Map of geographical distribution of the CaLsol haplotypes in Europe

‘Candidatus Liberibacter solanacearum’ (Lso) has been found in several important cultivated plants belonging to families Solanaceae (potato, tomato, sweet pepper and tobacco) in America and New Zealand and Apiaceae (carrot, celery, parsley and parsnip) in Europe. Phylogenetic analysis using the combination of the 16S rRNA, 16S-23S rRNA intergenic spacer region (ISR) and 50S ribosomal protein gene sequences, revealed that the Lso bacteria found in different geographic regions were diverse and could be assigned to five separate clades: haplotype A, B, C, D or E (Nelson et al., 2011; Teresani et al., 2014). Lso haplotypes A and B, associated with Zebra chip disease of potatoes (Secor et al., 2009) and transmitted by the psyllid Bactericera cockerelli, do not occur in Europe. Whereas, Lso haplotype C (LsoC) is associated with carrot yellowing disease in Northern Europe, where it is transmitted by the carrot psyllid, Trioza apicalis, causing severe yield losses in carrot due to the concomitant effects of the bacterial infections and psyllid feeding injuries (Munyaneza et al., 2010; Munyaneza et al., 2011; Nissinen et al., 2014). LsoC has also been reported to infect carrots in Sweden, Norway and Germany (Munyaneza et al., 2010, Munyaneza et al., 2012a; Munyaneza et al., 2012b). In Southern Europe, Lso haplotypes D and E (LsoD and LsoE, respectively) have been reported to infect carrot, celery, parsnip and parsley and are transmitted by the psyllid Bactericera trigonica (Alfaro-Fernandez et al., 2012; Nelson et al., 2013; Teresani et al., 2014; Alfaro-Fernandez et al., 2017; Antolinez et al., 2017). Although Lso has been detected in France the characterization of haplotypes and their distribution still remain to be established. Thus the main objective of this study, developed in the framework of task 3b of the project, was to improve the knowledge about the distribution of Lso haplotypes in Europe.