Detection and identification of the coconut lethal yellowing phytoplasma in weeds growing in coconut farms in Côte d’Ivoire

Coconut farms located in the southern coast of Grand-Lahou in Côte d’Ivoire are severely affected by a lethal yellowing disease (CILY) associated with the group 16SrXXII-B, ‘Candidatus Phytoplasma palmicola’-related strains. Given the high prevalence of weed species on most of the farms, plants growing within and in the periphery of five selected coconut farms were assessed for the presence of the CILY phytoplasma to identify potential alternative hosts. A total of 396 plant samples belonging to 84 plant species and 35 botanical families were collected. Total DNA was extracted and tested by nested PCR with primers targeting the 16S rRNA and the translocation protein (secA) phytoplasma genes, and sequenced. Twenty samples from six plant species and five botanical families yielded PCR amplicons of the expected size, and both the secA and 16S rDNA sequences showed over 99% similarity with that of the Côte d’Ivoire lethal yellowing phytoplasma previously identified from coconut palms grown in Grand-Lahou coconut farms. Plant species from the families Poaceae (Paspalum vaginatum, Pennisetum pedicillatum), Verbenaceae (Stachytarpheta indica), Plantaginaceae (Scoparia dulcis), Phyllanthaceae (Phyllantus muellerianus) and Cyperacea (Diplacrum capitatum) were positive for the presence of the CILY phytoplasma, suggesting they may have epidemiological implications for disease spread in coconut farms in Grand-Lahou.