Jenő HODONYI¹, Gabriella KAZINCZI², József BAKONYI³, Ernő TYIHÁK³, Árpád SZÉCSI³, József HORVÁTH⁴, Richard GÁBORJÁNYI⁴, András TAKÁCS<sup>2

1</sup>Sächsische Malzindustrie und Nährmittelfabrik GmbH, D-01909 Großhartau, Dresdner Str. 27, Germany
²Office for Academy Research Groups Attached to Universities and Other Institutions, Virology Group, University of Veszprém, Georgikon Faculty of Agricultural Sciences, H-8361 Keszthely, P.O.Box 71, Hungary
³Plant Protection Institute of Hungarian Academy of Sciences, H-1525 Budapest, Herman Otto u. 15, Hungary
⁴University of Veszprém, Georgikon Faculty of Agricultural Sciences, H-8361 Keszthely, P.O.Box 71, Hungary (contact e-mail: h11895hor@ella.hu)

Introduction

Malt has an importance in food industry. Because of its complex behavior its seems to be wery plausible that biological activity could some role in the plant protection. Natural chemicals and their use for integrated plant protection is one of the focuses of research works all over the world (Duke et al. 2002). These compounds could be used against different phytopathogen fungi (Orlikowski 2001). and their effects are also known to inhibit the spread and replication of viruses and to reduce the virus concentration in the infected leaves (Smookler 1971, Baranwal and Verma 1997, Manickam and Rajappan 1998, VIVANCO et al. 1999).

Experiments were carried out in order to study the effect of malt and plant extracts on plant growth, plant-virus interaction and phytopathogen fungi under laboratory conditions.

Material and methods

The effect of the malt samples and different extracts (No. 1-14) have been studied to phytopathogen fungi (Phytophthora infestans, Alternaria alternata, Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium avenaceum, F. culmorum, F. graminearum, F. moniliforme, F. sambucinum) in petri dishes (Table 1). Fusarium species were growing to 7 days in dark at 25^oC on potato-dextrose agar. Phytophthora infestans, Alternaria alternata, Botrytis cinerea and Sclerotinia sclerotiorum were maintained on pea-agar. The agar-plates with malt extracts were inoculated with disc (5 mm) fungi-gel cultures. After the treatment petri-dishes were kept in dark at 25^oC. The diameters of the fungal thalli were measured after 24 and 72 hours.

Table 1. The studied malt samples and plant extracts

The plant growth and virus susceptibility were studied in potato cv. Desiree, tomato cv. Manó and tobacco cv. Xanthi-nc in pot experiments. Potato-Potato virus Y (PVY), cucumber-Zucchini yellow mosaic virus (ZYMV), tomato-Cucumber mosaic virus (CMV), tobacco-Tomato spotted wilt virus (TSWV) and tobacco-CMV plant-virus interactions were studied. Tobacco, potato, tomato plants were infected at 6-8 leaf stages and cucumber plants at cotyledonous. Plants were treated (the soil was treated by malt solution, the plants were sprayed, or soil treatments and plant sprays together) two times per weak with different malt samples and plant extracts (No. 1-18). Two month later fresh weight of the plants and virus susceptibility by DAS-ELISA serological method after Clark and Adams (1977) were measured.

Results and discussion

The samples No. 13 and 14 (dilution 160 g/l) were reduced the growth of all Fusarium species by about 50 % and the samples 1, 4, 5, 6, 9, 11, 12, 13 and 14 inhibited the growth of P. infestans by 100 %. In some cases the malt samples were not enough effective or had stimulatory effect to some fugal species. In our experiments the P infestans, A. alternata and B. cinerea species were the most sensitive to treatments. However S. sclerotiorum were stimulated by majority the most malt samples. Among the malt samples the No. 3, 4, 5, 6, 11, 12, 13, and 14 showed the most strongest (22-34%) inhibitory effect (Table 2).

Table 2. The inhibitory effect of malt samples and plant extracts to growth of thallus (%)

In some cases malt samples stimulated the plant growth in the pot experiments. Except No. 14, all malt samples increased the fresh weight all of the tested plants. The pigweed - malt extract (No. 18) inhibited the ZYMV infection of the cucumber test plants in all cases. Malt extracts mixed with other plant component reduced the virus infection, showing the additional virus inhibitory effect of the plant extracts.

References

1. Baranwal, V. K. and Verma, H. N. (1997). Characteristics of a virus inhibitor from the leaf extract of Celosia cristatata. Plant Pathology 46, 523-529.

2. Clark, M. F. and Adams, A. N. (1977). Characteristics of the microplate method of enzyme-linked immunosorbent assay for the detection of plant viruses. J. Gen. Virol. 34, 475-483.

3. Duke, S.O., Rimando, A.M., Baerson, S.R., Scheffler, B.E., Ota, E. and Belz, R.G. (2002). Strategies for the use of natural products for weed management. J. Pesticide Sci. 27, 298-306.

4. Manickam, K. and Rajappan, K. (1998). Inhibition of antiviral activity of certain leaf extracts against tomato spotted wilt virus in cowpea. Ann. Plant Prot. Sci. 6, 127-130.

5. Orlikowski, L. B. (2001). Effect of grapefruit extract on development of Phytophthora cryptogea and control of foot rot of gerbera J. Plant Protection Res. 41, 3, 288-294.

6. Smookler, M. M. (1971). Properties of inhibitors of plant virus infection occuring in the leaves of species in the Chenopodiales. Ann. Appl. Biol. 69, 157-168.

7. Vivanco, J. M., Querci, M. and Salazar, L. F. (1999). Antiviral and antiviroid activity of MAP-containing extracts from Mirabilis jalapa roots Plant Dis. 83, 1116-1121, 1999.