The 2.8-kb transcript originates in the ψ region flanking one copy of the 4.2-kb repeat. RNA gel blot analysis of mitochondrial RNA isolated from ear shoots and preemergent tassels. (A–C) Lane S, S-B37 (rf9/rf9; rf3/rf3); lane +Rf9, B37S × A619 (Rf9/rf9; rf3/rf3); and lane +Rf3, S-B37XKy21 (rf9/rf9; Rf3/rf3). The same blot was hybridized sequentially with the orf355-specific probe (A), the ψ-specific probe (B), and the σ-specific probe cox1 (C).