Genome-wide non-mendelian inheritance

Nature 25 March 2005


"Genome-wide non-mendelian inheritance of extra-genomic information in
Arabidopsis"


Abstract;


"A fundamental tenet of classical mendelian genetics is that allelic
information is stably inherited from one generation to the next,
resulting in predictable segregation patterns of differing alleles1.
Although several exceptions to this principle are known, all represent
specialized cases that are mechanistically restricted to either a
limited set of specific genes (for example mating type conversion in
yeast2) or specific types of alleles (for example alleles containing
transposons3 or repeated sequences4). Here we show that Arabidopsis
plants homozygous for recessive mutant alleles of the organ fusion gene
HOTHEAD5 (HTH) can inherit allele-specific DNA sequence information
that was not present in the chromosomal genome of their parents but was
present in previous generations. This previously undescribed process is
shown to occur at all DNA sequence polymorphisms examined and therefore
seems to be a general mechanism for extragenomic inheritance of DNA
sequence information.We postulate that these genetic restoration events
are the result of a templatedirected process that makes use of an
ancestral RNA-sequence cache."


Do the learned folks here on T.O. suppose the following passage, if
borne out, spells death for the Central Dogma"?


"Perhaps even more intriguing is the possibility that the inheritance
of non-genomic templates occurs in wild-type and hth plants, but the
rate at which those templates are used to modify genomic sequences is
elevated in hth as a result of an indirect 'stress' put on the
plant by the absence of the HTH gene product. Under these circumstances
one could envisage a mechanism in which additional allelic information
is maintained outside the normal genomic context but could be used
under conditions that compromised the continued functioning of the
organism."