RNA in situ hybridization analysis of PeMYB2, PeMYB11, PeMYB12, and PebHLH1 transcripts in the stage 3 sepals of Phalaenopsis spp. Transverse sections of the sepals of Phalaenopsis spp. OX Red Shoe ‘OX1408’ were hybridized with antisense or sense RNA probes of PeMYB2 (A and B), PeMYB11 (D and E), PeMYB12 (G and H), and PebHLH1 (J and K). Transverse sections of the sepals of P. aphrodite ssp. formosana were hybridized with antisense probes of PeMYB2 (C), PeMYB11 (F), PeMYB12 (I), and PebHLH1 (L). Black arrows indicate the detected signals. ab, Abaxial surface; ad, adaxial surface. Bars = 0.1 mm.