Form Of Inoculum Research Articles

Ectomycorhization de Cedrus atlantica en conditions contr�l�es : efficacit� de deux formes d'inoculum myc�lien

Ectomycorrhization of Cedrus atlantica seedlings under controlled conditions: Efficiency of two forms of mycelial inocula. The effect of two mycelial inocula (mycelia grown in peat-vermiculite saturated by a nutritive medium, or entrapped into alginate) of two ecto- mycorrhizal species (Tricholoma tridentinum var. cedretorum and Hebeloma sinapizans) was tested, under controlled conditions, on the my- corrhization of Cedar seedlings grown on mineral substrate. One year after inoculation, the percentage of infected root tips and root ergosterol contents were higher with cedars inoculated using T. tridentinum peat-vermiculite inoculum than using alginate one. The opposite results were obtained with H. sinapizans. The degrees of mycorrhization of the seedlings inoculated with T. tridentinum were higher than those of the see- dlings inoculated with H. sinapizans. The mycorrhization of Cedrus atlantica seedlings using mycelial inocula was thus performed under con- trolled conditions which may be reproducible. The consequences of the inoculation of seedlings on their shoot and/or root biomass vary with the inoculum form and fungal species. Cedrus atlantica / Tricholoma tridentinum var. cedretorum / mycorrhization / mycelial inocula / ergosterol

Trichoderma koningii as a potential parasite of sclerotia of Sclerotium rolfsii

Abstract Three different inoculum forms of Trichoderma koningii were tested in vitro for their ability to parasitize the sclerotia of Sclerotium rolfsii . Tests were conducted under two temperature regimes and three incubation periods. Wheat bran was proved to be the most potent inoculum form of the antagonist in reducing 0the viability of the sclerotia. Microscopical observations revealed the presence of hyphae, chlamydospores and conidia of T. koningii in the medullar tissues of the sclerotia. This is the first report of the effect of different inoculum forms of T. koningii on the sclerotia of S. rolfsii and of propagule (chlamydospores and conidia) formation of the antagonist inside the sclerotia of S. rolfsii .

Effect of inoculum form on in vitro antifungal susceptibilities of Aspergillus spp.

The effect of inoculum form, i.e. ungerminated conidia, germinated conidia and hyphae on the in vitro antifungal susceptibility of 12 strains belonging to Aspergillus spp. was compared using a broth microdilution method. The isolates were tested three times on different days against amphotericin B, itraconazole and ketoconazole. There were no significant differences between MICs obtained with the three types of inoculum (P > 0.05) for any antifungal tested. The degree of reproducibility of the tests was high (>or=75%) for all antifungals with each type of inoculum, except for itraconazole (58.3%) when the inoculum was prepared with ungerminated conidia.

Factors affecting the course and severity of transnasally induced Staphylococcus aureus pneumonia in mice.

In order to examine several factors that may affect the course and severity of transnasally induced Staphylococcus aureus pneumonia in mice, bacteria were prepared in a free suspension or bound to fetal mouse cells. Immunosuppression was induced in five strains of mice (ICR, C57BL/6, BALB/c, C3H/He and CBA/J) by injection of cyclophosphamide (200 mg/kg body weight), 2 days before infection. Impairment of mucociliary clearance was induced by intranasal instillation of formalin. Mice were then infected with various doses and strains of the organism. Although no significant differences were observed between either form of inoculum, pretreatment with formalin plus cyclophosphamide was associated with a significant increase in lung bacterial counts. In particular, cyclophosphamide treatment was associated with a high mortality in mice infected with several strains of S. aureus irrespective of their toxin production profiles. Histopathological examination demonstrated that in mice treated with formalin plus cyclophosphamide, clusters of bacteria were observed in lung parenchyma, associated with a mild accumulation of inflammatory cells at day 2 and extensive cell infiltration at day 7. CBA/J mice represented the most susceptible strain among those examined, with 10(4)- and 10(2)-fold higher bacterial counts in the lungs at days 3 and 5, respectively. These results indicate that neutropenia and impaired mucociliary clearance are major factors that influence the severity of S. aureus pneumonia in mice. Analysis of the role of genetic background in enhancement of vulnerability to infection is warranted in future studies.

Methods of screeningAcer platanoidesL. seedlings for resistance to wilt (Verticillium dahliaeKleb.)

