Can forest trees compensate for stress-generated growth losses by induced production of volatile compounds?

Plants produce a variety of volatile organic compounds (VOCs). Under abiotic and biotic stresses, the number and amount of produced compounds can increase. Due to their long life span and large size, trees can produce biogenic VOCs (BVOCs) in much higher amounts than many other plants. It has been suggested that at cellular and tree physiological levels, induced production of VOCs is aimed at improving plant resistance to damage by reactive oxygen species generated by multiple abiotic stresses. In the few reported cases when biosynthesis of plant volatiles is inhibited or enhanced, the observed response to stress can be attributed to plant volatiles. Reported increase, e.g., in photosynthesis has mostly ranged between 5 and 50%. A comprehensive model to explain similar induction of VOCs under multiple biotic stresses is not yet available. As a result of pathogen or herbivore attack on forest trees, the induced production of VOCs is localized to the damage site but systemic induction of emissions has also been detected. These volatiles can affect fungal pathogens and the arrival rate of herbivorous insects on damaged trees, but also act as signalling compounds to maintain the trophic cascades that may improve tree fitness by improved efficiency of herbivore natural enemies. On the forest scale, biotic induction of VOC synthesis and release leads to an amplified flow of BVOCs in atmospheric reactions, which in atmospheres rich in oxides of nitrogen (NOx) results in ozone formation, and in low NOx atmospheres results in oxidation of VOCs, removal in ozone from the troposphere and the resulting formation of biogenic secondary organic aerosol (SOA) particles. I will summarize recent advances in the understanding of stress-induced VOC emissions from trees, with special focus on Populus spp. Particular importance is given to the ecological and atmospheric feedback systems based on BVOCs and biogenic SOA formation.     

Assessing VOC emission by different wood cores using the PTR-ToF-MS technology

To date, the chemical composition and the amount and diversity of volatile organic compounds (VOCs) released by different woody plants samples have been measured and characterized through one of the most common techniques, the gas chromatography–mass spectrometry. However, this technique is very time-consuming and requires sample preparation. By contrast, the Proton-Transfer-Reaction Time-of-Flight Mass spectrometry (PTR-ToF-MS) represents an innovative tool able to provide the whole mass spectra of VOCs with short response time, high mass resolution and without sample preparation. This technique is fast, non-invasive, highly sensitive with a rapid detection system and a very low mass fragmentation of the volatile molecules. The goal of this study was to characterize the VOCs profile of different wood sample cores using a PTR-ToF-MS tool and thereafter to assess whether VOC emissions were specific for some groups of trees. VOCs released from core wood samples belonging to 14 different species were analyzed and subsequently, using an advanced multivariate class-modeling approach, the groups (softwood and hardwood) and the different tree species were discriminated. PTR-ToF-MS was able to detect VOCs from wood and to discriminate between hardwood and softwood and among different species. The great potential and the rapidity of this analysis method allow the PTR-ToF-MS to become a commercial standard tool for monitoring VOCs emitted by wood.     

应用气候箱法测定胶合板的VOC释放

采用气候箱模拟室内气候环境,研究胶合板的甲醛释放规律,分析环境因素对处于稳定释放期的胶合板甲醛及其他VOC释放机理的影响.研究发现:在模拟的空气环境条件下,胶合板甲醛释放呈现的规律为:在较短时间内急速上升,达到最大值后逐渐衰减,直到趋于稳定值;在稳定释放状态,环境因素对甲醛及某些VOC散发有显著作用.同时对VOC作了化学成分的检测,受试胶合板主要释放有8种VOC.     

Labor-Versuche mit Neem-Samenextrakt zur Bekämpfung des Schwammspinners,Lymantria dispar L.

Effects of neem-extracts on cater pillars of the gypsy moth, Lymantria dispar L. The effects of neem extracts(Azadirachta indica) (0.02%; 0.2% 0.5%) were tested on caterpillars of the gypsy moth (Lymantria dispar). The laboratory experiments showed, that these concentrations suppress the development and prohibit the moultin of caterpillars. The mortality reached 100% in all experiments. Addition test carried out under field conditions indicated that the activity of neem extract sprayed on oakleafs(Quercus robur) remained unchange after 12 days of application.     

