排序方式： 共有12条查询结果，搜索用时 15 毫秒
1.
Wardatou Boukari Denis Filloux Jean Heinrich Daugrois Emmanuel Fernandez Dimitre Mollov Claudia Kaye Martha Hincapie Alexander Sanchez Jianping Wang Philippe Roumagnac Philippe Rott 《Plant pathology》2020,69(6):1060-1069
Viruses in the genus Mastrevirus (family Geminiviridae), including those infecting sugarcane, have natural geographical ranges almost exclusively restricted to Africa and the Indian Ocean islands off the African coast. Only sugarcane white streak virus (SWSV) in Barbados and sugarcane striate virus (SStrV) in Florida and Guadeloupe are known to infect a few sugarcane varieties in the Western Hemisphere. In this study, PCR assays were developed to detect these two viruses in sugarcane. Five hundred and seventy-one DNA samples from Saccharum species and interspecific hybrids from the Miami World Collection of sugarcane and related grasses were tested for the presence of SStrV and SWSV by PCR. No variety was found infected by SWSV but SStrV was detected in 19 varieties. PCR data were confirmed by sequencing amplified fragments (248 bp). These fragments shared 93%–100% nucleotide identity with SStrV sequences from the GenBank database. SStrV isolates were distributed in six phylogenetic groups, including the four strains of the virus. Most varieties infected by SStrV originated from Asia, thus confirming a previous hypothesis stating that this virus originated from this continent. Absence of SStrV in commercial sugarcane in Florida also suggested that this virus has not been spread in this location, while infected plants have been present for several decades. 相似文献
2.
The chemical reactivity of 5-(hydroxymethyl)-2-furaldehyde (HMF) with lysine, glycine, and proline was studied using isotope labeling technique. To confirm the formation of HMF adducts in glucose amino acid model systems, a useful strategy was developed in which products simultaneously possessing six glucose (HMF moiety) and any number of amino acid carbon atoms in addition to nitrogen were targeted using specifically labeled precursors such as [(15)N(α)]lysine·2HCl, [(15)N(ε)]lysine·2HCl, [U-(13)C(6)]lysine·2HCl, [(13)C(6)]lysine·2HCl, and [U-(13)C(6)]glucose in the case of lysine model system. In addition, model systems containing HMF and amino acids were also studied to confirm specific adduct formation. Complete labeling studies along with structural analysis using appropriate synthetic precursors such as HMF Schiff base adducts of piperidine and glycine have indicated that HMF generated in the glucose/amino acid model systems initially forms a Schiff base adduct that can undergo decarboxylation through an oxazolidin-5-one intermediate and form two isomeric decarboxylated Schiff bases. Unlike the Schiff bases resulting from primary amines or amino acids such as glycine or lysine, those resulting from secondary amino acids such as proline or secondary amines such as piperidine can further undergo vinylogous Amadori rearrangement, forming N-substituted 5-(aminomethyl)furan-2-carbaldehyde derivatives. 相似文献
3.
Thermal decomposition of HMF has been so far studied indirectly through carbohydrate degradation reactions assuming HMF as the main product. Such studies, however, do not necessarily generate relevant information on HMF decomposition because many other products are generated simultaneously. Direct thermal decomposition using different concentrations of HMF in silica gel was studied using pyrolysis-GC-MS. Undiluted HMF generated four peaks corresponding to 5-methylfurfural, 2,5-furandicarboxaldehdye, HMF, and a major unknown peak at retention time of 20.73 min. The diluted HMF in silica gel (15-fold) generated only the first three peaks. The generation of the unknown peak was dependent on the concentration of HMF, indicating the possibility of a dimeric structure; furthermore, when HMF was generated from [U-13C6]glucose in the reaction mixture, the highest mass in the spectrum of the unknown peak showed the incorporation of 11 carbon atoms from the glucose. Thermal decomposition studies of HMF have also indicated that in the absence of amino acids it can mainly dimerize and the initially formed dimer can degrade to generate 5-methylfurfural and 2,5-furandicarboxaldehyde. On the other hand, thermal degradation of HMF in the presence of glycine generated Schiff base adducts of HMF, 5-methylfurfural, and 2,5-furandicarboxaldehdye in addition to 2-acetyl-5-methylfuran and a newly discovered adduct, 5-[(dimethylamino)methyl]-2-furanmethanol. 相似文献
4.
