Figure 2.

Developmental restriction of Onsen retrotransposition. (A) Schematics of the experimental design: progeny of heat-treated nrpd1 plants from “early” or “late” siliques were screened for new Onsen insertions by whole genome sequencing. (B) Interplant variation in number of new insertions. The count of new Onsen insertions is shown for progeny of both “early” (E) and “late” (L) siliques in all five heat-treated nrpd1 lines analyzed. (C) Schematic representation of chromosome III of nrpd1 plant 2 and nrpd1 plant 5 progeny (E, early silique; L, late siliques) with new Onsen insertions (marked as red vertical lines). Note that for nrpd1 plant 2, all new insertions in 2E-2L are identical, but silique 2L acquired two additional insertions (one showed here for chromosome III as blue vertical line with a triangle), which is consistent with a single retrotransposition burst in the progenitor cell lineage of the two flowers. In nrpd1 plant 5, patterns of new insertions differ between early and late siliques (5E/5L1 and 5L2), suggesting two independent retrotransposition bursts; the two late siliques 5L1 and 5L2 share identical new insertions, consistent with a single retrotransposition in the progenitor cell lineage of the two late flowers. These data are consistent with two developmental windows for transpositional competency.