bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcription Profiling of Soybean Nodulation byBradyrhizobium japonicum
Authors: Brechenmacher Laurent , Kim Moon-Young , Benitez Marisol , Li Min , Joshi Trupti , Calla Bernarda , Lee Mei Phing , Libault Marc , Vodkin Lila O. , Xu Dong , Lee Suk-Ha , Clough Steven J. , Stacey Gary
Published: April 2008

Legumes interact with nodulating bacteria that convert atmospheric nitrogen into ammonia for plant use. This nitrogen fixation takes place within root nodules that form after infection of root hairs by compatible rhizobia. Using cDNA microarrays, we monitored gene expression in soybean (Glycine max) inoculated with the nodulating bacterium Bradyrhizobium japonicum 4, 8, and 16 days after inoculation, timepoints that coincide with nodule development and the onset of nitrogen fixation. This experiment identified several thousand genes that were differentially expressed in response to B. japonicum inoculation. Expression of 27 genes was analyzed by quantitative reverse transcriptase-polymerase chain reaction, and their expression patterns mimicked the microarray results, confirming integrity of analyses. The microarray results suggest that B. japonicum reduces plant defense responses during nodule development. In addition, the data revealed a high level of regulatory complexity (transcriptional, post-transcriptional, translational, post-translational) that is likely essential for development of the symbiosis and adjustment to an altered nutritional status.
Discovery of ADP-Ribosylation and Other Plant Defense Pathway Elements Through Expression Profiling of Four Different Arabidopsis–Pseudomonas R-avr Interactions
Authors: Adams-Phillips Lori , Wan Jinrong , Tan Xiaoping , Dunning F. Mark , Meyers Blake C. , Michelmore Richard W. , Bent Andrew F.
Published: April 2008

A dissection of plant defense pathways was initiated through gene expression profiling of the responses of a single Arabidopsis thaliana genotype to isogenic Pseudomonas syringae strains expressing one of four different cloned avirulence (avr) genes. Differences in the expression profiles elicited by different resistance (R)-avr interactions were observed. A role for poly(ADP-ribosyl)ation in plant defense responses was suggested initially by the upregulated expression of genes encoding NUDT7 and poly(ADP-ribose) glycohydrolase in multiple R-avr interactions. Gene knockout plant lines were tested for 20 candidate genes identified by the expression profiling, and Arabidopsis NUDT7 mutants allowed less growth of virulent P. syringae (as previously reported) but also exhibited a reduced hypersensitive-response phenotype. Inhibitors of poly(ADP-ribose) polymerase (PARP) disrupted FLS2-mediated basal defense responses such as callose deposition. EIN2 (ethylene response) and IXR1 and IXR2 (cellulose synthase) mutants impacted the FLS2-mediated responses that occur during PARP inhibition, whereas no impacts were observed for NPR1, PAD4, or NDR1 mutants. In the expression profiling work, false-positive selection and grouping of genes was reduced by requiring simultaneous satisfaction of statistical significance criteria for each of three separate analysis methods, and by clustering genes based on statistical confidence values for each gene rather than on average fold-change of transcript abundance.
Mutagenesis of Phytophthora infestans for Resistance Against Carboxylic Acid Amide and Phenylamide Fungicides
Authors: Rubin Avia (Evgenia) , Gotlieb Dror , Gisi Ulrich , Cohen Yigal
Published: April 2008

The carboxylic acid amide (CAA) fungicides mandipropamid, dimethomorph, iprovalicarb, and the phenylamide fungicide mefenoxam (MFX, the active enantiomer of metalaxyl) are anti-oomycete fungicides effective against downy mildews and late blight. Resistance against MFX was reported in nature in several oomycetes including Phytophthora infestans and Plasmopara viticola, whereas resistance against CAAs was reported in P. viticola but not in P. infestans. In this study the mutability of P. infestans for resistance against CAAs and MFX (as a control) was explored under laboratory conditions. UV light or chemical mutagens (e.g., ethyl methan sulfonate [EMS]) were applied to sporangia, and the emergence of mutants resistant to CAAs or MFX, or with altered mating type, was followed. Many mutants resistant to CAAs developed at generation 0 after mutagenesis, but all showed erratic, instable resistance in planta, diminishing after 1 to 8 asexual infection cycles, and failed to grow on CAA-amended medium. In contrast, 19 mutants resistant to MFX were obtained: 6 with UV irradiation (in isolates 28 or 96) and 13 with EMS (in isolates 408, 409, and 410). In three experiments, a shift in mating type, from A1 to A2, was detected. To elucidate whether or not resistance to CAAs is recessive and therefore might emerge only after sexual recombination, A1 and A2 mutants were crossed and the F1 and F2 progeny isolates were tested for resistance. Offspring isolates segregated for resistance to MFX, with resistant isolates maintaining stable resistance in vitro and in planta, whereas all progeny isolates failed to show stable resistance to CAAs in planta or in vitro. The data suggest that P. infestans could be artificially mutated for resistance against MFX, but not against CAAs.
Overwintering of Sclerotium rolfsii and S. rolfsii var. delphinii in Different Latitudes of the United States
Authors: Xu Z. , Gleason M. L. , Mueller D. S. , Esker P. D. , Bradley C. A. , Buck J. W. , Benson D. M. , Dixon P. M. , Monteiro J. E. B. A.
Published: April 2008

