Abstract:
Previously, we reported the generation of a virusinduced
systemic signal that increased the somatic
and meiotic recombination rates in tobacco mosaic
virus (TMV)-infected tobacco plants. Here, we
analyzed the progeny of plants that received
the signal and found that these plants also have
a higher frequency of rearrangements in the loci
carrying the homology to LRR region of the gene of
resistance to TMV (N-gene). Analysis of the stability
of repetitive elements from Nicotiana tabacum loci
and 5.8S ribosomal RNA loci did not show any
changes. Further analysis of the changes in the
progeny of infected plants revealed that they had
substantially hypermethylated genomes. At the
same time, loci-specific methylation analysis
showed: (1) profound hypomethylation in several
LRR-containing loci; (2) substantial hypermethylation
of actin loci and (3) no change in methylation in
the loci of repetitive elements from N. tabacum or
5.8S ribosomal RNA. Global genome hypermethylation
of the progeny is believed to be part of a
general protection mechanism against stress,
whereas locus-specific hypomethylation is associated
with a higher frequency of rearrangements.
Increased recombination events combined with the
specific methylation pattern induced by pathogen
attack could be a sign of an adaptive response by
plants