Headspace collection of grapevine volatiles in a Hungarian vineyard.

L. botrana is a major pest of the grapevine, the larvae is feeding on the flower buds and the berries. Because of the damage of the larvae, secondary fungal infection can be evolved by the grey mold (Botrytis cinerea). A special blend of plant volatiles are emitted by the host plant. Mated L. botrana females use olfactory cues to find their host plant and oviposition sites. Grapevine volatiles were collected in 2012 and the blend was analyzed with GC, numerous compounds were present in the collected blend. More grapevine volatiles will be collected in 2013, in several phenological stadia of different grapevine varieties.

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.

New host-virus relations between different Solanum species and viruses.

We have studied the susceptibility or resistance of Solanum capsicastrum Link. et Schauer, S. comatum Sendt., S. dulcamara L., S. luteum Mill., S. malacoxylon Sendt. and S. nigrum L. to three aphid transmissible viruses [alfalfa mosaic alfamovirus (AMV), potato M. carlavirus (PVM) and potato S carlavirus (PVS)]. Out of the species, S. capsicastrum, S. comatum, S. dulcamara, S. malacoxylon and S. nigrum to AMV, S. capsicastrum and S. malacoxylon to PVM and S. capsicastrum, S. luteum and S. nigrum to PVS showed the highest resistance (immunity). Symptoms could not be seen on inoculated plants and the virus could be detected by them neither by serological nor biological tests. Solanum luteum plants were susceptible to AMV. Solanum comatum, S. dulcamara, S. luteum and S. nigrum showed susceptibility to PVM. Solanum comatum and S. dulcamara were susceptible to PVS. Symptoms (necrotic lesions, mosaic and chlorosis) could be seen after inoculation and the absorbance values (DAS-ELISA) exceeded twice that of the healthy control samples during the serological tests.