bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of Potato Viruses Y and A in Tubers by Enzyme‐Linked Immunosorbent Assay after Natural and Artificial Break of Dormancy
Authors: Vetten H. J. , Ehlers U. , Paul H. L.
Published: May 2008

The effects of natural and artificial break of dormancy on the detection of potato viruses Y (PVY) and A (PVA) in tubers of field‐grown potato cultivars with primary and secondary infections were studied by enzyme‐linked immunosorbent assay (ELISA). Both viruses were at low concentration and unevenly distributed in dormant ‐tubers. Four to six weeks after treatment with Rindite, maximum concentrations of PVY and PVA were detected at both tuber ends with generally higher values at the rose end than at the heel end. Slower and smaller virus increase and a retarded and/or limited virus translocation were observed in treated tubers of resistant cultivars. Consequently, detectability of PVY and PVA was higher in tubers of susceptible cultivars than in those of the resistant ones. Detection of both viruses was very difficult and unreliable in tubers after natural break of dormancy. The very low concentration of PVY and PVA in dormant tubers and their drastic multiplication in Rindite‐ treated tubers appear to be characteristic of potyviruses and are unique among the major potato viruses.
Über Entstehung und Keimung der Chlamydosporen von Botrytis cinerea Pers.
Authors: Urbasch I.
Published: May 2008

On the genesis and germination of the chlamydospores of Botrytis cinerea Pers.

The chlamydospores of Botrytis cinerea are hyaline single cells of extremely variable form and size. They are formed under conditions unfavourable for growth as terminal or intercalary cells by transformation of vegetative mycelium parts and are liberated by hyphal disintegration.

The chlamydospore genesis in vitro in aging malt agar cultures began about after one month. But the chlamydospore formation could also be initiated earlier by different conditions of culture.

The chlamydospores germinated either with hypha or by microconidia — a herewith first described mode of germination. Intermediates of these both modes of chlamydospore germination could be regulated very differentiatedly by transferring the chlamydospores into malt solution (2%)and/or destilled water and by changing the duration of stay in the individual media. Under adverse external conditions no germination occurred.

The three Botrytis cinerea‐isolates did not show any differences in habitus, genesis and germination of their chlamydospores.

Also in vivo on outdoor‐ and greenhouse‐tomatoplants the occurrence of chlamydospores was no rarity. Since the chlamydospores are produced under very different adverse conditions of growth but cannot survive a period of drought lasting longer than three months without damage, they do not represent long‐termed resistant perennating structures, but temporary stages of the fungus for intervening periods.
A Test System for the Quantitative Assessment of Resistance to Mildew in Rye (Secale cereale L.)
Authors: Llnd V.
Published: May 2008

A test system is presented allowing the quantitative measurement of two resistance components, number of mildew infections per cm2 and spore production. The infection frequency is obtained from segments of the first leaf. The spore production is determined spectrophotometrically using suspensions from the infected second leaf of the same plant.

The assessment of resistance can be extended to later growth stages of the genotypes, thus providing information about the dynamics of mildew development and the existence of adult plant resistance. Multiple measurements of resistance (two components, several growth stages) increase the reliability of single plant evaluation and enhance the response to selection. This point is especially important in population breeding of rye.
Development of Cronartium flaccidum (Alb. et Schw.) Wint. on Vincetoxicum officinale Moench in Connection with some Environmental Factors
Authors: Ragazzi A.
Published: May 2008

Experiments on the development of Cronartium flaccidum on Vincetoxicum officinale in connection with environmental factors (temperature, moisture, brightness) in the years 1975, 1976, and 1977 are reported.

Uredia appeared from the 7th to the 13th day after inoculation and terminated from the 14th to the 18th day. Urediospores appeared from the 9th to the 18th day and ended from the 18th to the 25th day.

High temperatures advanced the beginning of the disease's development, but interfered with subsequent development.

Telial columns formed from the 18th to the 22nd day after inoculation. They were particularly influenced by precipitation, but high temperatures had a negative effect on their formation.

Telial columns ripened 2–3 days after their formation. Light affected the appearance of uredia and telial columns: many more uredia and telial columns were formed at 4000/5000 lux than at 5000/6000 and 8000/9000 lux.

The first occurrence of the symptoms was on the young leaves. Leaves of V. officinale, inoculated with dried aeciospores, did not show any infection.
Seasonal Changes in the Chloroplast Ultrastructure in Abutilon Mosaic Virus (AbMV) infected Abutilon spec. (Malvaceae)
Authors: Schuchalter‐Eicke Gabriela , Jeske Holger
Published: May 2008

Various kinds of pathological effects of the Abutilon Mosaic Virus (AbMV) in seasonal dependency have been observed on the macroscopic as well as on the microscopic level. The annual rhythmic fluctuation of light caused by the varying length and intensity of light incidence is directly correlated with the realization of symptoms, leading to an intensification of the leaf mosaic and to an increase in the light leaf areas during the summer. These macroscopic observations are correlated with an annual change in the plastid fine structure in the mesophyll of the lightest areas of the leaf. The grana‐stroma‐organization of the plastids is completely eliminated through a reduction and disorganization in the thylakoid system during the spring and summer, restored in the autumn, and preserved over the winter. This change in the plastid fine structure is limited to the leaf mesophyll. The plastids of the leaf stem, like the plastids of non‐infected plants, do not display any change in their fine structure.
Effects of Plant Nutrition on Susceptibility of Potato Leaves to Phytophthora infestans
Authors: Carnegie S. F. , Colhoun J.
Published: May 2008

A complete NPK fertilizer applied at planting, but not at later times, influenced the resistance of potato leaves to infection by Phytophthora infestans and the subsequent growth of lesions. Lesion size (7 days after inoculation) and lesion growth rate (between 7 and 9 days after inoculation) increased linearly with increasing fertilizer rates. Increasing rates of phosphate or potash, applied separately, did not significantly affect the development of blight lesions but a linear increase in lesion size was associated with increasing application rates of nitrogen.
Activation of Teliospore Germination in Uromyces appendiculatus var. appendiculatus1)
Authors: Gold R. E. , Mendgen K.
Published: May 2008

The effects of aging and temperature on teliospore germination in Uromyces appendiculatus var. appendiculatus were studied.

