SK278413B6 - An agent for preventive protection of plants - Google Patents

Abstract

A preventive agent used for protection of plants against viral diseases contains in 100 weight percent of water solution 0,1 up to 0,5 weight percent wall yeast water soluble alpha-1,3->manane with the bonds of alpha-1-3-> in the main and alpha -1,2-> and alpha 1,3-> in the side chains with a molecular weight 25 000 up to 50 000 Da, or it also contains wall yeast water soluble 1,3->glucan with the bonds beta 1,3-> in main and 1,6-> in side chains with a molecular weight of 200 000 up to 400 000 Da.

Description

Technical field

SUMMARY OF THE INVENTION

BACKGROUND OF THE INVENTION The invention relates to a composition for the preventive protection of plants against virosis, comprising yeast mannan or glucan as the active ingredient. 5

BACKGROUND OF THE INVENTION

Currently known antiviral agents can be divided into two groups. In the first group there are synthetic chemical preparations such as e.g. various nucleotide derivatives, ribavirin, polyacrylic acid, acetylsalicylic acid. The second group includes inhibitors of viral infection, which are natural substances isolated from 15 plants, insects or various microorganisms. These substances activate the host's enhanced immunity and can therefore be used as a preventive agent for the control of plant viruses (Ahl, P .: Lutte Contre les microorganisms Pathogenes des Vegetaux: Les Induc-20 teurs de Rsistance, Phytopath. Z. 190, 45- 64 (1984)).

Synthetic chemotherapeutics may find important applications in the elucidation of the viral replication mechanism or in the therapy of tissue cultures (production of virus-free propagation material). From the point of view of food safety, however, it is preferable to use natural substances which induce active plant defense mechanisms against viral diseases.

Extracellular linear mannan isolated from yeast cells of Candida tropicalis and Rhodotorula rubra as well as synthesized mannan sulphate (Kovalenko, AD, Korbelainen, ES) were used as inducers of tobacco (Nicotiana tabacum) and durman (Datura stramonium) resistance to tobacco mosaic virus. , Vitovskaya,

G.A., Elinov, N.P .: Voprosy virusologii 6, 732-737 35 (1988). When linear mannan was applied as an aqueous solution at a concentration of 1 mg / ml 24 hours before the virus, it caused a decrease in infectivity by 53.2% and mannan sulphate by 44.7%. When administered concurrently with the virus, the infectivity decreased by 90.9% in the first case and by 64.4% in the 40 case. The disadvantage of these substances, however, is that they have been prepared from pathogenic yeasts, but also that their availability is limited and safety and security requirements are sought (pathogenic products). A further disadvantage is that they are extracellular substances which are secreted from the microorganisms into the culture medium in small amounts and, moreover, because of their low water solubility, have to be derivatized with sulfate, so that their practical application to plants is very limited. 50

Another group of authors found that certain types of low molecular weight glucan fragments could be effective against mechanically transmitted viral infection (Koop, M., Rouster, J., Fritig, B., Darwill, A. G. and Albersheim,

P .: Plánt. Physiol. 90, 208-216 (1989); Darwill, A.G. and 55 Albersheim, P., Ann. Rev. Plant Physiol. 35, 243-257 (1984). By inoculation or spraying with a solution of oligosaccharide obtained from the mycelium of the fungus Phytophtora megasperma f. sp. Glycine at a concentration of 0.1 to 10g / ml.

The disadvantage of this application is that P. megasper-60 ma is a plant pathogen, and a process for isolating these carbohydrates, which is so complex and costly that their application to protect the plants in the required amount is practically out of the question.

The aforementioned drawbacks are eliminated by the composition for the preventive protection of plants against the viroses according to the invention, which consists in the fact that 100% by weight of the composition is present. % of the aqueous solution composition comprises 0.1 to 0.5 wt. wall yeast water-soluble alpha-1,3-> mannan with alpha-1, 3-> linkages in the main and alpha-1, 2->, and alpha-1,3-> side chains, with a molecular weight of 25,000 to 50 000 Da or wall yeast water-soluble beta-1,3-> glucan with beta-1,3-> linkages in the main and beta-1,6-> side chains, with a molecular weight of 200,000 to 400,000 Da.

