Secondary metabolites from pericarp of Juglans regia

Chemical investigation of the pericarps of Juglans regia led to the isolation of sixteen compounds, including five α-tetralone (1-5), five phenolic acids (6-10), two phenylpropanoids (11, 12), one diarylheptanoid (13), one sesquiterpene (14), and two α- tetralone dimers (15, 16). Among them, compounds 2, 4, 5, 11, 12 and 13 were isolated from J. regia for the first time, and compounds 10 and 14 were reported for the first time from Juglandaceae. The chemotaxonomic significance of these compounds was summarized.     

Natural wood colouring process in Juglans sp. (J. nigra, J. regia and hybrid J. nigra 23 ×J. regia) depends on native phenolic compounds accumulated in the transition zone between sapwood and heartwood

 Radial distribution of soluble phenolics was investigated at different heights in stems of Juglans nigra, J. regia and hybrids J. nigra 23 × J. regia. Four major phenolic compounds were studied: hydrojuglone glucoside (HJG), quercitrin (QUER) and two unknown compounds characterized as two ellagic acid derivatives E1 and E2. HJG and E1 content increased gradually in the sapwood, peaked in the sapwood-heartwood transition zone, and decreased drastically in the heartwood. QUER was accumulated preferentially around the transition zone, and its content was relatively low in the outer part of the sapwood and in the inner part of the heartwood. E2 content was low in the sapwood and increased in the heartwood. The heartwood formation was marked by the accumulation of new soluble compounds. The relationship between wood extractives and wood colour were evaluated and discussed. HJG was considered to be a major precursor of heartwood colour providing chromophores through hydrolysis (deglucosylation), oxidation and polymerization processes. Received: 2 September 1997 / Accepted: 23 November 1997     

First record of a walnut shield bearer Coptodisca (Lepidoptera: Heliozelidae) in Europe

A leafminer of the Nearctic genus Coptodisca Walsingham (Lepidoptera: Heliozelidae), a species of potential economic interest, is reported for the first time from Europe, infesting the black (Juglans nigra L.) and the common walnut (Juglans regia L.). Mines were collected since September of 2010 in several sites of two Italian regions (Campania and Lazio). The species is rather similar to Coptodisca juglandella (Chambers), the only Coptodisca known to attack walnuts, but at present, an unambiguous identification cannot be provided because of the unsatisfactory characterization of this leafminer and congeneric species. Three generations were recorded per year and leafminers overwinter as mature larvae. The first adults emerged in May–June while mature larvae of the last generation started the overwintering in September. During the last generation of the year, infestation levels of leaves were 100% in all sampled localities. Several species of parasitoids were reared from infested mines, with specimens belonging to the genus Chrysocharis (Hymenoptera: Eulophidae) being the most frequent parasitoids.     

Antioxidative Activities of Galloyl Glucopyranosides from the Stem-Bark of Juglans mandshurica

Two phenolics, 1,2,6-trigalloylglucose (1) and 1,2,3,6-tetragalloylglucose (2), isolated from the stem-bark of Juglans mandshurica were evaluated for their antioxidative activities. The results showed that compounds 1 and 2 exhibited strong scavenging activities against 1,1′-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-(3-ethylbenzenthiazoline-6-sulphonic) acid (ABTS^?+), and superoxide radicals (O₂ ^??), and also had a significant inhibitory effect on lipid peroxidation and low-density lipoprotein (LDL) oxidation. The strong superoxide radical scavenging of 1 and 2 resulted from the potential competitive inhibition with xanthine at the active site of xanthine oxidase (OX). In addition, compounds 1 and 2 displayed significant lipoxygenase inhibitory activity, the mode of inhibition also being identified as competitive. In comparison, the antioxidative activities of compounds 1 and 2, together with gallic acid, indicated that the number of galloyl moieties could play an important role in the antioxidative activity.     

