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Somatic hybrids were produced by PEGinduced symmetric and asymmetric protoplast fusions in order to transfer resistance to Alternaria brassicicola, A. brassicae, Phoma lingam, Plasmodiophora brassicae and Turnip mosaic virus (TuMV) into Brassica oleracea var. capitata (cv. 'Toskama') and botrytis (cv. 'Korso'). As resistance donors, ten species belonging to several genera of the family Brassicaceae including wild relatives were used. Of 2,189 plants (somatic hybrids, partially in vitro cloned) tested, 1,616 (73.8%) were resistant against at least one of the pathogens, indicating that, mostly, a successful resistance transfer has taken place. Five hundred and twenty-two hybrids showed multiple resistances to two, three and, in a single case, to four pathogens. Irrespective of the donor parents used in the fusion, a broad variability in symptom manifestation ranging from 0 (without symptoms) to 9 (highly susceptible) could be observed. With regard to the Alternaria pathogens, Sinapis alba, B. nigra and B. juncea were the most effective resistance donors, whereas fusions with Raphanus sativus resulted in the most hybrids with resistance to clubroot and TuMV. As could be shown especially in asymmetric fusions with S. alba, Barbarea vulgaris and Hesperis matronalis, transferred resistance to a pathogen may not correspond with resistance exhibited by the donor parent. Some combinations in which both parents were highly susceptible, e.g. R. sativus (?) B. oleracea var. capitata, yielded hybrids that exhibited strong resistance, e.g. to A. brassicicola, revealing that a new type of resistance might be occurring. With regard to the Alternaria pathogens, resistance expression was very unstable. Many hybrids into which (also variable) resistance of some donors, such as B. vulgaris, S. alba and B. carinata, was transferred became as highly susceptible as those of which the fusion parents did not show any resistance reaction (e.g. R. sativus). For reliable characterization of the resistance response, hybrids should be subjected to several resistance tests during growth period of the host, at least until flowering.

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A barley cDNA for the thaumatin-like protein Hv-TLP8 driven by the CaMV 35S promoter was introduced into oilseed rape (Brassica napus) via Agrobacterium-mediated transformation. Some transgenic lines were obtained which exhibited enhanced resistance to the clubroot pathogen (Plasmodiophora brassicae). To increase resistance, double haploid (DH) lines were generated from these transgenic plants. Of these, DH-line 189 showed stable inheritance of the transgenic trait and its associated resistance for at least three generations.

Five asparagus cultivars, three breeding lines and the wild relative Asparagus amarus were tested for natural infection by Asparagus virus 1 (AV-1) in experimental fields at two locations over 3 and 4 years, respectively. In the first year after re-planting the annual crowns in the field, more than 90% of tested plants of cultivars were infected by AV-1. In the third and fourth year, 100% of tested plants of cultivars were AV-1 infected. In comparison, all plants of the wild relative A. amarus were completely free of AV-1, suggesting a high level of resistance. Additionally, 1-year-old glasshouse-cultivated plants of A. officinalis and A. amarus were placed in an AV-1 provocation cabin under field conditions. Seven months later, 100% of the A. officinalis plants showed a high virus concentration in ELISA, whereas no AV-1 was detectable in the A. amarus plants. This result was confirmed by highly sensitive AV-1-specific RT-PCR. To exclude vector resistance, the feeding behaviour of green peach aphid Myzus persicae was tested over 12 h using the electrical penetration graph method. Both asparagus genotypes were accepted by the aphids as potential hosts, but the feeding time was significantly longer on A. amarus. A genetic distance analysis of the various cultivars of Asparagus officinalis and selected wild relatives of the JKI collection was carried out, resulting in a clear discrimination of cultivars and wild relatives, especially A. amarus. The potential breeding value of the putative resistance carrier is discussed. IntroductionVirus infections are an underestimated problem in asparagus production because symptoms are often inconspicuous or plants are symptomless. Currently, ten viruses have been identified in garden asparagus (Asparagus officinalis) worldwide, including three Asparagus viruses (AV-1, AV-2 and AV-3) for which asparagus is the only natural host. While AV-1 and AV-2 occur in many asparagus growing regions of the world, AV-3 has been found only in Japan (Fujisawa 1986;Tomassoli et al. 2012). Furthermore, apart from infecting various other vegetables, Tobacco streak virus (TSV), Cucumber mosaic virus (CMV) and Tobacco mosaic virus (TMV) have also been found infecting asparagus. Another four viruses -Alfalfa mosaic virus (AMV), Arabis mosaic virus (ArMV), Strawberry latent ring spot virus (SLRSV) and Tomato black ring virus (TBRV), that are of minor importance in asparagus have been reviewed by Knaflewski et al. (2008) and Tomassoli et al. (2012).The potyvirus Asparagus virus 1 (AV-1) is distributed worldwide and is transmitted in a non-persistent manner by aphids. Its main vector is the green peach aphid Myzus persicae, but it can be transmitted also by

