Inositols and methylinositols in sea buckthorn (Hippophaë rhamnoides) berries

Sea buckthorn (Hippophaë rhamnoides L.) berries, especially of ssp. sinensis, contain significant quantities of an unknown, water-soluble compound, evidently a cyclitol derivative. The compound was isolated by HPLC and analyzed by GC–MS [trimethylsilyl (TMS) derivative, selected ion monitoring (SIM) and total ion chromatogram (TIC) analyses], by ¹H and ¹³C NMR and by optical activity measurements. The results together with analyses of reference compound verified the unambiguous structure (?)-2-O-methyl-l-chiro-inositol (l-quebrachitol). In addition, chiro-inositol and myo-inositol existing in trace amounts were identified based on reference compounds, chromatographic data and mass spectra of the TMS derivatives. Methyl-myo-inositol was tentatively identified based on chromatography and mass spectrometry. Inositols and methyl inositols are bioactive compounds essential for regulating physiological processes of plants and humans. To our knowledge, this is the first report on the presence of chiro-inositol and myo-inositol in sea buckthorn and l-quebrachitol in edible berries. The identification of the inositols and l-quebrachitol in sea buckthorn may bring new insights into the sensory properties and also mechanisms behind the health effects of the berry.     

沙棘果油对过氧化氢诱导氧化损伤的保护作用

沙棘(Hippophae rhamnoides)是一种具有药用价值的植物,沙棘果油具有抗氧化、抗炎症及抗肿瘤等多种药理作用。为了探讨沙棘果油对H₂O₂造成氧化性损伤的细胞生长的影响及其抗氧化性,该研究选择H₂O₂对RAW264.7细胞氧化损伤模型,通过DPPH(1,1-二苯基-2-三硝基苯肼)自由基清除实验检测沙棘果油体外抗氧化能力,用[3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐]MTT法和流式细胞仪检测超氧化物阴离子荧光探针(DHE)信号,分别检测不同浓度沙棘果油对H₂O₂损伤细胞的存活率和超氧化物阴离子水平。结果表明:(1)在DPPH自由基清除实验中,当沙棘果油浓度小于4.9%时,沙棘果油的抗氧化能力大于维生素C。(2)通过MTT法发现,浓度为3.125%的沙棘果油对H₂O₂损伤细胞的存活率显著升高(P<0.01)。(3)从DHE检测发现,在同一检测时间点,随着沙棘果油浓度增加,DHE阳性细胞比例显著下降(P<0.01); 在不同检测时间点,随着沙棘果油浓度增加,DHE阳性细胞比例显著升高(P<0.01)。沙棘果油对过氧化氢诱导的RAW264.7细胞氧化损伤模型有一定修复作用,可能与细胞内超氧化物阴离子水平受到抑制有关,它具有抗氧化性损伤的潜能。     

A key volatile infochemical that elicits a strong olfactory response of the predatory mite <Emphasis Type="Italic">Neoseiulus californicus</Emphasis>, an important natural enemy of the two-spotted spider mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

Herbivore-induced plant volatiles (HIPVs) emitted from lima bean leaves infested with the two-spotted spider mites Tetranychus urticae strongly attract the predatory mites Neoseiulus californicus. Among these HIPVs, methyl salicylate and linalool can attract the predators. Three green-leaf volatiles (GLVs) of (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate and (E)-2-hexenal, found in the odor blends from T. urticae-infested leaves and physically damaged leaves, can also attract the predators. To search for a strong predator attractant, the olfactory responses of N. californicus to each synthetic compound or their combinations were investigated in a Y-tube olfactometer. When presented a choice between a mixture of the five compounds (i.e. the two HIPVs and the three GLVs) and T. urticae-infested leaves, N. californicus did not discriminate between these odor sources. The same trend was observed when either a mixture of the two HIPVs or methyl salicylate vs. T. urticae-infested leaves were compared. In contrast, the predators preferred T. urticae-infested leaves to linalool, each of the three GLVs, or a mixture of the three GLVs. These results indicated that methyl salicylate is a strong predator attractant, and its potential attractiveness almost equaled that of the blend of HIPVs from T. urticae-infested leaves.     

