Effect of different temperature and culture media on the growth of Macrophomina phaseolina.

The charcoal root disease caused by Macrophomina phaseolina (Tassi) Goidanich may cause considerable damages in hot as well as in dry seasons. The effect of temperature and culture media were studied on the growing patterns of 35 M. phaseolina isolates, collected from different districts of Hungary. The isolates were grown at 10, 15, 20, 25, 30, 35 and 40 degrees C temperatures respectively, and additionally at 25 degrees C on potato-dextrose-, malt-extract-, Czapek-Dox-, Sabouraud-glucose-, maize-flour- and watery agar media, using 90 mm Petri-dishes, 4 repetitions in each case. For all the isolates the most favourable temperature regime was 25 to 35 degrees C and the most advantageous media was the malt-extract-, Sabouraud-glucose- and potato-dextrose-agar media. At these conditions (temperatures and culture media) mycelia growth and the diameter of microsclerotial colonies reached the 90 mm at the 5th day. Mycelia growth of the pathogen was very low at 10, 15 and 40 degrees C, and did not form microsclerotia. On watery agar microsclerotial colony seldom developed, it needed 14 days, and no continuous mycelia developed even in a 8th months culture. Diameter of microsclerotia measured on different culture media varied between 39-308 microm.

Susceptibility of some Lycopersicon species and varieties to cucumber mosaic virus (CMV) and tobacco mosaic virus (TMV).

Susceptibility of 33 Lycopersicon species and varieties to Tobacco mosaic virus (TMV) and Cucumber mosaic virus (CMV) were studied. Plants were mechanically inoculated with the C/U1 strain of TMV and U/246 strain of CMV. Virus infection was checked by symptomatology, DAS ELISA and back inoculation (biotest). All the studied Lycopersicon species and varieties were susceptible to TMV-C/U1. L. esculentum Mill. convar. infiniens Lehm. var. flammatum Lehm., L. esculentum Mill. convar. fruticosum Lehm. var. speciosum Lehm. and L. esculentum Mill. convar. infiniens Lehm. var. validum Bail. showed extreme resistance to CMV-U/246. The other 30 species and varieties were susceptible to CMV-U/246. New compatible and incompatible host-virus relations have been reported. The extreme resistant Lycopersicon varieties could be used as resistance sources in tomato breeding.

Susceptibility of some weed species to Pepino mosaic virus (PepMV).

The aim of our investigations was to study the susceptibility of 22 weed species to Pepino mosaic virus (PepMV). Seven plants of each species were mechanically inoculated at 4-6 leaf stage with PepMV in a vector free virological glasshouse. Inoculated plants were tested on the basis of symptoms, by DAS ELISA serological method and back inoculation. Among the 22 weed species, only some Solanum ones (S. aethiopicum, S. dulcamara, S. luteum, S. nigrum) were susceptible to PepMV infection. All of them--except S. aethiopicum--belong to Hungarian weed flora, therefore these weeds--occurring mainly in tomato ecosystems--may play important role in the epidemiology of PepMV. Other 18 weed species seemed to be resistant to PepMV, and on the basis of back inoculation not even latent infection has been observed.

Experimental and natural weed host-virus relations.

Weeds, as alternative hosts of plant viruses and nutrient plants of virus vectors play important role in virus ecology and epidemiology. The aim of our study was to discover new weed-virus relations. Therefore some weed species were mechanically inoculated with 28 viruses (strains or isolates) maintained in our glasshouse. Different weed species with and without visible symptoms were collected from agro-, water ecosystems and wastelands of Hungary between 1997 and 2003. Virus infections were evaluated by biotests, DAS ELISA serological methods, electronmicroscopy and immunosorbent electronmicroscopy (ISEM). Under glasshouse conditions Ambrosia artemisifolia was considered as a virophob species, showing resistance to all viruses listed above. A series of new artificial (Chenopodium album--SoMV (LH+SH)*, AMV (LH+SH); C. berlandieri--PVY(NTN) (LH), AMV (LH+SH), CMV (LH), SoMV (LH+SH), ObPV (LH+SH), ZYMV-10 (LH): C. ugandae--ObPV (LH), SoMV (L); C. glaucum--ObPV (LH), SoMV (L); Echinocystis lobata--PVX (L), ZYMV (LH+SH); Solanum nigrum--MYFV (LH+SH), PVY(N) (L), PVY(NTN) (LH+SH), SoMV (LH), TMV (SH), CMV (SH); S. dulcamara--CMV-U/246 (SH), PVY(NTN) (LH), SoMV-H (L), TMV-O (L); S. luteum--PVY(N) (SH), PVY(NTN) (LH+L), TMV(SH).) and natural (Asclepias syriaca--TMV, AMV, TSWV; Alisma plantago-aquatica--PVY, SoMV; Ambrosia artemisiifolia--CMV; Chenopodium album--CMV, PVS, PLRV; C. hybridum--CMV; Cirsium canum--CMV, PVM; Carex vulpina--CMV; Comium maculatum--PVY; Datura stramonium--PVA, PVX, PVS, PVM, CMV, TMV; Lysimachia vulgaris--ArMV, BNYVV, CMV, TMV; Lythrum salicaria--ArMV; Malva neglecta--CMV; Mercurialis annua--SoMV; Solanum nigrum--CMV, PVY, PVY(N); Solidago gigantea--CMV, RpRSV, BNYVV; Stenactis annua--PVM, PVA) weed--virus relations were detected. The epidemiological role of perennial hosts (A. syriaca, A. planlago aquatica, C. canurm, L. vulgaris, L. salicaria, S. gigantea) is especially high, because they can serve as infection sources as well as overwintering hosts of different plant viruses.

