bluuebunny/crossref_metadata_2025 huggingface dataset:
Bestimmung pektolytischer Enzyme bei mehreren Schadpilzen von Citrusfrüchten
Authors: Rose W. , Knösel D.
Published: May 2008

Characterization of pectolytic enzymes From several fungi causing post‐harvest decay of citrus fruits

From culture filtrates of Penicillium digitatum Sacc., Trichoderma viride Penz., Phomopsis citri (Faw.) cf. Diaporthe citri (Faw.) Wolf, and Colletotrichum gloeosporioides Penz. endo‐polygalacturonase and endo‐polymethylgalacturonase have been isolated. Both enzymes were active under acid conditions only. The last named fungus additionally produced pectic acid‐transeliminase, the activity was found under alkaline conditions.
Helminthosporium maydis Suppresses Expression of Resistance to Helminthosporium carbonum in Corn
Authors: Pascholati S. F. , Nicholson R. L.
Published: May 2008

Inoculation of corn mesocotyls with Helminthosporium maydis (susceptible combination) at the same time or at intervals up to 45 h after inoculation with H. carbonum (resistant combination) suppressed the expression of resistance to H. carbonum. This occurred even when the ratio of H. carbonum to H. maydis spores was as much as 100:1. When inoculated at 60 h after H. carbonum, H. maydis was unable to suppress resistance expression and was also unable to establish a susceptible disease interaction.
Light Sensitivity of the Antagonism of Cladosporium Species to Races of Melampsora larici‐populina Kleb. on Cultivars of Populus×euramericana (Dode) Guinier
Authors: Sharma I. K. , Heather W. A.
Published: May 2008

Antagonism of five species of Cladosporium to production of uredinia by three races of Melampsora larici‐populina on leaf disks of poplar (Populas × euramericana) was generally higher with races A and E but lower with race D, at high light intensity (400 μ Em−2s−1) than at low light intensity (100 μ Em−2s−1). Colonization by all species of Cladosporium, of the uredinia induced by the races on the cultivars, was higher at the low than at the high light intensity. The extent of reduction in colonization with increasing light intensity depended on the race, cultivar and species of Cladosporium involved. While the species of Cladosporium was the most important major factor affecting both uredinial production and colonization, race, cultivar, light intensity of incubation and species of Cladosporium interacted significantly to determine disease level (uredinial number) on the leaf disks and the percentage of these uredinia subsequently colonized by the Cladosporium spp.
Carbon Dioxide Exchange in an Incompatible Barley/Powdery Mildew Combination
Authors: Walters D. R. , Ayres P. G.
Published: May 2008

CO2 exchanges in intact barley leaves were studied by infra red gas analysis after inoculation with an incompatible race of powdery mildew. Net photosynthesis was inhibited, and dark and photorespiration were stimulated, by inoculation. The increase in respiratory processes was approximately equal to the change in net photosynthesis indicating that CO2 fixation, “gross photosynthesis”, was unaffected by inoculation. It is concluded that changes in net photosynthesis may be the primary cause of the reduced quantity and quality of grain in incompatible barley/mildew combinations.
The Possible Role of Phenolic Compounds in Resistance of Horticultural Crops to Dematophora necatrix Hartig
Authors: Sztejnberg A. , Azaizia H. , Chet I.
Published: May 2008

Crops e. g., pecan, persimmon and passionflower, which show resistance to the fungus Dematophora necatrix, the causal agent of white root rot disease, contain phenolic compounds which inhibit its growth. Roots of resistant crops contain higher concentrations of phenolic compounds than those of suceptible crops, e. g., apple, almond and peach.

The fungus contains active polyphenoloxidase (PPO). The oxidation of phenols to quinones may decrease the inhibitory effect. Catechol, methylcatechol, hydroquinone and 8‐hydroxyquinoline significantly inhibited the growth of the fungus.

In greenhouse experiments, seedlings were irrigated with, or dipped in, phenols. Catechol, methylcatechol and hydroquinone delayed the appearance of disease symptoms.
Wissadula Proliferation in Jamaica
Authors: Dabek A. J. , Waters H. , Lavin D.
Published: May 2008

In Jamaica, phloem‐restricted prokaryotes were found associated with a little leaf proliferation disease of Wissadula periplocifolia (L.) C. Presl. ex Thwaites. Electron microscopy of single ultrathin sections revealed circular, ovate and elongate profiles 120—500 nm in diameter/width and 125—4200 nm long. Most were bound by a double membrane and resembled the phloem‐restricted rickettsialike organisms associated with a small number of other plant diseases; others which were peripherally ill‐defined or without an obvious double membrane were indistinguishable from mycoplasmalike organisms. Further work is required to elucidate their taxonomic status and possible role in the aetiology of the disease. No potential aetiological agent was discovered for a symptomatologically similar disease of Abuliton hulseanum (Torr. & A. Gray) Torr. ex Chapm. which accurred intermixed with the Wissadula disease. The names Wissadula proliferation and Abutilon proliferation have been used to describe these newly recorded diseases.
Detection of a Luteovirus in Groundnut Rosette Diseased Groundnuts (Arachis hypogaea) by Enzyme‐linked Immunosorbent Assay and Immunoelectron Microscopy
Authors: Sylke Meyer R. Casper , Lesemann D.‐E. , Ramanan Rajeshwari D. V. D. Reddy , Misari S. M. , Subbarayudu S. S.
Published: May 2008

In groundnut rosette diseased groundnut plants collected near Zaria, Nigeria, a luteovirus was detected by ELISA and ISEM. In ELISA only beet western yellows virus antiserum reacted, while in ISEM luteovirus particles were trapped by antisera beet western yellows virus, potato leafroll virus, pea leafroll virus and barley yellow dwarf virus. The data are in agreement with the interpretation that the assistor of groundnut rosette virus is possibly a member of the luteovirus group.
Studies in Heterobasidiomycetes, Part 31*). On the Anther Smuts of Silene vuigaris (Moench) Garcke
Authors: Deml G. , Oberwinkler F.
Published: May 2008

Microbotryum silenes‐inflatae (DC) G. Deml & Oberw. and Microbotryum violaceoirregulare (Brandenburger & Schwinn) G. Deml & Oberw., both parasitic in the anthers of Silene vulgaris (Moench) Garcke, are compared by their morphology, karyology, and some cultural characteristics.

