Highly Effective Preventive Measure against Bioterrorism in Plant Cultivation
A.A.Makarov, V.P.Dubovoj
All-Russian Research Institute of Phytopathology, Moscow region, Russia
A bioterrorism attack against agricultural plants can cause a non-natural epiphytoty - a large-scale infection of plants leading to considerable crops damage. Developing and growing plant species characterized by non-specific resistance to pathogens is an effective way to prevent bioterrorism. These species can counteract the epiphytoty development irrespective of the pathogen strains used by bioterrorists
The bioterrorism in plant growing implies an deliberate decrease or destruction of the crops of the major agricultural crops by using biological agents and the most dangerous phytopathogens can be used as such agents.
In plant growing the verified cases of bioterrorism are not very common, possibly because in a routine practice it is still very difficult1 to distinguish a natural epiphytoty from a non-natural one caused by the adverse actions of terrorist groups.
It is possible to assume that highly virulent and highly aggressive pathogenic strains either isolated from natural populations of phytopathogens or produced in the laboratory conditions including by using genetic engineering techniques are most likely to be used as biological agents. In both cases they will affect (i.e. overcome resistance) in the most widely spread target species.
The specified properties are typical of many fungi pathogen strains, especial1y if cultivated grades do not possess resistance and tolerance to diseases or are protected by specific protection genes that can be easily overcome by the complementary genes of pathogenic virulence.
With the well organized service of plant protection - regular monitoring of phytosanitary situation in crops, constant sufficient back-up stocks of fungicide and dissemination tools it is possible to cope with both with natural and non-natural epiphytoty although financial expenses for protective activities can be considerable depending on the affected area.
Implementation of the effective security and biosafety measures in the collection of strains of phytopathogens wil1 considerably reduce the risk of bioterrorism in plant cultivation. In this case bioterrorist will have no access and will have no possibility to carry out theft of the most virulent biological material that can be used in bioterrorist attack.
In our opinion, the most effective way of prevention of bioterrorism in plant growing is the creation and cultivation of species of agricultural crops with the so-called nonspecific (field, horizontal acc. to Van der Planck) resistance to infections. Such species are attacked by many if not by all the pathovars registered in a specific area, but the degree of damage is not usual1y high and no huge crops damage can occur.
This general rule is not absolute and we consider dividing the plant resistance into specific and non-specific, though conditional, but quite valid, because evaluation methods for the original and hybrid (selected) material for these types are different.
Species with nonspecific resistance to phytopathogens can be developed by genetic engineering and traditional selection methods. In the first case the assessment of transgenic lines expressing target genes of nonspecific resistance is performed in chamber and field experiments using corresponding criteria of nonspecific resistance for selection. In the second case the assessment of nonspecific resistance is carried out at every stage of the selection process from the evaluation and selection of the original material used in crossing.
The non-specific resistance criteria for any “agricultural crop – pathogen” pair are different, as well as the methodology of identifying selection material possessing the required properties.
So, to select the potato species with nonspecific resistance to phytophtora both methods field and as laboratory-field assessment methods usual1y come to use. In the first case the degree of field nonspecific stability of every sample of species is evaluated based on the rate of lesion formation tops of vegetable and on the decrease in productivity of fraction of standard tubers as opposed to the fungicide protected control.
The laboratory - field assessment method is used in the areas where the weather conditions unfavorable for the development of phytophtora cause frequent depressions of disease or in the areas where it is impossible to go out in the field with fungi pathogens not present in the local population, which is a very frequent case.
The selection the samples of potato species with genuine nonspecific resistance to phytophtora in the field-laboratory method is performed with a special test-kit of P.infestans pathovars of various geographic origin, different compatibility types and aggression potential and containing all known virulence genes. The basic criteria applied in evaluating identifying samples of species with nonspecific resistance are ‘infecting efficacy’, ‘growth rate of necrotic spot’ and ‘sporulating ability’.
The ‘growth of necrotic spot’ identified on the sixth day after inoculation is the most stable, informative and easily determined criteria in the assessment of nonspecific resistance to phytophtora in potato species.
The species with nonspecific resistance maintain the resistance against pathogens for a long time despite forms development processes in the pathogen populations and despite the appearance of new races.
Production cultivation of such species in wil1 serve an effective barrier on the route of bioterrorists irrespective of the type of pathogen races (natural or artificially produced) they can use for their criminal purposes.
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