Analyses based on the 16S rRNA and secA genes identify a new phytoplasma subgroup associated with a lethal yellowing-type disease of coconut in Côte d'Ivoire Rosete Yaima Arocha1,*, Konan-Konan Jean L.2, Diallo Atta H.3, Allou Kouassi2, Scott James1,4 1Sporometrics, 219 Dufferin Street, Suite 20C, Toronto, ON M6K 3J1, Canada 2Centre National de Recherche Agronomique (CNRA), Abidjan, Côte d'Ivoire 3Université Nangui Abrogoua, 02 BP 801, Abidjan-02, Côte d'Ivoire 4Dalla Lana School of Public Health, 223 College Street, Toronto, ON M5T 1R4, Canada *Corresponding author e-mail: Yaima Arocha Rosete (yarosete@sporometrics.com)
Online published on 2 January, 2015. Abstract A lethal yellowing-like disease named as Côte d'Ivoire Lethal Yellowing (CILY) has been spreading throughout the Ivoirian coastal coconut plantations of the Grand-Lahou department in Côte d'Ivoire causing losses of about 12,000 tons of copra/year, and has also become a threat for the coconut Genebank. Leaf, stem apex, heart and inflorescence samples of coconut palms exhibiting CILY symptoms that resemble those associated with Cape Saint Paul Wilt Disease (CSPWD) in Ghana, were sampled and nested PCR-tested for phytoplasma presence. The phytoplasma identified was further characterized based on the sequences of the 16S rRNA and secA genes. Phytoplasma universal primers yielded expected amplification products from 61 out of 84 samples from symptomatic trees tested, while samples from symptomless palms yielded no DNA amplification. Both the 16S rDNA and secA sequences of the CILY phytoplasma showed a 99% sequence identity with that of the CSPWD phytoplasma from Ghana, and clustered with previously identified West Africa phytoplasma strains of group 16SrXXII that includes the Ghanaian CSPWD strain. The phytoplasma was assigned to the sub-group 16SrXXII-B based on virtual RFLP of the 16S rDNA sequences. Results support possibility of disease spread from the neighbouring Ghana, posing a threat for the Ivorian coconut industry. Top Keywords 16SrXXII phytoplasma, coconut, RFLP, Cape Saint Paul wilt disease, ‘Candidatus Phytoplasma’. Top |