Diagnosis of "maladie des feuilles cassantes" or brittle leaf disease of date palms by detection of associated chloroplast encoded double stranded RNAs

The “Maladie des feuilles cassantes” (MFC) or “Brittle leaf disease” of date palms is associated with the accumulation of two populations of small, chloroplast-encoded RNAs. A plasmid vector containing a cDNA with partial sequences of both of these RNA populations was used to synthesize a DIG-labeled bifunctional probe by PCR. The probe has been tested to detect, by molecular hybridization, MFC-associated RNAs from dsRNA-enriched palm leaflet preparations. Leaflet samples from MFC-affected date palm trees consistently gave a positive hybridization signal regardless of the date palm cultivar, severity of symptoms, or geographical location, whereas samples from date palm trees affected by other biotic and abiotic stresses tested negative. The assay is specific for MFC and can be used for early diagnostic purposes

"Maladie des feuilles cassantes" or brittle leaf disease of date palms in Tunisia: Biotic or abiotic disease?

“Brittle leaf disease of date palms”, known in southern Tunisia since the 1960s, has assumed epidemic proportions from 1986 on. The symptoms are associated with manganese deficiency and the presence of a small double stranded RNA of host origin. Even though no pathogen has yet been found, some observations do not fit a purely abiotic cause of the disease. In particular, affected trees seem to cluster into foci, and mineral analyses show no significant differences between the soils of affected and unaffected trees. Further work is required to understand the etiology of the disease