Date: Sunday, January 15, 2012
Time: 2:30 PM
Time: 2:30 PM
Room: Golden Ballroom
Silencing of transposable elements lowers the mutagenic effects of transposition, but requires that TEs are recognized by the survelliance machinery. We have found that a specific class of COPIA retrotransposons are activated in Arabidopsis inter-specific polyploid hybrids, but only when matching small interfering RNA (siRNA) are absent from the seed parent. These COPIA elements lose DNA methylation, and hybrids accumulate 21nt "epigenetically activated siRNA" (easiRNA) normally found in pollen. They also accumulate extra-chromosomal cDNA transposition intermediates indicative of active transposition. Our results indicate that small RNA provides a recognition mechanism for transposons in inter-specific hybrids, reminiscent of hybrid dysgenesis and hybrid lethality in Drosophila, and may contribute to post-fertilization hybridization barriers in a similar way.