The infection of their hosts is similar in both species, but causes different sizes of the flowers and different color of the spore mass. The teliospore initials of that smuts are produced in dikaryotic sporogenous hyphae. During gelatinization of the hyphal coat, surface ornamentations on the teliospores are formed. Mature teliospores are monokaryotic, and presumably diploid, reticulate in Microbotryum silenes‐inflatae and echinulate in M. violaceo‐irregulare. Teliospores of both species germinate without a resting periode. Germination results in a commonly three‐celled promycelium, which in M. silenes‐inflatae separates from the producing teliospore, while in M. violaceo‐irregulare it remains on the teliospore during basidiospore formation. The basidiospores are monokaryotic and propagate by budding. Monokaryotic strains were isolated and characterized by standard yeast identification tests and by some enzymatic activities on solid media. While no differences in the enzymatic activities can be found, the species differ in their utilization of carbon sources.
Quantitative Studies of Resistance Induced By Avirulent Cultures of Erysiphe graminis f. sp. hordei in Barley
Authors: Chaudhary R. C. , Schwarzbach E. , Fischbeck G.
Published: May 2008

Quantification of resistance induced by avirulent cultures of Erysiphe graminis f. sp. hordei against virulent cultures in barley was attempted. Four mildew cultures and 4 barley varieties with known genes of virulence and resistance respectively were used. Pre, post and simultaneous inoculation of leaves was done with avirulent and virulent cultures. Pre‐inoculation with avirulent cultures induced resistance in the host such that the pustule number and spore production by later inoculation of virulent cultures was reduced significantly. Once induced, such resistance was active up to 8 days. There was some indication of induced susceptibility if the inducing culture was characterized by medium virulence. Increase of inceulum density of the avirulent (inducer) culture increased the amount of induced resistance Further studies of the phenomenon of induced resistance are needed in relation to possible applications for disease control through inoculations. varietal mixtures and multilines.
A Quantitative Description of The Colonization of Susceptible and Resistant Radish Plants by Plasmodiophora brassicae
Authors: Kroll T. K. , Lacy G. H. , Moore L. D.
Published: May 2008

The degree and rate of primary and secondary cycle development by Plasmodiophora brassicae in the root hairs and root medullary rays, respectively, of a completely resistant, a partially resistant and a susceptible radish (Raphanus sativus) cultivar were compared. Seeds were germinated in an infested soil mixture and seedlings were harvested 2, 4, 6 and 8 days after sowing seed for observations of the primary cycle and 6, 12, 18, 24, 30 and 36 days after sowing seed for observations of the secondary cycle. No differences in the degree or rate of primary phase colonization were detected among the three cultivars. Initially, uni and/or bi‐nucleate secondary plasmodial stages were found in the cortex of all three cultivars. The number of these plasmodia was greatest in resistant and least in susceptible cultivars. No further colonization or symptom expression occurred in the completely resistant cultivar. In the partially resistant cultivar the appearance of advanced stage‐s of the fungus secondary cycle development were delayed until day 30 as compared with colonization of the susceptible cultivar in which advanced stages appeared by day 18. It is concluded that resistance is expressed during the initial stages of secondary cycle colonization.
Has the Plant a Resistance System Based on Interferon‐like Proteins? (Impressions from a meeting)
Authors: Kassanis B.
Published: May 2008

The short communication contains observvations on the workshop on pathognesis‐related proteins in plants held at the Research Institute of Plant Protection, Wageningen. The main criticism is that the scientists working on the problem or natural resitance present in plants, neglected the practical side of the investigation which is to find a suitable chemical treatment which would induce resistance to infection without being phytotoxic
Natural Infection of Tomato and Pelargonium in Germany by a Tombusvirus Originally Described from Pepper in Morocco
Authors: Vetten H. J. , Koenig R.
Published: May 2008

Two serologically apparently identical tombusviruses were isolated from glasshousegrown tomato plants showing mottle and malformation of the upper leaves and stunting of the shoot tips and, at a low rate, from a pelargonium plant, respectively. Both plant species were received from growers in southern Germany. In agar gel double diffusion tests and immuno‐electrophoresis, the two virus isolates could not be distinguished from a tombusvirus (MPV) isolated from pepper in Morocco by Fischer and Lockhart (1977), although there were some minor differences in the reported host responses. In the tomato planting, strong symptoms were produced only temporarily. The majority of the 104 tomato plants of 15 different cultivars which had become infected by MPV following mechanical inoculation of the leaves showed only mild symptoms in contrast to a similar group of plants which developed severe stunting and foliar deformation when infected with the type strain of tomato bushy stunt virus. MPV was translocated only occasionally to the upper parts of tomato seedlings which had been grown in virus‐containing soil, although root infections were more frequent. MPV is apparently not a major threat to tomato cultivation in Germany.
Cytological Evidence of the Association of a Geminivirus with the Tomato Yellow Leaf Curl Disease in Tunisia
Authors: Cherif C. , Russo M.
Published: May 2008

