Fig. 2.

PPR-SMR1 is involved in splicing of maize group II introns. (A) Inefficient splicing of group II introns of nad1, nad2, nad4, nad5, and nad7 in the embryos and endosperms of ppr-smr1-1 mutants as determined by reverse-transcription PCR (RT-PCR). S, introns are spliced; U, introns are retained. (B) Quantitative real-time RT-PCR (qRT-PCR) analysis of the 22 intron-containing mitochondrial transcripts in ppr-smr1 mutants. Total RNA was extracted from embryos an endosperms of ppr-smr1 mutants and their wild-type siblings at 12 d after pollination. ZmEF1α was used to normalize the quantifications. Data are means (±SD) of three biological replicates. (C) Immunoblot analysis of core subunits of mitochondrial complexes in ppr-smr1-1 mutants. Immunoblots of embryo and endosperm extract (20 µg protein or the indicated dilutions) were probed with antibodies specific for subunits of Complex I (Nad9), Complex III (Cytochrome c₁, Cytc₁), Complex IV (Cox2), and ATP synthase (αATPase). AOX, alternative oxidase. Total protein input can be seen on the Ponceau S-stained blots below. (This figure is available in color at JXB online.)