Inhibition of Aspergillus flavus growth and detoxification of aflatoxin B1 by the medicinal plant zimmu (Allium sativum L. × Allium cepa L.)

Aflatoxins are carcinogenic, teratogenic and immunosuppressive secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin contamination of peanut is one of the most important constraints to peanut production worldwide. In order to develop an eco-friendly method of prevention of A. flavus infection and aflatoxin contamination in peanut, aqueous extracts obtained from leaves of 30 medicinal plants belonging to different families were evaluated for their ability to inhibit the growth of A. flavus in vitro. Among them the leaf extract of zimmu (Allium sativum L. × Allium cepa L.) was the only one that showed antifungal activity against A. flavus and recorded 73% inhibition of A. flavus growth. The antifungal activity of the zimmu extract was significantly decreased upon dialysis with a dialysis membrane having molecular cut off 12 kDa or autoclaving at 121°C for 20 min or boiling at 100°C for 10 min and recorded inhibition of 52, 16 and 21%, respectively. When A. flavus was grown in medium containing zimmu extract the production of aflatoxin B₁ (AFB₁) was completely inhibited even at a concentration of 0.5%. When AFB₁ was incubated with zimmu extract a complete degradation of AFB₁ was observed 5 days after incubation. When the roots of zimmu were incubated in water containing 70 ng of AFB₁/ml, a reduction (by 58.5%) in AFB₁ concentration was observed 5 days after incubation. A significant reduction in the population of A. flavus in the soil, kernel infection by A. flavus and aflatoxin contamination in kernels was observed when peanut was intercropped with zimmu. The population of the fungal antagonist, Trichoderma viride in the zimmu-intercropped field increased approximately twofold.     

Isozyme analysis of progeny derived from (Allium fistulosum ×Allium cepa) ×Allium cepa

Summary Relatively large quantities of seed were obtained from the interspecific backcross (A. fistulosum xA. cepa) ×A. cepa allowing, for the first time, an extensive study of the heritable traits exhibited by backcross progeny. Two backcross populations, BC1034 and BC1040, distinguished by differentA. fistulosum parents, were characterized for the isozyme markersIdh-1, Adh-1, andPgi-1. Statistical methods are described to calculate cell probabilities for a mixed population of F₂ and BC₁ progeny, using an estimate of the fraction of F₂ progeny in the population derived from the isozyme data. Cell probability distributions were calculated for a mixed population with independent pairs of loci and a mixed population with nonindependent pairs of loci. The isozyme lociIdh-1 andPgi-1 appear to be linked, with a map distance estimated at 33 centimorgans (cM) in BC1034 and 42 cM in BC1040. The probability distribution model for linked loci did not account for all of the distorted segregation ratios inIdh-1 ×Adh-1 orPgi-1 ×Adh-1. The cytological literature does not support linkage betweenIdh-1 ×Adh-1 orPgi-1 ×Adh-1. The distorted segregation ratios for these pairs of loci are likely the result of genetic incompatibilities between the two species.Journal Article No. 1578, Agricultural Experiment Station, New Mexico State University, Las Cruces, NM, USA     

Glu–Phe from onion (Allium Cepa L.) attenuates lipogenesis in hepatocytes

A Glu–Phe (EF) was isolated from onion (Allium cepa L. cv. Sunpower). The chemical structure of EF was determined by nuclear magnetic resonance and electrospray ionization–mass (ESI?MS) spectroscopy. We showed that EF reduced lipid accumulation in mouse hepatocytes by inhibiting the expression of sterol regulatory element-binding protein-1c (SREBP–1c) and its lipogenic target genes. We also found that AMP-activated protein kinase (AMPK) was required for the inhibitory effect of EF on lipid accumulation in mouse hepatocytes. Furthermore, EF was qualified in nine onion cultivars by selective multiple reaction-monitoring detection of liquid chromatography–ESI?MS. These results suggest that EF could contribute to the beneficial effect of onion supplement in maintaining hepatic lipid homeostasis.     

