Presencia de Candidatus Liberibacter solanacearum en Bactericera cockerelli Sulc asociada con enfermedades en tomate, chile y papa

The “permanent tomato”, “spotted tuber” or “zebra chip” in potato and “chlorotic buds” of chili, are three diseases described in Mexico with coincidental signs of flower abortion, obscuration of vascular tissue at the base of the stem and root of the plants. The association between these diseases and the emerging bacterium Candidatus Liberibacter solanacearum (CLs) as well as the psyllid Bactericera cockerelli as its vector has been mentioned. These diseases, which were initially located in three states of Mexico, have spread to the main Solanaceae producing regions, both in field conditions and in the greenhouse. The objective of the study was to know the presence of CLs associated with diseases that affect the tomato, para and chili crops in Mexico. The bacterium was identified by PCR of the 16S rDNA gene, cloning and sequencing. The alignment of nucleotide sequences was performed with the Clustal W method and the phylogenetic tree was built with the Neighbor-Joining algorithm from distances calculated with the Tajima-Nei method and a Felsenstein index of 1 000 replicas, using the software MEGA version 5.05. A total of 167 samples were analyzed, of which 86 were positive, from 14 states of Mexico. Five nucleotide sequences from Guanajuato, San Luis Potosi and Sinaloa corresponding to tomato, potato and chili, adults and eggs of B. cockerelli were obtained. The analysis of the sequences showed an identity of 99.4% when compared between these and up to 99.8% with GenBank accessions described for CLs in the USA, New Zealand and Canada.