Susceptibility of Capsicum breeding lines to NTN strain of Potato virus Y (PVY(NTN)) and Obuda pepper virus (ObPV).

The objective of this study was to examine the reaction of 12 Capsicum breeding lines to NTN strain of Potato virus Y (PVY(NTN)) and 16 lines to Obuda pepper virus (ObPV). Inoculated plants were symptomatologically and serologically checked for virus infection. Back inoculation was also carried out to Nicotiana tabacum 'Xanthi-nc' and N. tabacum 'Samsun' as indicator plants. Out of the 12 lines tested four (32.Bogyiszlói, 4/99 F2, 17/99 F2 and VI-61 in.) proved to be resistant (immune) to PVY(NTN). Seven Capsicum lines (9/99 F2, 17/99 F2, V-21 = 28/98 F3, V-28 = 36/98 F3, V-3 = 7/98 F2, V-6 = 13/98 F2, and V-10 = 17/98 F2) showed hypersensitive reaction to ObPV. Other breeding lines were susceptible to ObPV infection. One line (17/99 F2) showed immunity to PVY(NTN) and hypersensitivity to ObPV at the same time, therefore this one is considerably valuable for breeding pepper varieties for multivirus resistance.

Reaction of Lycopersicon species and varieties to Potato virus Y (PVY(NTN)) and Tomato mosaic virus (ToMV).

Virus susceptibility of 33 Lycopersicon species and varieties to NTN strain of Potato virus Y (PVY(NTN)) and Tomato mosaic virus (ToMV) were studied. Inoculated plants were tested for infection symptomatologically, serologically and by back inoculation as well. New incompatible and compatible host-virus relations have been determined. All tested plants were susceptible to ToMV. However, Lycopersicon esculentum Mill. convar. parviboccatum Lehm. var. cerasiforme (Dun.) Alef. s.l., L. peruvianum (L.) Mill. and L. hirsutum Humb. et Bonpl. were extreme resistant (immune) to PVY(NTN). Other species were susceptible. Resistant lycopersicon genotypes could be used as sources for virus resistance.

Antitumor effect of lysine-isopeptides.

Isopeptides (ϵ-peptides) of lysine, with a given Mw and low polydispersity (10-400 units), were synthesized to study the relationship between their chemical structure and biological effect. The designed compounds were of high purity, low polydispersity and high stereochemical purity. The effect of the compounds was tested on a human erythroleukemia cell line (K-562) and on four transplantable mouse tumors (L1210 lymphoid leukemia, P38 macrophage derived tumor, Ehrlich ascites carcinoma, Lewis lung tumor /LLT/). In case of the L1210 and P388 tumors and the Ehrlich carcinoma, survival of the animals was used as an indicator of the effect. In case of the Lewis lung tumor, the number and size of metastases in the lung and/or liver of treated and untreated mice were used as indicators. The polymers of polymerisation degree 80-120 (Mw 10.2-15.4 KD) showed the strongest antiproliferative effect both on K562 cells and the tumors growing in vivo. This effect was manifest with a significantly higher survival rate as compared to the control (L1210, P38, Ehrlich ascites), furthermore, by a decrease in the number and size of liver and lung metastases (LLT).

Serological characterization of Hungarian plum pox virus isolates.

Three Hungarian (no. 2, 4 and 9), and a Moldavian (K) plum pox virus isolates were compared with a characterized Spanish isolate (5.15) by RT-PCR, ELISA, dot-blot and Western blot analysis. Monoclonal antibodies prepared against the external, intermediate and internal sequences of the coat protein of the Spanish isolate were able to differentiate the four isolates. Hungarian isolate No. 2 proved to be serologically identical to the Spanish isolate, while No. 4 showed appreciable differences and No. 9 could be recognized only by the monoclonal antibodies representing the intermedial and internal parts of the coat protein. K isolate showed a more distant relationship to other isolates. Our experiment provided the first demonstration of the presence of D type isolates in Hungary.

Possibility of formation of excited formaldehyde and singlet oxygen in biotic and abiotic stress situations.

The results obtained prove that singlet oxygen and excited formaldehyde can be liberated from hydrogen peroxide and formaldehyde in free and bound L-lysine containing plant and other tissues, similarly to the model reactions. It can be concluded that these reactive molecules have extremely high reactivity and are possibly aggressive to cellular components like proteins, nucleic acids and to microbial systems within plant and other tissues. However, the manifestation of their activity depends on level of quenching systems in plant and other tissues. It seems that these special reactions and their products may be an important part of the resistance potential (e.g. natural disease resistance) in biological systems.

Antiviral activity of tiazofurine against barley stripe mosaic virus.

Tiazofurine (2-beta-D-ribofuranosylthiazole-4-carboxamide) was found to inhibit replication of barley stripe mosaic virus (BSMV) in barley and wheat plants. Treatment with this nucleoside analogue delayed and inhibited symptom development and suppressed virus multiplication. The most effective concentration applied twice as a foliar spray 3 h and one day after inoculation, was 10(-3) M. Decreased virus multiplication was obtained without marked phytotoxicity. Three weeks after treatment the antiviral effect declined.