Samples of tomato plants from Tunisia naturally or artificially infected with the yellow leaf curl disease were examined in thin sections with the electron microscope. Cytological changes were compared with those previously observed in similarly affected tomato plants from Israel. Evidence was obtained that also in Tunisia a non‐mechanically transmissible geminivirus is associated with the disease.
Detection of Avocado Sunblotch Viroid in Flower Buds by Polyacrylamide Gel Electrophoresis
Authors: da Grça J. V. , Mason T. E.
Published: May 2008

A Rapid PAGE index method for avocado sunblotch disease for field trees which takes only 6 h, compared with 2—5 days for other previously described tediniques, has been developed and tested. Flower bud? are used instead of leaves as source material. All 52 flower Duu Siimplcs irom known bunblotcn‐infcctcd trees tested positive whilst only 37 out of 72 in‐fccted leaf samples gave positive results.
Activation of Teliospore Germination in Uromyces appendiculatus var. appendiculatus1)
Authors: Gold R. E. , Mendgen K.
Published: May 2008

The effects of light and host volatiles on teliospore germination in Uromyces appendiculatus var. appendiculatus were studied.

1. Light intensities ranging 15–26 000 lux supported teliospore germination and basidiospore formation. The optimum light intensity was 17 000 lux under the described conditions. Light‐dark alternation was necessary for teliospore germination: no germination occurred under continuous light or continuous dark conditions. The process of teliospore germination, basidiospore formation, and basidiospore release followed a synchronous, rhythmic pattern of development. Teliospore germination was triggered by the phase change lights → dark (i.e. “light off”). Under long‐day conditions basidiospore release exhibited a nocturnal periodicity with peak maxima occurring ∼7 h after light was turned off.

2. Fifteen days after a 10 d exposure to host volatiles, 70–80 % of the treated spores germinated; minor increases in spore mortality were observed. Inoculations made with seedling‐treated teliospores resulted in heavy pycnial infections.

3. The heat and seedling activation methods developed for teliospores of bean rust proved ineffective when applied to dormant teliospores from six other unrelated rust species.
Comparative Studies on Some Isolates of Rhizoctonia solani in Egypt
Authors: Wasfy E. H. , Sheir H. M. , Darweesh M. M.
Published: May 2008

Nine isolates of Rhizoctonia solani from various hosts were selected for this study. The isolates were tested for their compatibility by an anastomosis test. Isolates were classified into two Egyptian anastomosis groups (EAG‐1 and EAG‐2). The isolates varied in virulence, thiamine requirement and quality and quantity of free and protein amino acids.
Release of Antifungal Phenolic Compounds from Cucumber Mosaic Virus‐Infected and Noninfected Cowpea Protoplasts
Authors: Ando Y. , Ehara Y. , Yamanaka S.
Published: May 2008

Fungitoxic phenolic compounds were released from cucumber mosaic virus (CMV)‐infected and noninfected cowpea protoplasts. These compounds were presumed by thin layer chromatography as similar compounds released into the leaf ambient fluids when CMV‐infected cowpea leaves were incubated in water. Larger amounts of the compounds were released from CMV‐infected cowpea protoplasts than from noninfected protoplasts.
Modulation de la Réponse du Xyléme selon la Nature de l'Agression Vasculaire
Authors: Moreau Mireille , Catesson Anne‐Marie
Published: May 2008

L'évolution des cellules contiguës aux vaisseaux dans le xylème caulinaire de l'œillet est comparée après simple entaille (s. e.), introduction de spores deV. dahliae(iV. d.) ou deP. cinerescens(iP. c.). Tous les traumatismes expérimentaux entraînent des modifications ultrastructurales aboutissant à l'apparition de nouveaux types cellulaires. Parallèlement, les polyphénols vacuolaires sont metabolises et des vésicules “à cœur dense” apparaissent. Il s'agit là de phénomènes précoces et indépendants. Dans tous les cas, l'œillet réagit plus vigoureusement chez les iV. d.que chez les iP. c.

L'étude de la gommose vasculaire révèle des differences quels que soient les critères retènus: vitesse d'installation, importance relative du phénomène, niveau de complexité structurale, chronologie d'apparition des différents constituants. Les relations éventuelles entre les structures cellulaires et les secretions gommeuses sont recherchées en comparant entre elles les situations de defense efficace (iV. d.) ou défaillante (iP. c.). Tous les elements d'analyse retenus dans ce mémoire confirment que, face a son parasite spécifique, la réponse de l'hôte est perturbée. On observe des blocages, des freinages, des déviations des voies de biosynthèse normalement mises en place par la plante en réponse à une agression fongique. Les differences de comportement de l'œillet vis‐a‐vis duVerticilliumet duPhialophoraprésentent une image de la spécificité parasitaire qui s'adapte bien au modèle récemment propose pardeWit(1981) pour le couple tomate/Cladosporium fulvum.
Effect of Azotobacter Exudates on Certain Micro‐Fungi Associated with the Phylloplane of Soybean
Authors: Singh R. P. , Singh Lokendra , Verma V. S.
Published: May 2008

The effect of different concentrations of Azotobacter chroococcum exudates on microfungi isolated from Soybean phylloplane was studied in vitro and in vivo. It has been found that the growth of some fungi was stimulated or suppressed whereas others showed fluctuations or remained unaffected depending upon the age of the plant, growth stage of the leaf, concentration of the exudates, method used to harvest fungi, and environmental conditions. Nutrient competition or production of biologically active substances like GA may be responsible for retarding the growth of fungi.
Fusarium Genus as a Citrinin‐Like Compound and Zearalenone Producer
Authors: Chelkowski J. , Mańka Malgorzata
Published: May 2008