环境温度对室内装修有害气体释放影响的研究

以东北地区两种代表性的品牌刨花板为研究对象,分析温度对挥发性有害气体（VOCs）释放量的影响。利用小型气候箱和手提式VOCs测试仪分别测量两种刨花板在15℃、23℃、25℃和35℃情况下的VOCs释放量。研究表明：温度为23℃时,板1VOCs的最初释放量高于板2;温度为35℃时,刨花板中VOCs释放量要高于其他温度情况下的释放量。由此可以看出环境温度对刨花板VOCs的释放量有明显的影响,即随着温度的升高板材有害气体的释放量增加。     

Effects of water stress on emission of volatile organic compounds by <Emphasis Type="Italic">Vicia faba</Emphasis>, and consequences for attraction of the egg parasitoid <Emphasis Type="Italic">Trissolcus basalis</Emphasis>

When plants are damaged by herbivorous insects, blends of volatile organic compounds (VOCs) are induced and released and can also be used by parasitoids to locate hosts. The aim was to determine whether VOCs induced by water stress affect the plant–herbivore–parasitoid system represented by broad bean (Vicia faba; Fabales: Fabaceae) stink bug (Nezara viridula; Heteroptera: Pentatomidae) egg parasitoid (Trissolcus basalis; Hymenoptera: Platygastridae). The effects of water stress (expressed as the percentage fraction of transpirable soil water [FTSW] supplied) alone and in combination with N. viridula damage (feeding plus oviposition) were determined according to: (1) the behavioural response of the egg parasitoid in a Y-tube olfactometer and (2) the plant VOCs collected and analysed by thermal desorption–gas chromatography–mass spectrometry. With pot water capacity as FTSW₁₀₀, water stress was applied as mild (FTSW₈₀), moderate (FTSW₅₀) and severe (FTSW₁₀). Bioassays with plants under abiotic stress alone showed that egg parasitoids are more attracted by FTSW₁₀ plants than by well-watered plants. When plants were under abiotic and biotic stress interactions, the egg parasitoids are more attracted by FTSW₁₀ and FTSW₅₀ plants than by well-watered plants infested with N. viridula. Considering VOCs emissions, projection to latent structures discriminant analysis (PLS-DA) separated treatments according to egg parasitoid responses. Water stress alone and in combination with biotic stress induced changes in VOC emissions of V. faba plants that attract egg parasitoids. These findings contribute to our understanding of how water stress affects the interactions between plants, insect pests and egg parasitoids.     

表达豇豆胰蛋白酶抑制剂转基因杨树的虫试试验

将转豇豆胰蛋白酶抑制剂基因的三倍体毛白杨回交杂种 [(毛新杨×毛白杨 )×毛白杨 ]]于春季萌发前截干 .用萌条上的树叶对 3种主要杨树害虫 :天幕毛虫 (Malacosomadisstria)、舞毒蛾 (Lymant riadisparL .)和杨雪毒蛾 (StilpnotiacandidaStaudinger)进行离体虫试试验 ,年底测量各转基因株系萌条树高和地径 ,以衡量其生长性状 .结果发现 ,与对照相比 ,转基因株系的树高和地径没有显著降低 ,说明外源基因的导入没有影响转基因杨树的速生特性 ,相反 ,TG0 4的树高和地径较对照有明显的提高 ,这可能是外源导入后促进转基因杨树生长的结果 ;转基因植株均能显著提高害虫的死亡率 ,降低幼虫的排粪量、蛹重、体重增加量和成虫的产卵量 ;其中 ,TG0 7、TG0 8和TG713个转基因株系的抗虫特性较为突出 ,表明CpTI基因在它们的树体内表达较为活跃和稳定     

Late leaf development in pedunculate oak (Quercus robur): An antiherbivore defence?

Abstract

Two phenological forms of the pedunculate oak co-occur in the same habitats throughout the species range: the early trees (Quercus robur var. praecox) develop leaves up to 5 weeks before the late ones (Quercus robur var. tardiflora). This study tests the idea that late leaf flushing serves as an antiherbivore defence, i.e. late trees, which develop leaves asynchronously with eclosion of folivorous caterpillars, avoid the costs of defoliation, which could offset the costs of a later onset of the growing season. Effects of folivorous caterpillars foraging on oaks were observed in 1998–2006 in remnants of primeval temperate lowland forest preserved in the Bia?owie?a National Park (eastern Poland). Observations covered trough and outbreak years of the major defoliator, the winter moth [Operophtera brumata L. (Geometridae)]. In seven out of nine seasons, including all peak caterpillar years, the amount of frass produced by folivorous caterpillars on late trees (n=8–18) was significantly (up to 7.1 times) lower than on the early ones (n=12–32). Assessment of the degree of defoliation in 2002–2006 showed that the late oaks were visibly defoliated only during a caterpillar peak (2003), while the early trees were affected in all years and in 2003 almost completely lost their leaves. The results confirm the effect of late budburst on lowering herbivore damage, and give support to the idea that late leaf flushing acts as an antiherbivore defence.     

Impact of ozone on monoterpene emissions and evidence for an isoprene-like antioxidant action of monoterpenes emitted by Quercus ilex leaves

Quercus ilex (L.) leaves emit monoterpenes, particularly alpha-pinene, beta-pinene and sabinene. Apart from the monoterpene pools that are stored in specialized structures and have a clear defensive or attractive role, the function of monoterpenes in Q. ilex leaves is unknown. We tested whether monoterpenes have an antioxidant role, as has previously been found for isoprene in isoprene-emitting leaves. We exposed Q. ilex leaves to either mild and repeated ozone exposure (Experiment I) or to a single acute ozone exposure (Experiment II) at temperatures ranging between 20 and 32 degrees C. Both ozone treatments rapidly stimulated monoterpene synthesis, but had no effect on photosynthesis and caused no visible damage to leaves maintained at 25, 30 or 32 degrees C. Ozone inhibited both photosynthesis and monoterpene synthesis in leaves maintained at 20 degrees C. To characterize the relationship between monoterpenes and ozone-induced damage, we fed detached leaves fosmidomycin, a selective inhibitor of isoprene synthesis. Fosmidomycin caused rapid and complete inhibition of monoterpene emissions in leaves maintained at 30 degrees C, confirming that monoterpenes are synthesized by the same biochemical pathway as isoprene. However, over the experimental period, fosmidomycin did not affect concentrations of compounds that are formed from chloroplastic isoprenoids and that might have conferred antioxidant protection, either directly (carotenoids) or indirectly (chlorophylls, xanthophylls). In leaves whose monoterpene synthesis had been inhibited by fosmidomycin, ozone rapidly and significantly inhibited photosynthesis and increased the production of hydrogen peroxide and malonyldialdehyde. We conclude that monoterpenes produced by Q. ilex leaves share the same biosynthetic pathway and function as isoprene. Furthermore, all volatile isoprenoids may have similar antioxidant properties and may be stimulated by the same stress-inducing conditions.     

Massenvermehrung von phyllophagen Schmetterlingen in Laubwäldern des Rheinlands

We investigated species assemblages of Lepidoptera which fed onQuercus petraea, Carpinus betulus andFagus sylvatica trees growing in commercial forests in the Rhineland (Germany). In total we found 63 different species of caterpillars. Several species (Operophtera fagata, O. brumata, Tortrix viridana, Agriopis leucophaearia, A. aurantiaria andErannis defoliaria) appeared in high abundances on oak trees, which they together defoliated. Defoliation ofCarpinus betulus as well as high feeding damages onFagus sylvatica were caused mainly by a single species,Operophtera fagata. From our observations of individual caterpillars and their extraordinarily high feeding damages (=45%) onFagus sylvatica trees which were growing in the shade of oak trees, in comparison to individualF. sylvatica trees not growing beneath oak trees (feeding damage= 7%), we made the following conclusions: Firstly, in the case of mass occurrence a severe influence of scramble competition occurs between caterpillars. Secondly, a prolongation of gradation of polyphagous caterpillars is caused when stratification byFagus sylvatica living as undergrowth of oak trees occurs. Defoliated trees occurred in sites with enhanced nutrient availability. This supports the resource availability hypothesis. Although there was a surplus of nutrients in the soil and within the roots we found a deficiency of P in the leaves.     