Resistance tests of 127 parsley accessions (Petroselinum crispum) were carried out during 2 years of field investigations involving natural infection for black leaf spot (Alternaria radicina), mildew (Erysiphe heraclei), leaf chlorosis (Fusarium oxysporum) and viruses, particularly celery mosaic virus (CeMV). In this first extensive evaluation of parsley for all tested pathogens accessions were found to be free of symptoms.Varieties of vars. crispum and tuberosum contained more accessions weakly infected or immune to black leaf spot than vars. vulgare and neapolitanicum. In a separate test five var. crispum accessions showed significantly reduced disease ratings, indicating their potential as sources of resistance. Mildew attacked almost the same number of accessions in both years: 29 accessions of var. crispum showed no symptoms, but 16 of the var. tuberosum accessions were highly susceptible. Whereas in the var. vulgare one half of the introductions were moderately or strongly infected by viruses, mainly CeMV, a high number of plants remained uninfected in the vars. crispum, neapolitanicum and tuberosum. In the case of F. oxysporum, the greatest amount of infection was in the var. crispum during both years. The sources of resistance described including multiple resistance would be of interest in future breeding programmes for resistance to the parsley pathogens discussed.

Zusammenfassung: Das Turnip mosaic virus (TuMV) ist Summary: Turnip mosaic virus (TuMV) is an important weltweit verbreitet und gehört zur Gruppe der Potyvi-pathogen in vegetable Brassica crops and belongs to ren. Es hat einen außerordentlich großen Wirtspflan-the Potyvirus group. The virus occurs worldwide and zenkreis von über 300 Arten und wird nicht persistent has a very wide host range of more than 300 plant durch 89 Aphidenarten übertragen. Bisher sind beim species including different Brassica crops. In white cabTuMV zwölf Pathotypen bekannt. Im Kohlgemüse ver-bage (Brassica oleracea var. capitata) TuMV infection ursacht das TuMV die so genannte Kohlschwarzring-causes up to 25 % yield reductions as well as necrosis fleckigkeit. Dabei handelt es sich um eine wirtschaft-during cold storage of the heads. An effective way of lich wichtige Virose, die beim Weißkohl bis zu 25 % Er-plant protection is the establishment of resistance to tragsausfall und Gewebenekrotisierungen, insbeson-different TuMV pathotypes in cabbage. dere während der Kühllagerung, bewirken kann. Zur TuMV isolates were characterized and resistance Sicherung eines hohen Ertrags-und Qualitätsniveaus screening methods utilizable under greenhouse and bei Kohlgemüse wurde begonnen, die Resistenz gegen field conditions were developed. The search for resistdiese Virose zu verbessern. Mit aktuellen, weitgehend ance to TuMV in more than 100 accessions of the Brascharakterisierten Erregerherkünften des TuMV wurden sicaceae family revealed some new resistance donors. Resistenzprüfmethoden weiterentwickelt und neue Re-Resistance to different TuMV pathotypes was found in sistenzquellen in der Familie der Brassicaceae erschlos-B. oleracea primitive forms, Chinese cabbage (B. rapa sen. Resistenzen gegen mehrere TuMV-Pathotypen lie-ssp. pekinensis), horse-radish (Armoracia rusticana) and ßen sich in B. oleracea-Primitivformen, in Chinakohl radish (Raphanus sativus). A high level of resistance to (B. rapa ssp. pekinensis), in Meerrettich (Armoracia ru-three TuMV pathotypes was also detected in sexually sticana), in Radies bzw. Rettich (Raphanus sativus) so-developed Raphanobrassica hybrids. In a B. oleracea wie in sexuell erzeugten Raphanobrassica-Hybriden landrace five inbred lines (I 6 ) were selected under field nachweisen. Die evaluierten TuMV-Resistenzen wur-conditions receiving a high level of resistance (infection den entsprechend der phylogenetischen Distanz zum rate 0 %) after inoculation with the high virulent Kohl durch Kreuzung bzw. durch Protoplastenfusion TuMV isolate 2. From two B. oleracea primitive forms in Kulturformen des Kohls übertragen. seven homozygous lines (I 5 ) were developed by successive selection and self-pollination. After inoculation with five TuMV isolates representing three pathotypes (Mix 1), resistant plants were symptom-less as well as DAS-ELISA negative. Resistance to TuMV in B. oleracea primitive forms could be transferred into white cabbage by crosses followed by successive screening and selection procedures. Somatic hyb...

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