Randles, J.W.Cueto, C.A.Vadamalai, G.Hanold, D.Adkar-Purushothama, C.R.Sano, T.Perreault, J.-P.Yanjarappa, S.M.Di Serio, F.Daròs, J.-A.2024-05-082024-05-082023Fundamentals of Viroid Biology, 2023 / Adkar-Purushothama, C.R., Sano, T., Perreault, J.-P., Yanjarappa, S.M., Di Serio, F., Daròs, J.-A. (ed./s), Ch.8, pp.151-1689780323996884https://hdl.handle.net/2440/140724The devastating cadang-cadang epidemic of coconut palm in the Philippines required the development of a program to identify the cause. The pursuit of a “virus” hypothesis led to the identification of disease-associated small RNA which was found to have molecular properties typical of the recently recognized viroids and named CCCVd. Uniquely infecting monocotyledonous species, its mode of natural spread and epidemiology are yet to be determined. This chapter summarizes the internationally supported studies done in the Philippines and Guam where coconut cadang-cadang and tinangaja viroids occur, respectively. The discovery that CCCVd is common in oil palm plantations has led to a research and development program in Malaysia. Surveys in Oceania and elsewhere have identified CCCVd-related sequences in coconut and other monocotyledons, which might provide evidence for a source of CCCVd. It is suggested that existing representatives of early plant life should be analyzed for viroid-related sequences, in support of Diener's speculation that viroids are fossils of an RNA world.en© 2024 Elsevier Inc. All rights reserved.Book chapter10.1016/B978-0-323-99688-4.00005-52024-05-07684405Randles, J.W. [0000-0003-2231-816X]