FIGURE 6.

Mapping of the 5′ ends of the psbD transcripts in Gnetaceae plants. (A) The psbD LRP transcripts of the Gnetaceae plants G. gnemon (lanes 1–3) and E. sinica (lanes 4 and 5) were analyzed by primer extension assays. Primers used are indicated by numbers on the top of each lane. The size of the extension product is shown on the right. Lane C shows an experiment with the control RNA and primer provided by the manufacturer that produces an 87-base primer extension product. (B) Representative maps of the psbD transcripts. The psbD transcript 5′-ends identified by the primer extension assay are shown by arrows. The position of primers and the size of the extension products are shown on the gene map. The deduced sites of the 5′-end of each transcript are shown as numbers in parentheses. No transcript was detected with #3 and #5 primers. (C) DNA sequences between –37 and +7 of the AAG-box containing psbD promoter transcription initiation sites of G. gnemon and E. sinica are shown. The corresponding sequences of the psbD upstream region of Welwitschia mirabilis are also shown. Transcription initiation sites are indicated by arrows. Potential –35 and –10 elements are underlined.