bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Fungicide Seed Treatments on Stand Establishment, Seedling Disease, and Yield of Soybean in North Dakota
Authors: Bradley C. A.
Published: December 2007

Seedling diseases of soybean (Glycine max) can be common under cool and moist soil conditions and may be caused by a complex of pathogens in North Dakota. Managing these diseases can be difficult due to wide host ranges of the pathogens and lack of resistant cultivars. Field trials were conducted to evaluate the effects of three different fungicide seed treatments and an untreated control on soybean at six locations in 2003 and eight locations in 2004 in North Dakota, for a total of 14 environments. The fungicides evaluated were fludioxonil + mefenoxam (Warden RTA), azoxystrobin + metalaxyl (SoyGard), and Bacillus pumilus GB34 (Yield Shield). Significant (P ≤ 0.05) environment–seed treatment interactions were observed, indicating that environment played a role in when benefits from seed treatments were observed. At least one of the fungicide seed treatments provided significant protection against plant stand and yield losses compared with the untreated control in 4 of the 12 environments where plant stand was measured and 4 of the 14 environments where yield was measured. Root lesions were reduced significantly by at least one of the fungicide seed treatments compared with the untreated control in 5 of the 11 environments where root lesions were evaluated. Yield and economic benefits with fungicide seed treatments were observed more often in environments that had low soil temperatures at planting (<15°C) and moist soil conditions. Based on this research, fungicide seed treatments may be a viable option for soybean growers in North Dakota when planting into cool and moist soil conditions.
Effect of Foliar Trimming and Fungicides on Apothecial Number of Sclerotinia sclerotiorum, Leaf Blight Severity, Yield, and Canopy Microclimate in Carrot
Authors: McDonald Mary Ruth , Kooi Kevin D. Vander , Westerveld Sean M.
Published: December 2007

Foliar trimming of the carrot canopy has potential for reducing the severity of Sclerotinia (Sclerotinia sclerotiorum) rot of carrot (Daucus carota subsp. sativus). The effect of trimming the carrot foliage once or twice, with and without fungicide application, was examined on carrot plants grown on organic soil for 3 years at the University of Guelph–Muck Crops Research Station in Ontario, Canada. The number of S. sclerotiorum apothecia, carrot leaf blight (CLB; Alternaria dauci and Cercospora carotae) severity, canopy microclimate, and total and marketable yield were assessed. The number of apothecia of S. sclerotiorum and relative humidity in the canopy were reduced by trimming done at either the first observation of apothecia or at 100 days after seeding (DAS). In both cases, the effects of trimming on canopy microclimate lasted between 2 and 4 weeks. Trimming the canopy twice during the season did not reduce the number of apothecia compared with trimming the canopy once at 100 DAS. Foliar trimming had little effect on CLB severity. This was attributed mainly to the lower requirement of the CLB pathogens for prolonged periods of high relative humidity and leaf wetness compared with S. sclerotiorum. Foliar trimming did not improve the efficacy of fungicide applications for CLB control. Trimming the canopy once or twice had no effect on total or marketable yield. Thus, trimming has potential to improve the management of Sclerotinia rot of carrot, and trimming both at first observation of apothecia and at 100 DAS could reduce apothecia production and relative humidity within the canopy.
Quantification of Phytophthora capsici Oospores in Soil by Sieving-Centrifugation and Real-Time Polymerase Chain Reaction
Authors: Pavón C. F. , Babadoost M. , Lambert K. N.
Published: December 2007

A procedure was developed to quantify Phytophthora capsici oospores in soil by combining a sieving-centrifugation method and a real-time quantitative polymerase chain reaction (QPCR) assay. Five soil samples representing three different soil textures were infested with oospores of P. capsici to produce 101, 102, 103, 104, or 105 spores per 10 g of air-dried soil. Each 10-g sample of infested soil was suspended in 400 ml of water and then passed through 106-, 63-, and 38-μm metal sieves. The filtrate was then passed through a 20-μm mesh filter. Materials caught on the filter were washed with water into two 50-ml centrifuge tubes and spun for 4 min (900 × g). The pellet was suspended in 30 ml of 1.6 M sucrose solution and centrifuged for 45 s (190 × g). The supernatant was passed through the 20-μm mesh filter. The sucrose extraction process of oospores was repeated five times to maximize oospore extraction. Materials caught on the 20-μm mesh filter were washed with water into a 50-ml tube and spun for 4 min (900 × g). The pellet was suspended in 1 ml of water, and the number of oospores was determined with a haemocytometer. The relationship between number of oospores recovered from the soil and number of oospores incorporated into the soil was Ŷ = –0.95 + 1.31X – 0.03X2 (R2 = 0.98), in which Ŷ = log10 of number of oospores recovered from the soil and X = log10 of number of oospores incorporated into the soil. The oospores were germinated after treatment with 0.1% KMnO4 solution for 10 min to induce germination. On the basis of the detection of ribosomal DNA, a QPCR method for P. capsici oospores was developed. PCR inhibitors were eliminated by extracting oospores from the soil by sieving-centrifugation. DNA was extracted and quantified from P. capsici oospores with suspensions of 101, 101.5, 102, 102.5, 103, 103.5, 104, 104.5, and 105 oospores per ml of water. The relationship between the DNA quantities and number of P. capsici oospores was Ŷ = –3.57 – 0.54X + 0.30X2 (R2 = 0.93), in which Ŷ = log10 (nanogram of P. capsici DNA) and X = log10 (number of oospores). The relationship between the quantity of DNA of P. capsici oospores recovered from the soil and the number of oospores incorporated into the soil was determined by Ŷ = –3.53 – 0.73X + 0.32X2 (R2 = 0.955, P < 0.05), in which Ŷ = log10 (DNA quantity of P. capsici oospores recovered from the soil) and X = log10 (number of P. capsici oospores incorporated into the soil). Utilizing the sieving-centrifugation and QPCR methods, oospores of P. capsici were quantified in soil samples collected from commercial fields.
Spatial Heterogeneity of Leaf Wetness Duration in Apple Trees and Its Influence on Performance of a Warning System for Sooty Blotch and Flyspeck
Authors: Batzer J. C. , Gleason M. L. , Taylor S. E. , Koehler K. J. , Monteiro J. E. B. A.
Published: December 2007

