Articles
DO VIRUSES SIGNAL TO THEIR VECTORS? OBSERVATIONS USING ORNAMENTAL HYBRID AND WILD BRASSICA SPECIES
Article number
568_17
Pages
123 – 126
Language
English
Abstract
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 red-purple foliage and TYMV caused bright yellow mosaics.
Field grown ornamental cabbages with red-purple foliage were uniformly free from infection by aphid transmitted viruses even when grown within 150 metres of B. oleracea types grown for food and universally infected by TuMV and CaMV. In glasshouse challenge tests, seedlings of ornamental cabbages were infectible with each of the manually transmissible brassica viruses (except CMV). Thus, it seemed possible that the red – purple foliage coloration, might lessen the attractiveness to vectors and thereby the probability of virus acquisition and spread.
As part of an ongoing investigation to understand the diverse factors that impact with viruses on wild plant fitness, tests were done to investigate virus-associations on the one hand and aphid colour preferences on the other.
Whereas aphids showed a preference for yellow surfaces, our tests showed that they were not responsive to red-purple.
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 red-purple foliage and TYMV caused bright yellow mosaics.
Field grown ornamental cabbages with red-purple foliage were uniformly free from infection by aphid transmitted viruses even when grown within 150 metres of B. oleracea types grown for food and universally infected by TuMV and CaMV. In glasshouse challenge tests, seedlings of ornamental cabbages were infectible with each of the manually transmissible brassica viruses (except CMV). Thus, it seemed possible that the red – purple foliage coloration, might lessen the attractiveness to vectors and thereby the probability of virus acquisition and spread.
As part of an ongoing investigation to understand the diverse factors that impact with viruses on wild plant fitness, tests were done to investigate virus-associations on the one hand and aphid colour preferences on the other.
Whereas aphids showed a preference for yellow surfaces, our tests showed that they were not responsive to red-purple.
Authors
M. Thurston, J.J. Cooper, D. Pallett, M.L. Edwards, W.D. Hamilton
Keywords
Brassica, tymovirus, potyvirus, polerovirus, carmovirus, caulimovirus sobemovirus
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