Submitted to: Bulletin of Insectology
Publication Type: Abstract Only
Publication Acceptance Date: 8/12/2007
Publication Date: 12/2/2007
Citation: Davis, R.E., Jomantiene, R., Zhao, Y. 2007. Dynamic structures in phytoplasma genomes: sequence variable mosaics (SVMs) of clustered genes. Bulletin of Insectology. LX(2):119-120.
Technical Abstract: Emergence of the phytoplasma clade from an Acholeplasma-like ancestor gave rise to an intriguing group of cell wall-less prokaryotes through a remarkable and continuing evolutionary process. In a ceaseless progression, phytoplasmas have evolved reduced genomes, losing biochemical pathways for synthesis of nutrients supplied by hosts, and have gained capabilities for transkingdom parasitism and pathogenicity in plants and insects. While continued genome degradation makes phytoplasmas increasingly host dependent, their small, AT-rich genomes have evolved conspicuous flexibility that enables rapid changes in response to host signals, evasion of host surveillance systems, and adaptation to shifting environments encountered during obligate, transkingdom parasitism. Recent work revealed that multiple, sequence-variable mosaics (SVMs) of clustered genes and repetitive extragenic palindromes are characteristic features of genome architecture in phylogenetically diverse phytoplasma species. The origin of SVMs was apparently an ancient event in evolution of the phytoplasma clade, while current forms of SVMs are results of dramatic and more recent events. The dynamic nature of SVMs could account for their composite structure and for rapid changes potentially significant in phytoplasma-host interactions.