To determine the effect of sensor placement on the performance of a disease-warning system for sooty blotch and flyspeck (SBFS), we measured leaf wetness duration (LWD) at 12 canopy positions in apple trees, then simulated operation of the disease-warning system using LWD measurements from different parts of the canopy. LWD sensors were placed in four trees within one Iowa orchard during two growing seasons, and in one tree in each of four orchards during a single growing season. The LWD measurements revealed substantial heterogeneity among sensor locations. In all data sets, the upper, eastern portion of the canopy had the longest mean daily LWD, and was the first site to form dew and the last to dry. The lower, western portion of the canopy averaged about 3 h less LWD per day than the top of the canopy, and was the last zone where dew formed and the first to dry off. On about 25% of nights when dew occurred in the top of the canopy, no dew formed in the lower, western canopy. Intracanopy variability of LWD was more pronounced when dew was the sole source of wetness than on days when rainfall occurred. Daily LWD in the upper, eastern portion of the canopy was slightly less than reference measurements made at a 0.7-m height over turfgrass located near the orchard. When LWD measurements from several canopy positions were input to the SBFS warning system, timing of occurrence of a fungicide-spray threshold varied by as much as 30 days among canopy positions. Under Iowa conditions, placement of an LWD sensor at an unobstructed site over turfgrass was a fairly accurate surrogate for the wettest part of the canopy. Therefore, such an extra-canopy LWD sensor might be substituted for a within-canopy sensor to enhance operational reliability of the SBFS warning system.
Nigrospora sphaerica Causing Leaf Spot and Twig and Shoot Blight on Blueberry: A New Host of the Pathogen
Authors: Wright E. R. , Folgado M. , Rivera M. C. , Crelier A. , Vasquez P. , Lopez S. E.
Published: December 2007

Blueberries (Vaccinium corymbosum) have recently become an important alternative crop in different ecological regions of Argentina. In surveys, a new disease characterized by leaf spots and twig and shoot blight has been observed on plants cultivated in Arrecifes, Mercedes, and San Pedro (provinces of Buenos Aires) and Concordia (province of Entre Ríos) since July 2004. Spots initially appear brown, circular, 1 to 2 mm in diameter, and irregularly distributed on the leaves and they eventually coalesce. Fruiting twig and shoot blight developed from the tips toward the base. Affected plants of cvs. O'Neal and Reveille were distributed randomly in the field and with a low incidence (average of 2%). The objective of this work was to identify the causal agent of this disease. Symptomatic plant material was surface disinfested with 0.2% NaOCl for 1 min and 70% ethanol for 1 min, washed once with sterile distilled water, blotted dry with paper towels, and plated on potato dextrose agar. Colonies were initially white, becoming light to dark gray with the onset of sporulation with black, sphaerical to subsphaerical conidia that measured 14 to 19 × 12 to 16 μm. These characteristics agree with published descriptions of Nigrospora sphaerica (Sacc.) Mason (1,4). To evaluate pathogenicity, all leaves, petioles, and stems of seven healthy potted plants of cv. O'Neal were punctured with flamed needles and sprayed with a suspension of 1 × 108 spores of the fungus per milliliter of sterile distilled water. Another seven nonwounded plants were sprayed with the spore suspension. Seven plants similarly injured and seven nonwounded plants were sprayed with sterile distilled water and served as controls. Each plant was covered with a water-sprayed polyethylene bag and maintained in a controlled environment chamber at 20°C with a 12-h photoperiod. The bags were removed after 3 days. All wounded inoculated plants began to show disease symptoms similar to those observed in the field 20 days after inoculation. Controls and nonwounded inoculated plants remained symptomless. The pathogen was reisolated from diseased tissues fulfilling Koch's postulates. N. sphaerica is a well-known saprophyte on many plant species but has been mentioned as pathogen on many hosts (2,3). To our knowledge, this is the first reference of N. sphaerica as a wound pathogen of blueberry. In the field, the fungus would have gained access to the plant through wounds caused by insects or frost after a long-term wetness duration.

References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN, 1989. (3) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA. 2007. (4) E. W. Mason. Trans. Brit. Mycol. Soc. 12:152, 1927.
Occurrence of Sclerotinia Stem Rot on Canola Caused by Sclerotinia minor in Argentina
Authors: Gaetán S. A. , Madia M.
Published: December 2007

Canola (Brassica napus) is a minor rotation crop grown since the 1990s in Buenos Aires Province, Argentina because of its potential as a source of biodiesel. During the spring of 2006, typical signs and symptoms of Sclerotinia stem rot were observed on canola plants (cv. Master) in one production field at 9 de Julio locality in Buenos Airs Province. Affected plants were distributed in patches throughout the rows at flowering and podfilling stages resulting in approximately 7 to 11% plant loss. Initial symptoms consisted of yellowing of mature leaves, decaying, and necrosis of lower stems. Ultimately, crowns and lower stems rotted, stems bleached, pods remained unfilled, and entire plants collapsed. White mycelium and numerous small sclerotia appeared on crown tissues. Samples of 20 infected plants were randomly collected in one production field, and 5- to 10-mm pieces of symptomatic tissues were cultured on potato dextrose agar (PDA) for 7 to 8 days after disinfestation with 2% sodium hypochlorite. Four colonies isolated from symptomatic tissues were identified as Sclerotinia minor Jagger (3) on the basis of white, fluffy mycelium containing black, irregularly shaped sclerotia (≤2 mm in diameter) abundantly scattered over the cultured surface. Crown inoculations were performed for two isolates by placing a plug taken from an actively growing culture of S. minor into wounds made on 6-week-old canola plants (cvs. Eclipse, Master, and Mistral). Control plants received plugs of sterile PDA. Inoculated and control plants were enclosed in plastic bags for 72 h. Symptoms similar to those in the affected fields were evident within 2 weeks of postinoculation on inoculated plants, whereas control plants remained healthy. The pathogen was successfully recovered from infected tissues fulfilling Koch's postulates. The experiment was repeated with similar results. Sclerotinia stem rot caused by S. sclerotiorum (Lib.) de Bary was previously reported on canola in Argentina in 2005 (2), and S. minor is a pathogen of B. napus in the United States (1). To our knowledge, this is the first report of Sclerotinia stem rot of canola incited by S. minor in Argentina.

