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At least 127 records · Page 7Linked to original sources
PubMed1993

Nuclear Ribosomal DNA as a Probe for Genetic Variability in the Japanese Pear Pathotype of Alternaria alternata.

A restriction fragment length polymorphism analysis of nuclear ribosomal RNA genes (rDNA) was used to measure the amount and distribution of genetic variability in populations of the Japanese pear pathotype of Alternaria alternata on both micro- and macrogeographical scales. A total of 322 isolates were obtained from 13 areas in Aichi, Gifu, and Tottori Prefectures in central and western Japan. The restriction fragment length polymorphism analysis revealed that the pathogen populations contained at least eight rDNA variants. The eight variant types differed in the lengths and in the presence of the restriction sites in spacer DNA outside the coding regions for rRNAs. A total of 271 isolates were classified into the eight types. The remaining 51 isolates were determined to have mixed rDNA types. Single pear fields typically contained two to five types of rDNA variants. The frequencies of rDNA variants in 11 populations in Tottori Prefecture were compared; in this prefecture orchards containing the susceptible pear are common. Except for one collection site, there were no significant differences in the composition of the rDNA variants among the populations. This suggests that dispersal of inocula has occurred frequently in Tottori Prefecture. In contrast, significantly different distributions were observed in the three prefectures, indicating that gene flow between prefectures might be limited by geographical isolation. DNA fingerprints resulting from hybridization with a moderately repetitive DNA sequence of the fungus revealed greater genetic variability and geographical differences in genetic population structure even within the same rDNA type.

Journal Article↗
PubMed1994

Enhancement of Biocontrol of Blue Mold with the Nutrient Analog 2-Deoxy-d-Glucose on Apples and Pears.

The glucose analog, 2-deoxy-d-glucose (2-DOG) enhanced biocontrol of blue mold (caused by Penicillium expansum), the most important postharvest disease of apples and pears. 2-DOG strongly inhibited P. expansum, and of the two antagonists investigated, Pseudomonas syringae was resistant to 2-DOG at 10 mg/ml whereas Sporobolomyces roseus was susceptible. A mutant of S. roseus resistant to 2-DOG was developed. Addition of 2-DOG at 4 mg/ml allowed more than a 10-fold reduction in the concentration of the antagonists applied to fruits without diminishing control. This effect was still apparent at an inoculum of 5 x 10 conidia of P. expansum per ml, which greatly exceeds concentrations found under normal commercial conditions. The effect of 2-DOG on biocontrol was stronger on apples than on pears. 2-DOG had no effect on populations of the antagonists, which increased greatly in wounds on apples and pears. The reduction in the concentration of the antagonists needed for control may improve the reliability and economy of the biocontrol system and may have a significant impact on commercialization of this new technology.

Journal Article↗
PubMed1998

Nucleotide sequence of seed- and pollen-transmitted double-stranded RNA, which encodes a putative RNA-dependent RNA polymerase, detected from Japanese pear.

The nucleotide sequence of the largest double-stranded (ds) RNA (named dsRNA1) of three species of seed- and pollen-transmitted dsRNA species detected from Japanese pear was analyzed, and one strand was found to contain a single long open reading frame (ORF) of 1434 nucleotides that encoded a putative polypeptide containing 477 amino acid residues with a molecular mass of 54.9 kDa. This polypeptide contained amino acid sequence motifs conserved in putative RNA-dependent RNA polymerases of RNA viruses. Attempts to visually identify or purify virus-like particles associated with the dsRNAs were unsuccessful. Slow sedimentation of the dsRNA fraction suggests that the dsRNAs may be unencapsidated. The concentration of dsRNAs in the host, Japanese pear, was about 16 times higher than that from a cryptic virus, radish yellow edge virus (RYEV). These results suggest that the dsRNAs were not from cryptic viruses. Partial nucleotide sequences of the two smaller dsRNAs (named dsRNAs 2 and 3) and two other dsRNAs (named dsRNAs 4 and 5) detected from only the Japanese pear cultivar (cv.) Akita Tazawa 3 Gou were analyzed, and encoded nearly the same amino acid sequence encoded by dsRNA1.

Amino Acid Sequence↗
PubMed2005

Action of particle films on the biology and behavior of pear psylla (Homoptera: Psyllidae).

