Dataset Information

Cospeciation of psyllids and their primary prokaryotic endosymbionts.

ABSTRACT: Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. Four-kilobase DNA fragments containing 16S and 23S ribosomal DNA (rDNA) were amplified from the primary (P) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. In addition, 0.54-kb fragments of the psyllid nuclear gene wingless were also amplified from 26 species. Phylogenetic trees derived from 16S-23S rDNA and from the host wingless gene are very similar, and tests of compatibility of the data sets show no significant conflict between host and endosymbiont phylogenies. This result is consistent with a single infection of a shared psyllid ancestor and subsequent cospeciation of the host and the endosymbiont. In addition, the phylogenies based on DNA sequences generally agreed with psyllid taxonomy based on morphology. The 3' end of the 16S rDNA of the P endosymbionts differs from that of other members of the domain Bacteria in the lack of a sequence complementary to the mRNA ribosome binding site. The rate of sequence change in the 16S-23S rDNA of the psyllid P endosymbiont was considerably higher than that of other bacteria, including other fast-evolving insect endosymbionts. The lineage consisting of the P endosymbionts of psyllids was given the designation Candidatus Carsonella (gen. nov.) with a single species, Candidatus Carsonella ruddii (sp. nov.).

SUBMITTER: Thao ML

PROVIDER: S-EPMC92089 | biostudies-literature | 2000 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Cospeciation of psyllids and their primary prokaryotic endosymbionts.

Thao M L ML Moran N A NA Abbot P P Brennan E B EB Burckhardt D H DH Baumann P P

Applied and environmental microbiology 20000701 7

Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. Four-kilobase DNA fragments containing 16S and 23S ribosomal DNA (rDNA) were amplified from the primary (P) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. In addition, 0.54-kb fragments of the psyllid nuclear gene wingless were also amplified from 26 species. Phylogenetic trees derived from 16S-23S rDNA and from the host wing ...[more]

PMID: 10877784

Similar Datasets

Project description:Bacteria associated with sap-feeding insect herbivores include not only symbionts that may increase their hosts' fitness but also harmful plant pathogens. Calophya spp. gall-inducing psyllids (Hemiptera: Calophyidae) are being investigated for their potential as biological control agents of the noxious weed, Brazilian peppertree (Schinus terebinthifolia), in Florida. Although there are no examples of plant pathogen transmission by members of the family Calophyidae, several insects in the superfamily Psylloidea are known to transmit pathogenic bacteria in the genera Candidatus Liberibacter and Candidatus Phytoplasma. To determine whether Calophya spp. harbor potentially harmful plant pathogenic bacteria, we sequenced small subunit (SSU) ribosomal RNA (rRNA) gene amplicons generated from individuals from four Calophya spp. populations: All microbial SSU gene sequences fell into the bacterial domain, with 98-99% belonging to the Proteobacteria. The Calophya microbiomes contained a relatively simple community, with 49-79 operational taxonomic units (OTUs; 97%) detected, and only 5-8 OTUs with greater than 1% abundance. Candidatus Carsonella showed the highest relative abundance, with OTUs from this candidate genus representing between 51-65% of all recovered sequences. The next most abundant clade observed was an unclassified Enterobacteriacae group closely related to bacteria from the genera Buchnera and Blochmannia that ranged from 20-31% in relative abundance. Wolbachia populations were the third most abundant group and represented 7-27% of the diversity in microbial OTUs. No SSU rRNA gene sequences from putative pathogenic bacteria from the genera Ca. Liberibacter or Ca. Phytoplasma were detected in the microbiomes of the four Calophya populations. The probability that infected psyllids were present in our colonies, but were not sampled, was extremley low (1.39 x 10(-10)). As far as we are aware, our study is the first to characterize the microbiome of a candidate biological control agent, and coupled with previous work demonstrating a high degree of host specificity and absence of plant viruses, suggests that releasing Calophya spp. in United States poses minimal risk to non-target plants.

Project description:Genome reduction in obligately intracellular bacteria is one of the most well-established patterns in the field of molecular evolution. In the extreme, many sap-feeding insects harbor nutritional symbionts with genomes that are so reduced that it is not clear how they perform basic cellular functions. For example, the primary symbiont of psyllids (Carsonella) maintains one of the smallest and most AT-rich bacterial genomes ever identified and has surprisingly lost many genes that are thought to be essential for its role in provisioning its host with amino acids. However, our understanding of this extreme case of genome reduction is limited, as genomic data for Carsonella are available from only a single host species, and little is known about the functional role of "secondary" bacterial symbionts in psyllids. To address these limitations, we analyzed complete Carsonella genomes from pairs of congeneric hosts in three divergent genera within the Psyllidae (Ctenarytaina, Heteropsylla, and Pachypsylla) as well as complete secondary symbiont genomes from two of these host species (Ctenarytaina eucalypti and Heteropsylla cubana). Although the Carsonella genomes are generally conserved in size, structure, and GC content and exhibit genome-wide signatures of purifying selection, we found that gene loss has remained active since the divergence of the host species and had a particularly large impact on the amino acid biosynthesis pathways that define the symbiotic role of Carsonella. In some cases, the presence of additional bacterial symbionts may compensate for gene loss in Carsonella, as functional gene content indicates a high degree of metabolic complementarity between co-occurring symbionts. The genomes of the secondary symbionts also show signatures of long-term evolution as vertically transmitted, intracellular bacteria, including more extensive genome reduction than typically observed in facultative symbionts. Therefore, a history of co-evolution with secondary bacterial symbionts can partially explain the ongoing genome reduction in Carsonella. However, the absence of these secondary symbionts in other host lineages indicates that the relationships are dynamic and that other mechanisms, such as changes in host diet or functional coordination with the host genome, must also be at play.

Dataset Information

Cospeciation of psyllids and their primary prokaryotic endosymbionts.

Publications

Cospeciation of psyllids and their primary prokaryotic endosymbionts.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets