DETECTION AND DIFFERENTIATION OF WHITEFLY-TRANSMITTED GEMINIVIRUSES IN PLANTS AND VECTOR INSECTS BY THE POLYMERASE CHAIN-REACTION WITH DEGENERATE PRIMERS

Degenerate oligonucleotide primers, designed for amplification of an approx. 500 bp fragment of DNA-A of five well characterised whitefly-transmitted geminiviruses, were used in the polymerase chain reaction (PCR) to detect known or putative geminiviruses infecting seven plant species and originally obtained from Africa, India, America or Europe. Although nucleotide sequences are published for only four of the viruses, all 13 were detected. Six of the viruses were also detected in single viruliferous whiteflies (Bemisia tabaci). Virus was detected both in fresh B. tabaci and in specimens that were frozen and dried before being dispatched from their country of origin. Individual viruses could be distinguished by the patterns of DNA fragments obtained by the action of restriction endonucleases on the PCR products. This approach also allowed six virus isolates from leaf curl-affected tomato to be assigned to four country-specific forms.