Influence of sea buckthorn (Hippophae rhamnoides L.) flavone on dermal wound healing in rats

The present investigation was undertaken to determine the efficacy of topical administration of flavone of sea buckthorn (Hippophae rhamnoides L.) on cutaneous wound healing in rats. Four full-thickness excision wounds were created on the back of rat and 1.0% w/v flavone prepared in propylene glycol was applied topically. Control animals received the vehicle alone in an identical manner. The healing of the wound was assessed by the rate of wound contraction, period of epithelialization, hydroxyproline, hexosamine, antioxidants estimation and histopathology of the granulation tissue. The sea buckthorn flavone promoted the wound healing activity as indicated by improved rate of wound contraction, decreased time taken for epithelialization (16.3 days versus 24.8 days in controls) and significant increase in hydroxyproline (26.0%) and hexosamine (30.0%) content. These findings were also confirmed by histopathological examinations. In addition, it was observed that sea buckthorn flavone possesses potent antioxidant properties as evidenced by significant increase in reduced glutathione (55.0%), vitamin C (70.0%) and catalase (20.0%) activities in wound granulation tissue. The flavone treatment also resulted in significant decrease in lipid peroxide levels (39.0%). The results suggest that the sea buckthorn flavone promotes wound healing activity.     

锰胁迫和性别竞争交互处理下沙棘雌雄幼苗生理响应特征

沙棘(Hippophae rhamnoides)是重要的雌雄异株人工林防护树种,但对其环境胁迫的性别响应差异研究不足,性别竞争与胁迫因子的交互效应响应特征尚不清楚。为了探讨锰胁迫和性别竞争交互处理下沙棘雌雄植株的生理响应特征和耐受能力,旨在为沙棘修复土壤重金属污染提供实践指导,该文研究了锰胁迫(4 000 mg·kg^-1)和3种不同性别组合模式(雌雄、雌雌、雄雄)处理下沙棘的生理响应,分别测定雌雄沙棘叶片中叶绿素、过氧化物酶(peroxidase,POD)、超氧化物歧化酶(superoxide dismutase,SOD)、丙二醛(malondialdehyde,MDA)、总酚(total phenols, TP)、游离脯氨酸(free proline,Pro)、可溶性糖(soluble sugar,SS)、甜菜碱(glycine betaine, GB)以及锰含量。结果表明:(1)锰胁迫下,在所有竞争组合中,性间竞争的雄株(M/FM)SOD活性最高,而MDA含量与对照相比未有明显升高,表明雄株的抗氧化能力更好,膜氧化损伤程度更小。(2)锰胁迫时M/FM积累了更多的游离脯氨酸,表现出更好的渗透调节能力和耐受能力。(3)交互效应分析显示性别互作和锰胁迫交互处理显著影响了沙棘雌雄叶片的光合色素、抗氧化酶活性和渗透调节能力; 主成分分析显示SOD、POD、MDA、叶绿素b(chlorophyll b, Chlb)、SS、Pro可作为重要的生理响应指示参数。该研究结果对于利用沙棘修复土壤重金属污染可提供一定的参考。     

Behavioural and electrophysiological responses of the European corn borer Ostrinia nubilalis to host‐plant volatiles and related chemicals

The European corn borer Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) is a worldwide pest of maize (Zea mays L.) and other crops. The semiochemicals released by maize plants and structurally‐related compounds can be used by adult female O. nubilalis for host‐plant location and oviposition. Headspace volatile compounds emitted by watered and water‐deprived maize plants are collected and identified by their retention indices and mass spectra. The most abundant compounds from watered plants are limonene, linalool, benzoic acid, indole, β‐caryophyllene and acetophenone, whereas, in water‐deprived plants, limonene, acetophenone, hexanoic acid, benzoic acid and indole are dominant. In addition, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene, 6‐methyl‐5‐hepten‐2‐one, anisole and 1‐carvone are undetected in the water‐deprived plants. Some of the identified compounds show electrophysiological activity (electroantennogram) in the antennae of both sexes, with the responses elicited by tridecane, tetradecane, dodecane, nonanal, decanal and 2‐ethylhexanol on males being particularly noteworthy. In a dual‐choice olfactometer, adult females show a preference for 2‐hexanol, heptanal, methyl salicylate, hexyl acetate, nonanal, methyl dodecanoate, β‐pinene and (E)‐2‐hexenyl acetate over hexane controls. Tetradecane, linalool, methyl hexanoate, methyl nonanoate, (Z)‐3‐hexenyl benzoate, tridecane, 2‐cyclopentylcyclopentanone, 3‐methylbutyl acetate, β‐myrcene and (Z)‐3‐hexenyl butanoate result in fewer females in the test arm compared with the control arm. No single compound displays an activity similar to watered maize plants, supporting the hypothesis that blends of volatiles in specific ratios are more effective than single volatile chemicals. The results of the present study suggest that methyl salicylate, which elicits also one of the highest electrophysiological responses in female antennae, plays a role in host preference by O. nubilalis females.     

