Fig. 5. kn1 gene expression in ear spikelets and florets. (A) kn1 expression in developing spikelets. A longitudinal section of a normal inflorescence shows only one spikelet of the spikelet pair. The lower floret forms at the abaxial side of each spikelet. (B) kn1 expression in developing ifa1-r spikelets. A longitudinal section reveals a portion of an extra spikelet (marked with *) that overlaps with the developing spikelet pair. The lower floret develops on the adaxial side in extra spikelets. (C) kn1 expression in an ectopic BM arising from within an ifa1-r zag1 ear floret. (D) kn1 is not expressed in the silk or ovule of normal plants. Expression is detected in the lower floral meristem and floral axis below the ovule. (E-H) Serial section of ifa1 mutant ovule primordium. kn1 is also down-regulated as the ovule primordium initiates, however, as shown in a series of 10 µm sections from the same floral apex, kn1 is expressed in a small group of cells at the center of the primordium. uf, upper floret; lf, lower floret; *, extra spikelet; ov, ovule; op, ovule primordium; ca, carpel; ov, ovule.