Out of 53 isolates Of Fusaria wheat, maize and barley 6 belonging o F. avena‐ceum produced citrin‐like compound.
A Survey of German Hops for the Presence of American Hop Latent Virus (AHLV)
Authors: Eppler A. , Sander Evamarie
Published: May 2008

The presence of rod‐shaped viruses in German hops has been known for a long time and Hop Mosaic Virus (HMV) and Hop Latent Virus (HLV) were proved to be present by serological techniques. When another CARLA‐Virus, the American Hop Latent Virus was detected in England an extensive survey was carried out in the German hop growing regions and among wild hops. No natural occurrence of the virus could be detected. Only recently introduced plants of the American clone USDA 21055 in an isolated breeding garden were infected. Spread of the virus to German seedlings could not be detected.
The Influence of Ustilago maydis Upon Free Radicals Concentration in the Reproduction Organs of Maize
Authors: Michalov J. , Komaaar J.
Published: May 2008

The reproduction organs of maize are those most often attacked by Ustilago maydis. In the male organs it produces a decline in free radicals concentration and, conversely, a rise of concentration in the female organs (in ears). The smut proper, grown on the flower, exhibits an essentially higher free radicals concentration than the smut grown out on the ear of that plant. A smut mixture from flower and ear has only a slightly higher free radicals concentration than the separate ear smut, but an essentially lower one than the smut of the flower.
Ribulose Bisphosphate Carboxylase Protein and Enzymes of CO2 Assimilation in Barley Infected by Powdery Mildew (Erysiphe graminis hordei)
Authors: Walters D. R. , Ayres P. G.
Published: May 2008

Effects were examined of barley powdery mildew (Erysiphe graminis f. sp. hordei) on the major leaf protein, ribulose‐l,5‐bisphosphate carboxylase (RuBPCase), and other enzymes of CO2 assimilation, phosphoenolpyruvate carboxylase (PEPcase) and malic enzymes, and enzymes associated with RuBPCase in the reductive pentose phosphate pathway. Activity of RuBPCase per unit fresh weight of leaf was inhibited by infection from the first sample, 3 days after inoculation, to the last sample, 24 days after inoculation, when healthy control leaves were visibly senescing. The inhibition occurred because the amount of RuBPCase protein (measured specifically by an immunological technique) was reduced from 6 days after inoculation and because activity per unit protein declined from 3 days until 21 days after inoculation, at which time there was little protein remaining. Activity of PEPcase per unit fresh weight of leaf was initially stimulated by infection but, thereafter, it was inhibited. Inhibition, like that also affecting malic enzymes (NAD) and (NADP), 3‐phosphoglycerate kinase, and glyceraldehyde‐3‐phosphate dehydrogenases (NAD) and (NADP), was associated with a decline in amounts of total soluble minus RuBP Case protein per unit fresh weight of leaf.

Reduced amounts of leaf protein may be associated with reduced nitrate uptake by roots and fungal demand for nitrogen in mildewed plants.
Scanning Electron Microscopy of Xanthomonas campestris pv. pruni in Plum Petioles and Buds
Authors: du Plessis H. J.
Published: May 2008

The possibility that Xanthomonas campestris pv. pruni (Xcp) invades Golden King plum twigs systemically through petioles of infected leaves was investigated by scanning electron microscopy. Masses of Xcp cells were detected in longitudinal sections of helical xylem vessels of vascular bundles in petioles of naturally infected and inoculated leaves. Xcp colonies were also found in cortex tissue of small shields of twigs, adjacent to petioles of infected leaves. Single bacterial cells were detected in meristematic bud tissues of naturally infected samples only. The main route of ingress of Xcp into plum twigs appears to be systemically through petioles of infected leaves.

The author thanks the staff of the SEM Unit of the FFTRI for assistance on scanning electron microscopy and Prof. M. J. Hattingh for critically reading the manuscript.
Antholysis in Cassava (Manihot esculenta Crantz) Possibly Caused by Mycoplasma‐Like Organisms
Authors: Jayasinghe U. , Pineda B. , Lozano J. C.
Published: May 2008

Phyllody and apostasis of cassava plants were frequently observed during recent disease surveys in the Cauca Valley of Colombia. Many valuable cassava clones have been affected rendering them unsuitable for hybridization. Light and electron microscopic observations have revealed the presence of mycoplasma‐like organisms in the diseased phloem tissues. The causal agent is sensitive to tetracycline and streptomycin at 1000 ppm a. i., but not to penicillin.
An Examination of the Effect of Human α‐Interferons on the Infection and Multiplication of Tobacco Mosaic Virus in Tobacco
Authors: Antoniw J. F. , White R. F. , Carr J. P.
Published: May 2008

Human α interferon had no direct effect on TMV RNA infectivity and when appiled to tobacco had no significant effect on local lesion development or virus multiplication.
Conidium Ontogeny in Pyricularia1
Authors: Rao K. Manibhushan , Jesudhas M. Louis
Published: May 2008

Conidium ontogeny of twenty‐three isolates of Pyricularia (including international races, some nutritional, coloured mutants and isolates obtained from cultivated and wild species of Gramineae) was studied. Among them, sixteen isolates were found to be of typical blastic type of conidiogenesis characteristic of the genus Pyricularia. Three coloured mutants and an international race showed gangliar type of conidiogenesis. However, two races and one nutritional mutant showed both the types.