1. Indoor storage was good at ∼ 4 °C in the dark. Under these conditions spores remained dormant for ∼ 9 mo, but thereafter germination gradually increased to a maximum (∼ 63 %) after 36 mo. Spores stored outdoors showed a marked increase in germination after ∼ 4 mo and reached maximum (∼ 73 %) at 7–8 mo.

2. The optimum temperature for germination was at 18°C. While freezing (–18°C) and thawing (20 °C) had no beneficial effect on spore germination, heat treatments from 30–32 °C for 3–4d proved effective in activating teliospore germination. Heat treatments caused an increase in spore mortality. Basidiospore release from heat‐treated teliospores was markedly reduced compared to control spores.

3. In all experiments the emergence of metabasidia was preceded by an obligatory 3–5 d lag period regardless of the treatment given, the age or level of germinability of treated and control spores.
Effect of Aliette on AMV Infection of Bean Leaves and on the Resultant Alterations in the Patterns of Proteins and Peroxidases
Authors: Abu‐Jawdah Y. , Kummert J.
Published: May 2008

Increased peroxidase activity as well as changes in the patterns of soluble proteins, and peroxidases were observed following infection of bean leaves with AMV.

Foliar sprays with Aliette® (phosethyl Al) at 2000 ppm a. i. delayed the appearance of necrotic local lesions and reduced their final number on primary bean leaves following inoculation with alfalfa mosaic virus (AMV).

The delay in the appearance of symptoms observed on Aliette‐treated inoculated leaves was correlative with a delay in all the above cited alterations, while reduction of final symptoms was correlative with a decrease of these alterations.
Radiation Effects on Cellular Metabolism and Disease Resistance of Jute
Authors: Purkayastha R. P. , Ray Chandi
Published: May 2008

Air dried seeds of seven jute (Corchorus capsularis L.) cultivars were irradiated with different doses of X‐rays. JRC 1108 and JRC 412 were most and least sensitive to X‐rays, respectively. JRC 412 was susceptible to Colletotrichum corchorum both before and after X‐irradiation while JRC1108 became more resistant after treatment. Leaf diffusates but not leaf exudates of both non‐irradiated and X‐irradiated (40,000 r) cvs. exhibited antifungal activity which was more pronounced in case of irradiated JRC 1108. JRC 412 contained greater amounts of amino acids than JRC 1108 both before and after X‐irradiation. Signifinon‐irradiated, infected ones. The physiological implications of the results are discussed in relation to greater resistance of X‐irradiated JRC 1108.
Lutte Contre le Chancre à Didymella lycopersici de la Tomate par Chauffage Solaire (Solarisation) des Tuteurs
Authors: Besri M.
Published: May 2008

Solar heating (solarization) of tomato supports for control of Didymella lycopersici stem canker Previous studies have shown that Didymella lycopersici survives mainly in reed canes (Arundo donax) and Eucalyptus stakes used to support tomatoes. The solarization of the supports during the hot months of the year (May‐August), by an old transparent plastic film (180μ) which was used for two years as a cover to a plastic tunnel, reduced considerably, and without any cost, the incidence of the disease. In the plots trellised with solarized and unsolarized supports, the percentage of plants with Didymella cankers at the last month of tomato crop was respectively 1.9 and 20.7%. The maximum temperatures recorded in the atmosphere, from May to September vary from 26 oC to 34 oC. The maximum temperatures recorded during the same period under plastic were always higher than 50 oC. U.S.
Common Leafspot of Alfalfa: Ascospore Discharge and Plant Infection in the Field
Authors: Semeniuk G.
Published: May 2008

Peak daily discharge of Pseudopeziza medicaginis ascospores in the field occurred after sunrise with attendant rises in temperature, wind, speed, and. dissipation of moisture. Protracted discharge over many days rose with initial development of robust, uncrowded apothecia and fell as these became spent and were joined by less productive, small, crowded ones. In the laboratory, detached field‐infected leaves discharged ascospores at 5°C to 32.5°C and at relative humidities as low as 90% when fresh, and at 94% or higher when wilted or dried. Pathogen‐free alfalfa plants placed overnight in a diseased affalfa plot were inoculated but uninfeeted more frequently in July than they were inoculated and infected. Artificially‐inoculated plants placed at the same time in a nearby sugar beet plot became infected every overnight. From early September through early October artificially inoculated plants placed in a plot of sugar beets or a plot of nearly disease‐free alfalfa for 24 h periods, became infected in 18 and 19 of 29 such periods. Light rain, fog and dew were frequent during these periods and early morning temperatures fell between ‐ 3 °C and 5 °C‐ in one‐half of the overnights. Dormant ascospores on foliage remained fully infective in the greenhouse for at least 10 days.
Isolation and Identification of Pythiaceous Fungi from Irrigation Water and their Pathogenicity to Antirrhinum, Tomato and Chamaecyparis lawsoniana
Authors: Pittis J. E. , Colhoun J.
Published: May 2008

Pythiaceous fungi were isolated from irrigation water using a variety of natural and artificial baits. Isolates were also obtained by plating water samples directly on the surface of selective agar media. The selective medium of Ocana and Tsaq (1966) PlOVP, was modified by substituting rifampicin and ampicillin (10 and 500 μg cm−3 respectively) for vancomycin to suppress bacterial growth from water samples.

