bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomic Diversity of Field Isolates of Burkholderia solanacearum in Japan
Authors: Ito S. , Fujji T. , Uushijima Y. , Tanaka S. , Kameya‐Iwaki M. , Yoshiwara S. , Kishi F.
Published: May 2008

Genomic differences between 18 isolates of Burkholderia solanacearum originated from diseased plants cultivated in nine different agricultural fields were examined by using four DNA‐based methods: repetitive DNA polymorphism analysis, restriction‐site analysis of polymerase chain reaction products, random amplified polymorphic DNA (RAPD) analysis, and macrorestriction analysis. Genomic diversity among the isolates was detected by RAPD and macrorestriction analysis. The latter revealed the regional variation of the genome structure among the isolates, suggesting that B. solanacearum populations consist of a number of independent clonal lines.
Lack of Specificity in Plant Extracts and Chemicals as Inducers of Systemic Resistance in Cucumber Plants to Anthracnose
Authors: Fought L. , Kuć J. A.
Published: May 2008

Canoia, lettuce, green bean, dwarf pea, tobacco, tomato, poplar, corn, wheat, and cucumber leaves were extracted by boiling with 95% ethanol. The ethanol was removed from the ethanol‐water extract, and the water‐soluble fraction was centrifuged and filtered to remove compounds with a molecular weight > 1 000 D. The undersides of the first true leaf of a cucumber plant (leaf 1) and the leaf above (leaf 2) were sprayed with each plant extract (induction), and 7 days later leaf 3 was inoculated with a conidial suspension of Colletotrichym lagenarium (challenge). Extracts from all plants tested induced systemic resistance in leaf 3 to C. lagenarium. Commercially available compounds were screened to determine structural similarities among the compounds which can induce systemic resistance. All compounds which induced resistance in leaf 3 caused some damage to leaves 1 and 2. but not all compounds which damaged leaves 1 and 2 induced resistance in leaf 3. Galacturonic acid, glucuronic acid, salicyhc acid, m‐hydroxybenzoic acid, p‐hydroxybenzoic acid, y‐resorcylic acid, protocatecbuic acid, gallic acid, hemimelletic acid, trimelletic acid, trimesic acid, phloroglucinol, and glycine induced systemic resistance, whereas catechol, resorcinol, hydroquinone, pyrogaLol, hydroxyhydroquinone, benzoic acid, phthalic acid, α‐resorcylic acid, β‐resorcylic acid, gentisic acid. 2, 3‐dihydroxybenzoic acid, benzaldehyde, 2,3‐dihydroxybenzaldehyde, β‐resorcaldehyde, protocatechuic aldehyde, benzyl alcohol, salicyl alcohol, myo‐inositol, phytic acid, pinitol, and quebrachitol did not. Structural similarities were not evident among either compounds which induced systemic resistance or those that did not.
Nature of Enhanced Severity of Anthurium Root Rot by Diuron Treatment for Weed Control
Authors: Guo L. Y. , Ko W. H.
Published: May 2008

Diuron treatment for weed control greatly increased anthurium root rot caused by Pythium splendens, P. spinosum, P. vexans and Calonectria crotalariac. Diuron in agar medium was inhibitory to the growth of mycelium, formation and germination of sporangia of P. splendens. Sporangia of P. splendens produced in diuron‐amended medium did not differ in pathogenecity to anthurium roots from those produced in diuron‐free medium. When diuron was applied to kill weeds in the planting medium, the population of P. splendens in it was not decreased during the test. Diuron was inhibitory to a number of micro‐organisms in the platiting medium. Exudation of anthursum roots was not increased by diuron treatment. Increase in severity of anthurium root rot by diuron treatment was similar whether the experiments were performed in the presence or absence of planting medium, suggesting that the enhancing effect of diuron on root rot is mainly due to an increase in susceptibility of the host plants.
Characterization of Two Strains of Cowpea Mild Mottle Virus Naturally Infecting Groundnut (Arachis hypogaea L.) in India
Authors: Sivaprasad V. , Sreenivasulu P.
Published: May 2008

Two viruses were isolated from commercial groundnut plants showing mild mottle (MM) and severe mottle (SM) symptoms in the Rayalaseema area of Andhra Pradesh State, India. The host range of both the isolates was restricted to Fabaceae. The physical properties of both isolates were: DEP 10‐6 to 10‐7. TIP 70–85 C and LIV 5–8 days. Partially purified virus preparations contained slightly flexuous filamentous particles. In ELISA and gel diffusion tests both isolates reacted similarly with anusera to the carlaviruses cowpea mild mottle, cassia mild mosaic and potato M. Particle morphology. sedimentation coefficient, and estimated sizes of the coat proteins and RNAs gave additional evidence that the viruses were carlaviruses. Bemisia labaci transmitted only the MM isolate and the two isolates also differed in electrophoretic mobility of intact particles and amino acid composition of the coat proteins. The isolates are identified as distinct strains of cowpea mild mottle virus.
Serodiagnosis of Pepper Veinal Mottle Virus in West Africa using Specific Monoclonal Antibodies in DAS‐ELISA
Authors: Huguenot C. , Furneaux M. T. , Clare J. , Hamilton R. I.
Published: May 2008

In order to develop a reliable diagnostic test for pepper veinal mottle virus (PVMV), a panel of monoclonal antibodies (mAbs), raised to a Nigerian isolate (PVMW‐Ni), was evaluated by double‐antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA) on infected pepper samples from seven West African countries. PVMV from different geographical locations was serologically very homogeneous and no significant epitope differences were detected even with a very sensitive double‐mAb sandwich ELISA. This ELISA format was optimized with mAb 6C12 and its application in a diagnostic test resulted in the identification of PVMV in Burkina Faso, Togo and Sénégal where it had not been previously reported.
Changes in Sugar Content During Induction of Systemic Acquired Resistance to Late Blight Caused by Phytophthora infestans (Mont.) de Bary in Potato
Authors: Engstrom K. , Strömberg A.
Published: May 2008

