Molecular Data and Phylogeny of Nosema Infecting Lepidopteran Forest Defoliators in the Genera Choristoneura and Malacosoma

Abstract

ABSTRACT. Nosema isolates from five lepidopteran forest defoliators, Nosema fumiferanae from spruce budworm, Choristoneura fumiferana; a Nosema sp. from jack pine budworm, Choristoneura pinus pinus and western spruce budworm, Choristoneura occidentalis (Nosema sp. CPP and Nosema sp. CO, respectively); Nosema thomsoni from large aspen tortrix, Choristoneura conflictana; and Nosema disstriae, from the forest tent caterpillar, Malacosoma disstria were compared based on their small subunit (SSU) ribosomal RNA (rRNA) gene sequences. Four of the species sequenced, N. fumiferanae, Nosema sp. CPP, Nosema sp. CO, and N. disstriae have a high SSU rDNA sequence identity (0.6%-1.5%) and are members of the ''true Nosema'' clade. They all showed the reverse arrangement of the (large subunit [LSU]-internal transcribed spacer [ITS]-SSU) of the rRNA gene. The fifth species, N. thomsoni has the usual (SSU-ITS-LSU) arrangement and is not a member of this clade showing only an 82% sequence similarity. We speculate, therefore, that a genetic reversal may have occurred in the common ancestor to the ''true Nosema'' clade. Although, the mechanism for rearrangement of the rRNA gene subunits is not known we provide a possible explanation for the localization. N. fumiferanae, Nosema sp. CPP, and Nosema sp. CO clustered together on the inferred phylogenetic tree. The high sequence similarities, the reverse arrangement in the rRNA gene subunits, and the phylogenetic clustering suggest that these three species are closely related but separate species.

Phylogenetic characterization of a microsporidium (Endoreticulatus sp. Zhenjiang) isolated from the silkworm, Bombyx mori

“…Refardt and Mouton (2007) suggested that compaction of the rRNA in microsporidia caused the loss of processing sites, which then facilitated the processability of such a rearranged cluster. Kyei-Poku et al (2008) speculated that the reverse organization of the rRNA gene in the phylum microsporidia, especially in the Nosema was the result of DNA recombination, with breakage and fusion of the fragment in the reverse orientation. Ribosomal rRNA gene units with both gene orders may have coexisted in the genomes of some microsporidian species.…”

Life cycle, ultrastructure, and molecular phylogeny of Crispospora chironomi g.n. sp.n. (Microsporidia: Terresporidia), a parasite of Chironomus plumosus L. (Diptera: Chironomidae)

“…In another case, three species of the genus Liebermannia, all from orthopteran insects, are similar in ultrastructure but different in nuclear phase, so that the presence of diplokaryotic spores is removed from the revised genus diagnosis (Sokolova et al 2009). Another example is the taxonomy of Nosema/Vairimorpha clade in which assignment to one of these two genera, formally based upon developmental sequence, is not congruent with phylogenetic relationships, substantiating the need for revision of these taxa (Baker et al 1995;Kyei-Poku et al 2008). It can be therefore expected that after a large-scale readjustment of microsporidian taxonomy, life cycle features will not be used in the diagnosis of microsporidian genera, including Crispospora.…”

Phylogenetic characterization of a microsporidium (Nosema sp.) isolated from the mulberry pest, Hemerophila atrilineata

“…cPP, Nosema sp. co and Nosema disstriae (Huang et al 2004, tsai et al 2005, Wang et al 2006, Ku et al 2007, Kyei-Poku et al 2008.…”