人造板VOCs检测方法与限量规定

VOCs为熔点低于室温而沸点在50～ 260℃的挥发性有机化合物的总称.本文介绍了人造板VOCs对人体及环境的危害,人造板VOCs的来源主要是胶粘剂、表面加工过程、染色过程以及木材本身含有,并综述了国内外人造板VOCs的检测方法和限量规定.     

Monitoring the effects of gypsy moth defoliation on forest stand dynamics on Cape Cod,Massachusetts: Sampling intervals and appropriate interpretations

Gypsy moth (Lymantria dispar L.) outbreaks affect stand dynamics and successional patterns in pine–oak woodlands of North America's Atlantic coastal plain. Species-poor overstories are dominated by pitch pine (Pinus rigida), black oak (Quercus velutina) and white oak (Quercus alba). Both oaks are preferred food for gypsy moth, and white oak is the dominant late-successional species. We documented, over a 21-year period, the effects of gypsy moth defoliation on forest stand dynamics at Cape Cod National Seashore, Massachusetts. Our goal was to better understand the influence of gypsy moth defoliation on temporal changes in stand composition. Tree species abundance and frequency were measured in 16 stands with varying abundances of pitch pine and oak. Regression of 2-dimesional rates of change calculated from principal components analysis showed that gypsy moth significantly influenced stand dynamics and successional patterns between 1981 and 1992/1993. Defoliation was virtually absent in the 1990s, and analysis of 1992/1993–2002 rates of change showed topographic slope to be the most important factor influencing stand dynamics during this time. For the period 1981–2002 rates of change analysis failed to identify either factor as influencing changes in stand dynamics. We conclude that the 1980s defoliation events had a transitory effect on upland forest composition, but that there exists the potential for significant long-term impact due to recurrent defoliation episodes. Stand composition should be monitored at intervals which roughly correspond to the time it takes for stands to recover to disturbance events, in the case of those we sampled, approximately 10 years.     

Volatile organic compounds (VOC) as biomarkers for detection of Ceratocystis platani

Ceratocystis platani causes canker stain of plane trees, and it represents a serious disease of Platanus spp. both in the United States and Europe. Current chemical or biological controls do not effectively manage C. platani, so new preventive methods need to be developed in order to limit this pathogen spreading. In this work, we have characterized the main volatile organic compounds (VOC) emitted in vitro from pure cultures of C. platani and other common pathogenic fungal species of hosts plants growing in the same ecosystems as plane trees. We found that C. platani emitted a similar blend of VOC compared with phylogenetically similar species C. populicola. In particular, C. platani was characterized by emission of isoamyl acetate and isobutyl acetate while C. populicola by ethyl acetate and isobutyl acetate, which were not released by any of the other out‐group fungal species grown on the same medium. Moreover, following a targeted approach based on the main VOC found in vitro, we have successfully validated in vivo that VOC uniquely emitted by C. platani (i.e. isobutyl acetate along with isoamyl alcohol) were released from the bark of plane trees following C. platani inoculation. Our results highlight the possibility to exploit VOC emitted specifically by C. platani as biomarkers to recognize Platanus x acerifolia plants infected by this pathogen.     

Tree mortality risk of oak due to gypsy moth

We present prediction models for estimating tree mortality resulting from gypsy moth, Lymantria dispar, defoliation in mixed oak, Quercus sp., forests. These models differ from previous work by including defoliation as a factor in the analysis. Defoliation intensity, initial tree crown condition (crown vigour), crown position, and species grouping classes were highly significant in categorical analysis of variance for mortality. Heavy defoliation intensity was shown to have a strong, consistent influence in increasing the probability of tree mortality. Classification and Regression Tree (CART) analysis, a binomial decision tree procedure, was used to develop prediction models of mortality risk for use by forest managers. The best decision tree had 65 groups that correctly classified 75% of the live trees and 76% of the dead trees. Models were run separately by defoliation class and provided correct classifications between 63 and 78% of the trees. Forest land managers can use these models to assign probabilities of death for moderate and heavy defoliation intensity levels and compare predicted mortality to mortality of undefoliated trees to determine how gypsy moth defoliation will affect their stands. The probabilities can be used to develop marking guides Lased on projected defoliation levels for implementing silvicultural treatments to minimize gypsy moth effects in forest stands prior to infestation.     