核桃种质资源遗传多样性的SSR分析

应用16对SSR引物对国内不同地理生态型的44个核桃样品、8个铁核桃样品和7个美国核桃样品进行了分析。结果显示,在16个SSR位点上共获得87个等位基因,每个位点扩增等位基因4～9个,平均5.4个。各SSR位点的观察杂合度为0～0.931 0,平均为0.389 4。各位点PIC值在0.376 2～0.786 3之间,平均为0.663 2。59个核桃样品的杂合度在0.133～0.813之间,平均0.387。聚类分析表明,来自秦岭山地的核桃样品与华北核桃属于同一生态类型;巩留的野核桃属于与新疆生态型和华北生态型不同的一个独立的生态型;美国核桃和铁核桃属于核桃种下不同的生态类型。     

东北温带森林常见树种粗根分解过程及调控因子

粗根是森林生态系统中重要的碳库和养分库，对生态系统的碳和养分循环起着重要的作用。但目前人们对于影响粗根分解的主要因素以及粗根分解模式的研究较少。采用埋袋法对东北温带森林常见的10个树种（黄檗、胡桃楸、水曲柳、色木槭、红松、落叶松、白桦、春榆、紫缎、蒙古栎）的粗根（5-10 mm）进行了为期1年的分解实验研究，来探索粗根分解和养分释放的动态变化规律。研究结果表明：黄檗、胡桃楸、水曲柳、色木槭、红松、落叶松、白桦、春榆、紫缎、蒙古栎粗根年分解系数分别为0.826、0.897、0.477、0.341、0.358、0.264、0.244、0.593、0.458、0.227。由此可见，胡桃楸分解速率最快，蒙古栎分解速率最慢。在粗根分解过程中，不同调控因子对根系分解的影响不同。研究结果表明，粗根的分解速率与根系的初始C/N比例呈显著负相关（P<0.0001），与初始木质素含量呈负相关（P<0.0001），与初始非结构性碳水化合物（NSC）含量呈正相关（P<0.0001）。初始C/N、木质素含量与非结构性碳水化合物含量分别可以解释所研究的10个树种粗根分解速率的68%、20%与65%。研究结论对于预测粗根参与的碳循环与养分释放具有重要意义。     

Phytochemical Study of Juglans regia L. Pericarps from Greece with a Chemotaxonomic Approach

Phytochemical research of different polarity extracts from green Juglans regia L. pericarps from Greece afforded 32 compounds: four pentacyclic triterpenes (1 – 4), three sesquiterpenes (5 – 7), four tetralones (8 – 11), two naphthoquinones (12 and 13), seven phenolic acids (14 – 20), one diarylheptanoid (21), one neo‐lignan (22), seven flavonoids (23 – 29), two phenylethanoids (30 and 31) and one hydrolysed tannin (32). Compounds 4 and 29 are isolated for the first time from the species, while compounds 3, 7, 20, 22, 23, 24, 25, 26, 28, 30 are reported for the first time in Juglandaceae. Chemotaxonomic significance of isolated compounds into Junglandaceae family is thoroughly discussed.     

Nachweis und Lokalisation von Tryptophan-Synthetase in Samen von Juglans regia L.

Summary Cell-free extracts from seeds of Juglans regia synthesize tryptophan from L-serine and indole. Tryptophan synthetase has maximal activity in the range between pH 7 and 8. The enzyme is associated with a particulate fraction (density 1,210 g/ml) which is separated from the mitochondria (density 1,191 g/ml) after isopycnic density centrifugation on a continuous sucrose gradient.     

Origin of somatic embryos from repetitively embryogenic cultures of walnut (Juglans regia L.): Implications forAgrobacterium-mediated transformation

Early stages of somatic embryo development from embryogenic cultures ofJuglans regia (Persian or English walnut) are described. Histological examination reveals that secondary somatic embryos arise from cotyledons and hypocotyls of primary embryos cultured in the dark. The embryos originate by transverse to oblique divisions of surface cells. Single-cell origin of the secondary embryos confirms the potential of the repetitive embryogenesis system forAgrobacterium-mediated transformation and regeneration of non-chimeric, transgenic walnut plants.     