Most of the isolates tested are morphologically indistinguishable and potentially pathogenic with the respective hosts and on differential cultivars. Possible alteration of morphogenetic pattern of conidiogenesis by mutation and temperature response is suggested.
Evidence that the Low Molecular Weight RNA Associated with Chicory Yellow Mottle Virus is a Satellite
Authors: Piazzolla P. , Rubino L.
Published: May 2008

Chicory yellow mottle virus, ringspot strain (CYMV‐RS), supports the replication of a low molecular weight RNA (0.17 × 106 daltons) associated with CYMV‐T (type stain).

Competition hybridization experiments revealed lack or nucleotide sequence homology between 0.17 × 106 mol. wt. RNA (Sat RNA) and CYMV‐RS genomic RNAs, and partial homology (33 %) with CYMV‐T genomic RNAs. However, such apparent partial homology can be due to contamination of CYMV‐T genomic RNAs with a multimeric form of Sat RNA having a similar molecular weight. On this account the hypothesis that CYMV‐T Sat RNA is a true satellite RNA becomes tenable.
A Technique for Continuous Observation of the Infection Process in Cucumber Anthracnose
Authors: Stumm D. , Gessler C.
Published: May 2008

A new light microscope preparation technique for high magnification observation of living plant tissue and fungal penetration is described. Agar immersion is used in differential interference contrast microscopy (DIC) instead of coverslips (lens 40) or instead of coverslips and oil (lens 100).

This technique is suitable for

(a) longtime observation of living tissue, because the tissue to be observed remains on the plant, and for

(b) thick and uneven samples, as no coverslips are required.

With this technique it was possible to observe the dynamics of penetration of Colletotrichum lagenarium into epideral cells of cucumber cotyledons for 72 hours.

A time lapse film using this technique is in preparation.
Response of Cucumber Cultivars and Other Cucurbitaceous Species to Infection by Hop Stunt Viroid1
Authors: Yaguchi S. , Takahashi T.
Published: May 2008

The response of 8 different species within the Cucurbitaceae to hop stunt viroid (HSV) was examined. Some of these plants developed several kinds of systemic symptoms depending upon species, variety or cultivar infected. Among 12 out of 26 cucumber cultivars become infected severely, so visual symptoms are reliable for diagnosis because symptom severity is correlated with viroid content. Other cucurbitaceous species except Citrullus lanatus, Cucurbita maxima and Cucurbita moschata were also susceptible. Among them, Benincasa hispida was found to be a more suitable bioassay plant than Suuyou cucumber which has been hitherto used.
Survival of Hop Stunt Viroid in the Hop Garden1)
Authors: Yaguchi S. , Takahashi T.
Published: May 2008

A lot of 105 specimens from 25 families including weeds or wild plants which had grown naturally in the severely infested hop garden were tested for detecting reservoir plants for hop stunt viroid (HSV). HSV was detected in hop plants only. Susceptibility tests with various cultivated plants including 14 families indicated that hop and Humulus japonicus developed visible symptoms, while tomato was symptomless. When infected hop plant residues, leaves and cones, were left to be weather‐beaten, infectivity of HSV was completely lost within 3 months. No transmission through the pollen or the ovule was demonstrated. HSV could survice in root systems of hop plants during the winter months. Based on these results, the route of HSV survival in the hop garden was discussed.
Blue‐Stain Fungi on Nothofagus from Chile—Including Two New Species of Ceratocystis Ellis & Halst.
Authors: Butin H. , Aquilar Angelica M.
Published: May 2008

A description is given of four species of the ascomycetous genus Ceratocystis isolated from different species of the tree‐genus Nothofagus in Chile. Two of these are described as new species based on the characteristics of their ascospores, ascocarps and conidial states in culture. Ceratocystis piceae (Münch) Bakshi and C. pilifera (Fries) C. Moreau were responsible for important blue‐stain in timber of Nothofagus pumilio (Poepp. et Endl.) Krasser; Ceratocystis nothofagi Butin sp. nov. and C. valdiviana Butin sp. nov. were found in native stands of different species of Nothofagus causing less intensive discoloration in bark and wood of dead trees.
Effect of Chitosan, Chitin and some Aminosugars on Growth of Various Soilborne Phytopathogenic Fungi
Authors: Stössel P. , Leuba J. L.
Published: May 2008

The effect of bleached chitin, 66% and 91% deacetylated chitosan, respectively, as well as some aminosugars on in vitro radial growth of several phytopathogenic oomycetes and deuteromycets was studied In contrast to chitin, chitosan was inhibitory to the fungi The antifungal activity depended on the degree of deacetylation, the particle diameter of the polymer, the growth medium and the pH. Likewise, deacetylation of the monomers different media varied, indicating a possible counteraction by the carbohydrate sources.
Studies in Heterobasidiomycetes, Part 38*)Sphacelotheca polygoni‐persicariae G. Demi & Oberw. spec. nov.
Authors: Deml G. , Oberwinkler F. , Bauer R.
Published: May 2008

A new species, Sphacelotheca polygoni‐persicariae, parasitizing the ovaries of Polygonum persicaria L. is described. This smut, collected several times in Madeira, Portugal, differs from other species of that genus, by its host plant and the reticulated teliospore ornamentation.

On the basis of the morphological and ultrastructural characters of S. polygoni‐persicariae, in connection with some recently published data on siderophore formation and 5S ribosomal RNA sequences it can be assumed that 1) members of the genus Sphacelotheca are separated from typical Ustilago species of Poaceae, 2) Sphacelotheca is restricted to species parasitizing Polygonaceae, and 3) species of Sphacelotheca and Microhotryum as well as those Ustilago species which parasitize in the flowers of Polygonaceae are closely related.
Einsatz von V. lecanii als biologisches Schädlingsbekämpfungsmittel gegen den Bohnenrostpilz U. appendiculatus var. appendiculatus im Feld und im Gewächshaus
Authors: Grabski G. C. , Mendgen K.
Published: May 2008

The use of Verticillium lecanii as a biological control agent against the bean rust fungus Uromyces appendiculatus var. appendiculatus in the field and in the glasshouse

The deuteromycete V. lecanii parasites uredo‐ and teliospores of the bean‐rust‐fungus U. appendiculatus var. appendiculatus. We investigated the conditions for the use of the hyperparasite as biological control agent in the field and in glasshouses.