References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) S. Gaetán and M. Madia. Plant Dis. 89:530, 2005. (3) C. L. Patterson and R. Grogan. Plant Dis. 72:1046, 1988.
First Report of Colletotrichum dracaenophilum on Dracaena sanderiana in Bulgaria
Authors: Bobev S. G. , Castlebury L. A. , Rossman A. Y.
Published: December 2007

In the winter of 2007, severe damage was observed on numerous indoor potted plants of Dracaena sanderiana hort. Sander ex Mast. (“lucky bamboo”) in Plovdiv, Bulgaria, which were imported from a country of unknown origin. These plants were already in the retail distribution stream. Initially, the internodes of infected stems appeared pale green with yellowish lesions. An upward spreading necrosis led to a weakness of the stems with wilt and death of the plants occurring within 2 weeks. Eventually, entire stems were covered with numerous, black, globose-to-ellipsoid acervuli with sparse, black setae. The fungus was aseptically isolated from stem lesions on potato dextrose agar (PDA) on which it produced fast-growing, pale pink colonies. On the plant and in culture, the conidia were hyaline, broadly clavate to cylindrical, occasionally slightly curved, and measured 20 to 34 × 6.7 to 10.0 μm (average 28 × 8.5 μm). On the basis of the symptoms on the plant and morphological, cultural, and molecular characteristics, the fungus was identified as Colletotrichum dracaenophilum D.F. Farr & M.E. Palm (1). Pathogenicity of the fungus was confirmed by artificial inoculation of healthy plants of D. sanderiana (three replicates). Stems were inoculated by inserting small mycelial plugs from 7-day-old PDA cultures into wounds that were subsequently covered with Parafilm strips. After 2 weeks, pale green lesions started developing on all inoculated plants and the fungus was successfully reisolated. No symptoms were found around the pure agar control wounds. The specimen from Bulgaria was deposited in the U.S. National Fungus Collections (BPI 877337) with the derived culture deposited as CBS 121453. In addition, the internal transcribed spacer region of the nrDNA of this isolate was sequenced and deposited as GenBank Accession No. EU003533. To our knowledge, this is the first report of C. dracaenophilum on potted plants outside of China and is the first report of this species in Bulgaria.

Reference: (1) D. F. Farr et al. Mycol. Res. 110:1395, 2006.
First Report of Powdery Mildew Caused by Podosphaera xanthii on Calendula officinalis in Italy
Authors: Garibaldi A. , Gilardi G. , Gullino M. L.
Published: December 2007

Calendula officinalis L. (Asteraceae) (pot marigold or English marigold) is an ornamental species grown in gardens and as potted plants for the production of cut flower. It was also used in ancient Greek, Roman, Arabic, and Indian cultures as a medicinal herb as well as a dye for fabrics, foods, and cosmetics. During the summer of 2007, severe outbreaks of a previously unknown powdery mildew were observed on plants in several gardens near Biella (northern Italy). Both surfaces of leaves of infected plants were covered with dense, white mycelia and conidia. As the disease progressed, infected leaves turned yellow and died. Mycelia and conidia also were observed on stems and flower calyxes. Conidia were hyaline, ellipsoid, born in short chains (four to six conidia per chain), and measured 27.0 to 32.1 (31.4) × 12.9 to 18.4 (18.2) μm. Conidiophores measured 49 to 77.3 (67.2) × 8 to 13.3 (10.8) μm and showed a foot cell measuring 44 to 59 (51.9) × 9.3 to 12.6 (11.3) μm followed by one shorter cell measuring 15.6 to 18.9 (17.6) × 10.4 to 13.6 (12.2) μm. Fibrosin bodies were present. Chasmothecia were spherical, amber colored, with a diameter of 89 to 100 (94.5) μm. Each chasmothecium contained one ascus with eight ascospores. On the basis of its morphology, the causal agent was determined to be a Podosphaera sp. (2). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 588 bp showed a 100% homology with the sequence of Podosphaera xanthii (2). The nucleotide sequence has been assigned GenBank Accession No. EU100973. Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy C. officinalis plants. Five plants were inoculated. Five noninoculated plants served as control. Plants were maintained in a greenhouse at temperatures ranging from 20 to 26°C. Eleven days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on C. officinalis in Italy. C. officinalis was previously described as a host to Sphaerotheca fuliginea (synonym S. fusca) in Great Britain (4) as well as in Romania (3). Voucher specimens are available at the AGROINNOVA Collection, University of Torino.