Particle films with different properties have been developed for arthropod pest control. Two basic film types are hydrophobic and hydrophilic films. The hydrophilic film formulations differ in the amount and kind of spreader-sticker that is incorporated into the kaolin particles. The effects of particle film type (hydrophobic versus hydrophilic) and formulation (Surround versus Surround WP) on the biology and behavior of pear psylla, Cacopsylla pyricola (Foerster), were investigated on pear in a series of laboratory studies. Scanning electron microscopy determined that the number of particles that attached to the front tibia of adult psylla differed by particle formulation but the particle sizes were fairly uniform and ranged from 3.6 to 4.5 microm in diameter. Adults had difficulty grasping particle film-treated leaves, and this effect was influenced by film type and leaf surface. Choice and no-choice tests indicated that adult settling and oviposition were very low, regardless of film type or formulation. Under no-choice conditions, adult mortality was low, in part, because the adults were able to feed through all 3% particle films, but at reduced rates. However, the mortality of adults sprayed with 3% particle film solutions ranged from 22.2 to 62.5% within 72 h after treatment, and mortalities differed most between the hydrophilic formulations. Nymphs born on particle film-treated foliage incurred high mortalities ranging from 58.9 to 82.0% by the time they reached the fifth instar and were affected most by particle film type. Nymphal development was not affected by particle film type or formulation. Egg fertility and nymphal hatch also were unaffected by particle films. These studies determined that there are a number of biological effects particle films have on pear psylla beyond the deterrence of adult settling and oviposition.

Animals↗
PubMed2006

Nutritional and medicinal use of Cactus pear (Opuntia spp.) cladodes and fruits.

Natural products and health foods have recently received a lot of attention both by health professionals and the common population for improving overall well-being, as well as in the prevention of diseases including cancer. In this line, all types of fruits and vegetables have been re-evaluated and recognized as valuable sources of nutraceuticals. The great number of potentially active nutrients and their multifunctional properties make cactus pear (Opuntia spp.) fruits and cladodes perfect candidates for the production of health-promoting food and food supplements. Although traditionally appreciated for its pharmacological properties by the Native Americans, cactus pear is still hardly recognized because of insufficient scientific information. However, recent studies on Opuntia spp. have demonstrated cactus pear fruit and vegetative cladodes to be excellent candidates for the development of healthy food. Therefore, this review summarizes current knowledge on the chemical composition of Opuntia cacti with particular emphasis in its use as food and medicine.

Fruit↗
PubMed2000

[Effect of a selective agent and a plant intron on the effectiveness of transformation and expression of heterologous genes in the pear (Pyrus communis L.)].

The effect of selective agents on the efficiency of Agrobacterium-mediated transformation of pear was shown. The transformation frequency of the pear stock PS no. 217 by a binary vector carrying the nptII gene conferring kanamycin resistance was 0.4 or 3.1%, while the hpt gene for hygromycin resistance used as a selective marker increased transformation frequency to 6.2 (11.5%). In addition, upon selection on hygromycin B, the proportion of pseudotransgenic regenerants considerably decreased. In four transformation experiments, twenty independent clones were recovered, and their transgenic nature was confirmed by PCR, histochemical, and fluorometric analyses of GUS activity. The presence of introns in the coding region of a heterologous gene was shown to influence the efficiency and stability of transgene expression in plant tissues. Fluorometric determination of GUS activity conducted for a period of two years demonstrated a threefold increase in transgene expression in the case that an intron-containing construct was used for transformation. The expression level was rather stable across several years. The transformation procedure developed may be used for successful expression of heterologous genes controlling agronomic characters in pear plants.

Base Sequence↗
PubMedDate not supplied

Simultaneous determination of six triazolic pesticide residues in apple and pear pulps by liquid chromatography with ultraviolet diode array detection.

A method is described for the simultaneous determination of diclobutrazol, flusilazole, flutriafol, hexaconazole, paclobutrazol, and tetraconazole in apple and pear pulps used in baby food at a limit of 0.01 mg/kg. Apple and pear pulp samples are subjected to selective solid-phase microdispersion (SPMD) with SPE-ED Matrix-38 and acetone-cyclohexane, and the extracts are cleaned up on a Florisil cartridge with hexane-cyclohexane-acetone. The extracts are then analyzed by liquid chromatography with ultraviolet detection, using an octadecylsilane column with a gradient-programmed acetonitrile-water mobile phase. Recoveries were determined by spiking apple and pear pulps with the 6 pesticides under investigation at 0.1, 0.05, 0.03, and 0.01 mg/kg. Six determinations were performed at each level for each pesticide. Recoveries were > or = 70% at the 0.01 mg/kg level.