Previously known only from the southern United States, hosta petiole rot recently appeared in the northern United States. Sclerotium rolfsii var. delphinii is believed to be the predominant petiole rot pathogen in the northern United States, whereas S. rolfsii is most prevalent in the southern United States. In order to test the hypothesis that different tolerance to climate extremes affects the geographic distribution of these fungi, the survival of S. rolfsii and S. rolfsii var. delphinii in the northern and southeastern United States was investigated. At each of four locations, nylon screen bags containing sclerotia were placed on the surface of bare soil and at 20-cm depth. Sclerotia were recovered six times from November 2005 to July 2006 in North Dakota and Iowa, and from December 2005 to August 2006 in North Carolina and Georgia. Survival was estimated by quantifying percentage of sclerotium survival on carrot agar. Sclerotia of S. rolfsii var. delphinii survived until at least late July in all four states. In contrast, no S. rolfsii sclerotia survived until June in North Dakota or Iowa, whereas 18.5% survived until August in North Carolina and 10.3% survived in Georgia. The results suggest that inability to tolerate low temperature extremes limits the northern range of S. rolfsii.
Macroarray Detection of Eleven Potato-Infecting Viruses and Potato spindle tuber viroid
Authors: Agindotan Bright , Perry Keith L.
Published: April 2008

A macroarray was developed for the detection of 11 potato viruses and Potato spindle tuber viroid. The 11 viruses detected included those commonly found or tested for in North American potato seed certification programs: Alfalfa mosaic virus, Cucumber mosaic virus, Potato mop top virus, Potato leafroll virus, Potato latent virus, Potato virus A, Potato virus M, Potato virus S, Potato virus X, Potato virus Y, and Tobacco rattle virus. These viruses were detected using oligonucleotide 70-mer probes and labeled targets prepared by a random primed amplification procedure. Potato plants analyzed included those infected with 12 reference virus stocks and 36 field isolates. Results from the macroarray were entirely consistent with those obtained using a standard serological assay (enzyme-linked immunosorbent assay). Four isolates of Potato spindle tuber viroid, in mixed infection with one or more viruses, also were detected in the array, although strong hybridization signals required amplification with viroid-specific primers in combination with anchored-random primers. In individual plants, up to four viruses, or a viroid plus two viruses, were detected, with no apparent competition or inhibition. Macroarrays are a cost-effective approach to the simultaneous diagnostic detection of multiple pathogens from infected plants.
Host Specificity and Tomato-Related Race Composition of Phytophthora infestans Isolates in Taiwan During 2004 and 2005
Authors: Chen Chien-Hua , Sheu Zong-Ming , Wang Tien-Cheng
Published: April 2008

Late blight, caused by Phytophthora infestans, is a major disease of tomato in cool and wet environments. In this study, we report on the host specificity, race composition, and variation among races revealed by amplified fragment length polymorphism (AFLP) of P. infestans isolated from tomato production areas in Taiwan. In all, 177 P. infestans isolates were collected in Taiwan during 2004 and 2005. All were aggressive on both potato and tomato. Nine physiological races were identified based on disease response on a set of tomato differentials developed by the Asian Vegetable Research and Development Center–The World Vegetable Center. Eighty-seven polymorphic bands from 32 isolates of four races were detected by AFLP. No significant correlation between the polymorphism and the races was found using cluster analysis. This study revealed that a high variability of race composition among the asexual population of P. infestans isolates existed in Taiwan during 2004 and 2005. Breeding new tomato cultivars for resistance to P. infestans is an urgent and ongoing need because new races of the pathogen appeared continuously in Taiwan in past years. Further analysis of the genomic diversity is necessary to determine whether the high genetic variation of P. infestans is related to the complex race composition.
Population Structure, Chemotype Diversity, and Potential Chemotype Shifting of Fusarium graminearum in Wheat Fields of Manitoba
Authors: Guo X. W. , Fernando W. G. D. , Seow-Brock H. Y.
Published: April 2008

This study was to investigate the variation of acetyl ester derivative of DON at 15-position oxygen (15ADON) and acetyl ester derivative of DON at 3-position oxygen (3ADON) chemotypes and potential chemotype shifting of Fusarium graminearum based on the population structure of this species in Manitoba. The study was conducted in 15 locations with wheat cvs. Superb and AC Barrie in Manitoba from 2004 to 2005. Percentages of chemotypes 3ADON and 15ADON of F. graminearum ranged from 0 to 95.7 and 4.3 to 100%, respectively. The 3ADON chemotype was distributed in the southern part of Manitoba and predominant in Morris and Horndean. The two chemotypes almost shared the same percentage in Portage la Prairie. The 15ADON chemotype was predominant in the other locations. Significant gene flow was found among the populations from Sanford, Portage la Prairie, Hamiota, Plumas, Rapid City, and Virden; the populations from Cartier, Rivers, Killarney, and Souris; and the populations from Morris, Kenville, and Dauphin. There were no differences between the populations from two wheat cultivars and two chemotypes. The great variation of chemotype likely resulted from the great genetic diversity of F. graminearum. Sexual recombination, population age, and cropping system could result in genetic and chemotypic diversities. Wheat seed shipment and long-distance spore transportation of F. graminearum potentially caused the genetic migration and chemotype shifting in Manitoba.
An RFLP-Based Technique for Identifying Fungi in the Sooty Blotch and Flyspeck Complex on Apple
Authors: Duttweiler K. B. , Sun G. Y. , Batzer J. C. , Harrington T. C. , Gleason M. L.
Published: April 2008

