SUMMARY

A procedure was developed for detecting viroids in citrus cuttings collected in the field and forced to sprout in a growth chamber. Leaves collected 15 days or one month after sprouting were tested in comparison with leaf and bark samples from field-grown source plants. Tests were made by using RT-PCR with primers specific for Citrus exocortis viroid (CEVd), the citrus strain of Hop stunt viroid (HpSVd-cit), Citrus bent leaf viroid (CBLVd), Citrus viroid III (CVd-III), or Citrus viroid IV (CVd-IV). Whereas no evidence was obtained for the presence of CBLVd and CVd-IV were not found where-as HpSVd-cit, CEVd, and CVd-III were detected con-sistently in forced cuttings even when no positive ampli-fication was obtained from field samples. This method may be a useful in the laboratory detection of citrus vi-roids. Key words: citrus, viroid, diagnosis, RT-PCR. A number of viroids are known to infect citrus, some of which, such as the agents of exocortis and cachexia, cause severe diseases (Duran Vila and Semancik, 2003). In Italy, a voluntary programme of citrus certification is being implemented that requires certified propaga-tion material to be free from viroids, as ascertained by biological indexing (Roistacher et al., 1973, 1977) and sequential polyacrylamide gel electrophoresis (sPAGE) (Boccardo et al., 1984). The first procedure is time-con-suming and expensive. The second allows the process-ing of a small number of samples at a time and its suc-cess depends on viroid concentration, which can vary with the environmental conditions (Tessitori et al.