References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (3) E. Eliade. Rev. Appl. Mycol. 39:710, 1960. (4) F. J. Moore. Rev. Appl. Mycol. 32:380, 1953.
First Report of Puccinia kuehnii, Causal Agent of Orange Rust of Sugarcane, in the United States and Western Hemisphere
Authors: Comstock J. C. , Sood S. G. , Glynn N. C. , Shine J. M. , McKemy J. M. , Castlebury L. A.
Published: December 2007

In June 2007, approximately 8 km east of Belle Glade, FL, a rust disease was observed on a sugarcane (a complex hybrid of Saccharum L. species) cultivar (CP 80-1743) considered resistant to brown rust caused by Puccinia melanocephala Syd. & P. Syd. Approximately 10 km south of Canal Point, FL, another cultivar (CP 72-2086), also considered resistant to P. melanocephala, was found to be infected with a rust. Samples were sent to the USDA-APHIS National Mycologist and the USDA-ARS Systematic Mycology and Microbiology Laboratory in Beltsville, MD for identification. Observed morphological features were consistent with P. kuehnii E.J. Butler. Uredinial lesions were orange and variable in size, measuring 650 to 850 × 26 to 32 μm, hypophyllous, ellipsoidal to fusiform in shape, and distinctly lighter than pustules of P. melanocephala that were present in the area along with P. kuehnii. Urediniospores were mostly obovoid to pyriform or broadly ellipsoidal, variable in size, 32 to 45 × 25 to 30 μm, and moderately echinulate with mostly evenly distributed spines 2 to 4.5 μm apart. Walls were orange-to-light cinnamon brown, 1 to 2.5 μm thick with a pronounced apical wall thickening as much as 7 μm, and 4 to 5 equatorial pores. Similar orange uredinial lesions were subsequently observed on the same two cultivars and several other cultivars, including CPCL99-1777 and CPCL01-1055, at different locations in South Florida. Telia and teliospores were not observed. The nuclear large subunit rDNA region of the rust infecting cv. CP 80-1743 (BPI 878243, GenBank Accession No. EU164549) and the ITS1, 5.8S, and ITS2 rDNA regions of the rust infecting CP 80-1743 (GenBank Accession No. EU176009) and CP 72-2086 (GenBank Accession No. EU176008) were sequenced (1,4). All sequences were identical to sequences of P. kuehnii and distinct from known sequences of P. melanocephala (4). To our knowledge, this is the first confirmed record of P. kuehnii infecting sugarcane in the Western Hemisphere, and the disease appears to be distributed widely in the South Florida sugarcane-growing area. Although listed by P. Holliday (3) as occurring in Cuba, the Dominican Republic, and Mexico, CMI map no. 215 ed. 4 (2) does not include these three countries in the known distribution of P. kuehnii. P. kuehnii has also been reported in the literature as present in Hawaii (4). However, examination of the specimen label found that the specimen cited in those papers (BPI 079624) was actually collected in Tahiti. Therefore, the report from Hawaii is erroneous.

References: (1) M. C. Aime. Mycoscience 47:112, 2006. (2) CMI. Distribution Maps of Plant Diseases. No. 215, ed. 4. CAB International, Wallingford, UK, 1981. (3) P. Holliday. Fungus Diseases of Tropical Crops. Cambridge University Press, Cambridge, 1980. (4) E. V. Virtudazo et al. Mycoscience 42:447, 2001.
First Report of Anthracnose of Salal Caused by Colletotrichum acutatum in British Columbia
Authors: Elmhirst J. F. , Verma N.
Published: December 2007

Gaultheria shallon Pursh (salal) is a native, Pacific Northwest forest understory plant produced by numerous commercial nurseries as a garden and landscape ground cover. Seed is sown in soilless media in greenhouse plug flats, and seedlings are transplanted into larger pots at 24 to 36 weeks. In October 2005, approximately 30% of 16-week-old G. shallon Pursh (salal) seedlings in a commercial greenhouse in coastal British Columbia, Canada were observed to be dying back. Black, water-soaked, cankers girdled the stems and petioles resulting in seedling necrosis. Cankers extended into the base of affected leaves, and irregular, black leaf spots with concentric rings were observed. A Colletotrichum sp. was isolated on potato dextrose agar (PDA) + 0.005% streptomycin. In May 2006, 160 20-week-old salal seedlings (two- to five-leaf stage) in four plug cell flats of 40 seedlings each were inoculated with a hand atomizer with a mycelial and spore suspension of approximately 1 × 108 CFU/ml (dilution plating) in 100 mL sterile dH2O; 120 seedlings (four flats of 30 seedlings each) were sprayed with water alone. Flats were covered with black plastic for 48 h and then placed randomly in a shaded greenhouse at 14 to 22°C with overhead watering. The percentage of necrotic seedlings with black, water-soaked cankers and leaf spots in the inoculated flats at 1 to 8 weeks was 3.8, 7.6, 8.2, 16.4, 44.9, 62.0, 79.7, and 81.6, consecutively; versus 2.5% at 8 weeks in the noninoculated flats. Infection of the noninoculated seedlings was presumably due to spore splash from irrigation. Both the original isolate used as inoculum and colonies reisolated on PDA from inoculated, surface-sterilized, symptomatic tissues were identified as Colletotrichum acutatum J.H. Simmonds based on morphology (2) and PCR using a species-specific primer (1). Hyaline, aseptate, fusiform conidia, measuring 8 to 16 × 2.5 to 4 μm, were produced in acervuli without setae on plants and in culture. The teleomorph (Glomerella) stage was not observed. To our knowledge, this is the first report of an anthracnose disease of salal.