The pythiaceous fungi were identified as Pythiitm dissotocitm, P. middletonii, P. mamillatum, P. rostratum, Pythium“group 1”, “group 2” and “group 3” and Phytophtbom gona‐podyides. All isolates of P. gonapodyides were the A1 strain and produced oospores when paired with an A2 isolate of P. drechsleri.

Isolates were tested for their pathogenicity to Antirrhinum, tomato and Chatmaecyparis lawsoniana cv. Ellwoodii. Pythium middletonii and Pythium“group 1” caused severe pre‐emergence damping‐off of Antirrhinum seedlings, P. mamillatuni, P. rostratum and Pythium“group 3” were less pathogenic to the same host while P. dissotocum, Pythium“group 2” and Phytophthora gonapodyides were non‐pathogenic. Only isolates of Pythium“group 1” were pathogenic to tomato seedlings. None of the fungi was pathogenic to rooted cuttings of Chamaecyparis lawsoniana cv. Ellwoodii.
The Use of a Simple Electron Microscope Serology Procedure to Observe Relationships of Seven Potyviruses
Authors: Walkey D. G. A. , Webb M. J. W.
Published: May 2008

The relationships between bean yellow mosaic (BYMV), bean common mosaic (BCMV), clover yellow vein (CYVV), lettuce mosaic (LMV), potato virus Y (PVY), turnip mosaic (TuMV) and celery mosaic (CeMV) viruses were studied in homologous and heterologous reactions, using simple and relatively rapid electron microscope serology decoration tests. The degree of relationship between these viruses was assessed by the intensity of antibody coating when the viruses were decorated by heterologous antibodies. A close relationship was observed between BYMV and CYVV, and between BYMV and LMV but not between CYVV and LMV. CeMV was quite closely related to BYMV and CYVV.

Antibodies to BCMV and BYMV intensely decorated different strains of their own virus, but decoration was negligible in cross reactions.
Dieback of Passion Fruit in Surinam
Authors: Power R. H. , Verhoeff K.
Published: May 2008

In Surinam, the commercial cultivation of the yellow passion fruit (Passiflora edulis f. flavicarpa) is difficult due to the occurrence of dieback. Symptoms referred to as dieback include a decrease in elongation of the shoot end internodes after a period of normal growth leading to wilting and death of the shoots. Fruits from plants showing dieback symptoms are much smaller than those from healthy plants. From shoots with dieback symptoms, three fungi were isolated including Colletotrichum gloeosporioides. However, inoculation experiments with these fungi on shoots of vigorously growing plants were negative, even after wound inoculation.

It appeared that plants with dieback symptoms had a poorly developed root system, From these roots Fusarium solani was isolated, which appeared to be highly pathogenic to roots of the yellow passion fruit. After inoculation of the roots of 3‐month‐old plants, roots became infected and the aerial plant parts showed typical dieback symptoms.

Plants with their root system reduced either by inoculating with F. solani or by clipping, and subsequently inoculated with C. gloeosporioides on the aerial parts 2 weeks later, showed dieback symptoms and infection by C. gloeosporioides in shoots with these symptoms. Thus, a badly functioning root system, for example caused by infection of F. solani leads to dieback and predisposes plants to infection by C. gloeosporioides. The latter fungus itself is not a primary pathogen of shoots of the yellow passion fruit in Surinam.
Antiphytovirale Verbindungen mit nichtzyklischer Azin Struktur
Authors: Schuster G. , Heinisch L , Schulze W. , Ulbright H. , Willitzer H
Published: May 2008

Antiphytoviral compounds with noncyclic azine structutre

The antiphytoviral activities of variously substituted compounds with noncylic azine structures have been studied f a total of 90 tested compunds 42 had the effect of more or less strong inhibiting the concentration of potato virus X (PVX) in inoculated and / or secondarily infected leaves of Nicotiana tabacum L. cv Samsun (Table.1) An effect on the virion of PVX in vitro couldn't be observed (Table.2) Thus the substances may interact with the virus replication. Some of them also reduced the number of local lesions caused by tabacco mosaic virus on leaves of Nicotiana glutinosa L. (Table‐3) Several Compounds proved exellent synergists of 2,4‐ dioxohexahydro‐ 1,3,5‐ triazine (DHT = 5 azadihydrouracil; Table 4) Pyridine‐ 3‐ aldehyde S ethyl isothiosemicarbazone and the Cu complex of 1‐ ethyl‐isatine S‐ ethyl isothisosemicarbazone when used in combination with 2,4 dioxohexahydro‐ 1,3,5, triazine, greatly increased the mass of potato tubers produced from plantlets grown up from patato eye cutting as compared with the indentical control Simultaneously the mentioned substances reduced the number of symptom bearing eye cutting plants Quinoline 2‐ aldehyde‐ N‐ oxide S‐ allyl‐isothiosemicarbazone had the effect of very greatly reducing the number of symptom‐bearing plants without substantially influencing the mass of tubers (Table 5). Thus some compounds with noncyclic azine structure especially when used in combinitation with DHT, may be of high interest for practical application Comparing the structures of compounds with noncyclic azine structure active against plant or human viruses it should be noted that antiphytoviral compounds active in these two different virus host systems often are closely related structurally.
Purification and Characterization of a Jordanian Isolate of Watermelon Mosaic Virus
Authors: Karam N. , Al‐Musa A.
Published: May 2008