Calibration↗
PubMed2004

Dead flower buds of pear: effect of tree growth control, and Alternaria alternata as causal agent.

Dead (dormant) flower buds of pear is an important phenomenon in pear production in the Netherlands. Vigourous or unbalanced tree growth and Pseudomonas syringae pv. syringae are mentioned as likely causes of dead flower buds. Several tree growth control treatments including ethephon. Regalis (Prohexadione-Ca) and root pruning were evaluated. Regalis increased disease incidence. The plant stimulant (foliar fertilizer) Resistim (potassium phosphonate) reduced disease incidence. Pseudomonas syringae pv. syringae was occasionally isolated from diseased flower buds. However, Alternaria alternata was nearly always isolated from diseased buds. Indicating a strong relation between this fungus and dead flower buds of pear.

Alternaria↗
PubMed2004

Species composition of leaf beetle assemblages in the canopies of apple and pear orchards in Hungary and Great Britain (Coleoptera: Chrysomelidae).

The species richness and species composition of Coleoptera assemblages were investigated in the canopies of apple and pear orchards in Hungary and in the apple orchards in Great Britain. The investigations were carried out in Hungary (Nagykovácsi: 3 plots, Kecskemét: 5 plots, Sárospatak: 4 plots) between 1990-94, and in Great Britain in Kent (East Malling, Marden and Robertsbridge) in 2001 and 2002. Former investigations in Hungary revealed that the diversity of Coleoptera assemblages in the canopy of apple and pear orchard were surprisingly high. As a result of our investigations it was found that altogether 324 species, almost 3% of the Hungarian beetle fauna were represented: 253 species in apple orchards and 188 species in pear orchards. Similar results were obtained in the investigations carried out in Great Britain between 2001-2002. In Hungary, the majority of the species belonged to the families Curculionidae, Chrysomelidae and Coccinelidae. The proportion of leaf beetles varied between 15 and 20%. The most common leaf beetle species in the canopy of the commercial orchards were Phyllotreta vittula, Phyllotreta atra, Phyllotreta nigripes, Oulemta melanopus, and Aphthona euphorbiae. In the abandoned orchards the most common species were Luperus xanthopoda, Smaragdina salicina and Orsodacne liieola. In Great Britain 44 leaf beetle species were found in the canopies of the investigated orchards. The species with higher abundance were Aphthona euphorbiae. Chaetocnema concinna and Longitarsus parvulus. We concluded, that leaf beetles give high part of the orchard canopy biodiversity and sometimes occur with high species richness and abundance. However, the reasons of their occurrence and their potential role are poorly known.

Animals↗
PubMed1992

[Inhibitory effects of balsam pear on the mutagenic activity of cyclophosphamide in vivo].

Inhibitory effects of balsam pear on the mutagenic activity of cyclophosphamide were studied in the cells of bone marrow of mouse in vivo. It was found that balsam pear juice itself showed no effect on the incidence of sister chromatid exchanges (SCE) and of micronuclei (MN) on the cells of bone marrow. But balsam pear juice reduced the incidence of SCE (from 29.1 times/cell to 13.27-28.38 times/cell) and MN (from 60.0% to 27.0%-50.0%) induced by cyclophosphamide respectively. The inhibitory effects showed a dose-dependent relation, which was statistically significant.

Animals↗
PubMed2006

[Detection of pear firmness using near infrared diffuse reflectance spectroscopy].

The objective of the present research was to study the potential of NIR diffuse reflectance spectroscopy as a way for nondestructive measurement of the firmness of "Xueqing" pear. NIR spectral data were collected in the spectral region between 800 nm and 2,630 nm, but only the data between 800 nm and 2,500 nm were used for the analysis. Spectral data smoothing of different gaps using Savitsky-Goaly method was discussed both qualitatively and quantitatively. The results showed that the smoothing of NIR original spectra had little influence on spectral data analysis. Statistical models were developed using partial least square method. Models for three kinds of mathematical treatments of spectra (original, first derivative and second derivative) were established in three spectral regions: 800-2,500 nm, 800-1,890 nm and 832-872 nm. The original spectra showed better results than the first derivative spectra and second derivative in all the three spectral regions. And for the three spectral regions, the full wavelength range of 800-2,500 nm offered the best result. The PLS model of original spectra in the range of 800-2,500 nm gave best predictions of pear firmness, with correlation coefficient (r) of 0.869 and root mean square errors of calibration (RMSEC) of 3.88 N for the calibration sample set and with correlation coefficient (r) of 0.840 and root mean square error of prediction (RMSEP) of 4.26 N for the validation sample set. The results of the study show that NIR diffuse reflectance specroscopy can be used to predict the firmness of "Xueqing" pear.