Resistance of plants to their pathogens may be systemically enhanced by a localized induction treatment, a characteristic named systemic acquired resistance (SAR). Changes in amounts and proportions of sucrose, glucose and fructose were examined in induced and noninduced potato plants (Solarium luberosum L. ev. Matilda) before, and 1–9 days after challenge inoculation. The potato plants were induced and challenged with Phytophthora infesians (Mont.) de Bary. Plants which were non‐induced and non‐challenged were also tested (referred to as non‐treated). The sugars were analysed using high‐performance anion exchange chromatography with pulsed electrochemical detection, HPAE‐PED (Dionex system). The amounts as well as the proportions of sucrose, glucose and fructose were similar throughout the experimental period in the non‐treated plants. In induced plants, before challenge inoculation, the amount of sucrose was 44% lower than in non‐treated plants. One day after challenge inoculation, the amount of sucrose had decreased by 79% in non‐induced plants compared with non‐treated plants, while the induced plants were much less affected. The total amount of all sugars were approximately the same 1 day hefore and 9 days after the challenge inoculation in ail treatments. However, 1 day after challenge inoculation, a 65% decrease in total amount was observed in the non‐induced plants compared with the smaller reduction of 37% in the induced plants. The large differences in sugar amounts and proportions between the different treatments are discussed.
Extraction from Plant Tissue and Germination of Oospores of Peronospora viciae f.sp. pisi
Authors: van der Gaag D. J. , Frinking H. D.
Published: May 2008

A protocol was developed to extract oospores of Peronospora viciae f.sp. pisi from plant tissue and control bacterial contamination in a germination assay. Oospores were extracted by comminuting infected leaves and pods in water, sonicating the suspension and sieving it through mesh sizes 53 and 20 pm, respectively. Germination of oospores was negatively influenced by addition of chloramphenicol and penicillin. A combination of ampicillin and rifampicin strongly inhibited bacterial growth at 10 C, and did not negatively affect germination. Washing oospores in water or 0.02% Tween‐80, and sonication did not influence germination. Treating oospore suspensions with cellulase buffered at pH 4.6 for 2 h digested most plant tissue but did not influence germination. Incubation in 0.05 m acetate buffer delayed germination. Germination was unaffected when oospores were incubated in 0.05 m citrate buffer.
Induced Systemic Resistance to Cercospora Leaf Spot of Carrot by Inoculation with Cercospora carotae
Authors: Mercier J. , Kuć J.
Published: May 2008

The possibility of inducing systemic disease resistance in carrot leaves was investigated with the pathogen Cercospora carotae as the agent for both induction and challenge. The inoculation of plants with C. carotae induced resistance in newly emerged leaves challenged 23 days later. There was an optimum inoculum concentration of 3 × 104 conidia ml‐1 for inducing resistance, the response decreasing with higher concentrations. Infection of carrot leaves by C. carotae could thus reduce susceptibility to subsequent infections by foliar pathogens later in the growing season. However, the inoculation of leaves with C. carotae did not increase the resistance of roots after harvest when they were wounded and challenged with Botrytis cinerea.
Constitutive and Inducible Proteins in the Root of Chinese Cabbage Infected with Plasmodiophora brassicae
Authors: Ito S. , Tanaka S. , Miyanaga C. , Takabayashi S. , Yano S. , Kameya‐Iwaki M.
Published: May 2008

A plant‐pathogen system consisting of a Chinese cabbage cultivar and two isolates of Plasmodiophora brassicae was developed for analysing root proteins accumulated in susceptible and resistant responses to the fungus. Proteins extracted at pH 2.8 were analysed by two‐dimensional gel electrophoresis. More than 150 protein spots were resolved. Spots indicating changes in the intensity by the infection of P. brassicae were classified into six types: class 1 contains proteins enhanced in susceptible response; class 2, proteins unique to susceptible response; class 3, proteins repressed in susceptible response: class 4, proteins enhanced in resistant response; class 5, proteins unique to resistant response; and class 6, proteins repressed in resistant response. Two proteins from class 1 and one protein from class 4 were subjected to an N‐terminal amino acid sequencing. One of the class 1 protein (25 kDa, pl 7.0) revealed high homology with pathogenesis‐related protein group 5.
The Systemic Infection by Tobacco Mosaic Virus of Tobacco Plants Coutaining the N Gene at Temperatures Below 28°C
Authors: White R. F. , Sugars J. M.
Published: May 2008

Tobacco plants containing the N‐gene are occasionally systemically infected with tobacco mosaic virus (TMV) at tempreratures below 28°C, but contain low concentrations of virus: they often fail to set seed, and can outlive healthy control plants. Infection is thus similar to that induced when N‐gene tobacco plants are grafted onto systemically infected tobacco lacking the N‐gene. Shoots from systemically infected N‐gene plants can induce systemic infection in other graft‐inoculated N‐gene plants. Stem sections of N‐gene tobacco plants act as good conduits for TMV between plants lacking the N‐gene, and girdling experiments suggest that virus movement probably occurs in the phloern.
Location of Soybean Mosaic Virus in Seed‐Parts of Individual Dormant and Germinating Mottled and Non‐mottled Soybean Seeds
Authors: Bajwa M. A. , Pacumbaba R. P.
Published: May 2008

