Figure 5.

Spr2 is involved in the splicing of multiple mitochondrial introns. A, Gene structure diagram of the maize nad1, nad2, nad4, nad5, and nad7 gene. Exons are shown as filled black boxes. The primers and expected amplification products are indicated. F: Forward primer, R: Reverse primer. B, RT–PCR analysis of inefficient splicing of mitochondrial introns of nad1, nad2, nad4, nad5, and nad7 in WT and spr2 mutants using primers as indicated in (A). Normalization was performed against ZmActin. S, intron spliced; U, intron unspliced; bp: base pair. C, RT-qPCR analysis of splicing efficiency of all 22 mitochondrial introns in spr2 alleles. The ratio of spliced to unspliced fragments was used to measure splicing efficiency. Data are means (±se) of three biological replicates.