We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-β-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-β-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa.

In winter and early spring 2004 unequivocal mosaic symptoms were detected for the first time in Germany on six plants of the barley cv. ÔTokyoÕ carrying the resistance gene rym5. By serological and electron microscopic investigations Barley mild mosaic virus (BaMMV) was identified in all plants and could be re-transmitted to cv. ÔTokyoÕ as well as to additional cultivars carrying rym5. In contrast to this, genotypes carrying the resistance genes rym1 + rym5, Rym2, rym4, rym7, rym9, rym11, rym12, rym13, Rym14 Hb , rym15 or Rym16 Hb turned out to be resistant. Furthermore, the BaMMV isolates were not transmissible to different dicotyledonous species. Sequence analyses in the VPg coding region of RNA1 revealed differences to the known sequence of the original BaMMV isolate (BaMMV-ASL1, AJ 242725) and also of a French pathotype (BaMMV-Sil, AJ 544267, AJ 544268) which is also able to overcome the resistance mediated by rym5. At least in one location a spread of the area infested by this new strain was observed in 2004 ⁄ 2005 and 2005 ⁄ 2006.

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Biolistic inoculation of Hordeum vulgare and Phalaris paradoxa with a brome streak mosaic virus (BrSMV) full-length cDNA clone (pBrSMV(fl)) led to typical leaf streak symptoms in both plant species. Infected H. vulgare plants showed a more stunted growth 8 weeks after symptom appearance compared to BrSMV wild type (BrSMV(wt))-infected plants. Moreover, a slightly higher virus titer was observed in BrSMV(fl)-inoculated H. vulgare, A. sativa and P. paradoxa plants. The biological activity of BrSMV(fl) and BrSMV(wt) was verified in vector transmission assays, providing the first experimental evidence that Aceria tosichella can act as a natural vector of BrSMV.