Soybean mosaic virus (SMV) was detected in individual embryos of both dormant mottled (50%) and non‐mottled (50%) seeds of certified soybean cvs Davis. Essex. Hutchinson, Ransom, Stonewall, and Young by using the double antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA). SMV was not detected in individual strained seed coats of mottled or non‐stained seed coats of non‐mottled dormant seeds and endosperms of either type of seed. SMV was not detected m individual stained and nonstained seed coats, epicotyls, and endosperms of mottled and non‐mottled seeds at 72 h post‐germination. However, the virus was detected in individual hypocotyls at an average level of 31% in post‐germinated seeds (mottled and non‐mottled) of all cultivars. Symptomless glasshouse‐grown 6–8‐week‐old seedlings from mottled and non‐mottled seeds of certified soybean cultivars occurred twice as often as those showing early symptoms. However, almost half of these symptomless plants were found to be SMV‐infected by DASELISA. Virus‐free soybean plants grown to maturity from non‐mottled seeds also produced mottled seeds.
Fungicidal Activity of Some Common Weed Extracts Against Different Plant Pathogenic Fungi
Authors: Qasem J. R. , Aau‐Blan H. A.
Published: May 2008

Aqueous extract effects of 64 weed species on growth and development of Alternaria solani Sorauer. Helminthosporium satirum King & Bakke and Rhizodonia solani Kuhn. plant pathogenic fungi were studied in vitro. Extracts varied in the strength and persistence of their antifungal effects against the three fungi species. Some stimulated, others inhibited or had no effect. Among all species tested, extracts of Chenopodium murale, Falearia vulgaris. Ranunculus asiaticus and Sisymbrium irio were the most toxic to A. solani. Anagallis arlensis. Atriptex leucoclada, Crepis aspera. Notobasis syriaca. R. asiatieus, Rumex crispu. S. irio. Sonehu.s oleraceous and Vieia narhonensis to H. satirum and R. asiatieus. S. oleraceous and Mercurialis annua to R. solani. However. R. asiatieus extract was the most effective and completely inhibited growth and sporulation of the three fungi species at all incubation periods.
Resistance to Tomato Yellow Mosaic Geminivirus and Presence of Viral DNA in Some Species of Solanaceae
Authors: Infante D. , Piven N. , de Uuzcátegui R.
Published: May 2008

In this work we studied tomato yellow mosaic geminivirus (ToYMV) symptoms and DNA presence in several species of Solanaeae: Lycopersivon esculentum, Lycoperstcon peru‐vianum. Lycium barbarum, Nicotiaiiu benthautian, Solunum lycopersioides. Solanum quitoense and Solanum rickli. After mechanical and insect transmission, in both greenhouse and open field, we found plants of Lyiium barbarum and Solanum lycopersicoides to be resistance to ToYMV, Polymerase chain reaction analysis showed that the resistant plants did not contain viral DNA.
Identification des acides caféoylshikimiques des racines du palmier dattier, principaux composés fongitoxiques vis‐à‐vis de Fusarium oxysporum f. sp. albedinis
Authors: Ziouti A. , El Modafar C. , El Mandili A. , El Boustani E. , Macheix J. J.
Published: May 2008

5‐caffeoylshikimic acid and its isomeres of position (dactylifric acid) found in the roots of date‐palms (Phoenix daetylijera L.) inhibit the germination of conidia and the growth of the mycelium of Fusarium oxysporum f. sp. albedinis. The acid content accumulated in resistant cultivars are toxic to fungi, whereas that accumulated in sensitive cultivars does not seem to affect growth and development of the parasite. This well demonstrates the implication of caffeoylshikimic acid in the resistance of the date‐palm to this fusarium disease. Moreover, these results will be of great use, especially for screening resistant genotypes obtained from directed crossings or from in vitro cultures.
A Robust DNA Amplification Fingerprinting System Applied to Analysis of Genetic Variation Within Fusarium oxysporum f.sp. cubense
Authors: Bentley S. , Bassam B. J.
Published: May 2008

Genetic variation among isolates of F. oxysporum f.sp. cubense (Foc) was analysed using a DNA amplification fingerprinting (DAF) system modified to improve reproducibility and transportability. This analysis was done after determining the widest tolerance range (or ‘window of reproducibility’) for each component in amplification reaction. Reproducible polymerase chain reactions (PCRs) were achieved with between 25 and 250 ng of template DNA, 9–15 μM primer, 4–6 mM MgCl2 and 2–4 units of Stoffel Fragment enzyme. For experimental work we used the middle value of these ranges which allowed at least 20% error tolerance for each component. Similarly, thermocycling and electrophoresis conditions were also improved. Manual scoring of the DNA fingerprints was compared to analysis of scanned gel images using the Gel Compar program (Applied Maths, Kortrijk, Belgium). The data were clustered by unweighted pair group method analysis (UPGMA) based on the Jaccard similarity coefficient. Isolates of Foc representing all known vegetative compatibility groups (VCGs) were examined and the genetic relationships between the VCGs were determined. Isolates of Foc were divided into two major groups with 30% genetic similarity. These optimized DNA amplification, thermocycling, and electrophoresis conditions were suitable for analysis of other organisms and should be applicable to other techniques that use arbitrary primers such as random amplified polymorphic DNA (RAPD) and arbitrarily primed‐PCR (AP‐PCR).
The Effect of Lodging and Time of Harvest on Deoxynivalenol Contamination in Barley and Oats
Authors: Langseth W. , Stabbetorp H.
Published: May 2008