中国大蒜(Allium sativum L.)18个品种的酯酶同工酶多态性分析

采用聚丙烯酰胺凝胶电泳(PAGE)分离了中国大蒜3个生态型(低温反应敏感型、低温反应中间型和低温反应迟钝型)中18个较典型的品种的酯酶同工酶,并用排序分析法对18个品种的亲缘关系进行了分析,将18个品种分为3个变种群：1．“苏联”蒜变种群(var．Russia),2．吉木萨尔白皮蒜变种群(var．：Jimusaer。),3．中国内陆大蒜变种群(var．China)。其中中国内陆大蒜变种群又可分为5个品种群：①关中蒜品种群,②西北蒜品种群,③西南蒜品种群,④云贵蒜品种群,⑤华东蒜品种群。实验结果初步证实,大蒜生态型不能完全等同于基因型,酯酶同工酶的变化可能更能说明大蒜的亲缘进化关系。     

Induction of systemic resistance to bacterial blight caused by Xanthomonas campestris pv. malvacearum in cotton by leaf extract from a medicinal plant zimmu (Allium sativum L. × Allium cepa L.)

Abstract

Aqueous extract (10%) from leaves of zimmu (Allium sativum L. × Allium cepa L.) when applied as foliar spray to first and second leaves of cotton plants induced systemic resistance in third and fourth leaves to a challenge infection with Xanthomonas campestris pv. malvacearum and reduced the number of lesions by up to 73% compared with water-treated control plants. The treated leaves exhibited significantly high activity of enzymes phenylalanine ammonia-lyase, peroxidase and polyphenol oxidase along with rapid accumulation of phenolics. The activities of chitinase and β-1,3-glucanase were greatly elevated in treated plants as compared to water-treated controls. An 11-fold increase in chitinase activity was evident 4 d after treatment. Western blot analysis revealed that a chitinase with an apparent molecular weight of 58 kDa that cross-reacted with a barley chitinase antiserum was induced in cotton leaves 3 d after treatment and the maximum induction of this chitinase was detected 4 d after treatment. The present study provides evidence for the induction of biochemical defence mechanisms in cotton leaves after treatment with leaf extract from zimmu.     

中国大蒜(Allium sativumL.)18个品种的酯酶同工酶多态性分析

采用聚丙烯酰胺凝胶电泳(PAGE)分离了中国大蒜3个生态型（低温反应敏感型、低温反应中间型和低温反应迟钝型）中18个较典型的品种的酯酶同工酶,并用排序分析法对18个品种的亲缘关系进行了分析,将18个品种分为3个变种群: 1.“苏联”蒜变种群(var.Russia),2.吉木萨尔白皮蒜变种群(var.Jimusaer),3.中国内陆大蒜变种群(var.China)。其中中国内陆大蒜变种群又可分为5个品种群：①关中蒜品种群,②西北蒜品种群,③西南蒜品种群,④云贵蒜品种群,⑤华东蒜品种群。实验结果初步证实,大蒜生态型不能完全等同于基因型,酯酶同工酶的变化可能更能说明大蒜的亲缘进化关系。     

γ-Tubulin is associated with a cortical-microtubule-organizing zone in the developing guard cells of Allium cepa L.

A key event in the differentiation of elliptically shaped guard cells such as those in Allium is the formation of a radial array of cortical microtubules (Mts) which, by controlling the orientation of wall microfibrils, plays an important role in cell shaping. Previous experiments strongly indicated that the array is nucleated in a zone adjacent to the new ventral wall soon after cytokinesis. In order to further clarify the function of this zone, we performed dual immunolocalizations on Allium guard cells with anti--tubulin, to detect Mts, and an antibody to -tubulin, a protein known to be present at Mt-organizing centers in other species and recently identified in plants as well. -Tubulin antibody stained the cortical zone adjacent to the ventral wall, while little or no fluorescence was present elsewhere along the radial Mt array or at other sites in the cell. The antibody also stained the mitotic poles and phragmoplast in guard mother cells, as it does in other material. No staining was seen when the primary antibody was omitted. The results are consistent with nucleation of the radial array at a cortical-Mt-organizing zone next to the ventral wall, and set the stage for more in-depth studies on the spatial and temporal control of Mt formation in differentiating cells.Abbreviations CLSM confocal laser scanning microscope - FITC fluorescein isothiocyanate - Mt microtubule - MTOC microtubule-organizing center This work was supported by National Science Foundation grant DCB-9019285 to B.A.P., National Institutes of Health (NS30009) and American Cancer Society (CD6255) grants to H.C.J., and a University of Georgia Graduate School Assistantship to B.L. We thank Dr. Mark Farmer and the University of Georgia Center for Advanced Ultrastructural Research for the use of the confocal microscope.     