A restriction fragment length polymorphism (RFLP)-based technique was developed to identify members of the sooty blotch and flyspeck (SBFS) disease complex on apple because these fungi are difficult to identify using agar-plate isolation and morphological description. The method includes polymerase chain reaction (PCR) amplification of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) using a fungal-specific forward primer (ITS1-F) and an SBFS-specific reverse primer (Myc1-R), followed by digestion of the PCR product by the HaeIII restriction enzyme. When applied to previously identified isolates of 24 SBFS-causing species in nine genera, the PCR-RFLP assay produced 14 unique banding patterns. Different genera never shared the same RFLP pattern. To evaluate performance in vivo, the technique was applied to DNA extracted directly from SBFS colonies on apple fruit from three Iowa orchards. The primers amplified the rDNA of only SBFS fungi, with the exception of a Cladosporium sp.; however, its RFLP banding pattern was distinct from those of SBFS fungi. The majority (60%) of SBFS colonies in the in vivo trial were identified to genus by RFLP analysis. The PCR-RFLP assay greatly streamlined the identification process by minimizing the need for culturing, indicating its value as a tool for field studies of the SBFS complex.
Triticum mosaic virus: A New Virus Isolated from Wheat in Kansas
Authors: Seifers Dallas L. , Martin T. J. , Harvey Tom L. , Fellers John P. , Stack James P. , Ryba-White Marietta , Haber Steve , Krokhin Oleg , Spicer Victor , Lovat Nicole , Yamchuk Andrej , Standing Kenneth G.
Published: April 2008

In 2006, a mechanically-transmissible and previously uncharacterized virus was isolated in Kansas from wheat plants with mosaic symptoms. The physiochemical properties of the virus were examined by purification on cesium chloride density gradients, electron microscopy, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), sequencing of the nucleotides and amino acids of the coat protein, and immunological reactivity. Purified preparations contained flexuous, rod-shaped particles that resembled potyviruses. The coat protein was estimated from SDS-PAGE to have a mass of approximately 35 kDa. Its amino acid sequence, as deduced from DNA sequencing of cloned, reverse-transcribed viral RNA and separately determined by time-of-flight mass spectrometry, was most closely related (49% similarity) to Sugarcane streak mosaic virus, a member of the Tritimovirus genus of the family Potyviridae. The virus gave strong positive reactions during enzyme-linked immunosorbent assays using polyclonal antibodies raised against purified preparations of the cognate virus but gave consistent negative reactions against antibodies to Wheat streak mosaic virus (WSMV), other wheat potyviruses, and the High Plains virus. When the virus was inoculated on the WSMV-resistant wheat cv. RonL, systemic symptoms appeared and plant growth was diminished significantly in contrast with WSMV-inoculated RonL. Taken together, the data support consideration of this virus as a new potyvirus, and the name Triticum mosaic virus (TriMV) is proposed.
Oidium longipes, A New Powdery Mildew Fungus on Petunia in the USA: A Potential Threat to Ornamental and Vegetable Solanaceous Crops
Authors: Kiss Levente , Jankovics Tünde , Kovács Gábor M. , Daughtrey Margery L.
Published: April 2008

This is the first North American report of Oidium longipes, an anamorphic powdery mildew species described recently in Europe. It was found on vegetatively propagated petunia grown in a commercial greenhouse in New Jersey, USA, where it caused a rapidly spreading disease. The pathogen might have originated offshore and may have already been distributed in the United States through horticultural trade. During field surveys in Europe, it was found on petunia in Hungary and Austria as well; this is the first report of O. longipes from these two countries. A detailed light microscopy study of American and European specimens of O. longipes, including freshly collected samples and authentic herbarium specimens, revealed that its conidiophore morphology is more variable than illustrated in the original species description or in subsequent works. Microcycle conidiation, a process not yet known to occur in powdery mildews, was repeatedly observed in O. longipes. The rDNA internal transcribed spacer (ITS) sequences were identical in colonies containing different conidiophore types as well as in a total of five specimens collected from petunia in the United States, Austria, Hungary, Germany, and Switzerland. A phylogenetic analysis of the ITS sequences revealed that the closest known relative of O. longipes is O. lycopersici, known to infect tomato only in Australia. Cross-inoculation tests showed that O. longipes from petunia heavily infected tobacco cv. Xanthi, while the tomato and eggplant cultivars tested were moderately susceptible to this pathogen. These results indicate that its spread represents a potential danger to a number of solanaceous crops. Our ad hoc field surveys conducted in 2006 and 2007 did not detect it outside New Jersey in the United States; all the other powdery mildew–infected petunias, collected in New York and Indiana, were infected by Podosphaera xanthii. In Europe, most of the powdery mildew–infected petunias examined in this study were infected by P. xanthii or Golovinomyces orontii. Our multiple inoculation tests revealed that the same petunia plants and even the same leaves can be infected concomitantly by O. longipes, O. neolycopersici, G. orontii, and P. xanthii. Thus, it is at present unclear to what extent O. longipes contributes to the powdery mildew epidemics that develop year after year on solanaceous plants in many parts of the world.
Porroca: An Emerging Disease of Coconut in Central America
Authors: Gilbert Gregory S. , Parker Ingrid M.
Published: April 2008

Porroca is a lethal disease of coconut (Cocos nucifera) emerging in Central America. Previously known only from Colombia, it has spread rapidly across the Isthmus of Panama in the last decade. Porroca is characterized by the production of stiff, dwarfed leaves, usually followed by the death of the palms within 2 years. We describe the long-distance spread of the disease as determined from regular censuses of more than 200,000 coconut palms in the indigenous Comarca of Kuna Yala and the Republic of Panama. Spread is temporally and spatially variable, with the disease moving across the landscape as much as 40 km per year. Porroca may represent a significant new threat to coconut production in the Caribbean Region.
First Report of Rhizoctonia solani on Mung Bean (Vigna radiata) Sprouts in California
Authors: O'Brien C. A. , Perez K. , Davis R. M.
Published: April 2008

