DO VIRUSES SIGNAL TO THEIR VECTORS?
Red-purple foliage is characteristic of one type of ornamental (Japanese hybrid) cabbage (Brassica oleracea). The leaves of these ornamentals mimic effects that, in a wild species (Brassica nigra), were associated with virus infection. Field grown wild B. oleracea in the United Kingdom are infected by combinations of the following:- beet western yellows polerovirus (BWYV); turnip mosaic potyvirus (TuMV); cauliflower mosaic caulimovirus (CaMV); turnip yellow mosaic tymovirus (TYMV) with all populations containing all viruses but with frequencies of infection differing from year to year and from site to site. Turnip crinkle carmovirus (TCV), turnip rosette sobemovirus (TRoV) and cucumber mosaic cucumovirus (CMV) were not found in any of these B. oleracea populations. By contrast, although TRoV, CaMV and BWYV were frequent and TRoV was found in all sympatric populations of B. nigra, TuMV was never detected.. In inoculated glasshouse-grown B. nigra seedlings, TuMV was lethal, TRoV caused r
