Plant genetics: hothead healer and extragenomic information.

Lolle et al. suggest that non-mendelian inheritance in Arabidopsis thaliana might be attributable to an ancestral RNA-sequence cache, whereby the RNA genome of previous generations causes a high rate of reversion of the plant's mutant hothead (hth) and erecta (er) genes. Here I describe a 'distributed genome' model that also explains their results, in which mutant hth DNA is restored by homologous sequences present in the genome itself. This model has implications for the generation of diversity without mating.