Biochemical characterization of a trypanosomatid isolated from the plant Amaranthus retroflexus

Phytomonas (Euglenozoa: Trypanosomatidae): Phylogenetic analyses support infrageneric lineages and a new species transmitted to Solanaceae fruits by a pentatomid hemipteran

The genus Phytomonas includes trypanosomatids transmitted to the fruits, latex, and phloem of vascular plants by hemipterans. We inferred the phylogenetic relationships of plant and insect isolates assigned to the previously defined genetic groups A-F and H of Phytomonas, particularly those from groups A, C and E comprising flagellates of Solanaceae fruits. Phylogenetic analyses using glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) and Small Subunit rRNA (SSU rRNA) genes strongly supported the monophyly of the genus Phytomonas and its division into seven main infrageneric phylogenetic lineages (Phy clades). Isolates from fruit or latex do not constitute monophyletic assemblages but disperse through more than one lineages. In this study, fruit flagellates were distributed in three clades: PhyA, formed by isolates from Solanaceae and phytophagous hemipterans; PhyC comprising flagellates from four plant families; and PhyE, which contains 15 fruit isolates from seven species of Solanaceae. The flagellates of PhyE are described as Phytomonas dolleti n. sp. according to their positioning in phylogenetic trees, complemented by data about their life cycle, and developmental and morphological characteristics in cultures, fruits of Solanum spp., and salivary glands of the vector, the phytophagous hemipteran Arvelius albopunctatus (Pentatomidae).

Purification and characterization of two iron superoxide dismutases ofPhytomonassp. isolated fromEuphorbia characias(plant trypanosomatids)

Two superoxide dismutases (SODI and SODII) have been purified by differential centrifugation, fractionation with ammonium sulphate followed by chromatographic separation (ionic exchange and affinity), from a plant trypanosomatid isolated fromEuphorbia characias, and then characterized for several biochemical properties. Both enzymes were insensitive to cyanide but sensitive to hydrogen peroxide, properties characteristic of iron-containing superoxide dismutase. SODI had a molecular mass of approximately 66 kDa, whereas the molecular mass of SODII was approximately 22 kDa, both enzymes showing single bands. The isoelectric points of SODI and SODII were 6·8 and 3·6, respectively. The enzymatic stability persisted at least for 6 months when the sample was lyophilized and preserved at −80 °C. Digitonin titration and subcellular fractionation showed that both enzymes were in the cytoplasmic fraction, although part of SODII isoenzyme was also associated with glycosomes. We assayed these activities (SOD) in 18 trypanosomatid isolates on isoelectric focusing gels, and have demonstrated that the SOD is a biochemical marker sufficient to identify a trypanosomatid isolated from a plant as belonging to the genusPhytomonasand to distinguish between a truePhytomonasand other trypanosomatids that are capable of causing transient infections in plants.