The Jordanian isolate of watermelon mosaic virus‐2 (WMV‐2Jo) was purified from infected Cucurbita pepo cv. Top Capi by extraction in 0.05 M sodium citrate buffer containing 0.01 M sodium diethyl dithiocarbamate and 0.01 M cysteine hydrochloride (0.01 M D + C), clarification with chloroform and n‐butanol, sedimentation by ultracentrifugation, and rate‐zonal centrifugation in 10–40% sucrose gradient. The purified virus had an ultraviolet absorption spectrum typical of a nucleoprotein with a low nucleic acid content. Homologous antiserum had a titre of 1: 256, as determined by the ring interface test. Electron microscopy of negatively stained purified virus revealed flexuous particles with a normal length of 750 nm. Cytoplasmic spindle‐shaped inclusions were readily detectable in infected epidermal cells under the light microscope. Thin sections of infected tissue revealed the presence of laminated aggregates, pinwheel and scroll inclusions. The virus reacted with antisera prepared to the Florida strain of WMV‐2 and zucchini yellow mosaic virus in a sodium dodecyl sulfate (SDS) agar gel diffusion test. Using the Derrick‐decoration combined technique of immune electron microscopy, the virus reacted strongly with the homologous antiserum and zucchini yellow mosaic virus antiserum, but less with antiserum prepared to the Florida strain of WMV‐2.
Detection of Seed‐Borne Inoculum of Peronosclerospora sorghi in Sorghum
Authors: Prabhu M. S. C. , Safeeulla K. M. , Venkatasubbaiah P. , Shetty H. S.
Published: May 2008

An alkali maceration technique has been developed to detect internally seed‐borne inoculum of Peronosclerospora sorghi in sorghum seeds. Optimum period for maceration was found to be 36 h. Oospores in the glumes and mycelia in the pericarp and endosperm were clearly demonstrated. Mycelium was found in the pericarp of 40 % of the seeds tested and in the endosperm of 5 % of seeds. The possibility of using this technique to detect seed‐borne downy mildew infection has been emphasized.
A Histochemical Study of Cytoplasmic Changes During Wall Layer Formation in the Oospore of Albugo candida
Authors: Kaur Darshan , Bhandari N. N. , Mukerji K. G.
Published: May 2008

The young multinucleate oogonium in Albugo is double‐walled with an outer layer exhibiting a negative staining reaction for insoluble polysaccharides and an inner layer which is strongly PAS‐positive. The oogonial nuclei exhibit an unusual staining behaviour with aniline blue showing an outer dark blue sheath of proteins surrounding a central hyaline nuclear core.

Various histochemical localizations were performed for tracing the chronological sequence of development of the wall layers of the oospore. The first wall of the fertilized oospore was laid at the interphase of the periplasm and the ooplasm. Subsequent wall layers were formed both on the inner and outer side of the first oosporic wall. The second oosporic wall was formed just internal to the first one and exhibited faint PAS positivity. The third wall of the oospore was formed external to the first one and the PAS‐negative material for this was apparently contributed by the periplasm. This wall layer at later stages acquired a ridged appearance and these ridges in a mature oospore appear as distinct “pegs”. The last wall to be formed is the innermost one and it completely surrounds the central ooplasm. This wall layer is callosic in nature.
An Efficient Microinoculation Procedure to Study Plant Virus Multiplication at Predetermined Individual Infection Sites on the Leaves
Authors: Konate G. , Fritig B.
Published: May 2008

The microinoculation procedure (inoculated are 0.02—0.05 mm2 was carried out using the very thin tip of a stretched Pasteur pipette. It was dipped in a 500 μg/ml suspension of purified TMV, brought into contact with the upper epidermis of the leaf which had been dusted With an abrasive and rotated twice without actually pricking the leaf tissue. Five minutes later, the excess abrasive and virus were removed by rinsing the leaves under water. The procedure was applied to several tobacco‐TMV combinations. It induced the formation of single local lesions with over 90% efficiency on hypersensitively reacting hosts. Comparable efficiencies were obtained with systemically reacting hosts, as evidenced by a radiochemical procedure coupled with indirect ELISA (KONATE and FRITIG 1983). It was found that residual virus originating from the inoculum was negligible and could casily be distinguished form newly synthesized virus, even shortly after the microinoculation. This makes it possible to measure the rates of virus cell‐to‐cell spread and of virus multiplication at various times after inoculation and at various distances form the points of virus entry. These approadies can be extended to the comparison between differently reacting hosts and to the study of interference between different viruses or different virus strains.
Phenolic Compounds and the Polyphenoloxidase and Peroxidase Activity in Callus Tissue Culture‐Pathogen Combination of Red Raspberry and Didymella applanata (Niessl.) Sacc.
Authors: Czech‐Kozbowska M. , Krzywaanaski Z.
Published: May 2008

The content of phenolic compounds as well as the activity of polyphenoloxidase and peroxidase in the red raspberry callus tissue after D. applanata infection were investigated. Two red raspberry cultivars: Latham — relatively resistant and M. Promise — susceptible were used.

In the M. Promise cultivar the amount of phenols, especially o‐diphenols, decreased after infection and stayed more or less on the same level in Latham cultivar. The activity of polyphenoloxidase increased in both of the investigated cultivars, however in the tissue of Latham cultivar this rise was more pronounced than in the M. Promise one. The changes in peroxidase activity after infection were inconsiderable.

The relation between the changes observed after infection in the phenolic metabolism and the differentiated susceptibility of callus tissue to D. applanata of the investigated cultivars was discussed.

