Genetic analysis of the imp gene encoding for the immunodominant membrane protein of phytoplasmas associated with Lethal Yellowing Type Syndromes of palms

Pilet Fabian. 2023. Genetic analysis of the imp gene encoding for the immunodominant membrane protein of phytoplasmas associated with Lethal Yellowing Type Syndromes of palms. In : 24th Congress of the International Organization for Mycoplasmology (Associated with the Japanese Society of Mycoplasmology) July 16th‒20th, 2023, Osaka, Japan: Conference Program. IOM, Japanese Society of Mycoplasmology. Osaka : IOM, Résumé, p. 114. Congress of the International Organization for Mycoplasmology (IOM 2023). 24, Osaka, Japon, 16 Juillet 2023/20 Juillet 2023.

Résumé : Background. Different Phytoplasma species are associated with Lethal Yellowing Type Syndromes (LYTS) that dramatically affect palms in different parts of the world. Among genes involved in phytoplasma transmission are the genes encoding for the immunodominant membrane proteins (IDPs). Here we present some imp genetic data for three LYTS phytoplasmas. Methods. Draft genomes of 'Candidatus Phytoplasma cocostanzania' (CPctz), '-palmae'(CPpal) and '-palmicola' (CPpml) were searched for IDPs genes based on the synteny usually observed. The unique target observed was amplified for some representative isolates of the three species. The nucleotide sequences were analyzed considering the complete sequences or by distinguishing the different domains (Signal Peptide, SP; Trans Membrane, TM; Extra Cellular, EC). Results. Among the different described IDPs, only imp gene was observed. Based on imp sequences, CPctz appears phylogenetically closer to the Caribbean phytoplasma CPpal than to the other African phytoplasma CPpml. The sequences appear to be highly conserved within each population, particularly the domains encoding SP and TM. Sequences coding for the EC domain are the most variable between populations and appeared to be submitted to positive selection while SP and TM are submitted to purifying selection when significative. Conclusion. In the absence of the other known IDPs, imp may play a predominant role in the interactions of LYTS phytoplasmas with their hosts. The positive selection on sequences encoding the extracellular domain of IMP suggests a capacity for adaptation of the phytoplasma to new insect vectors.

Auteurs et affiliations

• Pilet Fabian, CIRAD-BIOS-UMR PVBMT (REU) ORCID: 0000-0003-0079-216X

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606258/)

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