Poster: Plant Pathogen/Symbiont Interactions

Abs # 767: Stability of plant genome upon the pathogen encounter

Presenter:	Kovalchuk, Igor , igor.kovalchuk@uleth.ca
Authors	Kovalchuk, Igor  (A)   Filkowski, Jody  (A)   Hohn, Barbara  (B) (B)
Affiliations:	(A): University of Lethbridge (B): Friedrich Miescher Institute for Biomedical Research

Genome instability provides certain, distinct advantages to organisms. Homologous recombination is a well known mechanism for repairing damaged DNA but it also has the potential to generate new alleles through DNA recombination. For example, the major histocompatibility (MHC) locus, because of its high recombination rate, is capable of quickly generating diverse antibodies within the mammalian immune system, thereby protecting the host from diverse and highly mutable pathogens. Similar system could exist in plants. Genome stability in plants is influenced by many environmental abiotic factors (gamma and UV radiation, cold, draught etc) and could as well be influenced by biotic stresses, including bacteria, viruses, fungi, nematodes, and insects. We here report that upon infection of plants with either Tobacco Mosaic Virus (TMV) or Oilseed Rape Mosaic Virus (ORMV) an about threefold increase in the frequency of intramolecular homologous recombination is detected. Using grafting experiments elevated recombination frequencies were measured also in non-infected tissue suggesting the involvement of a systemic signal. Our experiments suggest that biotic stress promotes changes in the genome via systemic induction of homologous recombination. We present evidence that the systemic recombination signal (SRS) is different from that implicated in systemic acquired resistance (SAR). We also show that the SRS results in an increased frequency of meiotic recombination and discuss possible adaptive advantages of systemically enhanced genome flexibility following virus infection.