Cytogenetic and microtubule array effects of the zineb-containing commercial fungicide formulation Azzurro(®) on meristematic root cells of Allium cepa L

Zineb [ethylene bis(dithiocarbamate) zinc] is a widely employed foliar fungicide for agricultural and industrial applications. Allium cepa L. is a reliable model for the assessment of xenobiotic genotoxicity and cytotoxicity. We evaluated the effects of the zineb-containing commercial formulation Azzurro(?) (70% zineb) in cell cycle stages of the meristem root cells of A. cepa. The mitotic index (MI), chromosomal aberrations at anaphase/telophase (CAs), micronuclei (MN), and abnormalities in immunodetected microtubule structures, e.g., preprophasic band (PPB), mitotic spindle (MS), and phragmoplast (Phrag), were used as end-points. Azzurro(?) (1 and 10μg/ml) induced a significant increase in the frequency of CAs (P<0.05), and the higher concentration inhibited the MI (P<0.05) compared to control values. The frequency of MN did not differ from control values at any concentration. Treatment with 1μg/ml Azzurro(?) induced a significant increase in the frequency of abnormal PPB (P<0.01), MS (P<0.001), and Phrag (P<0.01) and, at 10μg/ml, enhancements in the frequencies of abnormal MS (P<0.05) and Phrag (P<0.05) were seen. A tubulin immunodetection assay showed that exposure to Azzurro(?) interferes with normal assembly of microtubule structures during mitosis.     

What makes Allium species effective against pathogenic microbes?

The antimicrobial activity of garlic (Allium sativum L.) has been known since ancient times. The first citation dates back to the Egyptian period of fifteenth century BC when garlic was reported to be used in folk medicine as a remedy for microbial infections. Scientific investigations on garlic started in 1858 with the work of Pasteur who first noted antibacterial properties of garlic extracts. From that date to the discovery of antibiotics, garlic has been used against amoebic dysentery and epidemic diseases such as typhus, cholera, diphtheria, and tuberculosis. But what makes garlic and Allium species effective against pathogenic microbes? The volatile allicin and other thiosulfinates, giving pungency to Allium plants, are well-studied antimicrobial agents. The thiosulfinates can decompose to form additional sulfur constituents, including diallyl, methyl allyl, and dipropyl mono-, di-, tri- e tetra-sulfides, and (E)- and (Z)-ajoene without losing antimicrobial activity. Besides these compounds, onion and garlic are characterized by polar compounds of steroidal and phenolic origin, often glycosilated, not pungent and more stable during cooking, showing also antimicrobial activity. Recently, there has been increasing scientific attention given to such compounds. Nitrogen organic compounds, like alkaloids and polypeptides, have also been isolated from these plants and have shown antimicrobial activity. In this paper, the literature about the major volatile and non-volatile organic compounds of garlic and other Allium plants has been reviewed. Particular attention is given to the compounds possessing antimicrobial activity and to the correlation between the observed activity and the chemical structure of the tested compounds.     