SummarySeveral methods of challenging young seedlings of Norway maple (Acer platanoides) with Verticillium dahliae were investigated to develop a method for screening seed provenances for wilt resistance. Seedlings were inoculated by pouring conidial suspension (106 conidia ml−1) over roots wounded in situ, or by dipping roots in the same conidial suspension at transplanting, or by transplanting germinated seed or seedlings into compost infested with a beet-seed or straw-cultured inoculum. On the basis of foliar symptoms during the growing season, and on seedling height, and vascular staining and the presence of V. dahliae in the wood at the end of the season, root-dipping was the most severe test; planting seeds or seedlings into straw-based inoculum was less severe than root-dipping but gave similar levels of infection. Beet seed was a less effective form of inoculum than straw, and inoculation of roots damaged in situ resulted in disease escape. A comparison of the root-dip technique using three, five-...

Application of modified international wood preservative chemical testing standards for assessment of biocontrol treatments

Previously reported results of agar interaction screening studies for biocontrol agents of wood decay basidiomycetes identified two Trichoderma viride isolates that killed 16 out of 19 target fungi. Testing of these isolates in wood was required to assess their performance in preventing decay of wood blocks. Standard testing of chemical wood preservatives is used to determine the toxic concentrations of preservative required to protect wood against decay by basidiomycetes. As no ratified standards for testing biocontrol agents exist, two amended wood block testing standards and a soil contact test were used to assess the effect of the Trichoderma isolates. An agar based system similar to European Standard EN 113 (1980), a soil-block test based on the AWPA Standard M10-77 (1977) and the soil contact system were used with Scots pine and Sitka spruce pre-treated with Trichoderma. Wood blocks treated with either Trichoderma isolate were completely protected against all the basidiomycetes tested, irrespective of the form of inoculum used (spores or mycelium), timber species or wood block test methodology. Implications of the results for the use of agar plate interaction studies for screening biocontrol agents for subsequent use in wood block testing are discussed as well as the merits of the modified standard tests for assessing biocontrol agents.

Susceptibility of root-knot and cyst nematodes to the nematode-trapping fungi Monacrosporium ellipsosporum and M. cionopagum

We compared the susceptibility of Meloidogyne javanica and Heterodera schachtii to the nematode-trapping fungi Monacrosporium ellipsosporum and M. cionopagum. The fungi were added in the form of fungal-colonized nematodes or hyphae pelletized in alginate to field soil in small vials. Suppression by the fungi was measured by comparing nematode invasion of roots in fungal treated and untreated soil. Meloidogyne javanica was much more susceptible than H. schachtii to both fungi, regardless of the form of fungal inoculum. Thus, when colonized nematodes were used as fungal inoculum, suppression of M. javanica and H. schachtii was 92 and 6% by M. ellipsosporum and 54 and 0% by M. cionopagum. Similarly, when pelletized hyphae were used, suppression of M. javanica and H. schachtii was 80 and 10% by M. ellipsosporum and 98 and 24% by M. cionopagum. In other tests, two additional populations of H. schachtii were relatively resistant and two additional species of root-knot nematode, M. incognita and M. chitwoodi, were relatively susceptible to these fungi. The results indicate that Meloidogyne spp in general are more susceptible than H. schachtii to M. ellipsosporum and M. cionopagum.

Phomopsis of sunflower in the ukraine and the development of breeding methods for resistance

Information on the structure of the population of Phomopsis species in Ukraine, that describes the structure of Phomopsis spp. cultivated on medium: the morfological characteristics, properties of pathogenicity and phytotoxicity. It is described the method of evaluation and selection of unsusceptible forms of sunflower to phomopsis. It includes the optimal infection level, the forms of an inoculum that is effective and optimal way for artificial infection.