In March 2007, mung bean (Vigna radiata) sprouts produced in an indoor sprouting facility in northern California developed brown lesions beginning 5 days after germination. Dark brown-to-reddish brown lesions with distinct margins developed on the stem, hypocotyl, and first true leaves of affected sprouts. Although all seed is routinely soaked in 20,000 mg Ca(OCl)2/liter of water for 15 min before germination, approximately 5 to 10% of the bean sprouts in several growing baskets (1.5 × 1.5 m) were affected and had to be discarded. Each basket contained approximately 1 t of sprouts. To isolate the causal organism, symptomatic stems were surface disinfested for 1 min in 0.5% NaOCl and incubated on acidified potato dextrose agar (PDA) at 25°C. Cultures were identified as Rhizoctonia solani on the basis of morphological features including right-angled branching of brown hyphae and the presence of sclerotia. PCR amplification of the internal transcribed spacer region was performed with primers RS1 and RS4 (2). Sequences were identical to R. solani AG4-HG-II in GenBank (Accession No. AF354074). To conduct pathogenicity tests, a 5-mm2-diameter disk from the margin of a culture of the fungus on PDA was placed in the center of 25 5-day-old germinated sprouts placed in a plastic box (15 × 10 × 5 cm) held at 25°C. Two isolates of R. solani cultured from different lots of sprouts were included in the assays. Controls received noncolonized agar. Treatments were replicated four times and each experiment was repeated three times. A moist paper towel was included in each box to maintain humidity. After 3 days, symptoms developed in the inoculated boxes but not in the noninoculated boxes. The fungus was reisolated from lesions, completing Koch's postulates. To our knowledge, this is the first report of R. solani on mung bean sprouts in a commercial sprouting facility. However, R. solani has been associated with root rot of mung bean plants in the field (1).

References: (1) T. R. Anderson. Can. Plant Dis. Surv. 65:1, 1985. (2) C. Guillemaut et al. Can. J. Microbiol. 49:556, 2003.
First Report of Dodder Transmission of ‘Candidatus Liberibacter asiaticus’ to Tomato (Lycopersicon esculentum)
Authors: Duan Y. P. , Gottwald Tim , Zhou L. J. , Gabriel D. W.
Published: April 2008

Citrus huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The disease is associated with three different species of fastidious α-proteobacteria, namely ‘Candidatus Liberibacter asiaticus’, Ca. L. americanus, and Ca. L. africanus (1). ‘Ca. L. asiaticus’ was first detected in South Florida in 2005 and has spread throughout the citrus-growing areas of Florida. ‘Ca. L. asiaticus’ is transmitted naturally by the Asian citrus psyllid, Diaphorina citri, and can also be transmitted by graft propagation and via various species of dodder (Cuscuta). HLB affects most if not all citrus and citrus relatives within the family Rutaceae (2), including the ornamental shrub Murraya paniculata (4). In addition, ‘Ca. L. asiaticus’ and ‘Ca. L. americanus’ can infect tobacco (Nicotiana xanthi) and periwinkle (Catharanthus roseus) (1,4). Here we report that ‘Ca. L. asiaticus’ can infect tomato (Lycopersicon esculentum) cvs. Manapal and FL47. Manapal and FL 47 plants grown from seed were placed adjacent to ‘Ca. L. asiaticus’-infected sweet orange (Citrus sinensis) plants with dodder (Cuscuta pentagona) already well established on them. Young dodder shoots still connected to the citrus were draped over the tomato plants and subsequently also became attached to the tomato stems. After 1 month, the tomato plants were detached from the citrus and most of the dodder removed. One month later, these tomato plants started to show vein clearing and subsequently the mature leaves became thicker and leathery. Some leaves showed blotchy mottle symptoms and some fruits became lopsided in a manner similar to HLB symptom expression on citrus. PCR amplification of the ‘Ca. L. asiaticus’ 16S rDNA with primers OI1/OI2c and the β-operon with primers A2/J5 (1) revealed the presence of ‘Ca. L. asiaticus’ DNA. Sequence analysis confirmed that the sequences of the cloned amplicons were identical to those from the HLB-infected citrus source plant. Both conventional and quantitative real-time PCR (3) revealed a much lower abundance of ‘Ca. L. asiaticus’ DNA in tomato as compared with ‘Ca. L. asiaticus’-infected citrus or periwinkle, indicating that ‘Ca. L. asiaticus’ bacteria multiplied at a lower titer in these tomato cultivars.

