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1

The use of rhizobacteria in plant growth promoting process

100%
Kalitkiewicz A., Kepczynska E.
Biotechnologia
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2008
|
issue 2
102-114
EN
This review focuses on the present knowledge about beneficial free-living soil bacteria that associate closely with plant as plant growth-promoting rhizobacteria (PGPR). Growth promotion can occur mainly by two mechanisms (1) directly by phytohormone production (e.g. gibberelin, auxin and cytokinin) or enzymatic lowering of plant ethylene levels (ACC deaminase), nitrogen fixation, iron chelating by siderophores, phosphorum solubilization or (2) indirectly by the reduction or prevention of the action of plant pathogens. The properties of PGPR offer a great promise for agronomic applications. This review presents examples of its application in practice.
2

Microorganisms in biological control of plant-parasitic nematodes

100%
Obrepalska-Steplowska A., Sosnowska D.
Biotechnologia
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2008
|
issue 2
115-130
EN
Nematodes are unsegmented roundworms that numerously and successfully adapted to all regions and environments on earth. The last ones were usually classified into feeding types: free-living, predaceous, and parasitic ? including plant-parasitic. They are of great significance in terms of damage they cause. Plant-parasitic nematodes have been reported to be responsible for the losses amounting to over $100 billion throughout the world. Because of the big difficulties in their eradication some of them are considered as quarantine species. The plant-parasitic nematodes are controlled using chemical methods ? mainly chemical nematicides. However, because of many drawbacks including health and environmental concerns, other control methods are considered. One of them is biological control and application of antagonistic microorganisms to decrease densities of nematodes populations. Microbial antagonists parasitizing various developmental stages of their hosts may affect nematodes by secretion of antibiotics, toxins and other secondary metabolites. The most important virulence factors are extracellular enzymes that participate in destroying the nematodes' cuticle or the egg-shell or in further phases of infection. This publication presents the examples of microorganisms investigated in terms of biological control, those that are already available commercially as well as some mechanisms involved in nematode-microbes interactions.
3

Health conditions of Castanea sativa Mill., incidence of the fungus Cryphonectria parasitica (Murr) Barr. and possibilities of its biological control in Slovakia

100%
Juhasova G., Berthelay-Sauret S.
Biotechnologia
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1993
|
issue 1
55-58
4

The first record of nucleopolyhedrovirus isolated from the Satin Moth Leucoma salicis L. (Lepidoptera, Lymantriidae) in Turkey

88%
Yaman M.
Folia Biologica
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2008
|
vol. 56
|
issue 3-4
273-276
EN
A nucleopolyhedrovirus was isolated and characterized for the first time from Leucoma salicis L. (Lepidoptera, Lymantriidae) in Turkey. The virus was observed in populations of L. salicis in G?m??hane. The dimensions of the polyhedrae fell between 2.08'0.31 (1.51-2.64) Fm (N=50). Virions contain 2 to 15 nucleocapsids per virion as seen in cross-section of polyhedrae. The sizes of the viral particles ranged between 250-290 x 32-40 nm. The virus was determined as a Turkish isolate of Leucoma salicis nucleopolyhedrovirus (LesaNPV-TR).
5

Beauvericin cytotoxicity to the invertebrate cell line SF-9

75%
Calo L., Fornelli F., Nenna S., Tursi A., Caiaffa M. F., Macchia L.
Journal of Applied Genetics
|
2003
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vol. 44
|
issue 4
515-520
EN
The cyclic hexadepsipeptide beauvericin, initially known as a secondary metabolite produced by the entomopathogenic fungus Beauveria bassiana and toxic to Artemia salina larvae, has been more recently recognized as an important mycotoxin synthesized by a number of Fusarium strains, which parasite maize, wheat and rice. Therefore, this mycotoxin may enter the food chain, causing yet unknown effects to the health of both domestic animals and humans. The cytotoxic effects of beauvericin on mammalian cells have been studied. We investigated the cytotoxicity of this compound in an in vitro invertebrate model, viz. the insect cell line SF-9 (immortalized pupal ovarian cells of the lepidopter Spodoptera frugiperda). Cultures of SF-9 cells in the stationary phase were exposed to beauvericin at concentrations ranging from 100 nM to 300 M, for different periods of time (from 30? to 120 h). The effects on cell viability were assessed by the trypan blue exclusion method. After 4 h of incubation no significant decrease in cell viability was recorded in SF-9 cell cultures exposed to low concentrations of beauvericin, i.e. 100 nM and 300 nM. However, a slight decrease in viability (3.9%) was seen already in cells exposed to the mycotoxin at the 1 M concentration. This effect became gradually more evident at higher concentrations ( 28% at 30 M, 50% at 100 M, 68% at 300 M). An even more pronounced reduction in cell viability was observed after a 24 h exposure. Under these conditions, 1 M beauvericin caused an approx. 10% decrease in the number of viable cells, which became more significant at higher concentrations 23% at 3 M, 47% at 10 M, 65% at 30 M, 90% at 100 M, 99% at 300 M). Therefore, the 50% cytotoxic concentrations (CC50) at 4 h and 24 h could be estimated as 85 M and 10 M, respectively. In time-course experiments, no effect of beauvericin (30 M) on cell viability could be seen after exposure for periods of time as long as 30?, 1 h and 2 h, respectively. In contrast, when SF-9 cells were exposed to the mycotoxin for longer periods of time, from 8 h to 120 h, we recorded a strong cytotoxic effect already in the low micromolar concentration range. Thus, the CC50 after both 72 h and 120 h exposure times was assessed as 2.5 M. Higher concentrations caused a virtually 100% cell death. The data collected suggest that beauvericin exerts a substantial dose- and time-dependent cytotoxic effect on invertebrate cells, comparable to the effects described in mammalian cells.
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