Transient expression of uidA constructs in in vitro onion ( Allium cepa L.) cultures following particle bombardment and Agrobacterium‐mediated DNA delivery

Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient -glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900–1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient -glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.Abbreviations GUS -glucuronidase - IE immature embryo - MUG methylumbelliferyl -D-glucuronide     

Cytogenetic Effects of γ-Radiation in Onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.) Seedlings

The effect of γ-radiation on the cytogenetic parameters of root meristem cells of onion seedlings was studied in laboratory experiments (Allium-test). An increase in the overall frequency of chromosomal aberrations and micronucleus frequencies in seedling cells at low γ-radiation doses (≤0.1 Gy) was detected for the first time. At a maximum absorbed dose of 13 Gy, chromosomal aberrations were detected in the majority of cells in the anaphase and telophase stages of the cell cycle, and the number of cells with multiple aberrations increased. The main contribution to the overall frequency of chromosomal aberrations, in addition to multiple aberrations, is made by the bridge-type aberrations, fragments, and lagging chromosomes. The data obtained allow using the cytogenetic indices of Allium cepa seedlings to assess the biological effects of lowdose γ-radiation.     

Die Verlagerungsfähigkeit des Zellinhaltes der Zwiebelschuppen von Allium cepa durch Zentrifugierung

Die Behandlung lebender Zellen mit der Zentrifuge veranlaßt in ihnen eine Verlagerung der toten und lebenden Bestandteile, wofern diese verschiedenes spezifisches Gewicht haben. Eine Verlagerung wird mit um so geringeren Zentrifugalkräften zu erreichen sein, je größer der Unterschied im spezifischen Gewicht benachbarter Teile ist, und je geringer diejenigen Kräfte sind, welche einer Bewegung der Teilchen entgegenwirken. Ihre Bewegung wird durch hohe Viskosität, andererseits durch Adhäsion an anderen Teilen, z. B. an der Membran, beeinflußt.Im folgenden soll von den durch Zentrifugenbehandlung erreichbaren Verlagerungen der Bestandteile lebender Zellen die Rede sein, sowie von den inneren und äußeren Faktoren, welche auf die Verlagerung Einfluß gewinnen können.Alle meine Untersuchungen wurden an den Geweben der Zwiebelschuppen (Allium cepa) ausgeführt. Ich ließ die Zentrifuge zunächst auf dünne, mit einer scharfen Rasierklinge abgeschnittene Epidermislamellen wirken und verfuhr dabei derart, daß ich die Schnitte mit einem Wattebausch in halb mit Wasser oder Lösungen gefüllten Köhren in einem Abstand von ca. 15 cm vom Zentrum in fixe Lage brachte. Weiterhin wurden aus den Zwiebelschuppen Gewebeprismen herausgeschnitten und zentrifugiert. Schließlich wurden auch ganze, intakte Zwiebeln geschleudert und die Zentrifugenwirkung an den aus ihnen angefertigten Epidermisschnitten geprüft.Neben frischen turgeszenten Epidermiszellen wurden in weiteren Versuchsserien Epidermisschnitte, die vorher mit verschiedenen Plasmolyticis behandelt worden waren, der Zentrifugenbehandlung ausgesetzt.Die Zentrifugenschnelligkeit schwankte zwischen 1200 und 3000 Umdrehungen in der Minute, entsprechend einer Fliehkraft von 375 bis 1500 g. Die Wirkungsunterschiede sind innerhalb dieser Grenzen bedeutungslos wie mehrere Versuche gezeigt haben; meistens habe ich mich mit einer Schnelligkeit von 1500 Umdrehungen begnügt.

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Seinem Leiter, Herrn Professor Dr. Küster, möchte ich hiermit meinen herzlichsten Dank für sein stetes Entgegenkommen aussprechen.     

Two different Bacillus thuringiensis toxin genes confer resistance to beet armyworm (Spodoptera exigua Hübner) in transgenic Bt-shallots (Allium cepa L.)