Characterization and identification of ISSR markers associated with resistance to dried-shrink disease in sea buckthorn

Sea buckthorn (Hippophae L.) is an economically important, globally distributed shrub with unique biochemical properties. This long-juvenile and long-lived woody plant can be more difficult to cultivate than other crop plants. Dried-shrink disease is a dangerous pathogen that destroys sea buckthorn and halts commercial production. We estimated variability of ISSR molecular markers in 52 accessions of 16 sea buckthorn varieties and lines to seek markers associated with dried-shrink resistance and help identify potential breeding varieties and lines. Fifteen ISSR primers generated 346 bands, with an average of 23 bands per primer. Genetic similarities (Jaccard coefficient) between pairs of accessions ranged from 0.216 to 0.781. At a Jaccard coefficient of 0.39, the dendrogram generated with 342 polymorphic bands clustered 51 accessions of H. rhamnoides into five groups and one H. salicifolia isolate. Four ISSR markers (887₁₉₀, 835₇₀₀, 809₂₉₀, and 811₂₈₀) were significantly correlated with resistance to dried-shrink disease (P < 0.001). These markers provide a potential method for breeding programs that select lineages resistant to dried-shrink disease, especially when no other genetic information such as linkage maps and Quantitative Trait Loci are available.     

Oriented responses of grapevine moth larvae Lobesia botrana to volatiles from host plants and an artificial diet on a locomotion compensator

Larvae of the grapevine moth Lobesia botrana (Lepidoptera: Tortricidae) are a major pest of vine, Vitis vinifera. As larvae have limited energy reserves and are in danger of desiccation and predation an efficient response to plant volatiles that would guide them to food and shelter could be expected. The responses of starved 2nd or 3rd instar larvae to volatile emissions from their artificial diet and to single host plant volatiles were recorded on a locomotion compensator. Test products were added to an air stream passing over the 30 cm diameter servosphere. The larvae showed non-directed walks of low rectitude in the air stream alone but changed to goal-oriented upwind displacement characterised by relatively straight tracks when the odour of the artificial diet and vapours of methyl salicylate, 1-hexanol, (Z)-3-hexen-1-ol, terpinen-4-ol, 1-octen-3-ol, (E)-4,8-dimethyl-1,3,7-nonatriene and (Z)-3-hexenyl acetate were added to the air stream. This chemoanemotactic targeted displacement illustrates appetence for certain volatile cues from food by starved Lobesia larvae. Analysis of the larval behaviour indicates dose dependent responses to some of the host plant volatiles tested with a response to methyl salicylate already visible at 1 ng, the lowest source dose tested. These behavioural responses show that Lobesia larvae can efficiently locate mixtures of volatile products released by food sources as well as single volatile constituents of their host plants. Such goal-oriented responses with shorter travel time and reduced energy loss are probably of importance for larval survival as it decreases the time they are exposed to biotic and abiotic hazards.     

Identification and field optimisation of the female sex pheromone of the rice leaffolder,Cnaphalocrocis medinalis in India

Analysis of ovipositor washings from virgin femaleCnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) of Indian origin by linked gas chromatography and electroantennography indicated the presence of three electrophysiologically-active compounds. These were identified on the basis of their gas chromatographic retention times and mass spectra as (Z)-11-hexadecenyl acetate, (Z)-13-octadecenyl acetate and (Z)-13-octadecen-1-ol with (Z)-13-octadecenyl acetate present in amounts of between 0.25 and 1.5 ng per ovipositor and the other two components at less than 10% of this. Trace quantities of octadecyl acetate were identified by mass spectrometry but no electroantennographic responses were observed to this compound. Field trials conducted with a range of blends of the three electrophysiologically-active compounds showed that blends containing between 5% and 30% (Z)-11-hexadecenyl acetate in (Z)-13-octadecenyl acetate dispensed from either white rubber septa or polythene vials were more attractive to male moths than a virgin female moth. Addition of (Z)-13-octadecen-1-ol reduced attractiveness to male moths in the blends and concentrations tested.     