References: (1) J. M. Bové, J. Plant Pathol. 88:7, 2006. (2) S. E. Halbert et al. Fla. Entomol. 87:330, 2004. (3) W. Li et al. J. Microbiol. Methods 66:104, 2006. (4) L. Z. Zhou et al. Plant Dis. 91:227, 2007.
First Report of Leaf Spot and Blight Caused by Ralstonia pickettii on Bird of Paradise Tree in Italy
Authors: Polizzi G. , Dimartino M. , Bella P. , Catara V.
Published: April 2008

Bird of Paradise tree (Strelitzia alba (L. f.) Skeels) is an ornamental perennial tropical plant grown in southern Italy. In the summer of 2006 and 2007, a widespread, severe leaf disease was observed on seedlings and 1- to 2-year-old plants in two glasshouses located in eastern Sicily. Disease incidence ranged from 10 to 25%. Symptoms on the leaves consisted of dark brown-to-black stripes of varying length and found between the lateral veins. Lesions sometimes coalesced into a large area of necrotic tissue. Symptomatic tissues were ground in a drop of sterile distilled water (SDW) with a scalpel. Suspensions were streaked on King's medium B (KB), nutrient agar, and yeast extract nutrient agar (2). Isolated strains were gram negative and oxidase positive, non-levan, negative in tobacco hypersensitivity test, white and nonmucoid on yeast dextrose calcium carbonate agar, did not produce fluorescent pigments on KB, and utilized glucose, mannitol, trehalose, arabinose, mannose, and N-acetylglucosamine. Bacterial strains were identified as Ralstonia pickettii by using the Biolog Identification System (MicroLogTM System Release 4.2; Biolog, Inc., Hayward, CA) with a similarity index ranging from 0.52 to 0.67. For an additional confirmation of identity, the small subunit rRNA gene (SSUrDNA) was amplified with primers 530F and Uni 1492R (1). The resulting nucleotide sequence was compared with sequences deposited in GenBank and showed the highest identity (99%) to sequences of R. pickettii strains. Pathogenicity tests were performed on 20 cm tall potted plants. Four S. alba plants were inoculated by infiltrating leaf veins with bacterial suspensions for each of the four isolates (107 CFU ml–1 in SDW) with a 25-gauge needle and syringe. Plants were placed in polyethylene bags 1 day before inoculation and maintained there for 3 days after inoculation. Four control plants were inoculated with SDW. Water-soaked areas in the lateral veins of leaves were observed in all inoculated plants 4 days after inoculation. Within 10 days, dark brown-to-black stripes that coalesced into dark necrotic areas were observed. All isolates induced similar symptoms. Control plants did not show any symptoms. The pathogen was reisolated from symptomatic tissue and identified as R. pickettii by Biolog. A similar disease on S. reginae caused by a Pseudomonas sp. was previously reported from Florida (3). To our knowledge, this is the first record in the world of leaf spot and blight caused by R. pickettii.

References: (1) D. J. Lane. 16S/23S rRNA sequencing. Page 115 in: Nucleic Acid Techniques in Bacterial Systematics. E. Stackebrandt and M. Goodfellow, eds. John Wiley and Sons, NY, 1991. (2) N. W. Schaad et al. Laboratory Guide for Identification of Plant Pathogenic Bacteria. The American Phytopathological Society, St. Paul, MN, 2001. (3) C. Wehlburg. Plant Dis. Rep. 55:447, 1971.
First Report of Tomato chlorosis virus Infecting Tomato in Single and Mixed Infections with Tomato yellow leaf curl virus in Cuba
Authors: Martínez-Zubiaur Y. , Fiallo-Olivé E. , Carrillo-Tripp J. , Rivera-Bustamante R.
Published: April 2008

Whitefly-transmitted viruses have caused severe losses in tomato crops (Solanum lycopersicum) in Cuba. In 2006 and 2007, tomato greenhouses across eastern Cuba exhibited high levels of Bemisia tabaci (B biotype) infestation. Some plants showed interveinal chlorosis and a severe yellow mosaic, combined with leaf brittleness. These symptoms were different from those induced by Tomato yellow leaf curl virus (TYLCV-IL(CU)). Only 12 of 31 symptomatic samples resulted in positive PCR assays with TYLCV-specific primers (CTGAATGTTTGGATGGAAATGTGC and GCTCGTAAGTTTCCTCAACGGAC). A reverse transcription (RT)-PCR analysis for Tomato chlorosis virus (ToCV) with generic (HS-11/HS-12) and specific primers (ToC-5/ToC-6) was also carried out (2). Sequence analysis of the cloned RT-PCR products (463 bp) confirmed the presence of ToCV in Cuba. The fragment had 97 to 98% identity with GenBank isolates from Spain (DQ136146), Florida (AY903448), and Reunion Island, France (AJ968396). Cloned TYLCV and ToCV amplicons were used as probes to reanalyze the selected 31 samples by a dot-blot hybridization assay in search of mixed infections (1). The assay showed 16 samples to be positive for ToCV, 4 for TYLCV, 8 for both, and 3 samples were negative. To our knowledge, this is the first report of ToCV and TYLCV/ToCV mixed infections in Cuba.

References: (1) Y. Abou-Jawdha et al. Plant Dis. 90:378, 2006. (2) C. I. Dovas et al. Plant Dis. 86:1345, 2002.
Emergence of Tan Spot Disease Caused by Toxigenic Pyrenophora tritici-repentis in Australia Is Not Associated with Increased Deployment of Toxin-Sensitive Cultivars
Authors: Oliver R. P. , Lord M. , Rybak K. , Faris J. D. , Solomon P. S.
Published: April 2008

