Indexing of citrus viroids by imprint hybridisation

A method based on the hybridisation of tissue imprints was developed for ro utine indexing of citrus viroids. For maximum sensitivity and reliability, the inoculation of Citrus medica (Etrog citron) as a viroid amplification h ost is required. Hybridisation against Digoxigenin-labelled RNA- or DNA-pro bes followed by detection of viroid-probe hybrids using anti-DIG-alkaline p hosphate conjugate and the chemiluminescence substrate CSPD was suitable fo r the detection of all citrus viroids with the same sensitivity as other av ailable methods. The overall process is extremely simple and allows quick a nalysis of large numbers of samples by easily trained personnel and minimum equipment.