Predator–prey interactions: olfactory adaptations of generalist and specialist predators

1 Olfactory responses of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), a generalist predator, Podisus maculiventris (Say) (Hemiptera, Heteroptera: Pentatomidae) (Pm), and a specialist predator, Perillus bioculatus (F.) (Hemiptera, Heteroptera: Pentatomidae) (Pb) were investigated. Volatiles tested included 20 compounds emitted by undamaged potato plants (Solanum tuberosum), plants that had been artificially damaged, or plants damaged by feeding by CPB larvae. 2 Coupled gas chromatography/electroantennogram detector (GC/EAD) recordings revealed five compounds for which reliable responses were recorded from CPB antennae: (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, (±)-linalool, nonanal, methyl salicylate, and indole. Both Pm and Pb responded selectively to the same compounds as the CPB with exceptions: (1) (Z)-3-hexenyl butyrate elicited reliable responses for both Pm and Pb, and (2) (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol were inactive for Pm and Pb under these conditions. Dose–response curves showed that CPB was at least 100 times more sensitive to (E)-2-hexen-1-ol than were the predators. Both predators were more sensitive to each of the other compounds than were CPB. Both CPB and Pm were attracted to a five component blend comprising (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol, (±)-linalool, nonanal and methyl salicylate. However, attraction of CPB to the blend occurred only with lower doses of (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol. 3 These results show that the herbivore (CPB) has olfactory receptors which are more sensitive to constitutive host plant volatiles, e.g. green leaf volatiles, while both generalist (Pm) and specialist (Pb) predators are more sensitive to systemic volatiles produced in response to prey feeding. Keywords Colorado potato beetle, constitutive compounds, host plant, induced compounds, olfaction, Perillus bioculatus, Podisus maculiventris, predator, prey, tritrophic.     

Orientation of Colorado potato beetle to natural and synthetic blends of volatiles emitted by potato plants

1 Behavioural responses of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), to volatiles emitted from solanaceous host plants (potato and tomato), a non‐host legume (soybean), and 13 synthetic blends or three individual chemicals emitted by potato plants were investigated in laboratory bioassays. 2 Both male and female CPB were attracted to volatiles emitted by mechanically damaged potato foliage, but not to mechanically damaged tomato foliage; CPB offered a choice between the two damaged solanaceous plants did not show a preference. 3 Among 16 odourous blends or individual chemical components of potato plant emissions tested, six blends were attractive, two were repellent, and eight elicited no preference in laboratory bioassays. Volatile blends containing relatively high amounts of the green leaf volatiles (E)‐2‐hexen‐1‐ol and (Z)‐3‐hexen‐1‐ol, or the sesquiterpene β‐ caryophyllene, were unattractive or repellent. Minimal blends attractive to CPB were comprised of (Z)‐3‐hexenyl acetate (±)‐linalool and methyl salicylate: the combination of all three chemicals elicited sexually dimorphic attraction of males; two component blends comprised of (Z)‐3‐hexenyl acetate and either (±)‐linalool and methyl salicylate attracted both sexes. Individual compounds were inactive. No significant difference was noted between two attractive blends, or an attractive synthetic blend vs. mechanically damaged potato foliage. 4 These results show that CPB are attracted to blends of specific chemicals emitted by their host plants and provide a basis for the use of plant attractants as a component of integrated management of pestiferous populations.     

Development of multi-component non-sex pheromone blends to monitor both sexes of Cydia pomonella (Lepidoptera: Tortricidae)

Nineteen host plant volatiles (HPVs) were screened for attractivity to adult codling moth Cydia pomonella (L.) as a fourth component of core blends (3K) including (E,Z)-2,4-ethyl decadienoate, (E)-4,8-dimethyl-1,3,7-nonatriene and acetic acid. Each new quaternary combination was compared with a previously reported attractive bisexual lure (4K), consisting of the 3K blend plus 6-ethenyl-2,2,6-trimethyloxan-3-ol (pyranoid linalool oxide, pyrLOX). All lure evaluations were conducted in apple, Malus domestica (Borkhausen). Several compounds were found to significantly lower total and/or female catches when added to the 3K blend, including (Z)-3-hexenol, (E)-2-hexanal and hexyl butanoate (female and total moths), and (Z)-3-hexenyl acetate and linalool (female moths). Other compounds when added to the 3K blend did not increase or decrease moth catches, including methyl salicylate, (E)-β-ocimene, limonene, β-caryophyllene, butyl hexanoate, farnesol, terpineol, terpinen-4-ol and α-pinene. A few added compounds significantly increased moth catches compared with the 3K blend, including β-pinene (male moths), (Z)-jasmone (male and total moths), (E)-β-farnesene and β-myrcene (female and total moths), and (E,E)-α-farnesene (male, female, and total moths). In addition, each of these five compounds when added to the 3K core blend performed similarly to the 4K lure (male, females, and total moths). Further studies should expand these results through tests of these and other new blends with a range of component ratios and total loading amounts. Field trials should also be replicated within all host crops of codling moth and across major geographical production regions.     

