ISHS Acta Horticulturae 585: VIII International Rubus and Ribes Symposium
VIRUS DISEASES OF RUBUS AND STRATEGIES FOR THEIR CONTROL |
| Author: | R.R. Martin |
| Keywords: | Aphid-borne viruses, nematode-borne viruses, pollen-borne viruses, epidemiology, control, resistance, engineered resistance |
| Abstract:
Over 30 virus and virus-like diseases infect Rubus species. In all instances, the number one priority for virus control is to establish plantings with virus-free material. Many aphid-borne viruses remain uncharacterized, due in part to their limited host range and in part to the limited number of people working on them. Breeding for aphid resistance has been successful in controlling the incidence and spread of aphid-borne viruses, primarily because within a geographic region, a single vector is responsible for transmitting these viruses. There are four nematode-borne viruses in Europe and three in North America that can cause serious diseases in Rubus species. Control of nematode-borne viruses was enhanced greatly with the introduction of soil fumigants to reduce nematode populations. However, as some of these chemicals are being removed from the market for environmental reasons, alternative control measures are needed. There are sources of genetic resistance to some of the nematode vectors but the use of these resistant genes has been a low priority in breeding programs. There are two pollen-borne viruses in Rubus, Raspberry bushy dwarf virus (RBDV) and Tobacco streak virus, the latter being of minor importance. RBDV has been controlled through the use of gene Bu that confers resistance to D-type isolates of RBDV. RBDV has become a serious problem in all raspberry production areas over the past 10 years due to the planting of newer cultivars that lack RBDV resistance and the presence of a new strain of RBDV that overcomes the resistance conferred by the Bu gene. With developments in molecular biology, new sources of virus resistance derived from the pathogens themselves have been developed for a large number of viruses. In Rubus, this type of resistance is being developed for RBDV in Scotland and North America and for Tomato ringspot virus in North America. With RBDV, we know that approximately 1/3 of the transgenic plants remain virus-free after grafting twice with RBDV-infected scions. These still need to be evaluated for fruit quality, yield and field resistance. At this time, it appears that genetically engineered virus resistance to the important viruses of Rubus will be developed, however, whether fruit produced from such plants will be accepted socially remains to be determined. | |
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