Outcrossing as an Explanation of the Apparent Unconventional Genetic Behavior ofArabidopsis thaliana hthMutants

Abstract

The reappearance of HTH alleles in the offspring of homozygous Arabidopsis hth mutants is not consistent with classical Mendelian genetics. It has been suggested that stored RNA may be used to restore genetic information. However, Peng et al. reported that hth mutants tend to display outcrossing and suggested that outcrossing might provide an alternative explanation for the apparent genetic instability. We have confirmed and extended these results, corroborating that the apparent non-Mendelian behavior of hth mutants can be explained by their susceptibility to outcrossing.

RNA-Mediated Epigenetic Programming of Genome Rearrangements

“…This transgenerational inheritance of DNA rearrangements demonstrates that these eukaryotic cells can pass information across generations via RNA. It also validates an earlier prediction (108) that a “backup copy of [the] grandparents’ genetic information encoded in RNA” can transmit instructions to the progeny, even though the original context was inheritance of a proposed RNA cache that permitted genotype reversion in Arabidopsis (75), a phenomenon later attributed to out-crossing (83). …”

De novo genetic variation revealed in somatic sectors of single Arabidopsis plants

“…Although an intrinsic mechanism was proposed 22 , cross-pollination with neighboring plants was subsequently put forward as the more likely explanation for the appearance of these wt revertant offspring 26,27 . To test the susceptibility of hth plants to out-crossing under our growth conditions, experiments were conducted using a pollen donor harboring a dominant gene conferring resistance to the herbicide glufosinate.…”

Shaped by the environment – adaptation in plants

“…Instead of 100% mutant progeny being segregated, ∼ 90% of the resulting plants are mutants, while the other ∼ 10%‘revert’ to a wild‐type phenotype. One trivial explanation for the existence of these ‘revertants’ is outcrossing with pollen from wild‐type plants, which could be plausible, owing to the fused reproductive organs in the hth mutants, and this is the explanation preferred by some researchers [47,48]. According to Lolle, however, in large‐scale experiments, detectable outcrossing events are too low in number to account for the high levels of reversion seen in the hth mutants.…”