Synergism between aromatic compounds and green leaf volatiles derived from the host plant underlies female attraction in the oriental fruit moth

Blends of volatile compounds emitted by host plants are known to mediate the attraction of gravid female herbivores to oviposition sites, but the role of individual odor components is still little understood. We characterized the olfactory response of mated female Cydia (Grapholita) molesta (Busck) (Lepidoptera: Tortricidae) to synthetic mixtures of compounds emitted by peach shoot, a key host plant of this herbivore, and investigated the role of important constituents of bioactive mixtures in moth attraction. Relative ratios of constituents of the mixtures corresponded to the natural ratio of volatile compounds collected in the plant's headspace. A significant attractant effect was found for a comparatively complex 10‐compound mixture that included four green leaf volatiles [(Z)‐3‐hexen‐1‐ol, 1‐hexanol, (E)‐2‐hexenal, and (Z)‐3‐hexen‐1‐yl acetate], five aromatics (benzaldehyde, methyl salicylate, methyl benzoate, benzonitrile, and phenylacetonitrile), and a carboxylic acid (valeric acid). Using a subtraction approach, the number of compounds was progressively decreased, resulting in a bioactive 5‐compound mixture composed of two constituents, green leaf volatiles and aromatic compounds. Further evaluations revealed that benzaldehyde and benzonitrile must be present in association with three distinct green leaf volatiles to produce an attractant effect on the female moths. This 5‐compound mixture was as attractive as natural peach shoot volatiles, which are known to comprise over 20 compounds. Results are discussed in light of the documented synergistic effect between the three general green leaf volatiles and the two specific aromatic compounds.     

Lotus japonicus Infested with Herbivorous Mites Emits Volatile Compounds That Attract Predatory Mites

Lotus Japonicus has an indirect defense mechanism against spider mites, Tetranychus urticae, we investigated the responses of predatory mites, Phytoseiulus persimilis, to volatile compounds released from T. urticae-infested L. japonicus in a Y-tube olfactometer. Plants infested with spider mites attracted more P. persimilis than did clean air. Uninfested plants and artificially damaged plants did not attract P. persimilis. When infested by spider mites, L. japonicus plants started emitting (Z)-3-hexenyl acetate, (E)-4,8-dimethyl-1,3,7-nonatriene, germacrene d, 1-octen-3-ol and methyl salicylate (MeSA). These compounds were considered to be T. urticae-induced plant volatile compounds. When three L. japonicus mutants deficient in nodule organogenesis were infested by the spider mites, they all attracted P. persimilis. However, two of the infested mutants emitted blends of induced volatile compounds that were qualitatively different from those emitted from infested wild type L. japonicus. Received 8 August 2000/ Accepted in revised form 12 October 2000     

Sea buckthorn (Hippophae rhamnoides L.) vegetative parts as an unconventional source of lipophilic antioxidants

The profile of lipophilic antioxidants in different vegetative parts (leaves, shoots, buds and berries) was studied in sea buckthorn (Hippophae rhamnoides L.) male and female plants collected in the end of spring. Five lipophilic compounds, i.e. three tocopherol homologues (α, β and γ), plastochromanol-8 and β-carotene, were identified in each vegetative part of male and female sea buckthorn plants at the following concentrations: 7.25–35.41, 0.21–2.43, 0.41–1.51, 0.19–1.79 and 4.43–24.57 mg/100 g dry weight basis. Additionally, significant amounts of α-tocotrienol (1.99 mg/100 g dry weight basis) were detected in buds. The α-tocopherol and β-carotene were predominant lipophilic antioxidants in each vegetative part, accounting for 78.3–97.0% of identified compounds. The greatest amounts of lipophilic antioxidants were found in leaves, especially of female plants. Nevertheless, apart from leaves, also shoots of plants of both sexes seem to be a good source of α-tocopherol and β-carotene.     

