Fig. 4.—

Birth of chimeric gene clusters in the Sciadopitys plastome. (A) Shuffling between rps2 and psbB operons and (B) between rpoB and petL operons. Syntenic genes in the corresponding operons of Cycas are used as references. Operons and their transcriptional directions are indicated by solid arrows. Syntenic blocks of genes are connected with gray lines. Paired open arrows are primers for amplifying cDNA fragments across junctions between two recombined operons. The expected sizes of amplicons are shown in parentheses. (C) RT-PCR analysis for detecting the transcripts comprising the genes originated from different operons. Primer pairs used for RT-PCR assays are shown above the gel panel, with minus and plus signs (in parentheses) denoting the use of RNA (negative control) and cDNA (experimental set) as templates, respectively. (D) YRTA motif of the NEP promoter upstream of rpoB.