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Tuesday, July 28 • 13:35 - 13:40
The elements of CRISPR-Cas-like system in genomes of 3 ecotypes of Arabidopsis thaliana

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It is well-known that mitochondria in higher plant species have an extremely large genome compared to small-sized genomes of some bacterial species. The genome of higher plants mitochondria is actively involved in horizontal gene transfer processes where it can act both as a donor and a gene acceptor. Another important feature of higher plants mitochondrial genome is the presence of species-specific sets of linear and circular plasmids in these organelles of many plant species studied in this regard. These plasmids behave like typical mobile genetic elements in terms of ability to perform gene transfer processes. It was shown earlier that mitochondrial plasmid of Vicia faba contains canonical CRISPR (clustered regularly interspaced short palindromic repeats) locus (Mojica et al., 2000).Taking into account the evolutionary origin of mitochondria and plant mitochondrial genome structure, we have attempted by in silico methods to search for genetic elements similar to those of bacterial and archaeal CRISPR-Cas systems in nuclear genomes of 3 ecotypes (Col-0, Ler, C24) of model plant Arabidopsis thaliana.
We have found sites corresponding to the organization of CRISPR loci of prokaryotic type in mitochondrial and nuclear genome of A. thaliana. Contextual analysis of complete sequence of mitochondrial genome of A. thaliana(ecotype C24, Genbank Accesion Number JF729200) allowed us to discover a site whose structure completely corresponds to the organization of CRISPR loci of prokaryotic origin. This CRISPR locus is formed by 3 perfect direct repeats, separated by 2 spacer sequences. Analysis of these sequences using a database of plant viruses showed that the detected spacers have homology with the DNA of two strains (isolate Cabb B-JI and altered virulence isolate D/H) of cauliflower mosaic virus, which is able to infect A. thaliana.
The search for the genetic elements of adaptive immunity of the prokaryotic type in the nuclear genome of A. thaliana made it possible to detect elements of the CRISPR-Cas system on all 5 chromosomes of this species in the form of relatively numerous CRISPR loci and some putative cas genes. The number of CRISPR loci ranged from 16 on chromosome 3 to 23 on chromosome 5.
We suggest that the main functions of the CRISPR-Cas-like system elements found in A. thaliana plants can be protection not only from viral and plasmid DNA, but possibly from any DNA of foreign origin. Nowadays there is no particular hypothesis about the origin of CRISPR-Cas-like elements in plant genetic apparatus. We believe that such elements may have appeared and then remained partially conserved during the eukaryogenesis since such an ancestors of eukaryotes as archaea and alphaproteobacteria possessed them.
The discovery of the components of adaptive immunity in plants creates, in addition to existing methods of genomic editing, a novel one using plant native CRISPR-Cas-like system permitting to create transgenic plants with much more wide spectrum of economically valuable properties for general consumption.

avatar for Ivan Petrushin

Ivan Petrushin

Assistant Professor, Irkutsk State University

Tuesday July 28, 2020 13:35 - 13:40 MSK
Zoom Conference https://zoom.us/j/94321101353?pwd=QlJBb09uM0NVVnVyK0FkbTJ3Nkcrdz09