The wheat disease tan (or yellow leaf) spot, caused by Pyrenophora tritici-repentis, was first described in the period 1934 to 1941 in Canada, India, and the United States. It was first noted in Australia in 1953 and only became a serious disease in the 1970s. The emergence of this disease has recently been linked to the acquisition by P. tritici-repentis of the ToxA gene from the wheat leaf and glume blotch pathogen, Stagonospora nodorum. ToxA encodes a host-specific toxin that interacts with the product of the wheat gene Tsn1. Interaction of ToxA with the dominant allele of Tsn1 causes host necrosis. P. tritici-repentis races lacking ToxA give minor indistinct lesions on wheat lines, whereas wheat lines expressing the recessive tsn1 are significantly less susceptible to the disease. Although the emergence and spread of tan spot had been attributed to the adoption of minimum tillage practices, we wished to test the alternative idea that the planting of Tsn1 wheat lines may have contributed to the establishment of the pathogen in Australia. To do this, wheat cultivars released in Australia from 1911 to 1986 were tested for their sensitivity to ToxA. Prior to 1941, 16% of wheat cultivars were ToxA-insensitive and hence, all other factors being equal, would be more resistant to the disease. Surprisingly, only one of the cultivars released since 1940 was ToxA insensitive, and the area planted to ToxA-insensitive cultivars varied from 0 to a maximum of only 14% in New South Wales. Thus, the majority of the cultivars were ToxA-sensitive both before and during the period of emergence and spread of the disease. We therefore conclude that the spread of P. tritici-repentis in Australia cannot be causally linked to the deployment of ToxA-sensitive cultivars.
Effect of Crop Growth and Canopy Filtration on the Dynamics of Plant Disease Epidemics Spread by Aerially Dispersed Spores
Authors: Ferrandino F. J.
Published: April 2008

Most mathematical models of plant disease epidemics ignore the growth and phenology of the host crop. Unfortunately, reports of disease development are often not accompanied by a simultaneous and commensurate evaluation of crop development. However, the time scale for increases in the leaf area of field crops is comparable to the time scale of epidemics. This simultaneous development of host and pathogen has many ramifications on the resulting plant disease epidemic. First, there is a simple dilution effect resulting from the introduction of new healthy leaf area with time. Often, measurements of disease levels are made pro rata (per unit of host leaf area or total root length or mass). Thus, host growth will reduce the apparent infection rate. A second, related effect, has to do with the so-called “correction factor,” which accounts for inoculum falling on already infected tissue. This factor accounts for multiple infection and is given by the fraction of the host tissue that is susceptible to disease. As an epidemic develops, less and less tissue is open to infection and the initial exponential growth slows. Crop growth delays the impact of this limiting effect and, therefore, tends to increase the rate of disease progress. A third and often neglected effect arises when an increase in the density of susceptible host tissue results in a corresponding increase in the basic reproduction ratio, R0, defined as the ratio of the total number of daughter lesions produced to the number of original mother lesions. This occurs when the transport efficiency of inoculum from infected to susceptible host is strongly dependent on the spatial density of plant tissue. Thus, crop growth may have a major impact on the development of plant disease epidemics occurring during the vegetative phase of crop growth. The effects that these crop growth-related factors have on plant disease epidemics spread by airborne spores are evaluated using mathematical models and their importance is discussed. In particular, plant disease epidemics initiated by the introduction of inoculum during this stage of development are shown to be relatively insensitive to the time at which inoculum is introduced.
Germination of Ascospores of Gibberella zeae After Exposure to Various Levels of Relative Humidity and Temperature
Authors: Gilbert J. , Woods S. M. , Kromer U.
Published: April 2008

Fusarium head blight (FHB) is one of the most important cereal diseases in the world and has caused major losses to the grain industry. The principal pathogen causing FHB in North America is Gibberella zeae (anamorph Fusarium graminearum). Information on survival and the conditions under which ascospores remain viable once released from perithecia may assist in refining disease forecasting models. This study measured germination of ascospores after exposure to different temperatures, 15, 20, and 30°C, and levels of relative humidity (RH), 30, 60, and 90% for 4, 24, or 48 h periods. Viability was tested by germination on water agar. Germination rates fell with increasing temperatures at all observation times and at all humidity levels. At 15 and 20°C after 48 h, germination ranged from 74 to 85%, and 52 to 72%, respectively. At 30°C, germination ranged from 36 to 59% after 24 h and from 13 to 47% after 48 h. Germination was highest at 90% RH, except at 30°C after 48 h, and lowest at 60% RH. Successful germination, even under extreme conditions, suggests that ascospores are sufficiently robust to constitute a source of inoculum under most environmental conditions encountered during the growing season.
Genetic Resistance to Peronospora tabacina in Nicotiana langsdorffii, a South American Wild Tobacco
Authors: Zhang S. , Zaitlin D.
Published: April 2008

Several accessions of Nicotiana langsdorffii, a wild tobacco relative native to South America, express an incompatible interaction in response to infection by Peronospora tabacina, an oömycete that causes blue mold disease of tobacco (N. tabacum) and many other species of Nicotiana. In resistant accessions of N. langsdorffii, such as S-4-4, incompatibility takes the form of necrotic lesions that appear 48 h after pathogen inoculation, restricting pathogen growth, and suppressing subsequent asexual sporulation. Significantly elevated levels of salicylic acid and expression of a defense-related gene (HSR203J) were observed in S-4-4 leaves following blue mold infection. Genetic segregation analysis in F2 and modified backcross populations showed that blue mold resistance is determined by a single dominant gene (NlRPT) present in S-4-4. Further characterization of this unique host–pathogen interaction has revealed that (i) necrotic lesion resistance is due to the hypersensitive response (HR), (ii) HR-mediated resistance is present in 7 of 10 N. langsdorffii accessions examined, but not in closely related species, (iii) in some accessions of N. langsdorffii, resistance is expressed in cotyledon tissue and seedling leaves as well as in adult plants, and (iv) several resistant accessions including S-4-4 express an unregulated (“runaway”) HR in response to P. tabacina infection.
Survival of Plant Pathogens in Static Piles of Ground Green Waste
Authors: Downer A. J. , Crohn D. , Faber B. , Daugovish O. , Becker J. O. , Menge J. A. , Mochizuki M. J.
Published: April 2008