The obtained results explain partially the browning of infected callus tissue of one of the investigated cultivar i.e. M. Promise which had already been observed in the earlier investigations.
A Messenger RNA for Tobacco Mosaic Virus Coat Protein in Infected Tobacco Mesophyll Protoplasts
Authors: Ogawa M. , Sakai F.
Published: May 2008

Synthesis of tobacco mosaic virus (TMV)‐specific low molecular weight component RNA (LMC) was investigated in relation to that of other TMV‐related RNAs and proteins, and formation of progeny virus particles using synchronously infected tobacco mesophyll protoplasts.

Timing of LMC synthesis was shown to be almost the same as, but somewhat earlier than that of TMV‐RNA synthesis. In contrast, synthesis of TMV‐specific double‐stranded RNAs (replicative intermediate, RI and replicative form, RF) as well as a high molecular weight virus‐induced protein (140 K protein) showed the maximum incorporation rate 4–6 h earlier than LMC synthesis. While, synthesis of coat protein and formation of progeny virus particles lagged behind LMC synthesis for 6–8 h.

LMC occurring in polysomes was also investigated during the course of virus replication. The amount of produced coat protein calculated theoretically from the amount of LMC in polysomes of infected protoplasts was shown to be well agreed with the experimental results, indicating that LMC in polysomes is actively functioning as messenger for coat protien synthesis in vivo.
Effect of Date of Sowing on the Incidence of Sclerotinia Stem Rot and Wilt of Gram (Cicer arietinum L.)
Authors: Singh U. P. , Singh R. B.
Published: May 2008

Gram (Cicer arietinum L.) was sown at different dates, viz., 15, 22, 29 Oct., 5, 12, 19 and 26 Nov., and 3 and 10 Dec. in 1978–1979 and 1979–1980 in four replications to enable observations to be made on the occurrence and severity of stem rot and wilt infection caused by Sclerotinia sclerotiorum (Lib.) de Bary. The plant height and canopy width were also measured and correlated with the disease intensity. Yield of each plot was taken as the criterion for suggesting to farmers the best period of sowing the gram crop. November was the most suitable period for this purpose.
Mycoparasitism by Coniothyrium minitans on Sclerotinia sclerotiorum and its Effect on Sclerotial Germination
Authors: Tu J. C.
Published: May 2008

Scanning electron microscopy showed that hyphae of Coniothyrium minitans produced appressorium‐like swellings when they came in contact with Sclerotinia sclerotiorum in dual culture on PDA. The parasitized hyphae gradually skrank and collapsed, and hyphae of the mycoparasite were found inside the host hyphae. The mycoparasite hyphae grew inter‐ and intracellularly within the sclerotia of S. sclerotiorum. In the later stages of parasitism, hyphae of the mycoparasite proliferated extensively within the sclerotia and formed pycnidia near the sclerotial surface. At this stage, the sclerotia became flattened, soft and disintegrated. Sclerotia parasitized by C. minitans failed to germinate either myceliogenically or carpogenically.
Appartenance Raciale et Pathogenie Comparée de Quelques Isolats de Verticillium dabliae (Kleb.) Obtenus a Partir de Tomateś Résistantes au Maroc
Authors: Besri M. , Zrouri M. , Beye I.
Published: May 2008

Pathogenecity and race classification of some isolates of V. dahliae from resistant tomato in Morocco

In Morocco, the cv. H 204, resistant to Verticillium dahliae race 1 is widely used under plastic tunnels. Use of this cultivar controlled the disease for many years but recently a high incidence of Verticillium on this hybird was obsereved. V. dahliae was isolated from 90 % of the wilted plants.The other 10 % were infected by F. oxysporum f. sp. lycopersici alone (7 %) or in association with V dabliae (3 %). The inoculation of the Verticillium susceptible cv. Vemone and of the race 1 resistant cv. H 204 by 120 isolates obtained from the resistant hybird, showed that (69 %) of the isolates are race 1 and 31 % are race 2. There are different virulence levels of V. dahliae race 2 both on the susceptible cv. Vemone and on the race 1 resistant cv. H 204. Race 2 on the average was less virulenton the susceptible than on the resistant cultivar.
Réactions histologiques de blés, résistants ou non àľinfection par Pseudocercosporella herpotrichoïdes
Authors: Khan A. R. , Bouriquet R.
Published: May 2008

Histological reactions of wheat resistant or sensitive against infection of Pseudocercosporella herpotrichoides

The microscopic observations reveal important histological differences between the sensitive or resistant varieties. The disease rapidly affect the whole of the first three leafsheath tissues in the “Étoile de Choisy” variety; in the “Roazon” variety, it only affects the first two sheaths. The inter‐ or intracellular mycelia can be observed both under the form of filaments more or less dilated or under the form of dense segments in the sensitive variety. However in the resistant variety, only short segments can be observed. The tissues of those two varieties are gradually destroyed when they are in contact with P. herpotrichoides hyphae, whereas the hyphae remain undamaged. In “Etoile de Choisy” the hyphae develop in great quantity whereas in “Roazon”, the development remains limited. In the variety Ae. ventricosa no. 11, which is very resistant, the parasite rarely penetrates into the more external cell layers of the first leaf sheath,‘those invaded host cells are destroyed by the mycelium but, at the same time, the mycelian hyphae degenerate and dilate. Thus, the Ae. ventricosa no. 11 tissues seem to be the seat of a strong fungic toxic reaction.
Sensibilité des plantules de Triticinées àľagent Pathogène du Piétin‐Verse [Pseudocercosporella herpotrichoïdes (Fron) Deighton]
Authors: Khan A. R. , Bouriquet R.
Published: May 2008