Distribution of unusual fatty acids in the mesocarp triacylglycerols of maturing sea buckthorn fruits

The pattern of distribution of X-FAs among individual positional species of the X-triacylglycerols (X-TAGs) in the sea buckthorn (Hippophaë rhamnoides L.) mesocarp oil by the 80th, 90th, and 105th day after pollination (DAP) was investigated. The X-FAs comprised oleic acid (O) as well as unusual FAs, viz. hexadecenoic (H), palmitolinoleic (Pl), and cis-vaccenic acid (V). During mesocarp growth, the number of X-TAG species decreased dramatically as a result of their metabolism, but their proportion in the total TAGs remained constant. H-TAGs predominating in the oil were similar to total TAGs in their composition and the pattern of their dynamics during maturation. As regards minor Pl-TAGs, there was a tendency for an increase in the level of species including palmitolinoleic acid in the middle (sn-2) position of their molecules. Throughout the entire process of fruit maturation, oleic acid was by 98.0–98.8% concentrated in the sn-2 position of O-TAGs. At the same time, cis-vaccenic acid, a Δ11-positional isomer of oleic acid, was predominantly incorporated in the side positions of V-TAGs, and its 98.1% concentration in these positions was achieved only by the 105th DAP. A virtually absolute selectivity of the distribution of oleic and cis-vaccenic acids in TAGs was found here for the first time. Discussed are the possible physicochemical and biochemical factors of a highly selective incorporation of these FAs in the sea buckthorn TAGs, the pathways of enzymatic biosynthesis of O- and V-TAGs, the metabolic role of discrimination of incorporation of some FA species in the glycerol residue of glycerolipids, and the causes for the disappearance of some TAG species during maturation.     

Neighborhood effects on soil properties,mycorrhizal attributes,tree growth,and nutrient status in afforested zones

A harmonious interspecies relationship is the key to the success of mixed afforestation. This study was conducted to assess the responses of afforestation species to their neighboring trees. We examined five types of stands—monocultures of Chinese pine (Pinus tabuliformis), black locust (Robinia pseudoacacia), sea‐buckthorn (Hippophae rhamnoides), and two mixtures (Chinese pine × black locust mixture and Chinese pine × sea‐buckthorn mixture)—in the Loess Plateau, northwestern China. The height and diameter at breast height of each tree species were measured, and rhizosphere soil, shoot, and root were sampled. In monocultures, black locust was taller than Chinese pine and sea‐buckthorn, while the height of Chinese pine and sea‐buckthorn was similar. In mixtures, Chinese pine grew better with sea‐buckthorn than alone as a result of modified soil properties and plant nutrition, but not with black locust. When Chinese pine was used as neighbors, it affected the level of arbuscular mycorrhizal (AM) colonization of black locust, soil properties and AM fungal spore density of black locust and sea‐buckthorn, but did not significantly affect their growth. Our results suggest that the reciprocal effects between tree species in mixture are not symmetric, and thus planning for efficient mixed afforestation requires knowledge of species‐specific growth rate, nutrient requirements, and species interactions.     

Fusarium infection in maize: volatile induction of infected and neighboring uninfected plants has the potential to attract a pest cereal leaf beetle, Oulema melanopus

Fusarium infection of maize leaves and/or roots through the soil can stimulate the emission of volatile organic compounds (VOCs). It is also well known that VOC emission from maize plants can repel or attract pests. In our experiments, we studied VOC induction responses of Zea mays L. ssp. mays cv. ‘Prosna’ having Fusarium infection (mix of four species) in leaves or roots, then tested for VOC induction of uninfected neighboring plants, and finally examined wind-tunnel behavioral responses of the adult cereal leaf beetle, Oulema melanopus L. (Chrysomelidae: Coleoptera) behavior to four induced VOCs. In the first part of our experiment, we confirmed that several green leaf volatiles (GLVs; (Z)-3-hexenal, (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-yl acetate, 1-hexyl acetate), terpenes (β-pinene, β-myrcene, Z-ocimene, linalool, β-caryophyllene), and shikimic acid pathway derivatives (benzyl acetate, methyl salicylate, indole) were positively induced from maize plants infected by Fusarium spp. The quantities of induced VOCs were higher at 7 d than 3 d post-infection and greater when plants were infected with Fusarium on leaves rather than through soil. In the second part of our experiment, uninfected maize plants also showed significantly positive induction of several VOCs when neighboring an infected plant where the degree of induction was negatively related to the distance from the infected plant. In the third part of our experiment, a Y-tube bioassay was used to evaluate upwind orientation of adult cereal leaf beetles to four individual VOCs. Female and male O. melanopus were significantly attracted to the GLVs (Z)-3-hexenal and (Z)-3-hexenyl acetate, and the terpenes linalool and β-caryophyllene. Our results indicate that a pathogen can induce several VOCs in maize plants that also induce VOCs in neighboring uninfected plants, though VOC induction could increase the range at which an insect pest species is attracted to VOC inducing plants.