Ground green waste is used as mulch in ornamental landscapes and for tree crops such as avocados. Survival of Armillaria mellea, Phytophthora cinnamomi, Sclerotinia sclerotiorum, and Tylenchulus semipenetrans was assessed for 8 weeks within unturned piles of either recently ground or partially composted green waste. S. sclerotiorum survived at the pile surface and at 10, 30, and 100 cm within the pile for the entire 8 weeks in both fresh green waste (FGW) and aged green waste (AGW). A. mellea and T. semipenetrans did not survive more than 2 days in FGW, while P. cinnamomi persisted for over 21 days in FGW. AGW was less effective in reducing pathogen viability than FGW, most likely because temperatures in AGW peaked at 45°C compared with 70°C in FGW. Survival modeling curves based on pile temperatures indicate the time to inactivate 10 propagules of pathogens was 11, 30, 363, and 50 days for A. mellea, P. cinnamomi, S. sclerotiorum, and T. semipenetrans, respectively. Sclerotia-forming pathogens pose the greatest risk for escape; to ensure eradication of persistent fungi, green waste stockpiles should be turned intermittently to mix pile contents and move pathogen propagules to a location within the pile where they are more likely to be killed by heat, microbial attack, or chemical degradation.
A Characterization of Grapevine Trunk Diseases in France from Data Generated by the National Grapevine Wood Diseases Survey
Authors: Fussler L. , Kobes N. , Bertrand F. , Maumy M. , Grosman J. , Savary S.
Published: April 2008

Farmers' field survey data sets represent extremely valuable information, often having a heterogeneous data format. A large number of methods are available to process this kind of information, which may be combined to address successive, connected hypotheses, with definite objectives. The National Grapevine Trunk Diseases Survey was established in France in order to monitor and analyze the importance and progress of several grapevine diseases, in particular Eutypa dieback and Esca decline. Here we report a first series of analyses pertaining to the years 2003 to 2005 to characterize the incidences of the two diseases, as well as grapevine mortality, in relation to grapevine age, crop management, cultivars, and growing regions. Information representing 256 individual vineyards indicated mean incidences of 2.23 and 3.25% for Eutypa dieback and Esca decline, respectively. A combination of approaches (hierarchical cluster analysis, multiple correspondence analyses, and binomial logistic regressions) indicated distinct patterns of variation in the incidences of the two diseases according to crop management practices; limited linkage of specific crop management practices with diseases, especially Esca decline; a shared contribution of both diseases to mortality; and a weak linkage of the (now banned) arsenite-based pesticides with reduced Esca decline symptoms, but no such association with grapevine mortality. Differences and complementarities of the analytical approaches are discussed, as well as the implications of these analyses on grapevine health.
Factors Affecting the Infection of Fruit of Vitis vinifera by the Bitter Rot Pathogen Greeneria uvicola
Authors: Longland J. M. , Sutton T. B.
Published: April 2008

Bitter rot, caused by the fungus Greeneria uvicola, is one of the most important fruit rot diseases that threaten the burgeoning winegrape (Vitis vinifera) industry in the southeastern United States. Epidemiological studies were conducted to examine the period of fruit susceptibility of V. vinifera to G. uvicola, influence of temperature and duration of wetness on infection, and relative susceptibility of cultivars to bitter rot. In field studies, susceptibility of Merlot, Chardonnay, and Cabernet Franc fruit increased from bloom until véraison in 2003 and from bloom until 2 weeks before véraison in 2004. When detached V. vinifera fruit were inoculated and incubated at 14, 22, 26, and 30°C for 6, 12, 18 or 24 h of wetness, 22.4 to 24.6°C and 6 or 12 h of wetness were the optimal conditions for infection of fruit by G. uvicola. The relative susceptibility of 38 cultivars and selections, including 23 V. vinifera cultivars and five French-American hybrids, was determined in a detached fruit inoculation assay. A wide range in susceptibility was observed among the cultivars and selections. Fruit of cultivars of V. vinifera were significantly more susceptible than French-American hybrids. Isolates of G. uvicola differed in aggressiveness when tested on cv. Chardonnay.
Different Ecological Affinities and Aggressiveness Patterns Among Didymella rabiei Isolates from Sympatric Domesticated Chickpea and Wild Cicer judaicum
Authors: Frenkel O. , Sherman A. , Abbo S. , Shtienberg D.
Published: April 2008

Domesticated chickpea (Cicer arietinum) and its wild relative C. judaicum grow in sympatric distribution in Israel and both are susceptible to Ascochyta blight caused by Didymella rabiei. C. arietinum was grown for millennia in drier and hotter Levantine spring conditions while C. judaicum grows in the wetter and milder winters. Accordingly, it is possible that D. rabiei isolates originated from C. arietinum are adjusted to the less favorable spring conditions. Here, 60 isolates from both origins were tested in vitro for their hyphal growth at 15 and 25°C. Isolates from C. arietinum had a significantly larger colony area at 25°C than at 15°C (P < 0.001) while no such differences were detected between isolates from C. judaicum. D. rabiei isolates from wild and domesticated origins were used to inoculate nine C. judaicum accessions and two domesticated chickpea cultivars and their aggressiveness patterns were determined using five measures. On domesticated chickpea, isolates from domesticated origin were significantly more aggressive in four out of the five aggressiveness measures than isolates from wild origin. On C. judaicum, isolates from wild origin were generally more aggressive than isolates from domesticated origin. The results suggest that the habitat segregation between wild and domesticated Cicer influences the pathogens ecological affinities and their aggressiveness patterns.
Photodynamic therapy with recombinant adenovirus AdmIL‐12 enhances anti‐tumour therapy efficacy in human papillomavirus 16 (E6/E7) infected tumour model
Authors: Park Eun Kyung , Bae Su‐Mi , Kwak Sun‐Young , Lee Sung Jong , Kim Yong‐Wook , Han Chan‐Hee , Cho Hyun‐Jung , Kim Kyung Tae , Kim Young‐Jae , Kim Hyun‐Jung , Ahn Woong Shick
Published: April 2008