Sensitiveness of seedlings of Triticinae against the pathogenic agens of Pseudocercosporella herpotrichoides (Fron) Deighton

The study of the sensitiveness of 16 varieties or lines of Triticinae against two races of Pseudocercosporella herpotrichoides shows that, whatever the strain used, the importance of the attacks is much less serious on seedlings of Ae. ventricosa no. 11, Ae. squarrosa no. 15, Ae. squarrosa no. 33 and Roazon, Roazon was the least sensitive among the Triticum. It is obvious that Ae. ventricosa is the most resistant one in all varieties or lines used.
A New Strain of Cucumber Mosaic Virus Causing Mosaic Disease of Muskmelon
Authors: Sharma O. P. , Khatri H. L. , Bansal R. D. , Komal H. S.
Published: May 2008

The virus causing mosaic of muskmelon in the Punjab is transmitted through seed, sap and aphids but not through beetle, whitefly, fungi or contact. It systemically infected Nicotiana tabacum (var. “White Burley” and CTRI‐Special), N. glutinosa, N. rustica and Capsicum annuum besides various cucurbit hosts when inoculated mechanically. The virus gave positive reaction with the antiserum of cucumber mosaic virus and the particles are spherical in shape. The virus has been identified as a distinct strain of cucumber mosaic virus and is designated as muskmelon strain of cucumber mosaic virus (CMV‐mst.).
Detection of Seed‐Transmitted Brome Mosaic Virus by ELISA, Radial Immunodiffusion and Immunoelectroblotting Tests
Authors: von Wechmar M. B. , Kaufmann A. , Desmarais F. , Rybicki E. P.
Published: May 2008

The extent of contamination of wheat seedlots by brome mosaic virus (BMV), and the possible transmission of the virus through seed, were investigated by radial immunodiffusion (RID), enzyme linked immunosorbent assay (ELISA), and enzyme‐assisted immunoelectroblotting (IEB) tests. BMV was purified from seed washings, and from plants grown from contaminated seed. All three serological tests proved of value in detecting contaminated seeds, while ELISA and IEB were especially useful in detecting virus in infected plants grown from such seed. Rhopalosiphum padi aphids were shown to increase the incidence of BMV infectLon in seedling batches containing a few seed‐infected plants. The implications of these findings for wheat breeding schemes are discussed.
The Abutilon Mosaic Virus (AbMV) in Different Leaf Tissues of Several Host Species of Malvaceae
Authors: Jeske H. , Schuchalter‐Eicke Gabriela
Published: May 2008

Cytological changes occurring after infection by Abutilon Mosaic Virus (AbMV) have been investigated in the host plants Abutilon sellovianum Rgl., Malva parviflora L., Malva silvestris L., and Sida micrantha Schr. Two types of virus‐like inclusions were found in different tissues: particles of 16–18 nm in diameter and elongated filaments with 6–8 nm in diameter. The particles are detectable in the nuclei (Abutilon sellovianum, Malva spec.) and cytoplasm (Malva spec.) of cells in the bundle area, and the filaments accumulate in the nuclei (Sida micrantha) and the plastids (Malva spec.) of leaf mesophyll cells.
Changes in Nucleic Acid Contents in Rice Plants Inoculated with Pyricularia oryzae
Authors: Padhi B. , Chakrabarti N. K.
Published: May 2008

RNA contents were reduced in rice leaves after infection by Pyricularia oryzea, Decrease was greater with race IE‐2 than with IC‐22. No clear cut differences were found between healthy resistant and susceptible plants but differences between susceptible healthy after inoculation plants were significant. A significant increae in DNA contents was observed after inoculation with either race of P.oryzae.
Role of Seed in Survival and Transmission of Xanthomonas campestris pv. oryzae Causing Bacterial Blight of Rice
Authors: Thri Murty V.S. , Devadath S.
Published: May 2008

Survival period and possibility of seed transmission of X. campestris pv. oryzae were studied. The bacterium survived for longer (170–180 days) in kharif than rabi (120–130 days) harvested seed. The percentage of infected seeds was higher in kharif than rabi. The infected seed when sown failed to produce the symptoms on respective seedlings due to the low number of bacterial population. Present studies indicated that infected seed though may not produce symptoms on the seedlings directly but serve as a source of inoculum form season to season.
Increased Resistance to the Spread of Tobacco Mosaic Virus in Pinto Bean Leaves Caused by Sugar and Light
Authors: Wu J. H. , Dimitman J. E.
Published: May 2008

Ultraviolet light (UV) irradiation increased expansion of TMV lesions in detached Pinto bean primary leaves incubated in darkness. However, if after UV‐irradiation the leaves were incubated in the light, no increase in lesion expansion occurred. The light effect was considered not to be due to photorepair of UV damaged DNA, since non‐photorepairing treatments such as incubation in red light, or delayed exposure to white light after UV irradiation also prevented increase in lesion expansion. The effect of visible light in preventing TMV‐lesion enlargement was shown to be related to photosynthetic energy supply to the host cell defense mechanism since incubation of infected leaves in the presence of the photosynthesis inhibitor 3‐(3,4‐dichlorophenyl)‐l,l‐dimethyl urea (DCMU) in light caused large lesions whether leaves were irradiated by UV or not. Supplying 0.1 M sucrose in the dark also inhibited lesion enlargement in UV‐irradiated or nonirradiated leaves. Dinitrophenol (DNP) negated the sucrose effect in the dark. However, in light incubation, DNP did not induce large lesions indicating that DNP did not interfere with energy supply in the light.

