RNA cache or genome trash?

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Abstract
Arising from: S. J. Lolle, J. L. Victor, J. M. Young & R. E. Pruitt Nature 434, 505–509 (2005); see also communication from Chaudhury; Lolle et al. reply. According to classical mendelian genetics, individuals homozygous for an allele always breed true. Lolle et al.1 report a pattern of non-mendelian inheritance in the hothead (hth) mutant of Arabidopsis thaliana, in which a plant homozygous at a particular locus upon self-crossing produces progeny that are 10% heterozygous; they claim that this is the result of the emerging allele having been reintroduced into the chromosome from a cache of RNA inherited from a previous generation. Here I suggest that these results are equally compatible with a gene conversion that occurred through the use as a template of DNA fragments that were inherited from a previous generation and propagated in archival form in the meristem cells that generate the plant germ lines. This alternative model is compatible with several important observations by Lolle et al.1.