A split‐split plot design was used to study the effect of lodging and time of harvest on the formation of the Fusarium toxin deoxynivalenol (DON). Altogether 19 experimental fields were included in the study, which was carried out over the period 1991–1993. There were two cultivars each of barley and oats tested. Half of each field was lodged artificially using a drum roller to flatten the crop about 3 weeks after ear emergence. The grain was harvested at the stage of mealy ripe and about 15 and 30 days after. The DON concentratioti in the grain was in descending order influenced by lodging, cultivar, experimental field, year and time of harvest. When paired plots were compared a distinct increase (more than 65%) in the DON concentration was found in samples from 49% of the plots with lodging compared with their pair plot. Both a decrease and an increase in the DON content were detected in the period from the first time of harvest to the second and third titne of harvest. The overall contamination level of DON was found to be higher in the samples of barley compared to oats.
Functional Studies of Complementary Sense Promoter (Replicase Promoter) from Tomato Yellow Leaf Curl Virus: Evidence for Transcription Capability in Non‐host Plants
Authors: Abdallah N. A. , Abou‐Salha A. , Soliman M. H.
Published: May 2008

The complementary sense promoter C1 that regulates the transcription of replicase gene in geminiviruses was cloned from tomato yellow leaf curl virus. A transcription fusion of β‐glucuronidase gene (GUS) coding sequence to complementary sense promoter, that replaced the viral replicase coding sequence, was constructed. Protoplasts of Nicotiana tabacum were electroporated to introduce the GUS gene controlled by the C1 promoter. The level of GUS transient gene expression was enhanced by the increase of the plasmid DNA concentration. Fluorometric GUS assays showed that the C1 promoter has a lower expression compared to the e35S promoter. Bombardment of the constructed plasmid. containing Cl promoter‐GUS ORF‐NOS terminator (pKSIR‐E), was performed to different plant genetic backgrounds and followed by the histochemical GUS assays. The results showed that there were GUS activities expressed in tomato (Lycopersicon esculentum), tobacco (Nicotiana tabacum) and datura (Datura stramonium), as host plants. While in non‐host plants, the GUS activities were observed in faba bean (Vicia faba) and squash (Cucurbita pepo), as examples of dicot plants, but not in maize (Zea mays) as a representative of monocote.
Subcellular Location and Expression of Tobacco Necrosis Necrovirus p7a Protein
Authors: Drouzas A. D. , Offei S. K. , Coutis R. H. A.
Published: May 2008

A putative movement protein (p7a) of tobacco necrosis Necrovirus, strain D (TNV‐D), produced in Escherichia coli using an expression vector, was used to raise an antiserum. Immunoblot analysis using this antiserum showed that the p7a protein was detectable only in the combined cell wall and cell membrane fraction prepared from TNV‐D infected Phaseolus vulgaris leaves. The p7a protein was detectable 1 day after inoculation and reached a maximum 3 days later, before declining, whereas coat protein was not detectable until 3 days after inoculation and continued to increase in concentration for a further 2 days before declining. Differences in the detectable amounts of both proteins may reflect their differential stability in extracts from necrotic tissue and/or the transient expression of the putative movement protein early in the replication cycle of TNV‐D.
A Basic Peroxidase Isoenzyme, Marker of Resistance Against Plasmopara viticola in Grapevines, is Induced by an Elicitor from Trichoderma viride in Susceptible Grapevines
Authors: Barceló A. Ros , Zapata J. M. , Calderón A. A.
Published: May 2008

The constitutive expression of basic peroxidase isoenzymes in the Plasmopara viticola‐resistant (Vitis vinifera × Vitis rupestris) × Vitis riparia crossing and in the P. viticola‐susceptible V. vinifera parent species was studied. The results illustrate that both leaves and stems of the (V. vinifera × V. rupestris) × V. riparia crossing showed the differential expression of a basic peroxidase isoenzyme B3 (pl = 8.9), this being almost completely absent from the P. viticola‐susceptible V. vinifera parent species. To test whether the basic peroxidase isoenzyme B3 may be considered as a molecular marker of disease resistance in Vitis spp., suspension cell cultures derived from the P. viticola‐susceptible V. vinifera parent species were treated with an elicitor (cellulase Onoztika R‐10) from the soil fungus Trichoderma viride, a specific and well‐known elicitor of disease resistance reactions in grapevines. The results showed that treatment with the elicitor induces, simultaneously with the activation of the disease resistance mechanism, the appearance of B3 in the cell cultures. These results suggest that the basic peroxidase isoenzyme B3 may be considered as a marker of disease resistance in Vitis species since it is present in the P. viticola‐resistant (V. vinifera × V. rupestris) × V. riparia hybrid and is induced by the elicitor Onozuka R‐10 in cell cultures of the P. viticola‐susceptible Vitis vinifera parent species. This conclusion is supported by the presence of this isoenzyme in other resistant and its absence in other susceptible Vitis spp.
Production and Characterization of Monoclonal Antibodies to Barley Yellow Mosaic Virus and Their Use in Detection of Four Bymoviruses
Authors: Hariri D. , Lapierre H. , Filleur S. , Plovie C. , Delaunay T.
Published: May 2008

Six monoclonal antibodies (MAbs) against a French isolate of barley yellow mosaic virus (BaYMV) pathotype 2 were produced and their isotypes determined. These MAbs were compared in ELISA for their reactivity with different isolates of BaYMV, wheat yellow mosaic virus (WYMV), wheat spindle streak mosaic virus (WSSMV) and oat mosaic virus (OMV).The six MAbs detected BaYMV in TAS ELISA and western blot, whereas in ACP ELISA no reaction was observed with isolates of BaYMV and WYMV. These MAbs could recognize the sequential motifs situated at the surface of viral particles. The six MAbs detected all the European isolates of BaYMV pathotype 1 and 2 and the Japanese isolate of this viral pathotype 1–1. In contrast to other MAbs, MAb IV did not react with the Japanese isolate of BaYMV pathotype II‐l. In TAS ELISA. MAbs I, II, III, and IV detected the Japanese isolate of WYMV and American isolates of WSSMV only when they were captured by anti‐WYMV polyclonal antibodies, A French isolate of OMV was detected only by the MAbs I and II in TAS ELISA with Polyclonal anti‐BaYMV.
The Effects of Light and Photo‐ and Protein‐synthetic Inhibitors on the Sekiguchi Lesion Formation by Magnaporthe grisea in Rice cv. Sekiguchi‐asahi*
Authors: Arase S. , Fukuyama R. , Tokizawa K. , Ikegami S. , Honda Y. , Nozu M.
Published: May 2008

