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Aetiology of tobacco leaf curl in southern Africa
Author(s) -
PAXIMADIS M.,
REY M E C
Publication year - 1997
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1997.tb05172.x
Subject(s) - leaf curl , biology , curl (programming language) , dot blot , virology , plant virus , tobacco leaf , veterinary medicine , botany , virus , gene , genetics , medicine , agricultural engineering , computer science , engineering , programming language
Summary Symptom variability of tobacco leaf curl disease has been reported by numerous researchers worldwide. It has been suggested that the different types of leaf curl may be caused by more than one geminivirus strain (McClean, 1940; Osaki & Inouye, 1981), although no evidence exists to support this hypothesis. Previously, several tobacco plants exhibiting a range of leaf curl symptoms were collected from South Africa and Zimbabwe and grouped according to symptomology (Paximadis, Dusterwald, Duyver & Rey, 1997). Three classes (I, II & III) of leaf curl were distinguished, and class I leaf curl from South Africa was shown not to be associated with a geminivirus infection, but was consistently associated with 12 double‐stranded RNA species, now believed to be of phytoreovirus origin. In this study, symptom descriptions of class II and III leaf curl have been reported, and, triple‐antibody sandwich ELISAs, dot‐blot hybridisation analysis, PCR, double‐stranded RNA analysis and seed‐transmission experiments were employed to screen class II and III tobacco plants for geminiviruses or other possible causal agents. Class II leaf curl symptoms were shown not to be associated with a geminivirus infection or with any double‐stranded RNA species. Class II leaf curl symptoms were however transmitted through seed. Class III leaf curl plants tested negative for double‐stranded RNA, but tested positive in PCR, dot‐blot hybridisation and ELISAs for geminiviruses. It is suggested that ‘tobacco leaf curl’ is not a single disease but rather a wide collection of symptoms incited by different agents, and should therefore be described as a disease complex or syndrome.