Complete Plastid Genome Sequences of Three Rosids (Castanea, Prunus, Theobroma): Evidence for At Least Two Independent Transfers of rpl22 to the Nucleus

Loading...
Thumbnail Image
Penn collection
Departmental Papers (Dental)
Degree type
Discipline
Subject
plastid genome
rpl22
gene transfer
rosids
Dentistry
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Jansen, Robert K.
Saski, Christopher
Lee, Seung-Bum
Hansen, Anne K.
Daniell, Henry
Contributor
Abstract

Functional gene transfer from the plastid to the nucleus is rare among land plants despite evidence that DNA transfer to the nucleus is relatively frequent. During the course of sequencing plastid genomes from representative species from three rosid genera (Castanea, Prunus, Theobroma) and ongoing projects focusing on the Fagaceae and Passifloraceae, we identified putative losses of rpl22 in these two angiosperm families. We further characterized rpl22 from three species of Passiflora and one species of Quercus and identified sequences that likely represent pseudogenes. In Castanea and Quercus, both members of the Fagaceae, we identified a nuclear copy of rpl22, which consisted of two exons separated by an intron. Exon 1 encodes a transit peptide that likely targets the protein product back to the plastid and exon 2 encodes rpl22. We performed phylogenetic analyses of 97 taxa, including 93 angiosperms and four gymnosperm outgroups using alignments of 81 plastid genes to examine the phylogenetic distribution of rpl22 loss and transfer to the nucleus. Our results indicate that within rosids there have been independent transfers of rpl22 to the nucleus in Fabaceae and Fagaceae and a putative third transfer in Passiflora. The high level of sequence divergence between the transit peptides in Fabaceae and Fagaceae strongly suggest that these represent independent transfers. Furthermore, Blast searches did not identify the “donor” genes of the transit peptides, suggesting a de novo origin. We also performed phylogenetic analyses of rpl22 for 87 angiosperms and four gymnosperms, including nuclear-encoded copies for five species of Fabaceae and Fagaceae. The resulting trees indicated that the transfer of rpl22 to the nucleus does not predate the origin of angiosperms as suggested in an earlier study. Using previously published angiosperm divergence time estimates, we suggest that these transfers occurred approximately 56–58, 34–37, and 26–27 Ma for the Fabaceae, Fagaceae, and Passifloraceae, respectively.

Advisor
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Publication date
2011-01-01
Journal title
Molecular Biology and Evolution
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
At the time of publication, author Henry Daniell was affiliated with the University of Central Florida. Currently, he is a faculty member at the School of Dental Medicine at the University of Pennsylvania.
Recommended citation
Collection