The growth rate of the hyperparasite was 0,3 cm per day at 25 °C. Under suitable conditions in the lab (25 °C, 100 % r. h.) it took about 20 days to invade 100 % of uredospores and 65 % of teliospores.

We failed to prevent the spread of bean‐rust‐fungus spores in the field, but we succeeded in the glasshouse by 68 %, compared to the untreated controls, using the hyperparasite V. lecanii as biological control agent.
Sugar‐specific Attachment of Pseudomonas syringae pv. glycinea to Isolated Single Leaf Cells of Resistant Soybean Cultivars
Authors: ÉRsek T. , Gáborjáanyi R. , Höltzl P. , Király Z.
Published: May 2008

Phase‐contrast and scanning electron microscopy showed races of P. synngae pv. glycinea uniformly distributed over and attached to the whole surface of isolated single leaf cells of resistant soybean cultivars, as early as 30 to 180 min after inoculation. On the contrary, attachment in the compatible interaction did not occur within 10—15 h. In a later period, compatibility was characterized by the formation of adherent bacterial clusters.

Early attachment of races 1 and 6 to cv. Harosoy and that of race 5 to cv. Flambeau leaf cells, each representing incompatible interaction, could be inhibited by L‐rhamnose and D‐glucose, respectively. Furthermore, the lack of Mn2+ and Fe2+ and heat‐treatment of plant cells also affected the early attachment in incompatible combinations and resulted in cluster formation, suggesting incompatibility rather than compatibility to be the active phenomenon.

Pre‐inoculation of cells with an incompatible race induced changes that caused compatible bacteria also to distributively attach to plant cell surface indicating that a transfer of information or surface alterations occur upon attachment in incompatible interaction.
Biological Control of Fusarium‐wilt in Carnation With Serratia liquefaciens and Hafnia alvei Isolated from Rhizosphere of Carnation
Authors: Sneh Baruch , Agami Orna , Baker Ralph
Published: May 2008

Serratia liquefaciens provided better protection of carnations from infection by Fusarium oxysporum f. sp. dianthi, than did Hafnia alvei. The protection occurred when the bacterial isolates were applied to the cuttings before rooting, but not when applied to the root system of rooted cuttings. S. liquefaciens was recovered from carnation stem segments along the stem up to the top after 60 days but after 120 days they were recovered only up to 2.5cm. Zones of inhibition of Fusarium‐conidia sprayed on agar plates previously incubated with stem segments appeared around the bacterial colonies of S. liquifaciens after additional incubation for 24—48h.
Physiological Changes Occurring in Picked Climacteric Fruit Infected with Different Pathogenic Fungi*)
Authors: Schiffmann‐Nadel Mina , Michaely H. , Zauberman G. , Chet I.
Published: May 2008

The main purpose of this work was to study the host‐parasite relationship between attacking fungi and the infected climacteric fruit. The study dealt mainly with physiological changes such as respiration and ethylene evolution pattern occurring in fruit inoculated with different fungi after picking. These physiological changes in infected fruit were found to be basically similar to those of uninfected fruit, but they were substantially accelerated. A direct correlation was obtained between the rate of fungal development in fruit (incubation period and rot development) and the extent of acceleration of respiration and ethylene evolution; in general, a faster development of the fungus was related to greater acceleration of ethylene and respiration rate of the infected fruit. Fungal infection was found to have an effect on fruits similar to that of exogenic ethylene treatment on sound fruit.
Improvements in Assays for Soil Populations, of Pythium ultimum and Macrophomina phaseolina
Authors: Chun D. , Lockwood J. L.
Published: May 2008

The method of Stanghellini and Hancock to enumerate Pythium ultimum Trow, populations in soil was modified by distributing 1 ml dilutions of soil containing the pathogen into 100–120, 2.5 mm diam. Wells made in 2% water agar in 9 × 15 mm Petri dishes. The modified method was more sensitive than the original method m which droplets or soil dilutions are placed on agar, it permitted the use of lower soil dilutions, and was rapidly performed. Sclerotia of Macrophomina phaseolina (Tassi) Goid. (=M. phaseoli [Maubl.] Ashby) were recovered by flotation using 60% sucrose, collected by aspiration onto nylon filters, and surface‐sterilized. The viable Sclerotia were enumerated by counting colonies growing on a selective medium. Efficiency of recovery was 95–97% of Sclerotia added to soil. Large numbers of samples could be processed rapidly by this method which utilized readily available materials, and gave higher counts than earlier methods, which involved only sieving or flotation.
Protein and Esterase Patterns of Pathogenic, Fusarium oxysporum f. sp. elaeidis and F. oxysporum var. redolens from Africa, and Non‐Pathogenic K oxysporum from Malaysia
Authors: Ho Y. W. , Varghese G. , Taylor G. S.
Published: May 2008

