Transmission of the coconut cadang‐cadang viroid to six species of palm by inoculation with nucleic acid extracts

Abstract

Seedlings of Areca catechu (betel nut palm), Corypha elata (buri palm), Adonidia merrillii (manila palm), Elaeis guineensis (oil palm), Chrysalidocarpus lutescens (palmera) and Oreodoxa regia (royal palm) were inoculated with nucleic acid extracts from coconut palms with cadang‐cadang disease. Within 2 years of inoculation, analysis using a 32P‐labelled DNA probe complementary to the coconut cadang‐cadang viroid (CCCV) showed that RNA sequences identical to CCCV were present in the inoculated seedlings. Electrophoresis in polyacrylamide gels showed that these palms also contained an RNA with mobility identical to CCCV. Four to five years after inoculation, the infected palms of four species were usually stunted compared with uninoculated palms, while betel nut and palmera were not stunted. Yellowing of leaflets was observed with defined spots or mottling of the older fronds in all except betel nut palms. All infected palms showed mild or severe yellow‐leaf spotting. These results widen the known host range and. hence, the potential number of viroid reservoir species in the field.