A Tale Of Three Phytopathogens: Impact Of Transposable Elements On Genome Evolution

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dc.contributor Vadnagara , Komal en_US
dc.date.accessioned 2010 -07 -19T19 :54 :36Z
dc.date.accessioned 2011 -08 -24T21 :43 :39Z
dc.date.available 2010 -07 -19T19 :54 :36Z
dc.date.available 2011 -08 -24T21 :43 :39Z
dc.date.issued 2010 -07 -19
dc.date.submitted January 2010 en_US
dc.identifier.uri http : / /hdl .handle .net /10106 /4882
dc.description.abstract The genus Phytophthora harbors some notorious plant pathogens like Phytophthora infestans (causal of Irish potato famine ) , Phytophthora sojae (soybean rot agent ) , and Phytophthora ramorum (responsible for sudden oak death ) that have significant economic , ecological and environmental impact . These phytopathogens exhibit remarkable phenotypic instability and vary tremendously in genome size from 65 Mb (P . ramorum ) to 240 Mb (P . infestans ) . Complete draft genome sequences revealed that a substantial portion of their genome is occupied by highly repetitive DNA . This extreme genome plasticity is due to an infestation of repetitive virus -like genomic parasites called transposable elements (TEs ) . TEs are sometimes called jumping genes due to their capacity to move from one place to another in the genome . TEs are usually perceived as potent mutagens and the result of their proliferation in genome is usually detrimental , although occasionally they can contribute to the evolution of the host in a variety of ways . One such mechanism is transduplication , whereby TEs capture host gene fragments , that is known to give rise to novel genes in plants . Pathogens are in a constant arms race due to their reliance on the host to reproduce and persist and the negative fitness that they impart . Therefore , it was hypothesized that the plastic P . infestans genome allows for a rapid response to the ever -changing environment imposed by this evolutionary arms race . To this end , we have employed bioinformatics tools (RepeatScout , RepeatMasker , BLAST tools ) to identify different superfamilies of TEs and assess their distribution across three Phytophthora species . Much to our surprise , we found 21 TE families carrying host genes accounting for 2 .4 % of the P . infestans genome . Overall , we observe a strong preference of TEs to capture genes that are involved in epigenetic regulation and critical in plant pathogenesis cycle . We report on the detailed structure of these transduplicates and their capacity to encode a functional transposase . Our results show capture of whole cellular genes by TEs and the existence of transcript evidence for the genes captured . This observed pattern of transduplication is different from what is known in plants and other species , where the capture involves gene fragments that are usually pseudogenized . Moreover , detailed analysis of the captured genes show retention of introns confirming that the transduplication events occurred at a DNA level . Cross species and molecular phylogenetic analyses further reveal that a few capture events might have predated the split of P . infestans from P . sojae and P . ramorum . Hereby , we present an in -depth analysis of various transduplication events and the impact they had in shaping the evolutionary trajectory of these phytopathogens . en_US
dc.language.iso EN en_US
dc.publisher Biology en_US
dc.title A Tale Of Three Phytopathogens : Impact Of Transposable Elements On Genome Evolution en_US
dc.type M .S . en_US

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A Tale Of Three Phytopathogens: Impact Of Transposable Elements On Genome Evolution. Available electronically from http : / /hdl .handle .net /10106 /4882 .

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