Raupen des MondvogelsPhalera bucephala L. (Lepid., Notodontidae) als Schädlinge an Obstgehölzen

Caterpillars of the buff-tip moth, Phalera bucephala L. (Lepid., Notodontidae) attacking cherry trees Observations were made on caterpillars of P. bucephala attacking cherry trees in 1972 near Schkopau (DDR). Informations are given about the symptoms of damage as well as about the food quantity needed by the pest larvae.     

Tree defoliation by winter moth Operophtera brumata L. during an outbreak affected by structure of forest landscape

Tree defoliation by winter moth Operophtera brumata L. (Geometridae, Lepidoptera) caterpillars was quantified in the Białowieża Forest (E Poland) during the recent outbreak (2002). To assess effects of forestry management on defoliation, comparisons were made between mixed species (Tilio–Carpinetum) old-growth stands of natural origin in strictly protected primeval and managed fragments. This forest type was continuous in the primeval part, but highly fragmented in the managed part. The old-growth remnants in the latter part were usually surrounded by younger tree stands (often coniferous plantations). We predicted the winter moth densities would be reduced in fragmented stands due to dispersal mortality incurred by the early stage larvae.As predicted, all species of host trees suffered greater defoliation in the primeval forest. Hornbeam Carpinus betulus L. was the heaviest defoliated host. Other trees, which developed leaves synchronously with hornbeam – maple Acer platanoides L., lime Tilia cordata Mill., and pedunculate oak Quercus robur L. – were strongly affected as well. While we do not show a causal mechanism, greater dispersal mortality in fragmented stands is a most plausible explanation for the observed patterns of defoliation.     

杏树林害虫为害与发生规律

为全面了 解杏树林 害虫的 为害与 发生 规 律, 给 防 治提 供依 据, 采用 标 准地 方法 对 不同类型的 杏扁林进 行了系 统调查。 结果表明 , 杏树林 害虫群 落共有６ 目２５ 科５５ 种, 优势 种集中于蚧虫 、蚜虫、卷 叶蛾等 类群及天 幕毛虫、 舞毒 蛾等 。树 木 年龄 可 影响 害 虫 群落 的 组 成、优势种数 量及危害 程度 。管 理水 平 对 害虫 发 生 有明 显 影响 , 一 般 管理 水 平高 者, 害 虫 种类 少、危害较轻 。杏树林 害虫的 年发生规 律 是发 生周 期 短、优 势 种高 峰期 出 现早 、为 害期 集 中、群落凋落 迅速。     

Plant VOCs emission： a new strategy of thermotolerance

Plant leaves may emit a substantial amount of volatile organic compounds （VOCs） into the atmosphere, which include isoprene, terpene, alkanes, alkenes, alcohols, aldehydes, eters, esters and carboxylic acids. Furthermore, most of these compounds actively participate in tropospheric chemistry. Great progresses have been made in linking emission of these compounds to climate. However, the VOCs emission function in plant is still not clear. Recently, some evidence has emerged that the production and the emission of VOCs, such as isoprene and monoterpenes, which account for 80% of total VOCs, exhibit plant protection against high temperatures. These increases in VOCs emissions could contribule in a significant way to plant thermotolerance. This perspective summarizes some latest literatures regarding the VOCs emission-dependent thermoprotection in plant species subjected to high temperature stress, presents the achievement in studies concerning plant VOCs emission-dependent thermotolerance, and then exhibits the proposed mechanisms of such plant thermotolerance. Finally open questions regarding the plant VOCs emission were shown, and the future researches were proposed.     