The significance of light irradiation in Sekiguchi lesion (SL) formation by infection with Magnaporthe grisea on rice cv. Sekiguchi‐asahi was investigated. When the leaf blades of cv. Sekiguchi‐asahi inoculated with M. grisea spores were kept under different wavelengths of light. SLs were formed under visible light regardless of the compatibility between fungal race and cv. Sekiguchi‐asahi. On the contrary, typical blast and/or nectrotic spot lesions were formed under near ultraviolet radiation from the black light fluorescent lamps and near infrared radiation from infrared fluorescent lamps. The effective wavelength for light‐dependent SL formation was 400–700 nm. Furthermore, the longer the wavelength of radiation, the bigger were the SLs. Such light‐dependent induction of the SL was suppressed by pretreatment of 3‐(3,4‐dichlorophenyl)‐l,l‐dimethylurea (DCMU) and cycloheximide (CY). These results suggested that photosynthetic and protein synthetic activities were involved in SL formation.
The Symptoms and Cause of Guava Wilt in South Africa
Authors: Schoeman M. H. , Benade E. , Wingfield M. J.
Published: May 2008

Wilt of guava (Psidium guajava), a serious disease occurring in most guava producing areas of the Northern and Mpumalanga provinces of South Africa, was shown to be induced by a fungus tentatively identified as Penicillium vermoesenii. This fungus is the cause of a blight of ornamental palms in the United States and Belgium and its occurrence on guava is enigmatic. Pathogenicity tests were conducted in the glasshouse and under field conditions. Symptoms on trees include wilting, chlorosis and defoliation.
Cytological and Physiological Reasons for the Latent Type of Infection in Sunflower Caused by Plasmopara halstedii
Authors: Heller A. , Rozynek B. , Spring O.
Published: May 2008

Lightmicroscopy was used to investigate cytological and physiological reasons for the latent type of infection of sunflowers with Plasmopara halstedii. Sections of the hypocotyl of inoculated, but healthy looking plants of compatible and incompatible host‐pathotype combinations revealed vital hyphae and oospores, thus indicating an uninterrupted life cycle of the pathogen. Plants with latent infections showed enhanced cell division activities which restricted the pathogen to the cortical parenchyma. Additionally, hypersensitive reactions inhibited further growth in the pith parenchyma. In contrast, for systemic infection a successful invasion by the pathogen of the pith parenchyma of the hypocotyl and a growth of the hyphae faster than the hypersensitive reactions of the host tissue are needed.
Bacillus pumilus, the Cause of Bacterial Blotch of Immature Balady Peach in Egypt
Authors: Saleh O. I. , Huang Pi‐Yu , Huang Jeng‐Sheng
Published: May 2008

Five pectolytic isolates of Bacillus were isolated from bacterial blotch of immature fruits and leaves of Balady peach (Prunus persica cv. Balady) grown in EI‐Minia Governorate in Egypt. Inoculation of the isolated bacteria into premature peach fruits and leaves resulted in the development of large brown spots. The isolated bacterium was identified as Bacillus pumilus from its physiological and biochemical properties, pathogenicity, electron microscopy and fatty acid composition analysis. B. pumilus also induced soft rot on wounded American stone and pome fruits such as Autumn Large and Southern peach, Large Red plums, Golden Delicious and Gala apple and Bartlet pear. Unwounded Autumn Large peach and Bartlet pear were also affected. Moreover, they degraded the parenchymatous tissues of many tested plant organs under experimental conditions. B. pumilus produced endopolygalacturonase (EC 4.2.2.1) and endopectin lyase (EC4.2.2.3) in vitro and in vivo. This is the first report of the disease occurring in Egypt.
Esterase Activity from Venturia nashicola: Histochemical Detection and Supposed Involvement in the Pathogenesis of Scab on Japanese Pear
Authors: Müller M. W. , Ishir H.
Published: May 2008

Conidia of Venturia nashicola were collected from naturally scab‐infected leaves of Japanese pear. Conidia‐derived esterase activity was detected histochemically during the course of infection in ungerminated conidia, germ tubes, appressoria and conidia exudates. The esterase activity derived from conidia was partly inhibited in vitro by the specific cutinase inhibitor o‐methyl‐o‐butyl‐o(3,5,6‐trichloro‐2‐pyridyl)phosphate and by the serine hydrolase inhibitor diisopropylfluorophosphate. The specific cutinase inhibitor applied at a concentration of 1.5 ppm did not influence the germination rate of the conidia on pear leaves but reduced the formation of subcuticular fungal structures by 64%, It was concluded that cutinase activity from conidia of V. nashicola probably plays an important role in the pathogenesis of scab during the invasion process.
Ultrastructural Studies on the Colonization of Banana Tissue and Fusarium oxysporum f. sp. cubense Race 4 by the Endophytic Bacterium Burkholderia cepacia
Authors: Pan M. J. , Rademan S. , Kunert K. , Hastings J. W.
Published: May 2008