Protein and esterase patterns of eleven isolates of F. oxysporum f. sp. elaeidis, one isolate of F. oxysporum var. redolens pathogenic to oil palm from Africa and six non‐pathogenic isolates of F. oxysporum from oil palm soils in Malaysia were studied by vertical disc‐electrophoresis and isoelectric focusing, to determine whether the pathogenic and saprophytic forms of F. oxysporum could be distinguished using these two methods. The protein patterns of all the isolates studied by the two methods were almost identical qualitatively and it was impossible to distinguish between the pathogenic isolates of F. oxysporum f. sp. elaeidis and F. oxysporum var. redolens from Africa and saprophytic isolates of F. oxysporum from Malaysia. Esterase zymograms of the isolates produced by the two methods were different. Esterase zymograms produced by vertical disc‐electrophoresis showed great variations between and within the African and Malaysian isolates, but the esterase patterns produced by isoelectric focusing were almost identical qualitatively.
Histopathology of Oil Palm Seedlings Infected by, Pathogenic Fusarium oxysporum Isolates from Africa
Authors: Ho Y. W. , Varghese G. , Taylor G. S.
Published: May 2008

Oil palm seedlings (one‐leaf stage) grown from Malaysian seed were inoculated with six African isolates of Fusarium oxysporum f. sp. elaeidis and one African isolate of Fusarium oxysporum var. redolens. All the isolates induced similar symptoms and anatomical responses in the inoculated palms. The pathogen invaded the root, bulb, leaf bases and leaves in that sequence. In the root and bulb, infection resulted in plugging of xylem elements with mycelium, conidia, tyloses and gums, disintegration and plugging of phloem tissues, disintegration of plugged vascular elements forming gaps and cavities, and collapse of cortical tissues leading to the isolation of the infected vascular tissues. Formation of hypertrophic or hyperplastic cells in the xylem parenchyma was not observed. Anatomical changes in the infected leaf bases and petioles were similar to those occurring in the infected bulb; except that tyloses were formed less frequently. Generally there was no sign of the pathogen in the wilted leaf blade, but the epidermal, hypodermal and mesophyll cells appeared shrunken or to have collapsed. No hyphae or anatomical changes were observed m the tissues of symptomless inoculated palms.
Brome Mosaic Virus Infection Mimics, Barley Yellow Dwarf Virus Disease Symptoms in Small Grains
Authors: VON Wechmar M. B. , Rybicki E. P.
Published: May 2008

Previous studies on the occurrence of “barley yellow dwarf virus (BYDV) disease” in South Africa have led to the conclusion that, although this virus is present, the main causative agent of “yellow dwarf” disease in cereals appears to be the unrelated brome mosaic virus (BMV). In this study, material from South Africa, Britain and Australia that had been identified symprtomatically as being infected with BYDV, was found by serological testing to contain BMV. No BYDV could be detected in the same samples. This report discusses the hazards of relying on symptom expression for the diagnosis of a common world‐wide disease problem.
Zur Mycelcharakterisierung holzzerstörender Pilze auf der Basis von unterschiedlichen Pilzproteinen
Authors: Gellen J. , Jung J. A.
Published: May 2008

Abstact

Abstract Characterization of Wood Destroying Fungi on the Basis of different Fungus‐Proteins

Isoelectric focusing proved as reliable separating method in the investigation of culture filtrate proteins of fungi. On a 5 cm separation distance can be discerned 159 protein bands within 3.75 pH units (from pH 2.15 to 5.90).

In the case of Basidiomycetes focused plants of nine genera and species show characteristic band‐patterns.

As identify‐typical characteristics can be considered distribution of major and minor protein‐bands, the number of bands and the pH‐range, in which the major protein focuse.

There are to state genus‐ and species‐specific distinctions based on characteristic protein‐patterns.
The Association of “Pathogenesis‐related” Proteins with Viral Induced Necrosis in Nicotiana sylvestris
Authors: Sherwood J. L.
Published: May 2008

The association of “pathogenesis‐related” (PR) proteins with protection from superinfection, systemic acquired resistance and production of localized necrotic lesions was examined with a system using tobacco mosaic virus (TMV) and Nicotiana sylvestris. Leaves of N. sylvestris with a mosaic from earlier inoculation with a systemically infecting strain of TMV (TMV‐C) and control plants were challenged with a necrotizing strain of TMV (TMV‐P), RNA of TMV‐P and turnip mosaic virus (TuMV). TMV‐P virions produced localized necrotic lesions only in the dark green areas of the mosaic of TMV‐C infected plants. Both RNA of TMV‐P and TuMV produced localized necrotic lesions in both light green and dark green areas of the mosaic of TMV‐C infected plants. All three challenge inocula produced localized necrotic lesions in previously uninoculated plants. Six days after challenge inoculation proteins were extracted from separated dark green and light green mosaic leaf tissue, and leaf material from control plants. Proteins were separated by electrophoresis in a 5 % polyacrylamide spacer gel and 10 % polyacrylamide running gel. PR proteins were found in tissue where localized necrotic lesions were produced as a result of challenge inoculation, but not in tissue that was not superinfected. PR proteins were not found in light green or dark green mosaic leaf tissue as a result of TMV‐C inoculation. No PR proteins were evident in protein extracts from light green tissue challenged with TMV‐P, although PR proteins were produced in dark green tissue, where necrosis occurred, from the same leaves. Systemic acquired resistance (reduction in size of lesions formed by a challenge inoculation) to TuMV or RNA of TMV‐P and PR protein concentration was measured at various times in light green areas of mosaic leaves where dark green areas of the mosaic leaves had been inoculated with TMV‐P. No quantitative or temporal relationship between the onset of resistance and PR protein production was found. It is concluded that PR proteins are a result of pathogen induced necrosis and not significantly involved in the mechanism(s) of viral induced resistance.
Post harvest Spoilage of Mangoes by Penicillium cyclopium and its Control by Gamma‐Radiation and a Fungicide
Authors: Palejwala V. A. , Modi V. V.
Published: May 2008

