Volume 16, Number 2, Mars-Avril 2009
|Page(s)||97 - 101|
|Section||Agronomie – Environnement|
|Published online||15 March 2009|
Review of Coconut “Lethal Yellowing” type diseases Diversity, variability and diagnosis
CIRAD, Etiologie - dépérissement, UPR 29, Campus international de Baillarguet, 34398
Montpellier cedex 5, France
2 OPRI-CIRAD Laboratory, Coconut Programme, P.O. Box 245, Sekondi, Ghana
Coconut palms (Cocos nucifera L.) can be affected by several types of Lethal Yellowing (LY) diseases worldwide. Some of the syndromes are caused by phytoplasmas, small bacteria that are impossible to detect by light microscopy. Amplification of a given gene of the phytoplasmas by polymerase chain reaction (PCR) is the most convenient diagnosis method. The problem is that there are at least 28 “groups” of phytoplasmas and only one pair of primers -P1/P7- commonly used for PCR. As these primers belong to a very conserved gene, false positives are frequent. Consequently, alternative primers specific to one “strain” (or subgroup) have to be used, such as LY-F/LY-R for the Caribbean LY, Rohde primers for LD Tanzania. Such specific primers are sometimes restrictive. Indeed, there is variability within each strain and the sequence of the primers has to be adapted to that variability. There are at least five LY subgroups. The subgroups can only be identified by restriction fragment length polymorphism or sequencing. In Africa, two subgroups of LY phytoplasmas have been identified so far.
Key words: coconut / Lethal Yellowing / Cape Saint Paul Wilt / diversity / variability / phytoplasma / PCR / 16S rDNA / syndrome / Ghana / Mozambique / Tanzania
© John Libbey Eurotext 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.