Variations among woody plants in stomatal conductance and photosynthesis during and after drought

Acer saccharum, Fraxinus americana, Juglans nigra, Acer rubrum, Cornus amomum, and Ulmus americana seedlings were subjected to a soil drying cycle and then rewatered. At frequent intervals during the drying cycle and following rewatering, determinations were made of equilibrium photosynthesis rates, leaf conductances and leaf water potentials. As the drying cycle progressed, leaf water potentials decreased, stomata closed, and rates of transpiration and photosynthesis were reduced. Stomata of the two Acer species initially were more sensitive to water stress than were those of the other species. At low leaf water potentials, stomata of Juglans and Cornus were more open than those of the other species. Photosynthesis of Acer saccharum, Fraxinus and Juglans was significantly reduced by plant water stress, while photosynthetic water use efficiency of Cornus and Juglans was most unfavourable. Photosynthesis/leaf conductance ratios in water stressed leaves were higher in Fraxinus than in the other species. Immediately after rewatering, only limited stomatal opening occurred in Acer saccharum and Cornus with recovery of stomatal opening most protracted in Fraxinus and Ulmus. There was extended reduction of photosynthesis of all species as a result of the soil drying treatment. This effect was most significant in Acer saccharum and Juglans. Survival of plants on moist and dry sites is discussed in relation to stomatal control of transpiration and metabolic responses to water stress. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison and the International Shade Tree Conference. The cooperation of the Wisconsin Department of Natural Resources is acknowledged. Research supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison and the International Shade Tree Conference. The cooperation of the Wisconsin Department of Natural Resources is acknowledged.     

Wall ultrastructure and biochemical features of the Juglans regia L. and Juglans nigra L. male gametophyte

Summary The Juglans regia x Juglans nigra hybrid cannot be obtained because of stable interspecific barriers. We have analyzed and described various morphological and biochemical characters in J. regia and J. nigra pollen: differences in the mineral composition, polysaccharide reserves, wall ultrastructure and protein pattern of soluble cytoplasm, membranes, and cell-wall fractions. The absence of a glycoprotein fraction in the wall of J. nigra suggests that the regulation of critical steps in the interspecific matching with female tissues could be affected.     

Isolation of Eutypa lata from Juglans regia, and Pathogenicity Studies on Different Wood Plants

The fungus Eutypa lata was isolated from diseased walnut trees (Juglans regia) exhibiting small cankers. The morphological characteristics of the culture and the pathogenicity were compared with those of known isolates of the fungus from other hosts. Inoculation tests with walnut isolates on grape, walnut, almond and apricot yielded characteristic cankers. Furthermore, pathogenicity tests on walnut with isolates from other different hosts resulted in differences in virulence. Similar differences in virulence were observed between 13 single ascospore isolates of the fungus ex apricot inoculated on walnut.     

DNA markers identify hybrids between butternut (Juglans cinerea L.) and Japanese walnut (Juglans ailantifolia Carr.)

Butternut (Juglans cinerea L.) is a temperate deciduous hardwood native to the eastern USA and southern Canada valued for its nuts and wood. Butternut’s survival is threatened by butternut canker, a disease caused by the exotic fungus Sirococcus clavigignenti-juglandacearum Nair, Kostichka & Kuntz. Field observations indicate that trees commonly called buartnut (a hybrid of butternut and its close congener Japanese walnut (Juglans ailantifolia × J. cinerea)) may be more resistant to butternut canker than is either parental species. Hybrids are difficult to distinguish morphologically from butternuts, and scientists have expressed concern over the possibility of range-wide genetic invasion by Japanese walnut via hybridization with butternut. We used pair-wise combinations of 40 random primers to screen bulked DNA pools of butternut, Japanese walnut, and buartnuts to identify genomic regions unique to Japanese walnut. We ultimately identified one ITS region marker, one chloroplast marker, one mitochondrial marker, and six nuclear markers. The utility of the markers for identifying hybrids was tested and verified using more than 190 genotypes. The markers will be used to identify buartnut hybrids based on the presence of introgressed genomic fragments inherited from Japanese walnut. We confirmed that hybrids have a complex genetic history and present features of the parental species in all possible combinations. These results will assist in the identification and testing of (non-hybrid) butternut for breeding and reintroduction of the species to its former habitats.     

