1. The role of allelopathy in host- virus relations G.Kazinczi 1, J.Horvath 2, A.Takacs 1, I.Béres 2, R.Gáborjányi 2, M.Nádasy 2 1 Office for Academy Research Groups Attached to Universities and Other Institutions, University of Veszprém, Georgikon Faculty of Agricultural Sciences 2 University of Veszprém, Georgikon Faculty of Agricultural Sciences

2. Allelopathy (Molish 1937) A type of interference among higher plants, where products of secondary metabolism inhibit (less promote) the development of neighbourhood plant Earlier only plant-plant, today plant- microorganism interactions It is considered as a new alternative way for biological control

3. Plant viruses make up about 15-30% out of the whole plant diseases Virus particles create close biologial unit with the plant cell Chemical plant protection against viruses is unsuccesfull in vivo Some natural substances are known to inhibit replication and cell- to cell movement of viruses and reduce virus concentration

4. Mode of action It is not yet known exactly, but it can be presumed that natural inhibitors may modify special receptor places on the plant cell surface, therefore adhesion of virus particles can not be happened

5. The aim of the study To examine the effect of allelopathic weed extracts on some host-virus relations

6. MATERIALS AND METHODS

7. Fresh plant parts were collected and grinding Asclepias syriaca Abutilon theophrasti Cirsium arvense DONOR SPECIES Convolvulus arvensis Chelidonium majus

8. Plant water extracts were made using 25 g fress biomass/100 ml distilled water Extracts were used to spray daily test plants from their 2-4 leaf stages until the end of experiments

9. Host-virus relations (recipient species)

10. Chenopodium amaranticolor-Alfalfa mosaic virus

11. Chenopodium quinoa-Sowbane mosaic virus

12. Cucumis sativus’Delicatesse’ -Zucchini yellow mosaic virus

13. Solanum nigrum- Obuda pepper virus

14. Virus infection (DAS ELISA) From the extinction values we can conclude from the virus concentration; samples are considered resistant to virus infection: if extinction values do not exceed two times those of the negative control Fresh weight (five weeks after inoculations)

15. RESULTS

16. The effect of C. majus extracts on the virus concentration in test plants (a, C. majus root extract; b, C. majus shoot extract; c, positive control; d, negative control)  Slight, significant reduction in AMV concentration due to C. majus root extract  Enhanced virus concentration in S. nigrum  No difference in virus concentration in C. quinoa and C. sativus

17. The effect of C. majus extracts on the fresh weight of test plants (a, C. majus root extract; b, C. majus shoot extract; c, positive control; d, negative control) 1st column, C. majus root extract; 2nd, C. majus shoot extract; 3rd, positive control; 4th, LSD 5% )

18. The effect of water extract on the ObPV concentration in S. nigrum (1, A. syriaca root; 2, A. syriaca shoot; 3, C. arvense shoot; 4, C. arvensis shoot; 5, A. theophrasti shoot; 6, positive control; 7, negative control)

19. The effect of water extracts on the fresh weight of S. nigrum 1, A. syriaca root; 2, A. syriaca shoot; 3, C. arvense shoot; 4, C. arvensis shoot; 5, A. theophrasti shoot; 6, positive control

20. Conclusions Sprayed plant extracts did not inhibit virus infection Allelopathic plant extracts have different effect on the development and virus concentration in hosts One exception was in case of C. majus root extracts, which reduced significantly not only AMV concentration but also fresh weight of C. amaranticolor It seems that there is no relation between allelopathic inhibitory effect of weeds on the development of test plants and virus inhibitory effect in the hosts