RESUMO
Members of the family Trypanosomatidae infect many organisms, including animals, plants and humans. Plant-infecting trypanosomes are grouped under the single genus Phytomonas, failing to reflect the wide biological and pathological diversity of these protists. While some Phytomonas spp. multiply in the latex of plants, or in fruit or seeds without apparent pathogenicity, others colonize the phloem sap and afflict plants of substantial economic value, including the coffee tree, coconut and oil palms. Plant trypanosomes have not been studied extensively at the genome level, a major gap in understanding and controlling pathogenesis. We describe the genome sequences of two plant trypanosomatids, one pathogenic isolate from a Guianan coconut and one non-symptomatic isolate from Euphorbia collected in France. Although these parasites have extremely distinct pathogenic impacts, very few genes are unique to either, with the vast majority of genes shared by both isolates. Significantly, both Phytomonas spp. genomes consist essentially of single copy genes for the bulk of their metabolic enzymes, whereas other trypanosomatids e.g. Leishmania and Trypanosoma possess multiple paralogous genes or families. Indeed, comparison with other trypanosomatid genomes revealed a highly streamlined genome, encoding for a minimized metabolic system while conserving the major pathways, and with retention of a full complement of endomembrane organelles, but with no evidence for functional complexity. Identification of the metabolic genes of Phytomonas provides opportunities for establishing in vitro culturing of these fastidious parasites and new tools for the control of agricultural plant disease.
Assuntos
Kinetoplastida/genética , Doenças das Plantas/genética , Análise de Sequência de DNA , Trypanosomatina/genética , Animais , Cocos/genética , Cocos/parasitologia , Café/genética , Café/parasitologia , França , Genoma , Humanos , Kinetoplastida/patogenicidade , Doenças das Plantas/parasitologia , Sementes/parasitologia , Trypanosomatina/patogenicidadeRESUMO
Fractionation of an antitrypanosomal lipophilic leaf extract from Strychnos spinosa led to the isolation of eight triterpenoids and sterols in this plant part for the first time. Two of these were found to possess in vitro antitrypanosomal activity, namely, saringosterol (14) and 24-hydroperoxy-24-vinylcholesterol (15), with IC(50) values of 7.8 +/- 1.2 and 3.2 +/- 1.2 microM, respectively. The latter compound was isolated from a plant source for the first time. A comparative study on the antitrypanosomal activity of the isolated triterpenoids and sterols and some related compounds has indicated that the presence of an oxygenated function at C-28 or an oxygenated side chain at C-17 seems to be important for the antitrypanosomal activity of triterpenoids and sterols, respectively.