Fig. 4.

In planta expression analysis of small RNAs and related-regulators during panicle development. a In situ hybridization of mature miR2118 (1–4), PH12 mRNA precursor (5–8) and phasiPH12-1 (9–10) in spikelet meristem (SMs), floret meristem (FMs) and differentiated floret in O. barthii (B88) and O. glaberrima (CG14). Mature miR2118 transcripts were detected in the outer cell layer of stamens (i.e. hypodermis) (1–2) and later in pollen sac (3–4). Precursor PH12 mRNAs were detected in the spikelet meristem (5–6) and in pollen sac of the anthers (arrow) (7–8). The phasiPH12-1 small RNAs were detected in the pollen sac of the anthers in florets (9–10). This panel of photos illustrates stages for which the transcripts were detected. le, lemma; pa, palea; st, stamen; ca, carpel; ov, ovule. Arrowheads, lemma and palea primordium formation in SMs; arrow, anthers. Scale bars: 100 μm. b Schematic view of the expression profiling of PH12 mRNA precursor, mature miR2118 and phasiPH12-1 regarding meristem state and developmental timing based on in situ hybridization data. Blue boxes illustrate transcript detection periods. BM: branch meristem; SM: spikelet meristem; FM: floret meristem