It is concluded that the Pinto bean leaf cells can use energy derived both from mitochondria and chloroplasts for building the resistance mechanism to virus spread. In this case, cellular resistance to virus spread seems to be correlated with callose deposition on the walls of noninfected cells adjacent to the necrotic cells. Energy supply in various forms will assist host cells in building the resistance mechanism as well as retarding senescence. Detachment, prolonged dark incubation, or exogenous supply of DNP led to accelerated senescence which in turn led to secondary enlargement of lesions. The cause of such secondary enlargement may be explained by starvation of cells and disappearance of callose.
Variability in Xanthomonads of Grain Legumes
Authors: Jindal J. K. , Patel P. N.
Published: May 2008

Pulse xanthomonads could not be differed on the basis of their bacteriological propertries. Colonies from cowpea, mungbean, guar, and bean showed differences in virulence related to the degree of mucoidness than to the rate of multiplication. Very weakly virulent mutants of the bean fuscous pathogen produced distinctive reaction in bean pods. White mutants were as virulent as their yellow forms.
Selection for Resistance to Leptosphaerulina Leaf Spot in Alfalfa
Authors: Michaud R. , Richard C. , Surprenant J.
Published: May 2008

Significant differences were observed among 11 alfalfa cultivars for the percentage of plants resitant to Leptospbaerulina briosiana after one inoculation. Screening for resistance was done by inoculating 18 day old plants (cv. Europe), held in a moist chamber, with L. briosiana. The self‐ and cross‐progenies of plants resistant to L. briosiana after two inoculations showed slightly higher resistance to Leptosphaerulina leaf spot than the unselected original population but the difference was significant for the cross‐progeny only. Larger variations were observed among self‐progenies than cross‐progenies. No correlation was found between self ‐ and cross‐progenies. At least three inoculations may be necessary to eliminate most susceptible plants.

Mas selection was as effective as the polycross progeny test to improve the level of resistance of the selected populations as compared with the unselected one but the difference was agronomically unimportant.

Under field conditions, the plants selected as resistant after two inoculations in the laboratory showed better resistance to L. briosiana than the susceptible ones but only on the first of three notations. The population derived from plants selected from cv. Europe as resistant to L. briosiana in the laboratory was not significantly more resitant than cv. Europe in the filed but generally showed less foliar infection.
Degradation of Raspberry Suberin by Fusarium solani f. sp. Pisi and Armillaria mellea
Authors: Zimmermann W. , Eeemüller E.
Published: May 2008

When submers cultures of Fusarium solani f. sp. pisi and Armillaria mellea were grown in a medium supplemented with 0.5 % suberin isolated from raspberry periderm, hydrolytic enzymes were produced and measured by a spectrophotometric assay using p‐nitrophenyl butyrate as substrate. The enzymatic activity in the culture fluids reached its peak after 32 to 44 days of incubation. In a gas‐chromatographic assay of the enzymatic degradation of suberin, concentrated culture fluids of suberin‐grown fungi were incubated with raspberry suberin. The culture fluids of F. solani and A. mellea catalyzed the release of chloroform‐soluble products, which were analyzed by gas‐liquid chromatography. Suberin monomers like fatty alcohols and acids with chain‐lengths from C16 to C26 as well as C16 and C18ω‐hy‐droxyacids could be identified as products. The suberin‐induced enzymes showed catalytic properties similar to cutin‐hydrolyzing enzymes previously isolated from different fungi.
Decay and Chemical Changes in the Wood of Bambusa arundinacea Caused by Daedalea flavida
Authors: Samajpati N.
Published: May 2008

Daedalea flavida Lév. causes considerable damage to bamboos. Bamboo tissues become soft, discoloured and fibrous. The pathogen causes considerable decay of internodes (about 22%) and rhizomes (about 38%). The pathogen attacks the cells of vascular bundles, bundle sheath sclerenchyma and phloem cells; it does not attack epidermis, hypodermis, and peripheral sclerenchyma tissues. Fungal hyphae grow longitudinal and transverse in host tissues. The parasite decomposes both cellulose and lignin.
Light and Fluorescent Microscopic Studies on Little Leaf Disease of Eucalypts
Authors: Ghosh S. K. , Ali M. I. Mohamed , Balasundaran M.
Published: May 2008

Histopathological and cytopathological abberations detected by anatomy and staining reactions indicated the association of mycoplasma‐like organisms with the little leaf disease of eucalypt in Kerala.

These light and fluorescent microscopic techniques, specially dienes’reaction, can be used routinely to distinguish between little leaf disease caused by mycoplasma‐like organisms and little leaf induced by some other factor.
Effect of Fungicides on the Viability of Phylophthora cactorum Propagules m the Soil
Authors: Rana K. S. , Gupta V. K.
Published: May 2008

Out of eleven fungicides, Ridomil, Aliette (systemic) and Euparen M were most effective in inactivating the fungus mycelium in the soil within 2 day. They also completely inhibited the production of sporangia and oospores. These fungicides and Antracol also reduced the viability (50–100%) of sporangia in the soil. They also reduced the viability of oospores along with Mancozeb, Zineb liquid Ziram. Euparen M, Antracol, Mancozeb, Zineb and liquid Ziram completely killed Zoospores; Ridomil, Previcur and Aliette were also effective. These fungicides can thus reduce the incoculum potential of the pathogen in the soil and reduce the chances of new infections.
Comparison of Methods for Characterizing and Distinguishing Isolates of Prune Dwarf Virus
Authors: Kunze L. , Clark M. F. , Flegg Caroline L.
Published: May 2008

