only one quarter that of non-morphogenic cultures. The rate of ethylene production in the morphogenic callus cultures during early stages of differentiation of protocorm-like bodies leading to plantlet regeneration was 10-fold higher than that during callus proliferation. In cultures sealed with gastight serum caps, fresh weight gain was reduced 2-to 3-fold compared to those that were closed with Kaputs. Treatment with 1-aminocyclopropane-1-carboxylic acid ( 100 M) caused complete inhibition of plant regeneration from the morphogenic callus on subsequent culture under inductive conditions. Silver nitrate and aminoethoxyvinylglycine also reduced plant regeneration. These results indicate that while high levels of ethylene were inhibitory, a low level of endogenous ethylene production may be necessary during the plant regeneration phase in callus cultures of Heliconia.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - AC activated charcoal - ACC 1-aminocyclopropane-1-carboxylic acid - AVG aminoethoxyvinylglycine - BM basal medium - CH casein hydrolysate - DM development medium - MM maintenance medium - PLB protocorm-like body     

Significance of terpenoids in induced indirect plant defence against herbivorous arthropods

Many plants respond to herbivory by arthropods with an induced emission of volatiles such as green leaf volatiles and terpenoids. These herbivore-induced plant volatiles (HIPVs) can attract carnivores, for example, predators and parasitoids. We investigated the significance of terpenoids in attracting herbivores and carnivores in two tritrophic systems where we manipulated the terpenoid emission by treating the plants with fosmidomycin, which inhibits one of the terpenoid biosynthetic pathways and consequently terpenoid emission.
In the 'lima bean' system, volatiles from spider-mite-infested fosmidomycin-treated plants were less attractive to the predatory mite Phytoseiulus persimilis than from infested control plants. In the 'cabbage' system, fosmidomycin treatment did not alter the attractiveness of Brussels sprouts to two Pieris butterflies for oviposition. The parasitoid Cotesia glomerata did not discriminate between the volatiles of fosmidomycin-treated and water-treated caterpillar-infested cabbage. Both P. persimilis and C. glomerata preferred volatiles from infested plants to uninfested ones when both were treated with fosmidomycin.
Chemical analysis showed that terpenoid emission was inhibited more strongly in infested lima bean plants than in Brussels sprouts plants after fosmidomycin treatment.
This study shows an important role of terpenoids in the indirect defence of lima bean, which is discussed relative to the role of other HIPVs.     

The effect of headspace renewal in a Temporary Immersion Bioreactor on plantain (Musa AAB) shoot proliferation and quality

The positive effect of ventilation of the culture container on in vitro shoot proliferation and quality was already proven for different species. Hereafter we report on the evolution of the headspace during in vitro culture of plantain in a Temporary Immersion Bioreactor (TIB) on the one hand, and culture on semi-solid medium on the other hand. The CO₂ and C₂H₄ concentration reached a maximum of 12% and 0.45 μl l⁻¹, respectively in the control treatment on semi-solid medium, compared to 5.7% CO₂ and 0.06 μl l⁻¹ C₂H₄ in TIB. The minimal O₂-concentration on semi-solid medium was 15.1%, compared to 19.3% in TIB. The multiplication rate was best in TIB, 6.4 compared to 4.3 in semi-solid conditions, and this was also the case for shoot height (4.3 cm compared to 3.3 cm), and leaf number (2.6 compared to 1.6). Moreover shoots produced on semi-solid medium showed distorted leaves. A typical day-night pattern in CO₂ and O₂ concentration was observed in TIB, as well as on semi-solid medium; this is illustrative for the photosynthetic capacity of the plant material produced in both systems.     

钝叶榕榕果挥发物成分及其构成特征分析

为揭示钝叶榕与其传粉榕小蜂及两种协同进果的非传粉榕小蜂Diaziella yangi和Lipothymus sp.间的化学联系与分配机制,采用顶空动态法提取钝叶榕(Ficus curtipes Corner)雌花期和传粉后的榕果挥发物,用定性和定量的方法鉴定、分析了挥发物的成分和变化动态。结果表明:从钝叶榕榕果中共鉴定出45种挥发物成分,主要是单萜类和倍半萜类化合物。6-甲基-5-庚烯-2-酮、β-罗勒烯、反-β-金合欢烯、α-金合欢烯、α-派烯、香桧烯、顺-β-罗勒烯、顺-β-香柠檬烯、大香叶烯D和4,8-二甲基-1,3,7-壬三烯可能是构建钝叶榕特异性化学信息的基础。雌花期榕果挥发物释放量明显高于传粉后挥发物的释放量,且两者在时间和空间上存在异质性。这说明榕蜂育幼繁殖系统间存在着化学信息的联系。     

Seasonal, populational and ontogenic variation in the volatile oil content and composition of individuals of Origanum vulgare subsp. Hirtum, assessed by GC headspace analysis and by SPME sampling of individual oil glands

Small-scale GC headspace analyses combined with SPME sampling of individual oil glands have been used to measure the variation in volatile content and composition in and within different oregano plants as affected by age, season and developmental state. The main monoterpenes found were p-cymene, carvacrol and their precursor gamma-terpinene. The early season preponderance of p-cymene over carvacrol was reversed as the season progressed and this pattern could also be seen at any time within the plant, from the latest leaves to be produced (low in cymene) to the earliest (high in cymene). Seedlings from the same mother plant developed this pattern at different rates. Within individual leaves the pattern was not observed, even within the youngest developing leaves. However it was found that the oil composition of individual glands within a single leaf varied considerably, most notably in respect of the production of carvacrol and its isomer thymol.     

Development and validation of method for analysis of some ototoxic solvents in saliva matrix by headspace gas chromatography/mass spectrometry

The aim of this study was to develop an analytical method to monitor the saliva matrix for ototoxic solvents absorption: the method is based on headspace gas chromatography/mass spectrometry and represents an alternative biological monitoring for investigating low exposure to hazardous ototoxic solvents. Simultaneous determination of toluene, ethylbenzene, xylenes and styrene has been carried out and the method has been optimized for both instrumental parameters and samples treatment. Chromatographic conditions have been set in order to obtain a good separation of xylene isomers due to the interest in p-xylene as ototoxic one. Method validation has been performed on standards spiked in blank saliva by using two internal standards (2-fluorotoluene and deuterated styrene-d₈). This method showed the possibility to detect the target compounds with a linear dynamic range of at least a 2 orders of magnitude characterized by a linear determination coefficient (r²) greater than 0.999. The limit of detection (LOD) ranged between 0.19 ng/mL (styrene) and 0.54 ng/mL (m-xylene) and the lower limit of quantification (LLOQ) ranged between 0.64 ng/mL (styrene) and 1.8 ng/mL (m-xylene). The method achieved good accuracy (from 99 to 105%) and precision for both intra- and inter-assay (relative standard deviation ranging from 1.7 to 13.8%) for all six compounds concerned. The repeatability was improved by adding sodium sulphate to the matrix. Saliva samples resulted stable for at least 7 days after collection, if stored in headspace vials, at the temperature of 4 °C. An evaluation of the main sources of uncertainty of the method is also included: expanded uncertainties ranges between 10 and 16% for all of the target compounds. In summary, the headspace gas chromatography/mass spectrometry method is a highly sensitive, versatile and flexible technique for the biological monitoring of exposure to ototoxic solvents by saliva analysis.