References: (1) S. Freeman et al. Plant Dis. 82:596, 1998. (2) J. E. M. Mordue. No. 315 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1971.
First Report of Powdery Mildew on Pyrus calleryana Caused by Podosphaera leucotricha
Authors: Vajna L. , Kiss L.
Published: December 2007

Callery pear (Pyrus calleryana Decne.) is native to Asia and its varieties are planted as ornamentals in urban areas worldwide. It is also used as a source of resistance to fireblight in some breeding programs. In April 2007, symptoms of powdery mildew infection were observed on the foliage of almost every P. calleryana cv. Chanticleer tree planted along a 1.5-km road in Budapest, Hungary. These trees were planted 5 to 6 years ago and were the first callery pears used as ornamentals in Hungary. Powdery mildew infections were also detected on P. calleryana trees planted in other parts of the city. White powdery mildew mycelium appeared on the lower and sometimes upper leaf surfaces, especially on young shoots, and caused chlorotic spots on the upper leaf surfaces and severe distortions of leaves. The spread of the infection was monitored between April and August of 2007 in several sample sites. More than 100 trees that were examined became heavily infected by May 2007. Powdery mildew conidiophores were typical of the genus Oidium subgen. Fibroidium, the anamorph of the teleomorph genus Podosphaera (2). Conidia developed in chains, contained fibrosin bodies, germinated at one of their ends with germ tubes terminating in unlobed appressoria, and measured 16 to 27 × 10 to 15 μm. Hyphal appressoria were nipple shaped or inconspicuous. The teleomorph was not found. To precisely identify the pathogen, DNA was extracted from conidia collected with a sterile brush from a single leaf using a Qiagen DNeasy Plant Kit (Hilden, Germany), and the internal transcribed spacer (ITS) sequence of the ribosomal DNA was amplified and determined as described by Szentiványi et al. (3). The ITS sequence, deposited in GenBank under Accession No. EU148597, was identical to those determined in Podosphaera leucotricha (Ell. & Ev.) Salmon collected from apple in Australia (GenBank Accession No. AF073353) and Canada (GenBank Accession No. AY157844) and also from pear in Canada (GenBank Accession No. AY157845). Thus, the pathogen was identified as Podosphaera leucotricha on the basis of the host genus, morphology of the anamorph, and ITS sequence. Specimens were deposited under Accession No. BPI878262 at the U.S. National Fungus Collection. To our knowledge, Podosphaera leucotricha has not been reported on P. calleryana in any parts of the world so far. An Oidium sp. infecting this plant in Australia was listed by Amano (1), but the exact identity of that fungus is not known. Thus, this is the first report of an identified powdery mildew fungus on P. calleryana.

References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press, Tokyo, 1986. (2) U. Braun et al. Pages 13-55 in: The Powdery Mildews: A Comprehensive Treatise. R. R Bélanger et al., eds. American Phytopathological Society, St Paul, MN, 2002. (3) O. Szentiványi et al. Mycol. Res. 109:429, 2005.
Metrics of sequence constraint overlook regulatory sequences in an exhaustive analysis at phox2b
Authors: McGaughey David M. , Vinton Ryan M. , Huynh Jimmy , Al-Saif Amr , Beer Michael A. , McCallion Andrew S.
Published: December 2007

Despite its recognized utility, the extent to which evolutionary sequence conservation-based approaches may systematically overlook functional noncoding sequences remains unclear. We have tiled across sequence encompassing the zebrafish phox2b gene, ultimately evaluating 48 amplicons corresponding to all noncoding sequences therein for enhancer activity in zebrafish. Post hoc analyses of this interval utilizing five commonly used measures of evolutionary constraint (AVID, MLAGAN, SLAGAN, phastCons, WebMCS) demonstrate that each systematically overlooks regulatory sequences. These established algorithms detected only 29%–61% of our identified regulatory elements, consistent with the suggestion that many regulatory sequences may not be readily detected by metrics of sequence constraint. However, we were able to discriminate functional from nonfunctional sequences based upon GC composition and identified position weight matrices (PWM), demonstrating that, in at least one case, deleting sequences containing a subset of these PWMs from one identified regulatory element abrogated its regulatory function. Collectively, these data demonstrate that the noncoding functional component of vertebrate genomes may far exceed estimates predicated on evolutionary constraint.
Molecular Basis for Resistance of
Acanthamoeba
Tubulins to All Major Classes of Antitubulin Compounds
Authors: Henriquez Fiona L. , Ingram Paul R. , Muench Stephen P. , Rice David W. , Roberts Craig W.
Published: December 2007

Tubulin is essential to eukaryotic cells and is targeted by several antineoplastics, herbicides, and antimicrobials. We demonstrate that
Acanthamoeba
spp. are resistant to five antimicrotubule compounds, unlike any other eukaryote studied so far. Resistance correlates with critical amino acid differences within the inhibitor binding sites of the tubulin heterodimers.
Thiopurine Drugs Azathioprine and 6-Mercaptopurine Inhibit
Mycobacterium paratuberculosis
Growth In Vitro
Authors: Shin Sung Jae , Collins Michael T.
Published: December 2007

The in vitro susceptibility of human- and bovine-origin
Mycobacterium paratuberculosis
to the thioupurine drugs 6-mercaptopurine (6-MP) and azathioprine (AZA) was established using conventional plate counting methods and the MGIT 960 ParaTB culture system. Both 6-MP and AZA had antibacterial activity against
M. paratuberculosis
; isolates from Crohn's disease patients tended to be more susceptible than were bovine-origin isolates. Isolates of
Mycobacterium avium
, used as controls, were generally resistant to both AZA and 6-MP, even at high concentrations (≥64.0 μg/ml). Among rapidly growing mycobacteria,
Mycobacterium phlei
was susceptible to 6-MP and AZA whereas
Mycobacterium smegmatis
strains were not. AZA and 6-MP limited the growth of, but did not kill,
M. paratuberculosis
in a dose-dependent manner. Anti-inflammatory drugs in the sulfonamide family (sulfapyridine, sulfasalazine, and 5-aminosalycilic acid [mesalamine]) had little or no antibacterial activity against
M. paratuberculosis
. The conventional antibiotics azithromycin and ciprofloxacin, used as control drugs, were bactericidal for
M. paratuberculosis
, exerting their killing effects on the organism relatively quickly. Simultaneous exposure of
M. paratuberculosis
to 6-MP and ciprofloxacin resulted in significantly higher CFU than use of ciprofloxacin alone. These data may partially explain the paradoxical response of Crohn's disease patients infected with
M. paratuberculosis
to treatment with immunosuppressive thiopurine drugs, i.e., they do not worsen with anti-inflammatory treatment as would be expected with a microbiological etiologic pathogen. These findings also should influence the design of therapeutic trials to evaluate antibiotic treatments of Crohn's disease: AZA drugs may confound interpretation of data on therapeutic responses for both antibiotic-treated and control groups.
Hepatotoxicity Observed in Clinical Trials of Aplaviroc (GW873140)
Authors: Nichols W. G. , Steel H. M. , Bonny T. , Adkison K. , Curtis L. , Millard J. , Kabeya K. , Clumeck N.
Published: December 2007