A virus isolated from sour cherry trees with reduced growth in an orchard near Frankfurt/Main was shown by symptomatology, serology and various other tests to be strain of prune dwarf virus (PDV). A comparison of two isolates of this virus with three other PDV isolates already described by other authors indicated that groupings of the viruses made on the basis of symptomatology or component ratios determined by density gradient centrifugation were inconsistent and not reliable. However, electrophoresis in a sugar gradient or immuno‐electrophoresis appeared to offer a satisfactory means of characterizing the viruses and of assigning the isolates to one of three biologically different groups of the virus.
Xylem Fluids of White Lupin (Lupinus albus) Cultivars Susceptible and Resistant to Fusarium oxysporum f. sp. Lupini Race 3
Authors: Salleh B. , Owen H.
Published: May 2008

Xylem fluids from white lupin cv. Neuland, susceptible to wilt causes by Fusarium oxysporum f. sp. lupini, promoted germination of conidia and chlamydospores of he pathogen, and the production of micro‐conidia, to a greater extent than did xylem fluids from the resistant cv. Primorskij No sugars, organic acids or phenolic compounds were detected in the xylem fluids, but a number of amino acids were found, and the concentration of some differed in xylem fluids from the two cultivars; on the whole, concentrations were greater in the susceptible cv. Neuland. Synthetic amino acids were supplied to the fungus in vitro and both stimulatory and inhibitory effects (according to the compound and its concentration) were noted upon the germination of conidia and chlamydospores and on mycelial growth and the production of conidia. The role of amino acids and other compounds in the susceptibility of white lupin to wilt is discussed.
The Effects of Polyacrylic Acid, Acetylsalicylic Acid and Salicylic Acid on Resistance of Cucumber to Colletotrichum lagenarium
Authors: Mills P. R. , Wood R. K. S.
Published: May 2008

Injection of cucumber cotyledons with polyacrylic acid (PA), acetylsalicylic acid (ASA) and salicylic acid (SA) induced resistance to inoculations with Colletrichum Iagenarium when inoculation followed injection by 96 h but not by 24 h. Size and number of lesions were greatly decreased. Resistance was greatest in injected cotyledons but was also pronounced in non‐injected halves of cotyledons and occasionally in first or second leaves.

Incorporation of PA, ASA and SA into liquid shake cultures did not significantly affect growth of the pathogen.

Gel electrophoresis of soluble proteins extracted from cotyledons showed that induction of resistance was not accompanied by the appearance of novel soluble proteins.
Effect of the Compound CGA 78039 and Streptomycin on the Expression of Bacterial Stem Rot in Dieffenbachia
Authors: Vantomme R. , Swings J. , Calus A. , Van Luchene I. , de Ley J.
Published: May 2008

Bacterial stem rot, due to Erwinia chrysanthemi, is a serious problem in ornamental crop protection, e.g. in Dieffenbachia. It was our aim to compare the effect of the synthetic compound CGA 78039 and streptomycin sulphate on the suppression of stem rot disease in Dieffenbachia. Different treatments were applied under natural and artificial infection pressures. Pretreatment of the mother plants with CGA 78039, followed by dipping of the cuttings overnight in the same solution before potting and five subsequent weekly foliar sprays during growth reduced the expression of stem rot in Dieffenbachia significantly.
Survival in the Field of Pseudomonas cichorii (Swingle) Stapp, Causal Agent of Lettuce Varnish Spot*)
Authors: Bazzi C. , Piazza C. , Mazzucchi U.
Published: May 2008

The survival in the field of P. cichorii was studied using a twice‐marked mutant resistant to 200 μg/ml of both nalidixic acid and rifampicin. The mutant was used to contaminate head lettuce cv. Verpia in an experimental field. The survival of P. cichorii was evaluated on the basis of the results of quantitative reisolations, on appropriate selective medium, form asymptomatic leaves, nerval lesions, surface debris and soil after the debris had been incorporated. The mutant was found on symptomless leaves up to 63 days after contamination. It cannot be concluded that P. cichorii is a resident epiphyte because the mutant was already found associated with nerval lesions only 28 days after field contamination.

The mutant was successfully reisolated from the lettuce debris, but not form the soil after its incorporation. 115 days after incorporation of the debris the mutant was found associated with nerval lesions in lettuces planted the following year in the same field.

The means by which P. cichorii survives are discussed. Experimental evidence indicates that it survives in the soil, associated with infected lettuce debris, but that the population level was below the sensitivity threshold of the detection method.
Mechanische Verletzung des Plasmalemmas als mögliche Voraussetzunlg Für die Virsinfektion von Pflanzen
Authors: Hein A.
Published: May 2008

Mechanical injury of the plasmalemma As a possible pre requisite for virus infection of plants

A basic requirement of the infection in case of mechanical inoculation f viruses could be that the plasmalemma of cells is to be injured, for a clearance between cell wall and plasmalemma at the time of inoculation in cells, which are suitable for primary infection prevented the infection.

By means of the hypertonic concentration of 0.7 mol/l of the plasmolytica ethylenglycol, sucrose, glucose, sorbitol and mannitol, which permeate with different speeds, and by modifications of the mannitol treatment, a withdrawal of the plasmalemma to varied distances from the cell wall was induced in cell of the upper side of leaf disk from Nicotiana glutinosa and N tabacum“samsun” This could be observed microscopically in the leaf disks after embedding in liquid paraffin

Treated leaf disk were inoculated with tobacco mosaic virus and incubated floating on tap water

The infection rate, determined by the number of local lesions in case of leaf disks from Nicotiana glutinosa and by the extractable infectivity in case of “Samsun”proved to be dependent on the degree of withdrawal of the plasmalemma from the wall of cell of the upper disk side A strong withdrawal by rounding of the protoplasts in all or almost all cells, caused by the non permeating mannitol or sorbitol, did hardly permit infection