Fig. 2: Development processes of conical cells, short trichomes, and long hairs as well as expression profiles of key candidate genes in Nigella damascena petals.

a The development of long hairs (LHs), short trichomes (STs), and conical cells (CCs). Images below petals show magnified views of the boxed regions containing STs (sky blue) and CCs (yellow). Red, sky blue, and yellow arrowheads point to the emerging LH, ST, and CC, respectively. For each stage, at least 5 petals were observed. Scale bars: (Rows 1 and 2) 100 μm; (Row 3) 50 μm. b Expression profiles of key candidate genes across eight developmental stages of petals. Red, sky blue, and yellow bars indicate the stages when LHs, STs, and CCs arise, respectively. c Sampling strategy for the digital gene profiling of the S10 petal. I, II, III, and IV represent four sampled parts. d Expression profiles of key candidate genes in the four parts of the S10 petals. Note that in (b) and (d), except NidaCPR5-2, which is a nuclear replication activator candidate, all other genes are candidates for CC or trichome specification. For expression profiles of other candidates, see Supplementary Fig. 3. Source data for (b) and (d) are provided in Supplementary Data 2. e A hypothetical model showing genes involved in the formation of LHs, STs, and CCs. The interaction and regulatory relationships among proteins of candidate genes are illustrated in reference to Arabidopsis thaliana. Note that the broadly expressed TTG1 is shown in the model as a potential partner of GL1/MYB5-1/MYB5-2 and GL3/TT8.