Project title
Development of a large-scale detection method for grapevine leafroll associated virus type 3

Project leader
Pietersen, G

Institution
ARC. Plant Protection Research Institute.

Project description
Grapevine leafroll disease is a serious problem for the South African Wine Industry but in recent years a successful control strategy based on rouging of infected vines, control of mealybug numbers and dispersal has been developed. Rouging can be effectively achieved in red cultivars by visual vine-for-vine detection annually in late autumn. Visual assessment of leafroll infection can however not be done with white cultivars as leafroll symptoms are not obvious in these and to achieve control of leafroll vines must be subjected to a virus detection method annually prior to rouging. Currently the sensitive techniques, PCR or real-time PCR, which allow combining of large numbers of vines for tests (to make the tests cheaper) are too expensive, because of their infrastructure requirements, to be done on the scale required to achieve yearly testing of individual white cultivar vines. Furthermore these tests must be conducted in laboratories with relatively well trained personnel. We propose a project to develop and assess the ability of relatively new nucleic acid isothermal amplification techniques called loop mediated isothermal amplification (LAMP) (Notomi et al., 2000) and cycleave isothermal and chimeric primer-initiated amplification (Cycleave ICAN) (Urasaki et al., 2008) for the detection of grapevine leafroll associated virus type 3 (GLRaV-3), the cause of leafroll disease in South Africa. The techniques will be adapted to do large-scale decentralized detection of GLRaV-3, in order to identify individually infected white cultivar vines to allow their ultimate removal in order to control the disease. Should one or both of these techniques work well the project will be expanded by two years to develop similar techniques for grapevine virus A and B (which currently are tested by ELISA using expensive important reagents.

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