Figure 6.

Underdominant rRNA genes suppressed in vegetative tissues are expressed in floral tissues of B. napus. Vegetative leaves, cauline leaves, floral buds, sepals, petals, anthers, and siliques from a single mature B. napus plant were harvested on the same day. An equal amount of total RNA from each type of organ was subjected to S1 nuclease protection analysis using probes specific for B. rapa (lanes 3–10) or B. oleracea (lanes 11–18) rRNA transcripts, as in Fig. 4. RNA from diploid B. rapa or B. oleracea served as controls (lanes 3 and 11) and show that the two probes were similar in specific activity. Note that B. oleracea genes are readily detected in all organs derived from the floral meristem (lanes 14–18) but are not detected in vegetative leaves or cauline leaves (lanes 12 and 13). DNA sequencing reaction products served as size markers in lanes 1 and 2.