Fig. 4.

Emp12 is required for intron 1, intron 2, and intron 4 splicing of mitochondrial nad2. (A) qRT-PCR analysis of all group II introns in maize mitochondrial genes. Total RNA was isolated from the emp12-673 and emp12-20 mutant kernels at 12 DAP. Values represent the log2 ratio of spliced to unspliced forms for each transcript in the mutants compared with WT maize kernels. Each value is the mean of at least three biological replicates. (B) Structure of the maize nad2 gene. Exons are shown as filled gray boxes. The closed and open lines stand for cis- and trans-introns. Primers (F1+R1, F2+R2, F3+R3, F4+R4, and F1+R4) indicate the PCR products by using flanking exon–exon primers as described previously (Xiu et al., 2016). E1–E5, exon1–exon5. (C) RT–PCR analysis of the intron splicing of nad2 introns using exon–exon primers as indicated in (B). Arrows and asterisks indicate the spliced and unspliced PCR products, respectively.