Synergistic Antimicrobial Activity of Camellia sinensis and Juglans regia against Multidrug-Resistant Bacteria

Synergistic combinations of antimicrobial agents with different mechanisms of action have been introduced as more successful strategies to combat infections involving multidrug resistant (MDR) bacteria. In this study, we investigated synergistic antimicrobial activity of Camellia sinensis and Juglans regia which are commonly used plants with different antimicrobial agents. Antimicrobial susceptibility of 350 Gram-positive and Gram-negative strains belonging to 10 different bacterial species, was tested against Camellia sinensis and Juglans regia extracts. Minimum inhibitory concentrations (MICs) were determined by agar dilution and microbroth dilution assays. Plant extracts were tested for synergistic antimicrobial activity with different antimicrobial agents by checkerboard titration, Etest/agar incorporation assays, and time kill kinetics. Extract treated and untreated bacteria were subjected to transmission electron microscopy to see the effect on bacterial cell morphology. Camellia sinensis extract showed higher antibacterial activity against MDR S. Typhi, alone and in combination with nalidixic acid, than to susceptible isolates.” We further explore anti-staphylococcal activity of Juglans regia that lead to the changes in bacterial cell morphology indicating the cell wall of Gram-positive bacteria as possible target of action. The synergistic combination of Juglans regia and oxacillin reverted oxacillin resistance of methicillin resistant Staphylococcus aureus (MRSA) strains in vitro. This study provides novel information about antimicrobial and synergistic activity of Camellia sinensis and Juglans regia against MDR pathogens     

Food plants and life cycle of Lymantria bantaizana Matsumura (Lepidoptera: Lymantriidae) in northern Honshu, Japan

The food plants and life cycle of Lymantria bantaizana were investigated in Iwate Prefecture, northern Honshu, Japan from 2000 to 2002. Eggs laid in July hatched approximately 10 days after oviposition. Hatched larvae fed only on Juglandaceae, Juglans mandshurica var. sachaliensis, J. regia var. orientalis and Pterocarya rhoifolia when reared in the laboratory. In field rearing, the plants of Juglans enabled the moth to complete its life cycle. Differing from all other known Lymantria species in Japan, the moth overwintered not in the egg stage but in the fifth or sixth instar larval stage. Lymantria bantaizana had eight larval instars in both sexes. Moth emergence occurred mostly in July at a field‐trapping site in Iwate Prefecture.     

Beiträge zur Morphologie der Pollenkörner vonJuglans regia undJ. nigra

Zusammenfassung Die Pollenkörner vonJuglans regia undJ. nigra sind, entgegen anderen Angaben, im gequollenen Zustand annähernd kugelig-rund und im trockenen Zustand kugelig-eingedellt. Trockene Pollenkörner runden sich, sobald man sie in eine Flüssigkeit gibt, blitzartig ab. Gleichzeitig mit der Form der Pollenkörner ändert sich auch die Beschaffenheit des Pollenkitts, der auf den Pollenkörnern gelagert ist; auf gequollenen Pollenkörnern bildet er kleinere und größere, ölige Kügelchen; auf Trockenpollen erscheint er als eine ± zähflüssige, formlose Masse. Das Sporoderm besteht aus drei Schichten: einer punctitegillaten Sexine, einer strukturlosen Nexine und einer dünnen Intine, die im Bereich der Keimporcn linsenförmige Verdickungen, sog. Zwischenkörper, bildet. Die Zwischenkörper sind meist voneinander isoliert und bestehen in der Hauptmasse aus Pektinverbindungen. In der Regel sind 12–16 Keimporen ausgebildet, die beiJuglans regia kreisrund und beiJ. nigra elliptisch sind.Die AngabenSchanderls über die ölreiche Endoexine und den Ölauspreßmechanismus beiJuglans regia wurden widerlegt. Es konnte gezeigt werden, daß die Pollenkörner vonJuglans regia undJ. nigra einen ähnlichen Bau besitzen wie viele andere Vertreter windblütiger Familien.     