Agrobacterium-mediated genetic transformation was applied to produce beet armyworm (Spodoptera exigua Hübner) resistant tropical shallots (Allium cepa L. group Aggregatum). A cry1Ca or a H04 hybrid gene from Bacillus thuringiensis, driven by the chrysanthemum ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (Rubisco SSU) promoter, along with the hygromycin phosphotransferase gene (hpt) driven by the CaMV 35S promoter, was employed for genetic transformation. An average transformation frequency of 3.68% was obtained from two shallot cultivars, Tropix and Kuning. After transfer of the in vitro plants to the greenhouse 69% of the cry1Ca and 39% of the H04 transgenic shallots survived the first half year. After one year of cultivation in the greenhouse the remaining cry1Ca and H04 transgenic plants grew vigorously and had a normal bulb formation, although the cry1Ca transgenic plants (and controls) had darker green leaves compared to their H04 counterparts. Standard PCR, adaptor ligation PCR and Southern analyses confirmed the integration of T-DNA into the shallot genome. Northern blot and ELISA analyses revealed expression of the cry1Ca or H04 gene in the transgenic plants. The amount of Cry1Ca expressed in transgenic plants was higher than the expression levels of H04 (0.39 vs. 0.16% of the total soluble leaf proteins, respectively). There was a good correlation between protein expression and beet armyworm resistance. Cry1Ca or H04 gene expression of at least 0.22 or 0.08% of the total soluble protein in shallot leaves was sufficient to give a complete resistance against beet armyworm. This confirms earlier observations that the H04 toxin is more toxic to S. exigua than the Cry1Ca toxin. The results from this study suggest that the cry1Ca and H04 transgenic shallots developed could be used for introducing resistance to beet armyworm in (sub) tropical shallot.     

Increases in α-mannosidase activity in the arbuscular mycorrhizal symbiosis of Allium schoenoprasum

 Mycorrhizal and nonmycorrhizal roots of Allium schoenoprasum were tested for activities of α-mannosidase, β-glucosidase and arabinosidase. Mannosidase activity was higher by a factor of two in mycorrhizal than in nonmycorrhizal root extracts. The apparent molecular weight of the enzyme was 152 kDa and its K_M was 1.25 mM in colonized roots and 1.85 mM in uncolonized roots. α-Mannosidase activity was further characterized by an acid pH optimum and Zn²⁺ dependency. No significant differences could be found between mycorrhizal and nonmycorrhizal roots for β-glucosidase and arabinosidase activities. Accepted: 28 August 1995     

沙葱(Allium mongolicum Regel)离体培养再生可育植株

以沙葱（Allium mongolicum Regel)的叶基切段作外植体,成功地诱导出愈伤组织和再生植株。诱导愈僵组织的培养基为附加2mgL^-22,4-D和0.2mgL^-1KT的MS培养基。愈伤组织转移到附加2mgL^-16BA和0.4mgL^-1NAA的MS培养基后分化出大量的苗;分化苗在含有IBA1mgL^-1的1/2MS培养基上生根最佳。再生植株移栽成活率在95%以上。移栽到田间的植株第二年以后可正常开花结实。     

Dynamics of replication foci and nuclear matrix during S phase in <Emphasis Type="Italic">Allium cepa</Emphasis> L. cells

The sequential organisation of replication foci during S phase in onion ( Allium cepa) and their relationship to the nuclear matrix were investigated. To discern their structural features and temporal firing sequence, immunodetection of 5-bromo-2'-deoxyuridine (BrdU) was carried out after in vivo feeding in synchronised cells released from a 14-h-long hydroxyurea block. Replication foci consisted of small replication granules, called replisomes, which clustered together. Analysis of synchronous binucleate cells that maintained in their two nuclei the specular symmetry of distribution of sister chromosomes in anaphase, showed that replication starts in small replication foci at the telomeric pole (pattern I), though the telomeres themselves formed large foci that were late-replicating. The rDNA replication foci (pattern II) also become replicated in early S phase. Replication of large foci, including the heterochromatin (IV), occurred in late S phase and finished at the centromeric nuclear pole (pattern V). Labelling of proliferating cell nuclear antigen (PCNA) in nuclear matrices, prepared from S-phase nuclei after extensive DNase digestion, demonstrated that replication foci were always stably anchored to the nuclear matrix. Thus, association with the nucleoskeleton is not exclusively mediated by the replicating or nascent DNA. The overlapping of patterns I, II and III in the nuclear matrix, in contrast to the results of BrdU localisation in nuclei, suggests that PCNA becomes associated with the nuclear matrix before the replication foci are operative, and remains bound during replication.