The advantage of the preventive agent according to the invention is, in particular, that they are non-toxic substances. In addition, said mannan and glucan, which constitute the major component of the cell walls of some industrial yeasts (e.g. Saccharomyces cerevisiae or Candida utilis), mainly used for food and feed purposes, are water-soluble non-toxic substances (polysaccharides) and can be relatively easily extracts isolate. These water-soluble mannan and glucans penetrate sufficiently through the leaf surfaces and can therefore be used for preventive treatment of plants e.g. spray. As mentioned above, they are nontoxic and do not produce any residues by their decomposition in nature - after their active action they are decomposed by plant enzyme systems to the basic carbohydrates mannose and glucose, which fit into the metabolism of living organisms.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Insoluble glucan from yeast cell wall of Saccharomyces cerevisiae CC Y 21-4-13 was obtained according to the procedure of Manners et al. (Manners, D. J., Masson, A. J., Patterson, J. C., Biochem. J. 135, 19-30 (1973)). From the insoluble glucan thus obtained, the water-soluble glucan was obtained as follows:

1 g of insoluble glucan is dissolved in 50 ml of 33% formic acid and hydrolyzed for 30 min. at 100 ° C under reflux. The mixture was evaporated in vacuo and the residue suspended in 100 ml of water and heated in a boiling water bath for 3 hours to remove the form of hunting. The suspension is dialyzed against distilled water, the dialysate is concentrated to 30 ml in vacuo, and 200 ml of ethanol are precipitated. The glucan prepared in this way contained 1,3-> glycosidically linked D-glycopyranosil units with a small amount of side chains linked by 1,6-> bonds, having a molecular weight of from 100,000 to 120,000 Da.

The thus prepared glucan was used as a means to inhibit infectivity of tobacco necrosis virus (TNV) on cucumbers. It was applied as a 0.5% (w / w) aqueous solution 48 hours before virus inoculation. Increased plant immunity caused a decrease in virus infectivity.

Percent inhibition is calculated from a 100 × (1-0 / k) relationship, where o is the number of lesions on the treated leaves and k is the number of lesions on the untreated leaves. The results are documented in a table.

The average number of lesions on the leaves

inspection leaves treated with 0.5% glucan % inhibition 17.25 7.79 54.8 21.25 6.73 68.3

Example 2

Mannan was isolated from yeast Saccharomyces cerevisiae CCY 21-4-13 by the method of Kogan et al. (Kogan, G., Pavliak, V., Masler, L., Can Research 172, 243-253 (1988)). The basic structure of mannan was linear alpha-1,6-> linkages with side chains containing 3 manege units (mainly alpha-1,2- and less alpha-1,3-> linkages, with a molecular weight of 30,000 to 50,000 Da) .

The mannan thus obtained was used as a means to inhibit the infectivity of tobacco necrosis virus on cucumbers and beans. It was applied in the form of 0.005 to 0.5% (w / w) aqueous solution on cucumber and bean leaves 48 hours prior to virus inoculation. Increased plant immunity caused a decrease in virus infectivity. The results are documented in a table.

manganese concentration 0,005 0,025 0.05 0.2 0.5 % inhibition - beans 25 62 73 82 % inhibition - cucumbers 20 30 42 50 60

Industrial usability

The invention can be used as a preventive agent in agriculture, vegetable production and in the protection of greenhouse cultures against viral diseases without genetically altering the properties of plants.

Claims (1)

PATENT CLAIMS A composition for preventive protection of plants against virosis, characterized in that it contains from 0.1 to 0.5% by weight of an aqueous solution. wall yeast water-soluble alpha-1,3-> mannan with alpha-1,3-> linkages in the main and alpha-1,2-> and alpha-1,3-> side chains, with a molecular weight of 25,000 to 50 000 Da, or a wall yeast water-soluble beta-1,3-> glucan with beta-1, 3-> linkages in the main and beta-1, 6-> side chains, with a molecular weight of 200,000 to 400,000 Da.