Fruit↗
PubMed1977

Pearly penile papules: incidence.

Eight hundred forty consecutive male patients were examined for the presence of pearly penile papules. The age, race and presence or absence of circumcision were recorded. Two hundred fifty-three (30.1%) of patients had lesions, and there was a significantly increased incidence of pearly penile papules in Negroes and uncircumcised men. A significantly greater proportion of Negroes were uncircumcised, possibly explaining the racial difference. The incidence of papules was greatest in young adults and tended to decrease with increasing age. A higher percentage of men over 40 had pearly penile papules than previously reported.

Adolescent↗
PubMed2000

Optimisation of ion trap parameters for the quantification of chlormequat by liquid chromatography/mass spectrometry and the application in the analysis of pear extracts.

Optimisation of the activation parameters for ion trap mass spectrometric analysis of the chlormequat cation using simplex optimisation enabled the product ion (m/z 58) response to be improved 1000-fold. A comparison of the sensitivity of the optimised ion trap mass spectrometer with that of a triple quadrupole mass spectrometer for liquid chromatography/tandem mass spectrometry (LC/MS/MS) showed that similar limits of detection (LODs) could be achieved. For the MS/MS transition of the (35)Cl precursor to the most abundant product, LODs were 0.8 ng cation mL(-1) (0.004 mg cation kg(-1) pear equivalent) and 1.0 ng cation mL(-1) (0.005 mg cation kg(-1) pear equivalent) on the triple quadrupole and ion trap instrument, respectively.

Chlormequat↗
PubMed2000

Extended alternating-temperature cold acclimation and culture duration improve pear shoot cryopreservation.

Meristems of many pear genotypes can be successfully cryopreserved following 1 week of cold acclimation, but an equal number do not survive the process or have very little regrowth. This study compared commonly used cold acclimation protocols to determine whether the cold acclimation technique used affected the cold hardiness of shoots or the regrowth of cryopreserved meristems. In vitro-grown pear (Pyrus L.) shoots were cold acclimated for up to 16 weeks, then either the shoot tips were tested for cold hardiness or the meristems were cryopreserved by controlled freezing. Cold acclimation consisted of alternating temperatures (22 degrees C with light/-1 degrees C darkness with various photo- and thermoperiods) or a constant temperature (4 degrees C with an 8-h photoperiod or darkness). Compared with nonacclimated controls, both alternating- and constant-temperature acclimation significantly improved postcryopreservation regrowth of P. cordata Desv. and P. pashia Buch. -Ham. ex D. Don meristems. Alternating-temperature acclimation combined with either an 8-h photoperiod or darkness was significantly better than constant-temperature acclimation. Alternating-temperature shoot acclimation for 2 to 5 weeks significantly increased postcryopreservation meristem regrowth, and recovery remained high for up to 15 weeks acclimation. Postcryopreservation meristem regrowth increased with 1 to 5 weeks of constant-temperature acclimation and then declined with longer acclimation. Shoot cold hardiness varied with the acclimation procedure. The LT(50) of shoots acclimated for 10 weeks with alternating temperatures was -25 degrees C; that with constant temperature was -14.7 degrees C; and that of the nonacclimated control was -10 degrees C. Less frequent transfer of cultures also improved acclimation of shoots. Shoots grown without transfer to fresh medium for 6-12 weeks had higher postcryopreservation recovery with shorter periods of acclimation than shoots with a 3-week transfer cycle.

Acclimatization↗
PubMed2005

Development of an Agrobacterium-mediated transformation method for pear (Pyrus communis L.) with leaf-section and axillary shoot-meristem explants.