Aplaviroc (APL) was a new CCR5 antagonist that was investigated in two dose-ranging studies with antiretroviral therapy-naïve, human immunodeficiency virus-infected adults: ASCENT, in which 147 subjects were randomized 2:2:1 to receive zidovudine-lamivudine (ZDV-3TC) plus APL 600 mg twice a day (BID), APL 800 mg BID, or efavirenz (EFV), respectively, and EPIC, in which 195 subjects were randomized 2:2:2:1 to receive lopinavir-ritonavir (LPV-RTV) plus APL 200 mg BID, APL 400 mg BID, APL 800 mg once a day, or ZDV-3TC BID, respectively. Both studies (and, ultimately, the clinical development of APL) were discontinued after a mean of 14 weeks of therapy because of higher than anticipated severe liver toxicity; grade 2 or higher treatment-emergent elevations in alanine aminotransferase (ALT) levels were observed in 17/281 (6.0%) APL recipients but only 2/55 (3.6%) control recipients, while grade 2 or higher elevations in total bilirubin levels occurred in 29/281 (10.3%) APL recipients but only 4/55 (7.3%) controls. Two APL recipients developed grade 3 or higher treatment-emergent elevations in both ALT and total bilirubin levels, and one of these individuals had a severe case of hepatic cytolysis that was attributed to APL. Despite the high intersubject variability in APL plasma exposures, a Pearson correlation analysis of the combined study data did not reveal any significant associations between plasma concentrations and the liver enzyme elevations observed during the study. The mechanism for the idiosyncratic hepatotoxicity observed in the clinical trials of APL is unknown but is likely intrinsic to the molecule rather than its novel mechanism of action.
Combined Real-Time PCR and Pyrosequencing Strategy for Objective, Sensitive, Specific, and High-Throughput Identification of Reduced Susceptibility to Penicillins in
Neisseria meningitidis
Authors: Thulin Sara , Olcén Per , Fredlund Hans , Unemo Magnus
Published: December 2007

A segment of
penA
in
Neisseria meningitidis
strains (
n
= 127), including two nucleotide sites closely associated to reduced susceptibility to penicillins, was amplified and pyrosequenced. All results were in concordance with Sanger sequencing, and a high correlation between alterations in the two Pen
i
-specific sites and reduced susceptibility to penicillins was identified.
Tetracycline Resistance Gene
tet
(W) in the Pathogenic Bacterium
Clostridium difficile
Authors: Spigaglia Patrizia , Barbanti Fabrizio , Mastrantonio Paola
Published: December 2007

In this study, the
tet
(W) gene region of a human clinical isolate of
Clostridium difficile
resistant to tetracycline was characterized. This gene was a new allele showing 99% sequence identity to the gene found in the human strain
Bifidobacterium longum
F8, and it is not transferable by “in vitro” mating experiments.
Calcineurin Inhibitor Agents Interact Synergistically with Antifungal Agents In Vitro against
Cryptococcus neoformans
Isolates: Correlation with Outcome in Solid Organ Transplant Recipients with Cryptococcosis
Authors: Kontoyiannis Dimitrios P. , Lewis Russell E. , Alexander Barbara D. , Lortholary Olivier , Dromer Françoise , Gupta Krishan L. , John George T. , del Busto Ramon , Klintmalm Goran B. , Somani Jyoti , Lyon G. Marshall , Pursell Kenneth , Stosor Valentina , Muňoz Patricia , Limaye Ajit P. , Kalil Andre C. , Pruett Timothy L. , Garcia-Diaz Julia , Humar Atul , Houston Sally , House Andrew A. , Wray Dannah , Orloff Susan , Dowdy Lorraine A. , Fisher Robert A. , Heitman Joseph , Albert Nathaniel D. , Wagener Marilyn M. , Singh Nina
Published: December 2007

Synergistic interactions were observed between CIs and antifungal agents against 53 (90%) of 59
Cryptococcus neoformans
isolates from solid organ transplant recipients with cryptococcosis and may account for better outcomes in patients with cryptococcosis receiving these immunosuppressive agents.
Azurin-Like Protein Blocks Invasion ofToxoplasma gondiithrough Potential Interactions with Parasite Surface Antigen SAG1
Authors: Naguleswaran Arunasalam , Fialho Arsenio M. , Chaudhari Anita , Hong Chang Soo , Chakrabarty Ananda M. , Sullivan William J.
Published: December 2007