Penicillium cyclopium has been isolated from spoiled ripe alphonso mango, Spores were found resistant up to a 500 krad dose of γ‐radiation. A 25 krad dose treatment which is normally used for the prolongation of shelf life of mangoes could not protect them against artificial or natural infection. Bavistin (2‐(methoxy carbamoyl)‐ benzimidazole) inhibited completely spore germination at a concentration of 100 mg/1. A post harvest dip of unripe mangoes into an aqueous solution of this fungicide lowered the degree of spoilage considerably.
Characterization of Virion RNAs of Southern Bean Mosaic Virus by Electron Microscopy
Authors: Sehgal O. P. , El‐Hassan S. , Murti K. G. , Hsu C. H.
Published: May 2008

Electron microscopy of denatured RNA of southern bean mosaic virus (SBMV) shows two principal linear components, 0.31 ± 0.08 μm (subgenomic RNAs, MW 0.51 × 106) and 0.80 ± 0.17 μm (genomic RNA, MW 1.3 × 106 25S). Nondenatured RNA (∼ 32S) from heat‐inactivated virions measure 1.0 ± 0.20 μm (MW 1.64 × 106) but is poorly‐infectious. Upon denaturation the 325 RNA disaggregates into components of lengths typical of the genomic and subgenornic RNAs and infectivity is restored.
Growth, Sporulation and Spore Germination of Colletotrichum capsici as Influenced by Tobacco Mosaic Virus Infection in Capsicum annuum L.
Authors: Bansal R. D. , Khatri H. L. , Sharma O. P.
Published: May 2008

Growth and sporulation of C. capsici were lesser in different solid and liquid media containing of virus infected leaves than in media containing extracts of healthy leaves. Spore germination and formation of appressoria in different dilutions of the extract were poor as compared to healthy leaf extracts The antimetabolite/inhibitor in TMV infected plants is water soluble.
Identification of Phytopathogenic Virus Strains by their Luminescent Properties
Authors: Trubitsyn A. G. , Reifman V. G.
Published: May 2008

A quick test has been developed to identify phytopathogenic virus strains by variations in their photoluminescence parameters. When heated, the virus suspension shows a jumpwise drop or rise in fluorescence intensity caused by conformational changes in the macromolecules of the virion protein capsules. The relative value of the jump in fluorescence intensity and the temperature value at which the jump occurs are essentially strain‐specific. The minimum time needed for one test is from 15 to 20 minutes.
Lectin Binding Studies on the Cell Walls of Soybean Rust (Phakopsora pachyrhizi Syd.)
Authors: Ebrahim‐Nesbat F. , Hoppe H. H. , Rohringer R.
Published: May 2008

Walls of uredospores, infection structures, intercellular hyphae and haustoria of the soybean rust fungus (Phakopsora pachyrhizi) were studied by electron microscopy using gold‐labeled wheat germ lectin (WGL) and Concanavalin A (ConA) as cytochemical probes. Receptors for WGL (probably chitin) were detected in all fungal walls included in this study. WGL‐binding occurred throughout the entire walls (uredospores, appressorial cone, penetration hyphae, haustorial mother cells) or only to the inner wall layers (germ tubes, appressoria, intercellular hyphae).
Plant Reactions to Inoculation of Roots with Fungi and Bacteria
Authors: Gerhardson B. , Alström S. , Rämert B.
Published: May 2008

The potential of 120 isolates of fungi and bacteria from plant rhizospheres to interfere with plant development and growth was studied in greenhouse experiments. The pure cultured isolates were obtained from plant roots in the field and applied as suspensions to the roots of eight test plant species. 10–20% of the isolates caused distinct symptoms on shoots, growth retardations without other symptoms or growth promotions. Responses of treated plants ranged from death of plants soon after treatment to up to about 40% higher shoot fresh weight than in control plants. Two bacterial isolates induced strong reactions in most of the plant species tested while other isolates showed a more or less pronounced specificity by giving reactions in only some of the plant species tested.
Resistance Mechanism of Cultured Plant Cells to Tobacco Mosaic Virus
Authors: Toyoda H. , Oishi Y. , Matsuda Y. , Chatani K. , Hirai T.
Published: May 2008

In somaclonal tissues obtained from systemically TMV‐infected tobacco plants, a relation between changes of TMV amounts and the callus growth was examined. The culture medium was suitable for maintaining a constant concentration of TMV as well as active callus growth. By using the shake‐culture method, somaclonal tissues were separated into two classes on the basis of callus sizes. In large callus tissues, TMV amounts were constant during subculturing but the tissues did not either grow or release the newly divided cells after the last subculture. On the other hand, smaller callus tissues grew markedly and the TMV amounts were conspicuously lowered. After shake‐subculture of smaller tissues, they were successfully regenerated to plantlets. None of the plantlets expressed any mosaic symptoms, while plantlets from the original somaclones showed severe mosaic symptoms of TMV in leaflets. Thus, the present report describes the successful production of virus‐free plantlets from infected somaclonal callus cultures.
Wachstum und Sporenbildung einer schweizerischen Rasse von Puccinia graminis tritici in vitro
Authors: Naef‐Roth S. , Kern H.
Published: May 2008

Growth and spore formation of a Swiss race of Puccinia graminis f. sp. tritici in vitro

On a medium containing Evans Pepton and yeast Extract, the rust formed aecidiospores in great number. The aecidiospores were able to infect wheat plants. On media 4–9 (Table 1) uredospores and teliospores are formed. Highest numbers of teliospores were produced on substrates with ATP, nucleotide bases, and ribose.