We have developed a new Agrobacterium-mediated transformation method for the low-frequency-regenerating pear (Pyrus communis L.) cvs. Silver bell and La France. Leaf sections derived from in vitro shoots were initially used for the transformation procedure. Under optimum transformation conditions, which included culture and selection on 30 mg/l kanamycin (Km) combined with 500 mg/l sulbenicillin, a 3.2% transformation efficiency was obtained for cv. Silver bell, but no transformants of La France were obtained because of the very low regeneration frequency. Axillary shoot meristems were then examined as potential explants for La France. Selection in 5 mg/l Km and 375 mg/l carbenicillin resulted in transformed shoots being produced at an efficiency of 4.8%, and the apparent white Km-sensitive shoots were not formed during a 2-year subculture on micropropagation medium containing 50 mg/l Km. Therefore, transformations using axillary shoot meristems may be an alternative method for pear cultivars recalcitrant to regeneration from leaf sections.

Agrobacterium tumefaciens↗
PubMed2006

Overwintering phenology of a predacious mite, Typhlodromus vulgaris (Acari: Phytoseiidae), on Japanese pear trees, observed with Phyto traps.

Phyto traps were attached to twigs, main branches and trunks of Japanese pear trees in central Japan in autumn of 2004, to evaluate the effectiveness of the trap as a tool to study overwintering phenology of arboreal phytoseiid mites. A subset of the traps was inspected and replaced at two-weeks intervals ("short-term Phyto trap"), in order to evaluate movement of phytoseiid mites on the trees in a short-term. The remaining traps were left undisturbed and collected monthly from January to May 2005 ("long-term Phyto trap"), to know what species overwinter in the traps and when they leave them. Most phytoseiid mites were collected in the traps on twigs. The most abundant phytoseiid species was Typhlodromus vulgaris Ehara. In the short-term traps on twigs, adult females and males of T. vulgaris were collected until mid-November 2004, when the pear trees became completely defoliated, but few mites were collected from December to April. On the other hand, adult females of T. vulgaris were abundant in the long-term traps on twigs sampled from January to April, but other stages of mites were never collected. These results indicate that T. vulgaris had moved to the long-term traps by late November, and that only adult females had overwintered in the traps. These females began to move and reproduce in early May. By that time immature developmental stages of T. vulgaris were also recorded in the short- and long-term Phyto traps. Our results confirmed that the Phyto trap was a useful tool for estimating overwintering phenology of phytoseiid mites on trees.

Animals↗
PubMed1984

N-demethylation of p-chloro-N-methylaniline catalyzed by subcellular fractions from the avocado pear (Persea americana).

Subcellular fractions from the avocado pear ( Persea americana) catalyzed formation of p-chloroaniline from p-chloro-N-methylaniline. Fractions prepared by centrifugation of avocado homogenates at 20, 000g for 20 min formed p-chloroaniline (2900 +/- 500 pmol min-1 mg protein-1) with an NADPH-generating system. p-Chloroaniline formation required reduced pyridine nucleotide (NADPH was 6-7 times more effective than NADH) and O2. N-Demethylation was inhibited by CO (55% inhibition at CO:O2 = 1) and was not inhibited by CN. Cytochrome P-450 was detected in the 20, 000g pellet at levels of 300-380 pmol/mg protein. This particulate preparation was also active in catalyzing the NADPH-dependent epoxidation of the chlorinated cyclodiene aldrin. Improvements to a colorimetric procedure for measuring p-chloroaniline increased the sensitivity of the procedure fourfold, and allowed use of samples containing high amounts of lipid. Avocado pear is suitable tissue for further studies on the oxidation of foreign compounds by higher plants.

Aniline Compounds↗
PubMed2004

Sodium bicarbonate enhances biocontrol efficacy of yeasts on fungal spoilage of pears.

The addition of 2% (w/v) sodium bicarbonate (SBC) in the suspensions of antagonistic yeast Cryptococcus laurentii or Trichosporon pullulans significantly limited spore germination and germ tube elongation of Penicillium expansum and Alternaria alternata in potato dextrose broth (PDB) medium. Biocontrol activity of C. laurentii or T. pullulans against postharvest decay caused by P. expansum and A. alternata in pear fruits was significantly increased when C. laurentii or T. pullulans combined with SBC. Combining C. laurentii or T. pullulans with SBC provided a more effective control on P. expansum and A. alternata than applying the antagonistic yeast or SBC alone. Effects of C. laurentii with and without SBC on controlling P. expansum and A. alternata were better than those of T. pullulans. C. laurentii in combination with SBC showed the best control of disease caused by A. alternata in pear fruits.

Alternaria↗