PCR-based quarantine procedure for the detection of cocoa swollen shoot virus

Abstract

Cocoa (Theobroma cacao) is an economic tree crop which dominates the economy of most West African countries. Cocoa swollen shoot virus (CSSV) a badnavirus, transmitted by the mealy bug is a threat to the cocoa industry. Traditionally, indexing of cocoa trees for CSSV was usually carried out by budwood grafting donor materials onto disease-free Amelonado cocoa trees with symptoms of the virus expressed on the second or third leaf flushes. In CSSV budwood grafted transmissions involving genotypes other than Amelonado, symptoms may fail to develop on the leaves although the recipient trees may be infected. PCR/capillary electrophoresis was sensitive in detecting the CSSV and highlighted the disease well in advance of the appearance of visual symptoms. The design of the primer across the six published sequences of the cocoa genome capable of detecting all strains of the CSSV has the potential of improving the robustness of quarantine procedures for the international exchange and long term conservation of cocoa germplasm.