Optimization of cultivation and nutrition conditions and substrate pretreatment for solid-substrate fermentation of wheat straw byCoriolus versicolor

Bioconversion of wheat straw by solid-substrate fermentation (SSF) with Coriolus versicolor was optimized by varying its physiological parameters. Selective delignification (more lignin than holocellulose degradation) and increases in crude protein (CP) content and in vitro dry matter digestibility (IVDMD) were taken as the criteria to select optimum levels of these parameters. The fungus behaved optimally under the following set of cultural and nutritional conditions: pH 5.5, moisture level 55%, temperature 30 degrees C, duration of fermentation 21 d, form of inoculum--grain culture, turning frequency--once at mid-incubation, urea (nitrogen source) 1.5% (sterile) or 3.0% (nonsterile), single superphosphate (phosphorus + sulfur source) 1.0%, no addition of free polysaccharides (as whey or molasses). A maximum of 17.5% increase in IVDMD involving 4.3% degradation of lignin, was attained in the optimized SSF under laboratory conditions. The digestibility improvement could be further increased by using a substrate pretreatment (physical/chemical/biological) in the following order of preference: NaOH treatment, urea or urine treatment, ensiling, steaming, grinding. For practical farm applications, urea treatment and ensiling appeared most feasible. The laboratory optimized process was also scaled up to 4 kg (sterile and unsterile) and 50 kg (unsterile) fermentations.

Screening for sclerotial mycoparasites of Sclerotinia sclerotiorum

A comparison of the ability of ten known mycoparasites to infect sclerotia of Sclerotinia sclerotiorum was made using five combinations of inoculum form and substrate type. Inoculum forms consisted of spore suspensions prepared in distilled water or 1% peptone water and a maizemeal-perlite solid substrate formulation. Substrate types consisted of acid-washed sterile sand or non-sterile soil. In every combination, Gliocladium virens and Coniothyrium minitans , both originally isolated from sclerotia of Sclerotinia species, infected and decreased viability of sclerotia more frequently than the other mycoparasites tested. Inoculum form of these two mycoparasites and substrate type had significant effects on the degree of sclerotial infection and viability. The ability to sporulate on the surface of inoculated sclerotia is not considered a useful method of assessing mycoparasitism. The relevance of these results to the choice of screening system for mycoparasites of sclerotia of S. sclerotiorum is discussed.

Pathogenicity to wheat seedlings of wheat-type and rye-type isolates of Pseudocercosporella herpotrichoides

Four groups of isolates of Pseudocerosporella herpotrichoides (wheat-type carbendazimsensitive, wheat-type carbendazim-resistant, rye-type carbendazim-sensitive and rye-type carbendazim-resistant) were tested for pathogenicity to wheat seedlings (cv. Armada), using mycelial or conidial inoculum. With either form of inoculum, wheat-type isolates usually produced more severe lesions than rye-type isolates, although the most pathogenic rye-type isolates were as pathogenic as the least pathogenic wheat-type isolates. Regressions of pathogenicity score on spore concentration (log 10 -transformed) were calculated for each of the four groups of isolates and showed that the data were best fitted by two lines with different slopes and different intercepts, one for the wheat-type isolates and one for the rye-type isolates. Conidia of wheat-type isolates generally included a greater proportion of curved spores than those of rye-type isolates. There was little difference between conidia of the wheat-type and rye-type isolates in length, number of cells or ability to germinate, nor between carbendazimsensitive and carbendazim-resistant isolates of either wheat- or rye-type in pathogenicity or spore characteristics.

Inocula of Gaeumannomyces graminis var. Tritici for field and glasshouse studies

The food reserves of whole oat-grain inoculum of Gaeumannomyces graminis var. tritici (Ggt) are unrealistically large compared to infective propagules in field situations, so in this study we examined the infectivity of different sized fractions of the ground oat inoculum. Minimum disease was obtained with the fraction <0.25mm dia and maximum disease with the 0.71–1.0 mm fraction. Alternative forms of Ggt inoculum were developed and tested. Attapulgite amended with nutrient solution and seeds of ryegrass, millet and oats were colonized by Ggt and assessed in glasshouse experiments as forms of inoculum of the pathogen. Inocula in ryegrass and millet seed were also assessed in field trials. Attapulgite colonized by Ggt produced infection but had no effect on shoot growth of wheat seedlings in a glasshouse experiment. Both ryegrass and millet seed-borne propagules of Ggt reduced shoot weight of wheat seedlings in a glasshouse experiment. Increasing inoculum densities of ryegrass seed inoculum in glasshouse experiments and of ryegrass or millet seed inocula in field experiments produced dose responses in disease, plant growth and grain yield. Transmission electron microscopy of the different forms of inoculum showed that most of the hyphae of Ggt in attapulgite were moribund, whereas hyphae in the seed inocula were viable and contained many lipid droplets and melanin particles.