Immunotherapy with photodynamic therapy (PDT) offers great promise as a new alternative for cancer treatment; however, its use remains experimental. Here we investigated the utility of adenoviral delivery of interleukin‐12 (AdmIL‐12) as an adjuvant for PDT in mouse tumour challenge model. PDT was performed by irradiating Radachlorin in C57BL/6 mice transplanted with TC‐1 cells. PDT plus AdmIL‐12 treatment for tumour suppression as well as specific immune responses were evaluated with the following tests: in vitro and in vivo tumour growth inhibition, interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) assay, and cytotoxic T lymphocyte (CTL) assay. Direct intratumoral injection of AdmIL‐12 resulted in a significant suppression of tumour growth compared to the control group. Treatment of PDT along with AdmIL‐12 further enhanced antitumour effects significantly higher than either AdmIL‐12 or PDT alone. This combined treatment resulted in complete regression of 9‐mm sized tumour in every animal. We also evaluated immune responses induced by these treatments. Combined treatment significantly increased the production level of IFN‐γ and TNF‐α compared with that by AdmIL‐12 or PDT alone. PDT plus AdmIL‐12 enhanced antitumour immunity through increased expansion of the CTL subset mediated by CD8+ T cells. Taken together, these results indicate that the high anti‐cancer activity of PDT with AdmIL‐12 is a powerful tool against cancer therapy and is a promising subject for further investigation.
Cachexia in the non‐obese diabetic mouse is associated with CD4+ T‐cell lymphopenia
Authors: Zhao Chunfang , Wang Zhuanzhi , Robertson Michael W. , Davies Joanna D.
Published: April 2008

One of the long‐term consequences of Type I diabetes is weight loss with muscle atrophy, the hallmark phenotype of cachexia. A number of disorders that result in cachexia are associated with immune deficiency. However, whether immune deficiency is a cause or an effect of cachexia is not known. This study examines the non‐obese diabetic mouse, the mouse model for spontaneous Type I diabetes, as a potential model to study lymphopenia in cachexia, and to determine whether lymphopenia plays a role in the development of cachexia. The muscle atrophy seen in patients with Type I diabetes involves active protein degradation by activation of the ubiquitin–proteasome pathway, indicating cachexia. Evidence of cachexia in the non‐obese diabetic mouse was determined by measuring skeletal muscle atrophy, activation of the ubiquitin–proteasome pathway, and apoptosis, a state also described in some models of cachexia. CD4+ T‐cell subset lymphopenia was measured in wasting and non‐wasting diabetic mice. Our data show that the mechanism of wasting in diabetic mice involves muscle atrophy, a significant increase in ubiquitin conjugation, and upregulation of the ubiquitin ligases, muscle RING finger 1 (MuRF1) and muscle atrophy F box/atrogin‐1 (MAFbx), indicating cachexia. Moreover, fragmentation of DNA isolated from atrophied muscle tissue indicates apoptosis. While CD4+ T‐cell lymphopenia is evident in all diabetic mice, CD4+ T cells that express a very low density of CD44 were significantly lost in wasting, but not non‐wasting, diabetic mice. These data suggest that CD4+ T‐cell subsets are not equally susceptible to cachexia‐associated lymphopenia in diabetic mice.
Differential regulation of SOCS‐1 signalling in B and T lymphocytes by hepatitis C virus core protein
Authors: Yao Zhi Qiang , Prayther Deborah , Trabue Christopher , Dong Zhi Ping , Moorman Jonathan
Published: April 2008

Hepatitis C virus (HCV) infection is characterized by a strong propensity toward chronicity, autoimmune phenomena and lymphomagenesis, supporting a role for lymphocyte dysregulation during persistent viral infection. We have shown that HCV core protein inhibits T‐cell functions through interaction with a complement receptor, gC1qR. Here, we further report that B cells also express gC1qR that can be bound by HCV core protein. Importantly, using flow cytometry, we demonstrated differential regulation of B and T lymphocytes by the HCV core–gC1qR interaction, with down‐regulation of CD69 activation in T cells but up‐regulation of CD69 activation and cell proliferation in B cells. HCV core treatment led to decreased interferon‐γ production in CD8+ T cells but to increased immunoglobulin M and immunoglobulin G production as well as cell surface expression of costimulatory and chemokine receptors, including CD86 (B7‐2), CD154 (CD40L) and CD195 (CCR5), in CD20+ B cells. Finally, we showed down‐regulation of suppressor of cytokine signalling‐1 (SOCS‐1) using real‐time reverse transcription–polymerase chain reaction, accompanied by up‐regulation of signal transducer and activator of transcription‐1 (STAT1) phosphorylation in B cells in response to HCV core protein, with the opposite pattern observed in HCV core‐treated T cells. This study demonstrates differential regulation of B and T lymphocytes by HCV core and supports a mechanism by which lymphocyte dysregulation occurs in the course of persistent HCV infection.