Colonization on banana roots and on the pathogenic fungus, Fusarium oxysporum f. sp. cubense race 4, causing banana wilt disease, by the endophyte Burkholderia cepacia isolated from asparagus, which might be used as a biological control agent, was investigated with the aid of scanning and transmission electron microscopy. B. cepacia was able to colonize the surface of hyphae of F. oxysporum f. sp. cubense and the fungal macrospores. In vitro colonization ofthe fungus by the endophyte resulted in mycelial deformation with terminal and intercalary swelling. In the banana plant B. cepacia was closely associated with banana roots. A matrix was frequently found to be present between the bacterium and the plant surface. Transmission electron microscopy observations showed that B. cepacia exists mainly in the intercellular space of the banana root tissues.
Les Phénolamides des Rachis de Palmes, Composants de la Réaction de Défense du Palmier Dattier vis‐à‐vis de Fusarium oxysporum f.sp. albedinis, Agent Causal du Bayoud
Authors: Ramos T. , Bellaj M. EL , Idrissi‐Tourane A. EL , Daayf F. , Hadrami I. EL
Published: May 2008

Phenolamides in the Rachis of Palms: Components of the Defence Reaction of the Date‐palm towards Fusarium oxysporum f.sp. albedinis, the Causal agent of ‘Bayoud’

This is the first study showing evidence of the production of phenolic and phenolamidic compounds in date palm tissues in response to attack by Fusarium oxysporum f.sp. albedinis (Foa), the causal agent of the wilt called bayoud. Marked quantitative and qualitative differences were recorded in the production of such compounds when infected and healthy rachis, were compared. In addition, localized accumulation of some compounds was detected when infected and healthy parts of the same rachis were analysed. Three induced hydroxycinnamoylamides were detected in high concentrations. They were isolated and tested for their toxicity against Foa. These compounds were shown to strongly inhibit conidial germination and germ tube growth of the pathogen and must be considered as phytoalexins. The role of amides in the date palm resistance to the bayoud is discussed.
Induced Resistance in Pepper Leaves Infiltrated with Purified Bacterial Elicitors from Xanthomonas campestris pv. vesicatoria
Authors: Romeiro R. S. , Kimura O.
Published: May 2008

Cell components (lipopolysaccharide (LPS), exopolysaccharide (EPS), capsular glycoproteins and the cell envelope) were extracted and purified from cells of compatible and incompatible isolates of Xanthomonas campestris pv. vesicatoria and infiltrated into pepper leaves in an attempt to protect them against a compatible isolate. All cell components induced protection but only EPS and the cell envelope elicited phytoalexins. Therefore, resistance mechanisms other than phytoalexins may exist in pepper leaves and appear to be more effective than phytoalexins.
Detection of Polymorphism in Puccinia hordei using RFLP and RAPD Markers, Differential Cultivars, and Analysis of the Intergenic Spacer Region of rDNA
Authors: Jennings J. M. , Newton A. C. , Buck K. W.
Published: May 2008

A world‐wide range of isolates of Pucinia hordei and P. striformis f. sp. hordei and UK isolates of P. striformis f. sp. tritici and P. recondita were characterized using DNA restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNAs (RAPDs), ribosomal DNA (rDNA) intergenic sequence(IGS) or virulence on differential cultivars. The different species were readily distinguished by both RFLPs and RAPDs. Within a species, variability was detected using differential cultivars, RAPDs, and RFLPs with probes from the rDNA region, indicating their potential for population analysis. However, RFLPs within a species were not detected using a wide range of random (anonymous) probes from a P. hordei genomic library. Previous assumptions about the general uniformity of rust genotypes were reassessed from these data.
Cytopathology of Developing Anthers and Pollen Mother Cells from Lettuce Plants Infected by Lettuce Mosaic Potyvirus
Authors: Hunter D. G. , Bowyer J. W.
Published: May 2008

Ultrastructural studies of developing anthers from young flowers of lettuce (Lactuca saliva L.) infected with lettuce mosaic potyvirus (LMV) revealed infection in the pollen mother cells of one of three plat. Within the infected pollen mother cells, structures reminiscent of bundles and partly formed pinwheel inclusions were observed, Immunogold labelling showed that particles of LMV were associated with these structures. Neither large aggregates of LMV particles nor complete pinwheel inclusions were observed in pollen mother cells. Infection of pollen mother cells was consistently correlated with infection of the adjacent tapetal cell layer. Pollen mother cells of two other LMV‐infected plants were not infected. This study supports the hypothesis that early invasion of the floral meristem is necessary for virus infection of mature pollen grains.
Involvement of Toxins Produced by Pseudomonas fuscovaginae in Aetiology of Rice Bacterial Sheath Brown Rot
Authors: Batoko H. , Bouharmont J. , Kinet J.‐M. , Marite H.
Published: May 2008

The incidence of bacterial sheath brown rot of rice was assessed throughout the whole cycle of rice plat cultivation after seedling inoculation, under greenhouse conditions. Typical symptoms of the disease were expressed at the booting. The degree of disease susceptibility could be determined after heading by monitoring panicle emergence rate of diseased plants. Inoculation at the booting stage showed that tolerance could be associated with reduced bacterial growth 4 days after inoculation. Rice plants were sensitive to purified bacterial toxin at all growth stages. The toxins reproduced symptoms observed on diseased plants. In particular, poor panicle emergence, due to inhibition of culm elongation during heading, could be clearly attributed to the detrimental effects of the toxins. For the cultivars investigated in this study, the severity of the toxin damage was related to the degree of cultivar susceptibility to the pathogen, although the phytotoxins are non‐host‐specific. These phytotoxins can therefore be considered as integral part of the plant pathogen‐interaction.
Phenolic Compounds of Apple and their Relationship to Scab Resistance
Authors: Mayr U. , Michalek S. , Treutter D. , Feucht W.
Published: May 2008

