CHARACTERIZATION AND DETECTION OF PLANT TRYPANOSOMATIDS BY SEQUENCE-ANALYSIS OF THE SMALL-SUBUNIT RIBOSOMAL-RNA GENE

The complete sequences of the genomic small subunit ribosomal RNA gene from two Phytomonas isolates: one associated with palm pathologies (P . cocos FGuiana) and one found in lactiferous plants with no apparent pathology (P. Euphorbe Senegal), were analyzed. Partial sequences from a number of other Phytomonas isolates were also determined. The seque nces obtained were used to determine the phylogenetic relationships be tween Phytomonas and other trypanosomatids as well as within the genus Phytomonas. The analysis showed that the intraphloemic isolates assoc iated with pathologies in palm trees formed a homogeneous group that d iverged from the more heterogeneous group of non-pathogenic isolates f ound in latex plant. Sequence comparisons of the full and partial SSU rRNA gene, identified sequences which are specific to the genus Phytom onas and an EcoRI restriction nuclease site which specifically identif ies the Phytomonas isolates associated with diseases in palm trees.