Thirteen nuclear microsatellite loci for butternut (Juglans cinerea L.)

Butternut (Juglans cinerea L.) is an eastern North American forest tree severely threatened by an exotic fungal pathogen, Sirococcus clavigignenti‐juglandacearum. We report here 13 nuclear microsatellites for genetic evaluation of the remaining natural populations. Summary statistics are reported for individuals from a population of butternuts in central Kentucky (N = 63). All markers were polymorphic, with an average of 13.7 alleles per locus observed. Four loci exhibited significantly fewer heterozygotes than expected under Hardy–Weinberg equilibrium (P < 0.05).     

Rubrifacine fromErwinia rubrifaciens

For the main component of the pigments ofErwinia rubrifaciens, we suggest the hitherto unknown structure of a 3-(3-carboxymethyl-4,5-dihydro-4,5-dioxo-2-pyrrolyl)-4,5,6-trihydroxy-pyridine-2-acetic acid. Its isolation and characterization are described. Inasmuch as arylpyrrolindiones are known to be red, the proposed structure can account for the color of the pigment. The 2,3,4-trihydroxypyridine moiety probably inhibits the electron transport in mitochondria. This could explain the toxic action ofErwinia rubrifaciens onJuglans regia.     

Small CyclenImidazolium‐Containing Molecules and Their Interactions with DNA

Three small organic molecules containing different numbers of cyclen and imidazolium units were synthesized. Their interactions with plasmid DNA and their potential for gene delivery vectors were investigated. Agarose gel retardation and ethidium bromide exclusion assays revealed that these molecules can effectively condense DNA, and compounds with higher molecular weights are needed to lower w/w ratio for full condensation. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) indicated that these compounds may form nanosized spherical particles with DNA. Furthermore, the complex formed from 10 , i.e., 10 /DNA, can partially release DNA from compact state at a relatively higher concentration of NaCl (200 mM ). In the presence of the lipid 1,2‐dioleoyl‐sn‐glycero‐3‐phosphoethanolamine (DOPE), 10 could transfer plasmid DNA into BEL‐7402 cells. In addition, these compounds exhibited much lower cytotoxicity than PEI 25 kDa.     

Chalcone synthase activity and polyphenolic compounds of shoot tissues from adult and rejuvenated walnut trees

Changes in the metabolism of naphthoquinone and flavonoids during the growth of half-sib adult and rejuvenated walnut shoots (Juglans nigra × Juglans regia L.) were studied at the tissue level for two years after pruning. Moreover, the role of chalcone synthase (CHS; EC 2.3.1.74) in the regulation of flavonoid biosynthesis was investigated at the level of enzyme activity. The end products of walnut flavonoid biosynthesis, myricitrin and quercitrin, which accumulated in the bark and phloem at the end of growth, did not inhibit the biosynthetic process at concentrations of up to 100 μM each. There was no evidence of CHS regulation by feedback or similar mechanisms which might modulate enzyme activity. Mathematical correlation of CHS activity and flavonoid accumulation during shoot growth, however, indicated that CHS is the rate-limiting enzyme of the pathway in bark and phloem and that flavonoids seem to be transported from phloem to bark where they accumulated mainly during growth. In defoliated shoots, naphthoquinone metabolism appeared to be a marker of the walnut rejuvenation stage in the medulla, phloem and buds immediately after cutting and thereafter mainly in buds one year after cutting. Chalcone synthase and flavonoid contents appeared to be markers of the adult stage in the phloem. Received: 30 September 1996 / Accepted: 17 March 1997