Specific identification of coconut tinangaja viroid
Tinangaja is a lethal disease of coconut palm which was first described in 1917 in Guam. This disease resembles coconut cadang-cadang which occurs in the Philippines and is caused by coconut cadang-cadang viroid (CCCVd - EPPO A1 quarantine pest). Coconut tinangaja viroid (CTiVd) is associated with tinangaja disease, although it has not been verified that inoculation of this viroid causes the disease. These two viroids although similar (65% homology) are distinct. It is reported that since the early outbreaks of tinangaja, coconut groves have been neglected on Guam, and the disease has not been considered as economically important. However, a high incidence of tinangaja has again been observed in some areas of Guam. Therefore, there is a need for adequate diagnostic methods to understand better the epidemiology of the disease and develop control measures. A method has been developed to detect and identify CTiVd in leaf samples. Detection is based on extraction from plant tissues followed by agarose gel electrophoresis. Confirmation of the identity of CTiVd (and also detection of low levels of viroid) is achieved by using molecular techniques (DOP-hybridization (diagnostic oligonucleotide probe) or RT-PCR). This procedure can also be used for CCCVd, and oligoprobes designed to be specific for either CCCVd and CTiVd can distinguish between the two viroids in coconut leaf extracts
Sources
Hodgson, R.A.J.; Wall, G.C.; Randles, J.W. (1998) Specific identification of coconut tinangaja viroid for differential field diagnosis of viroids in coconut palm.
Phytopathology, 88(8), 774-781.