Abstract
Tagosodes orizicolus Muir (Homoptera: Delphacidae), the endemic delphacid species of tropical America carries yeast-like symbiotes (YLS) in the abdominal fat bodies and the ovarial tissues, like other rice planthoppers of Asia. These YLS are obligate symbiotes, which are transmitted transovarially, and maintain a mutualistic relationship with the insect host. This characteristic has made in vitro culture and classification of YLS rather difficult using conventional methods. Nevertheless, microorganisms of similar characteristics have been successfully classified by using molecular taxonomy. In the present work, the YLS of Tagosodes orizicolus (YLSTo) were purified on Percoll gradients, and specific segments of 18S rDNA were amplified by PCR, cloned and sequenced. Sequences were aligned by means of the CLUSTAL V (DNASTAR) program; phylogenetic trees were constructed with the Phylogeny Inference Package (PHYLIP), showing that YLSTo belong to the fungi class Pyrenomycetes, phylum Ascomycota. Similarities between 98% and 100% were observed among YLS of the rice delphacids Tagosodes orizicolus, Nilaparvata lugens, Laodelphax striatellus and Sogatella fur cifera, and between 89.8% and 90.8% when comparing the above to YLS of the aphid Hamiltonaphis styraci. These comparisons revealed that delphacid YLS are a highly conserved monophyletic group within the Pyrenomycetes and are closely related to Hypomyces chrysospermus.
Highlights
Palabras clave: Tagosodes orizicolus, simbiontes semejantes a levaduras, DNAr 18S, relación genética, Pyrenomycetes, saltahojas del arroz
The purpose of this research is to determine the phylogenetic relationships of the yeast-like symbiotes of the delphacid Tagosodes orizicolus with other ascomycetes fungi, as well as to determine the nucleotide similarity of the YLS of T. orizicolus with the YLSs of Nilaparvata lugens, Sogatella furcifera, Laodelphax striatellus and Hamiltonaphis styraci, using partial sequences of the 18S rDNA
List of fungi* and yeast-like symbiotes (YLS)+ from which the 18S rDNA sequences were used for phylogenetic analysis and their respective accession numbers in the databases
Summary
Palabras clave: Tagosodes orizicolus, simbiontes semejantes a levaduras, DNAr 18S, relación genética, Pyrenomycetes, saltahojas del arroz. Tagosodes orizicolus (Homoptera: Delphacidae) is one of the most important insects affecting rice (Oryza sativa) in tropical America (McGuire et al 1960, Trujillo 1968). It is a rice feeder, which is the vector for the rice hoja blanca virus (RHBV) (McGuire et al 1960, Gálvez 1968, 1969, Everett 1969, Nault 1994). This species is endemic and restricted to tropical America, unlike the rice delphacids Laodelphax striatellus, Sogatella furcifera and Nilaparvata lugens that are distributed throughout Asia. In the case of Tagosodes orizicolus, YLS inhabit the intracellular spaces in the fat bodies of the insect’s abdomen, in diffuse patterns associated with syncitia, but without forming mycetomes (Espinoza et al 2004)
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