舞毒蛾不同地理种群基于AFLP分子标记的遗传分析

舞毒蛾是一种食性很广、危害很大的世界性林木害虫,根据其地理分布和生活特性,现在被分为亚洲型和欧洲型2种。对来自俄罗斯远东地区、蒙古、日本、美国和中国5个地理种群,共26份舞毒蛾样品进行AFLP分子标记研究。成功建立并优化舞毒蛾AFLP分析体系,从16对引物组合中筛选出3对扩增条带多、多态检出率高的荧光标记引物组合,利用CEQ-8000遗传分析仪进行毛细管电泳及数据分析,共检测到507个多态性位点。通过PAUP软件对AFLP数据进行UPGM和NJ树的聚类分析以及遗传距离分析,结果表明:5个地理种群舞毒蛾明显分成欧洲型(美国种群)和亚洲型,其中亚洲型又可分成俄罗斯、日本、中国及蒙古3个类群。美国种群间遗传变异比其他种群较大,中国种群与美国种群遗传距离最大,而与蒙古种群遗传分化最小。从分子水平上研究舞毒蛾不同种群的遗传分类情况,揭示利用AFLP分子标记技术可以区分舞毒蛾不同地理种群的基因型,为研究舞毒蛾的起源、入侵与扩散、遗传与变异以及检疫措施的制定等方面提供科学依据。     

Localized ozone fumigation system for studying ozone effects on photosynthesis, respiration, electron transport rate and isoprene emission in field-grown Mediterranean oak species

We used a localized ozone (O3) fumigation (LOF) system to study acute and short-term O(3) effects on physiological leaf traits. The LOF system enabled investigation of primary and secondary metabolic responses of similarly and differently aged leaves on the same plant to three different O3 concentrations ([O3]), unconfounded by other influences on O3 sensitivity, such as genetic, meteorological and soil factors. To simulate the diurnal cycle of O3 formation, current-year and 1-year-old Quercus ilex (L.) and Quercus pubescens (L.) leaves were fumigated with O3 at different positions (and hence, different leaf ages) on the same branch over three consecutive days. The LOF system supplied a high [O3] (300+/-50 ppb) on leaves appressed to the vents, and an intermediate, super-ambient [O3] (varying between 120 and 280 ppb) on leaves less than 30 cm from the vent. Leaves more than 60 cm from the O3 vent were exposed to an [O3] comparable with the ambient concentration, with a 100 ppb peak during the hottest hours of the day. Only leaves exposed to the high [O3] were affected by the 3-day treatment, confirming that Mediterranean oak are tolerant to ambient and super-ambient [O3], but may be damaged by acute exposure to high [O3]. Stomatal and mesophyll conductance and photosynthesis were all reduced immediately after fumigation with high [O3], but recovered to control values within 72 h. Both the intercellular and chloroplast CO2 concentrations ([CO2]) remained constant throughout the experiment. Thus, although treatment with a high [O3] may have induced stomatal closure and consequent down-regulation of photosynthesis, we found no evidence that photosynthesis was limited by low [CO2] at the site of fixation. One-year-old leaves of Q. ilex were much less sensitive to O3 than current-year leaves, suggesting that the low stomatal conductance observed in aging leaves limited O3 uptake. No similar effect of leaf age was found in Q. pubescens. Dark respiration decreased during the treatment period, but a similar decrease was observed in leaves exposed to low [O3], and therefore may not be an effect of O3 treatment. Light respiration, on the other hand, was mostly constant in ozone-treated leaves and increased only in leaves in which photosynthesis was temporarily inhibited by high [O3], preventing them from acting as strong sinks that recycle respiratory CO2 in the leaves. There was no evidence of photochemical damage in Q. ilex leaves, whereas Q. pubescens leaves exposed to a high [O3] showed limited photochemical damage, but recovered rapidly. Biochemical markers were affected by the high [O3], indicating accumulation of reactive oxygen species (ROS) and increased denaturation of lipid membranes, followed by activation of isoprene biosynthesis in Q. pubescens leaves. We speculate that the high isoprene emissions helped quench ROS and normalize membrane stability in leaves recovering from O3 stress.