Graham Bird Paul A. Brewer Mark G. Macklin Mariyana Nikolova Tsvetan Kotsev Mihail Mollov Catherine Swain 《Water, air, and soil pollution》2010,206(1-4):105-127
Metal dispersal in the Danube and Maritsa drainage basins resulting from metal mining activities in Bulgaria has been assessed through the collection of 611 samples of river water, river channel and floodplain sediment, and mine waste from over 218 sites. Concentrations of Cd, Cu, Pb, and Zn in river water were found to be highest in close proximity to locations of Cu and Pb–Zn mining regions in the Maritsa catchment. Downstream dispersal of solute metals in these catchments, and into the River Danube, was found to be limited by physical dilution and a well-buffered pH environment. Dispersal of contaminant metals in channel and floodplain sediment was found to be extensive. Contamination was particularly severe in the Rivers Timok and Iskar (Danube catchment) and the Topolnitsa, Chepelarska, and Arda Rivers (Maritsa catchment) and creates the potential of transboundary dispersal of contaminant metals. 相似文献
5.
Georgi Georgiev Zdravko Hubenov Margarita Georgieva Plamen Mirchev Maria Matova Leellen F. Solter Daniela Pilarska Plamen Pilarski 《Phytoparasitica》2013,41(2):125-131
Interactions between the gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae), pathogenic fungus Entomophaga maimaiga, and the tachinid parasitoid (Diptera: Tachinidae) complex in gypsy moth larvae were investigated in Bulgaria, where E. maimaiga was recently released as a biological control agent. Gypsy moth larvae were collected in oak stands where E. maimaiga was originally introduced (nine sites) and in sites where the pathogen has invaded by natural extension of the range (ten sites). In total, 4,375 host larvae were examined and 401 tachinid larvae emerged from parasitized hosts. Host mortality caused by tachinids varied from 0 to 48.5% among sites, with an overall average of 9.2%. Emerging adult tachinid parasitoids included 54 individuals belonging to six species: Compsilura concinnata, Exorista larvarum, Senometopia separata, Senometopia excisa, Drino incospiqua and Zenilia libatrix; the remaining parasitoids (86.5%) died in the pupal stage. E. maimaiga azygospores were observed on puparia surfaces, an indication that the gypsy moth host larvae were infected with the fungus. No azygospores were observed in parasitoid tissues. The high parasitoid mortality may be the result of the competition with E. maimaiga during development in the same host. 相似文献
6.
Shikov V Kammerer DR Mihalev K Mollov P Carle R 《Journal of agricultural and food chemistry》2008,56(18):8521-8526
Thermal degradation and color changes of purified strawberry anthocyanins in model solutions were studied upon heating at 85 degrees C by HPLC-DAD analyses and CIELCh measurements, respectively. The anthocyanin half-life values increased significantly due to the addition of rose (Rosa damascena Mill.) petal extracts enriched in natural copigments. Correspondingly, the color stability increased as the total color difference values were smaller for anthocyanins upon copigment addition, especially after extended heating. Furthermore, the stabilizing effect of rose petal polyphenols was compared with that of well-known copigments such as isolated kaempferol, quercetin, and sinapic acid. The purified rose petal extract was found to be a most effective anthocyanin-stabilizing agent at a molar pigment/copigment ratio of 1:2. The results obtained demonstrate that the addition of rose petal polyphenols slows the thermal degradation of strawberry anthocyanins, thus resulting in improved color retention without affecting the gustatory quality of the product. 相似文献
7.
8.
Evidence of potato virus Y asymptomatic clones in diploid and tetraploid potato-breeding populations
Potato virus Y (PVY) is a potyvirus affecting potato productivity by reducing yield and quality. To reduce the amount of PVY in potato production systems, state seed certification agencies have established threshold criteria, which simultaneously increase quality. Research has documented several commercial cultivars lacking symptom expression of PVY despite infection. The presence of PVY asymptomatic clones in production and breeding populations is particularly important because it may provide an inoculum source in breeders’ seed and this reduces the efficiency of selection. The objectives of this research were to determine to what extent PVY asymptomatic clones are present in potato-breeding populations, and if PVY expression is influenced by the environment. After exposure to PVY, genotypes from different 2x and 4x populations were evaluated for the presence of PVY both visually and by ELISA assay. PVY asymptomatic genotypes were identified in both 2x and 4x populations. Chi square indicated dependency between PVY symptom expression and (1) ploidy, (2) genetically distinct 4x germplasm enhancement populations, and (3) expression in a north temperatevs. tropical environment using 4x progeny from five half-sib families. Dependency was not found between two 4x genetically related sub-populations and PVY asymptomatic expression. Analysis of variance (ANOVA) indicated that clones within family, families, location, and the interaction of location by clone were significant sources of variation for PVY symptom expression, ELISA, and visual evaluation. PVY asymptomatic clones were present in both 2x and 4x populations with higher frequencies in a north temperate compared to a tropical environment, suggesting that PVY symptom expression may be influenced by the environment. 相似文献
9.
10.