Some pathogenic bacteria produce factors that have evolved a capacity to neutralize competing microbes. The cupredoxin family protein azurin, produced byPseudomonas aeruginosa, exhibits a remarkable ability to impede invasion of a number of diverse intracellular pathogens, including the human AIDS virus human immunodeficiency virus type 1 and the protozoan parasitePlasmodium falciparum(which causes malaria). Here we report that azurin and an azurin-like protein (Laz) from gonococci/meningococci have activity againstToxoplasma, an apicomplexan parasite that causes opportunistic infection in immunocompromised individuals. We demonstrate that the mechanism of action for Laz involves interfering with the ability ofToxoplasmato adhere to host cells. Computer structural analysis reveals that azurin shares structural features with the predominant surface antigen SAG1, which is known to play an important role in parasite attachment. Interestingly, azurin also has structural similarities to a monoclonal antibody to SAG1. Surface plasmon resonance binding studies validate that SAG1 interacts strongly with Laz and, to lesser extent, azurin. Moreover,Toxoplasmamutants lacking SAG1 are not as susceptible to the growth-inhibitory effects of Laz. Collectively, our data show thatToxoplasmaadhesion can be significantly impaired by Laz, and to some extent by azurin, via interactions with SAG1. These observations indicate that Laz can serve as an important tool in the study of host-pathogen interactions and is worthy of further study for development into potential therapeutic agents.
Population Pharmacokinetics of Levofloxacin, Gatifloxacin, and Moxifloxacin in Adults with Pulmonary Tuberculosis
Authors: Peloquin Charles A. , Hadad David Jamil , Molino Lucilia Pereira Dutra , Palaci Moises , Boom W. Henry , Dietze Reynaldo , Johnson John L.
Published: December 2007

The objective of this study was to determine the population pharmacokinetic parameters of levofloxacin, gatifloxacin, and moxifloxacin following multiple oral doses. Twenty-nine patients with tuberculosis at the University Hospital in Vitória, Brazil, participated. Subjects received multiple doses of one drug (levofloxacin, 1,000 mg daily, or gatifloxacin or moxifloxacin, 400 mg daily) as part of a 7-day study of early bactericidal activity. Serum samples were collected over 24 h after the fifth dose and assayed using validated high-performance liquid chromatography assays. Concentration-time data were analyzed using noncompartmental, compartmental, and population methods. The three drugs were well tolerated. Levofloxacin produced the highest maximum plasma concentrations (median, 15.55 μg/ml; gatifloxacin, 4.75 μg/ml; moxifloxacin, 6.13 μg/ml), largest volume of distribution (median, 81 liters; gatifloxacin, 79 liters; moxifloxacin, 63 liters), and longest elimination half-life (median, 7.4 h; gatifloxacin, 5.0 h; moxifloxacin, 6.5 h). A one-compartment model, with or without weight as a covariate, adequately described the data. Postmodeling simulations using median population parameter estimates closely approximated the median values from the original data. Area under the concentration-time curve/MIC ratios for free drug were high. All three quinolones showed favorable pharmacokinetic and pharmacodynamic indices, with the most favorable results in this population being seen with levofloxacin at the comparative doses used.
In Vivo Pharmacodynamic Characterization of Anidulafungin in a Neutropenic Murine Candidiasis Model
Authors: Andes D. , Diekema D. J. , Pfaller M. A. , Prince R. A. , Marchillo K. , Ashbeck J. , Hou J.
Published: December 2007

Multiple in vivo studies have characterized the pharmacodynamics of drugs from the triazole and polyene antifungal drug classes. Fewer studies have investigated these pharmacodynamic relationships for the echinocandin drug class. We used a neutropenic murine model of disseminated
Candida albicans
,
Candida tropicalis
, and
Candida glabrata
infection to characterize the time course of activity of the new echinocandin anidulafungin. The pharmacokinetic-pharmacodynamic (PK-PD) indices (the percentage of time that the drug concentration was above the MIC, the ratio of the area under the concentration-time curve from 0 to 24 h [AUC
0-24
] to the MIC, and the ratio of the maximum serum drug concentration [
C
max
] to the MIC) were correlated with in vivo efficacy, as measured by organism numbers in kidney cultures after 96 h of therapy. The kinetics following intraperitoneal anidulafungin dosing in neutropenic infected mice were monitored. Peak levels and AUCs were linear over the 16-fold dose range studied. The drug elimination half-life in serum ranged from 14 to 24 h. Single-dose postantifungal-effect studies demonstrated prolonged suppression of organism regrowth after serum anidulafungin levels had fallen below the MIC. Of the four dosing intervals studied, treatment with the more widely spaced dosing regimens was most efficacious, suggesting the
C
max
/MIC ratio as the PK-PD index most predictive of efficacy. Nonlinear regression analysis suggested that both the
C
max
/MIC and AUC/MIC ratios were strongly predictive of treatment success. Studies were then conducted with 13 additional
C. albicans
,
C. tropicalis
, and
C. glabrata
isolates with various anidulafungin susceptibilities (MICs of anidulafungin for these strains, 0.015 to 2.0 μg/ml) to determine if similar
C
max
/MIC and AUC
0-24
/MIC ratios for these isolates were associated with efficacy. The anidulafungin exposures associated with efficacy were similar among
Candida
species.
Are All the DNA Gyrase Mutations Found in
Mycobacterium leprae
Clinical Strains Involved in Resistance to Fluoroquinolones?
Authors: Matrat Stéphanie , Cambau Emmanuelle , Jarlier Vincent , Aubry Alexandra
Published: December 2007

Mycobacterium leprae
DNA gyrases carrying various mutations, previously described in clinical strains, were investigated for quinolone susceptibility by inhibition of supercoiling and DNA cleavage promotion. We demonstrated that the
gyrA
mutations leading to G89C or A91V confer fluoroquinolone resistance whereas the
gyrB
mutation leading to D205N does not.
Prevalence of and Molecular Basis for Tuberculosis Drug Resistance in the Republic of Georgia: Validation of a QIAplex System for Detection of Drug Resistance-Related Mutations
Authors: Gegia Medea , Mdivani Nino , Mendes Rodrigo E. , Li Haijing , Akhalaia Maka , Han Jian , Khechinashvili George , Tang Yi-Wei
Published: December 2007

