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Etiology

Tinangaja and Bristle Top, Coconut Diseases of Uncertain Etiology in Guam, and Their Relationship to Cadang-Cadang Disease of Coconut in the Philippines. Guido Boccardo, Istituto di Fitovirologia Applicata del C.N.R., Via O. Vigliana 104, 10135 Torino, Italy; R. G. Beaver(2), J. W. Randles(3), and Julita S. Imperial(4). (2)University of Guam, College of Agricultural and Life Sciences, P.O. Box EK, Agaņa, Guam 96910, Marianas Islands; (3)Waite Agricultural Research Institute, Department of Plant Pathology, University of Adelaide, Glen Osmond, South Australia 5064; (4)Philippine Coconut Authority, Albay Research Center, Guinobatan, Albay 4908, The Philippines. Phytopathology 71:1104-1107. Accepted for publication 11 February 1981. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-1104.

The symptomatologies of tinangaja and bristle top, two disorders afflicting coconut palms on the island of Guam, were compared with cadang-cadang disease in the Philippines. Nucleic acids were extracted from leaf samples from healthy and diseased palms through a procedure involving precipitation with polyethylene glycol, phenol and chloroform extractions, fractionation with 2 M LiCl, and further purification with cetyltrimethylammonium bromide. Comparative electrophoretic analysis established that two low-molecular-weight RNAs with the same apparent mobilities in 5% polyacrylamide gels as the diagnostic viroidlike RNAs (ccRNA-1 and ccRNA-2) associated with cadang-cadang disease were correlated uniquely with tinangaja symptoms. A ³H-labeled DNA probe complementary to ccRNA-1 (cDNA) was used to show that the tinangaja-related RNAs have nucleotide sequences equivalent to ccRNA-1. Tinangaja is therefore considered to have the same etiology as cadang-cadang, a disease formerly believed to be restricted to the Philippines. Nucleic acids extracted from coconuts affected with bristle top did not contain such viroidlike RNAs.