The contents of 15 different phenolic compounds in apple leaves and fruit skin from various orchards were determined by HPLC. High concentrations of flavan‐3‐ols were found in those orchards which were not infected by Venturia inaequalis. This observation corroborates earlier findings on different cultivars. The hypothesis that these compounds could be involved in the resistance of apple to scab was tested by inhibiting the key enzyme of the phenol biosynthesis, the phenylalanine‐ammonia‐lyase, in young shoots of the resistant genotype ‘Sir Prize'. After inoculation of the inhibitor‐treated leaves, severe symptoms of the disease occurred. The fungal infection was confirmed by histological studies. No flavonal‐accumulation could be observed at the infection site which was the case in the non‐inhibited but inoculated controls.
Somatic Embryogenesis from Style Culture as a Possible Means for Virus Elimination in Citrus
Authors: D'Onghia A.M. , de Pasquale F. , Carimi F. , Savino V. , Crescimanno F.G.
Published: May 2008

Somatic embryos were obtained from stylar tissues of three lemon plants, one of cv Lunario, one of Femminello Zagara Bianca, and one of Femminello Santa Teresa. These plants, as shown by visual observations and indexing on woody indicators, were affected by exocortis and two or more virus‐like diseases such as psorosis, concave gum, impietratura and cristacortis. Two of the sources contained also mechanically transmissible viruses. Twelve 18‐month‐old plantlets originating from style culture‐derived somatic embryos, four from each source, consistently gave negative reactions when assayed by grafting, mechanical inoculation, and serologically for the presence of viruses, virus‐like agents and viroids. It was concluded that, similar to other woody species (e.g. grapevine), somatic embryogenesis opens new possibilities for the sanitary improvement of Citrus.
RAPD‐based Molecular Diagnosis of Mixed Fungal Infections on Oilseed Rape (Brassica napus): Evidence for Genus‐ and Species‐specific Sequences in the Fungal Genomes
Authors: Schleier S. , Voigt K. , Wostemeyer J.
Published: May 2008

Oilseed rape (Brassica napus) is attacked by many parasitic fungi which often occur in mixed infections. Monitoring of these phytopathogens by morphological criteria is restricted due to their appearance especially in the later stages of disease development.

We have developed molecular markers for a clear‐cut differentiation of a variety of rape seed pathogenic fungi based on randomly amplified polymorphic DNA (RAPD). Twenty polymorphic fragments have been selected in Southern hybridization experiments to test their taxon‐specificity. In summary, only four amplification products gave unspecific cross‐hybridization patterns, one fragment corresponds to a genetic element common to three species within the genus Alternaria, and 15 RAPD markers were highly specific for distinct fungal species. This report demonstrates the value of the RAPDPCR technique to amplify taxon‐specific DNA fragments that can be used as hybridization probes for the diagnosis of a variety of rape seed pathogens (Alternaria brassicae, A. brassicicola, A. raphani: Cylindrosporium concentricum; Fusarium moniliforme; Phoma lingam; Pythium sp.; Rhizoctonia solani, Sclerotinia sclerotiorum; Verticillium dahliae, V. latericium).
The Potential for Pollen‐borne Virus Transfer in a Plum Orchard Infected With Prunus Necrotic Ringspot Virus
Authors: Milne J. R. , Walter G. H.
Published: May 2008

Prunus necrotic ringspot virus (PNRSV) is borne in stonefruit pollen. Previous work has shown that virus particles can enter cucumber seedlings when virus‐bearing pollen grains contact puncture holes made in plant cells by thrips feeding. Stonefruit plant parts on which pollen is deposited and thrips spend considerable time feeding, are likely sites of PNRSV inoculation. The principal agents of pollen deposition may therefore play a key role in PNRSV epidemiology. We determined the principal sites of pollen deposition on Japanese plum trees and the major pollen depositing agents in a PNRSV‐infected orchard in southeastern Queensland. Plum pollen was deposited mostly onto flowers, with few grains being found on leaves or stems. Within the flowers, pollen grains were distributed mostly on the petals, but some were found on the sepals, filaments and carpels. Honey bees were the most frequent visitors to plum flowers and they deposited more than any other insects. Flies visited flowers at low frequencies and also deposited pollen. Significant amounts of pollen were deposited onto flowers by unidentified nocturnal agents. Thrips were not observed during the study period, although they were present in the orchard. Previous studies have assumed that thrips carry virus‐bearing pollen as well as bring it into proximity of feeding wounds. Our results suggest that, although thrips carriage of pollen may occur, it is not necessary for PNRSV spread in stonefruit orchards.
Deoxynivalenol and Acetyldeoxynivalenol Accumulation in Field Maize Inoculated with Fusarium graminearum
Authors: Perkowski J. , Proñczuk M. , Chelkowski J.
Published: May 2008

Seven selected maize hybrids (Smolimag, Ruten, KLG 2210, Zenit, Betulisa, RAH BE 86101 and RAH BE 90102) were toothpick inoculated in the ear (at ∼ 10 days after midsilk) with a single isolate of Fusarium graminearum in order to determine their reaction to infection and susceptibility to mycotoxin accumulation in the tissues. Deoxynivalenol (DON), 15‐acetyldeoxynivalenol (15‐AcDON), and 3‐acetyldeoxynivalenol (3‐AcDON) were detected in differing amounts in kernels, husks, stalks (nodes and internodes) and roots. DON was recovered from stems, husks and damaged kernels at levels of 864, 278 and 93mg/kg, respectively, while 15‐AcDON was recovered at 235, 55 and 11mg/kg and 3‐AcDON was recovered at 3, 2 and 0.5 mg/kg, respectively. Maize hybrids Smolimag and Ruten were most resistant to infection and contained the lowest amounts of mycotoxins in the tissues while Zenit, RAH BE 90102, RAH BE 86101 and Betulisa were most susceptible to infection and accumulated higher amounts of mycotoxins.
Investigations on the Activity of Cell Wall‐degrading Enzymes in Young Wheat Plants After Infection with Pseudocercosporella herpotrichoides (From) Deighton
Authors: Mbwaga A. M. , Menke G. , Grossmann F.
Published: May 2008