Infectivity of vesicular arbuscular mycorrhizal inocula after storage under various environmental conditions

The infectivities of various propagules of vesicular arbuscular mycorrhizas were determined after storage, using Medicago sativa as a test plant. Temperature and relative humidity (r.h.) had significant effects on spores of Glomus clarum . The spores were still infective after 12 weeks' storage at 35 °C and 45% r.h. but not at 14 and 75% r.h. At each r.h. the spores were infective up to 12 weeks' storage when kept at 5°. Spores did not retain their infectivity after 6 weeks in sand and 45%. Hyphal fragments from G. fasciculatum , root segments from maize containing G. clarum and root segments from bluebell containing G. caledonium and Acaulospora laevis} were affected by temperature and time of storage. Mycorrhizal maize root segments retained infectivity longer than either bluebell root segments or hyphal fragments over a range of temperatures and humidities. Spores collected from four continents showed differences amongst themselves and in their longevity when exposed to various environments. Comparison of three carrier materials at two moisture levels and three temperatures, using spores of G. clarum and unidentified spores collected from India, showed that infectivities of both inocula were higher in wet than in dry sand and soil. Wet and dry peat were very poor carrier materials. Storage properties of each form of inoculum under simulated tropical conditions are discussed along with the potential use of carrier materials for field trials.

Role of Seed in Survival and Transmission of Xanthomonas campestris pv. oryzae Causing Bacterial Blight of Rice

AbstractSurvival 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.

The role of vesicular arbuscular mycorrhizal fungi in agriculture and the selection of fungi for inoculation

Vesicular arbuscular (VA) mycorrhizas are roots infected with particular soil fungi which form symbiotic associations. It is often assumed that VA mycorrhizal fungi could be used to increase the efficiency of phosphate fertilizers in agriculture. Our principal concern is the question: 'Can the symbiosis be exploited on a large scale?'. VA mycorrhizas increase nutrient uptake, and hence plant growth, by shortening the distance that nutrients must diffuse through soil to the root. Mycorrhizal roots do not appear to have a lower threshold concentration of nutrients for absorption from solution than do non-mycorrhizal roots. Most soils contain VA mycorrhizas. Hence, for plant growth to respond to inoculation with VA mycorrhizal fungi, agricultural soils must have either a low incidence of indigenous VA mycorrhizal fungi or alternatively, species which are less effective than the inoculant fungi in their ability to stimulate nutrient uptake by plants. The distribution of species of VA mycorrhizal fungi varies with climatic and edaphic environment, as well as with land use. However, the factors which control their distribution are poorly understood. Differences among VA mycorrhizal fungi in their ability to increase nutrient uptake appear to be due to differences in their ability to form mycorrhizas rapidly and extensively. The importance of other differences among the fungi, such as in the absorption of nutrients from solution or in the distribution and amount of external mycelium, has yet to be clearly demonstrated. Inoculant VA mycorrhizal fungi must be capable of persisting in soils at a high inoculum potential, as well as being able to increase nutrient uptake. Until now, little attention has been paid to characteristics which enable the fungi to persist after inoculation. We are critical of many of the methods employed in experiments aimed at selecting 'efficient' VA mycorrhizal fungi. For practical purposes, selection can only be achieved by means of comparisons performed in untreated field soils, with phosphorus supply limiting plant growth. Because the form of inoculum can affect the relative abilities of VA mycorrhizal fungi to infect and improve plant growth, appropriate inocula are needed for each agricultural situation. The survival of many species of fungi in various types of inocula requires further study so that procedures can be developed for introducing particular fungi into agricultural soils. This review emphasizes many gaps in our knowledge. For example, we need more information on how and to what extent species or strains of VA mycorrhizal fungi differ in their ability to increase plant growth. We know even less about their beneficial effects in years following that of field inoculation. The ecology of indigenous VA mycorrhizal fungi in field soils has also been largely neglected. These and other deficiencies preclude any immediate recommendations for large-scale inoculation with selected VA mycorrhizal fungi.