We developed a QIAplex system for the simultaneous detection of 24
Mycobacterium tuberculosis
gene mutations responsible for resistance to isoniazid (INH), rifampin (RIF), streptomycin (STM), and ethambutol (EMB) in 196
M. tuberculosis
isolates recovered in the Republic of Georgia. In comparison to phenotypic susceptibility tests, the QIAplex showed sensitivity and specificity of 85.4% and 96.1% for INH, 94.4% and 99.4% for RIF, 69.6% and 99.2% for STM, 50.0% and 98.8% for EBM, and 86.7% and 100.0% for multidrug resistance, respectively. The dominant resistance mutations revealed were a mutation in
katG
resulting in S315T (
katG
S315T),
rpsL
K43R, and
rpoB
S531L. Mutations
katG
S315G and S315T and
rpoB
S531L were detected with higher frequencies in pretreated patients than in naive patients (
P
< 0.05). Simultaneous detection of 24 common drug resistance-related mutations provides a molecular tool for studying and monitoring
M. tuberculosis
resistance mechanism and epidemiology.
In Vitro Activities of Doripenem and Six Comparator Drugs against 423 Aerobic and Anaerobic Bacterial Isolates from Infected Diabetic Foot Wounds
Authors: Goldstein Ellie J. C. , Citron Diane M. , Merriam C. Vreni , Warren Yumi A. , Tyrrell Kerin L. , Fernandez Helen T.
Published: December 2007

Against 182 anaerobe and 241 aerobe strains obtained from diabetic foot infections, doripenem was the most active carbapenem against
Pseudomonas aeruginosa
(MIC
90
, 2 μg/ml), more active than imipenem against
Proteus mirabilis
, and ertapenem was more active against
Escherichia coli
and
Klebsiella
spp. The MIC
50
and MIC
90
values were ≤0.125 μg/ml for methicillin-sensitive
Staphylococcus aureus
and all streptococci and 0.25/1 for
Bacteroides fragilis
.
Genetic and Biochemical Characterization of CAD-1, a Chromosomally Encoded New Class A Penicillinase from
Carnobacterium divergens
Authors: Meziane-Cherif Djalal , Decré Dominique , Høiby E. Arne , Courvalin Patrice , Périchon Bruno
Published: December 2007

Carnobacterium divergens
clinical isolates BM4489 and BM4490 were resistant to penicillins but remained susceptible to combinations of amoxicillin-clavulanic acid and piperacillin-tazobactam. Cloning and sequencing of the responsible determinant from BM4489 revealed a coding sequence of 912 bp encoding a class A β-lactamase named CAD-1. The
bla
CAD-1
gene was assigned to a chromosomal location in the two strains that had distinct pulsed-field gel electrophoresis patterns. CAD-1 shared 53% and 42% identity with β-lactamases from
Bacillus cereus
and
Staphylococcus aureus
, respectively. Alignment of CAD-1 with other class A β-lactamases indicated the presence of 25 out of the 26 isofunctional amino acids in class A β-lactamases.
Escherichia coli
harboring
bla
CAD-1
exhibited resistance to penams (benzylpenicillin and amoxicillin) and remained susceptible to amoxicillin in combination with clavulanic acid. Mature CAD-1 consisted of a 34.4-kDa polypeptide. Kinetic analysis indicated that CAD-1 exhibited a narrow substrate profile, hydrolyzing benzylpenicillin, ampicillin, and piperacillin with catalytic efficiencies of 6,600, 3,200, and 2,900 mM
−1
s
−1
, respectively. The enzyme did not interact with oxyiminocephalosporins, imipenem, or aztreonam. CAD-1 was inhibited by tazobactam (50% inhibitory concentration [IC
50
] = 0.27 μM), clavulanic acid (IC
50
= 4.7 μM), and sulbactam (IC
50
= 43.5 μM). The
bla
CAD-1
gene is likely to have been acquired by BM4489 and BM4490 as part of a mobile genetic element, since it was not found in the susceptible type strain CIP 101029 and was adjacent to a gene for a resolvase.
Modulation of Gene Expression in Human Macrophages Treated with the Anti-
Leishmania
Pentavalent Antimonial Drug Sodium Stibogluconate
Authors: El Fadili Karima , Imbeault Michaël , Messier Nadine , Roy Gaétan , Gourbal Benjamin , Bergeron Marc , Tremblay Michel J. , Légaré Danielle , Ouellette Marc
Published: December 2007

Within the mammalian host,
Leishmania donovani
is an obligatory intracellular protozoan parasite that resides and multiplies exclusively in the phagolysosomes of macrophages.
Leishmania
control relies primarily on chemotherapy, with the mainstay being pentavalent antimony (SbV) complexed to carbohydrates in the form of sodium stibogluconate (Pentostam) or meglumine antimoniate (Glucantime). The mode of action of SbV is still not known precisely. To explore the effect of SbV on macrophage gene expression, a microarray analysis was performed using Affymetrix focus arrays to compare gene expression profiles in noninfected and
L. donovani
-infected THP-1 monocytic cells treated or not treated with sodium stibogluconate. Under our experimental conditions, SbV changed the expression of a few host genes, and this was independent of whether cells were infected or not infected with
Leishmania. Leishmania
infection had a greater effect on the modulation of host gene expression. Statistical analyses have indicated that the expression of eight genes was modified by at least twofold upon SbV treatment, with six genes upregulated and two genes downregulated. One gene whose expression was affected by SbV was the heme oxygenase gene
HMOX-1
, and this change was observed both in the monocytic cell line THP-1 and in primary human monocyte-derived macrophages. Another pathway that was affected was the glutathione biosynthesis pathway, where the expression of the glutamate-cysteine ligase modifier subunit was increased upon SbV treatment. Our analysis has suggested that, under our experimental conditions, the expression of a few genes is altered upon SbV treatment, and some of these encoded proteins may be implicated in the yet-to-be-defined mode of action of SbV.