In earlier investigations, it has been demonstrated that Pseudocercosporella herpotrichoides (Fron) Deighton is capable of producing pectolytic and cellulolytic enzymes as well as hemicellulases in vitro. The investigation of enzyme activity in extracts from wheat plants infected with P. herpotrichoides (isolates 21e and R6) and from non‐infected plants revealed the activity of the following enzymes: pectin methylesterase (PME), polymethylgalacturonase (PMG), pectin lyase (PL), carboxymethylcellulase (CMCase), xylanase and arabanase. Compared to non‐infected plants, the enzyme activity in infected plants was considerably higher; in some experiments, only traces of enzyme activity could be found in control plants. The difference in the enzyme activity in infected as compared to non‐infected plants was, in most cases, statistically significant, especially beginning at the end of the second week after inoculation.

The enzyme activity depended on the temperature during plant cultivation; with the exception of pectin methylesterase (PME), the activity of all investigated enzymes increased with temperature and the highest activity was found in plants grown at 20°C. The highest PME activity was measured in plants grown at 10°C; the activity of this enzyme was generally lower at 15 and 20°C.
Distribution of Antagonistic Streptomyces griseoviridis in Rhizosphere and Nonrhizosphere Sand
Authors: Kortemaa H. , Pennanen T. , Smolander A. , Haahtela K.
Published: May 2008

The ability of Streptomyces griseoviridis to colonize roots was studied on turnip rape (Brassica rapa ssp. oleifera) and carrot (Daucus carota) using the sand‐tube method. The biofungicide Mycostop or a spore suspension of S. griseoviridis was mixed in sterile and in non‐sterile sand. Population densities of the antagonist in the rhizosphere were significantly higher than in non‐rhizosphere and in root‐free sand. There was no significant difference between the plant species and root depths on distrubution of the antagonist. Higher rates of detection were achieved when root segments were placed on petri plates of agar than when homogenized and subsequently dilution plated. Homogenization of sand samples increased the detected population densities of S. griseoviridis. Muramic acid assay with HPLC indicated higher densities in the rhizosphere compared with non‐rhizosphere and rootfree sand. Distribution of S. griseoviridis in the rhizosphere was observed using scanning electron microscopy. The antagonist produced high spore densities in the root‐hair zone of turnip rape. S. griseoviridis mixed in sterile and non‐sterile sand survives in the rhizosphere, non‐rhizosphere and root‐free sand where it probably exists both as spores and mycelia.
Endo‐ and Exochitinase Activity in Kiwifruit Infected with Botrytis cinerea
Authors: Wurms K. , Long P. , Greenwood D. , Sharrock K. , Ganesh S.
Published: May 2008

Endo‐ and exochitinase activities were determined in autoclaved leaves, live leaves, and fruit of kiwifruit (Actinidia deliciosa var. deliciosa cv. Hayward [A. Chev.]Liang and Ferguson) following infection with Botrytis cinerea (Pers.). Appreciable endochitinase activity was found in healthy and diseased leaves and fruit at harvest and after cool‐storage, but was absent in plant tissue killed by autoclaving. Later harvested fruit produced more endochitinase activity in storage than did early harvested fruit. Exochitinase activity was only associated with diseased tissue, and was present in diseased autoclaved leaves. The results suggest that endochitinase activity originates from the plant whilst exochitinase is associated with the pathogen. The significance of these findings is discussed.
Induced Resistance to Erwinia carotovora ssp. atroseptica, Through the Treatment of Surface Wounds of Potato Tubers with Elicitors
Authors: Dutton M. V. , Rigby N. M. , Macdougall A. J.
Published: May 2008

We have investigated the ability of mixed oligogalacturonides, a cell wall hydrolysate from Phytophthora sojae Hildebrand, and chitosan oligomers to induce resistance to Erwinia carotovora ssp. atroseptica in potato tubers (cv. Pentland Squire). Natural infection by Erwinia in stored potatoes generally originates in the surface tissues which have a markedly different biochemical composition to the perimedullary tissue. We therefore investigated the effect of different elicitors in inducing resistance in 2 mm deep wounds made on the surface of potato tubers. When wounded in this way and stored at 20°C and 100% relative humidity, tubers developed a significant level of natural resistance within 24 h. When the potatoes were treated with oligogalacturonides, or Phytophthora cell wall hydrolysate at the time of wounding and challenged with inoculum 8 h later, a significant reduction in disease occurred. Treatment with the chitosan elicitor had no effect on resistance.
Germination and Infectious Potential of Microconidia of Sclerotium cepivorum
Authors: Gindro C. , L'Hoste G.
Published: May 2008

Observation with the scanning electron microscope showed that microconidia of Sclerotium cepivorum are able to germinate on onion plants. A young hypha penetrated the plant cuticle. Cytochemical techniques gave evidence of phenoloxydase and esterase activities in microconidia and thus confirmed their infectious potential. Massive production of microconidia was induced by immersion of the fungus in water.

These elements suggest that in high moisture conditions microconidia of S. cepivorum might play a crucial role in survival and dissemination of the fungus.