結紮家兎腸管における&lt;I&gt;Clostridium perfringens&lt;/I&gt; A型生菌のEnterotoxin産生に関与する要因について

Viable cells of Clostridium perfringens Types A were administered into the rabbit ileal loop in order to clarify the mechanisms involved in the diarrhea by these organisms.1. Fluid accumulations were observed only by the strains producing, in vitro, enterotoxins of 640 MCD (2.4 μg)/ml or more, when 19 strains possessing various enterotoxin productivities were inoculated with 10% skim milk solution. Among the enterotoxin positive strans t eh more the enterotoxin production in vitro, the fewer the minimum number of cells required for the reaction. Little difference in reaction was observed between vegetative cells and spores as the initial form of inoculum, and enterotoxin levels from 800 to 92, 160 MCD (3 to 346 μg) were observed per positive loop. Rabbits seemed to be destined to death, when the enterotoxins more than 28, 880 MCD were recovered totally from the accumulated fluids.2. When Osaka F4105, a strongly-enterotoxin-producing strain, was inoculated with various media, various degrees of fluid accumulation and enterotoxin production were observed in the loop, among which the liver extract was the most effective for both the sporulation and enterotoxin production.3. No inhibition of the fluid accumulation in the loops was noted in the rabbits immunized with the purified enterotoxin before the viable cell inoculation.

Response of Coprosma robusta to different forms of endomycorrhizal inoculum

Coprosma robusta seedlings were inoculated by spores or root segments infected by a smallspored species of Glomus or Acaulospora laevis . More rapid growth stimulation occurred with root segments than with spores and with Glomus than with Acaulospora . Accordingly the Glomus infected plants were ultimately the larger, but the Acaulospora infection seemed no less effective once established. Application of P or complete fertilizer reduced the ultimate shoot weight of the mycorrhizal plants, probably through delaying mycorrhizal infection.

Survival Mechanisms of Phytopathogenic Bacteria

Natural habitats usually do not provide bacteria the continuity of agricultural crops. With continuous culture. perpetuation of pathogen is no problem. Although agricul­ tural practices provide some discontinuity between crops. it is less than that in nature. Uniformity of crop germ plasm also favors inoculum buildup and perhaps perpetuation of the pathogens. The growth of most plant pathogens is discontinuous, because of the seasonal effect upon either the pathogen or the host. A successful pathogen must be able to bridge discontinuities, such as the gaps between successive crops and seasons. To reestablish when conditions are again favorable, inoculum must survive. Facultative saprophytes or facultative parasites are not as handicapped by discontinuous growth as are obligate parasites. Discontinuous growth of the pathogen mainly decreases the amount of inoculum (bacteria that cause disease when placed in suitable contact with the host). The success of a bacterial plant pathogen depends in part on the amount of inoculum (bacterial cells) it produces. Because bacteria have a short generation time, a small amount of surviving primary inoculum can rapidly produce an epidemic. What is the minimum amount of inoculum necessary to initiate disease? Enough for mere survival is not necessarily the answer since transmission to a host is necessary. The source, exit, and transmission of primary inoculum are all necessary for occur­ rence of disease, for survival, and for continuity of the bacterial species. Establish­ ment of a curtain between host and pathogen may be simpler and cheaper during the primary inoculum phase than thereafter: The longevity of primary inoculum is important in the success of bacterial patho­ gens and depends upon its ability to escape or endure adverse environmental condi­ tions (62). Survival varies with the form of primary inoculum and may depend on external factors as well as on the internal makeup of the pathogen. Because there are about 200 different species of bacterial plant pathogens. variations in modes of

Infection of stored celery plants by Centrospora acerina

SUMMARYChlamydospores in tissue near the bases of plants and in attached soil particles were the main form of inoculum of Centrospora acerina (Hartig) Newhall found on celery plants prepared for storage. Most of these spores remained ungerminated for several weeks but subsequently formed germtubes, terminal appressoria and infection‐pegs, which usually penetrated the plant surface through either the intact cuticle or damaged areas. For several weeks after the beginning of storage the plants were highly resistant to infection. During this time, appressoria failed to penetrate the intact cuticle and, if the fungus entered through damaged areas, hyphal growth in tissue was suppressed. Infection was often found to be associated with abrasion or splitting of the cuticle in commercially stored plants and, in experiments, deliberate damage enhanced the probability of infection. The development of the disease was much slower at 2 d̀C than at 15 d̀C.