Figure 1.

Rapid morphological changes and dynamic gene expression accompany CaAM formation. A–D, Optical sections of calcofluor-stained WT axillary regions following the SD to LD transition. A and B, Main panel: transverse optical section (with respect to the main stem axis), lower: reconstructed optical tangential section, right: reconstructed optical radial sections. Horizontal and vertical lines mark the position of the tangential and radial sections. C and D, Optical tangential sections. The number of days under LD conditions is indicated. E–L, Maximum projections of transverse (E, G, I, and K) and tangential (F, H, J, and L) optical sections of a line co-expressing pWUS:VENUS-NLS (E–H) and pCLV3:mCHERRY-NLS (I–L) reporters during CaAM formation. (F, J, H, and L) are a merge between reporter fluorescence and transmitted light. The number of days under LD conditions is indicated. M–P, Schemes showing the 3D structures of the apex with the SAM, the cauline leaf primordium and the developing CaAM. Schemes of the expression patterns of WUS and CLV3 are shown. The schemes of the optical sections are shown below. Scheme M corresponds to (E) and (I), scheme N to (F) and (J), and so on. Q–X, Maximum projections of transverse optical sections of a line co-expressing pCUC2:erRFP (Q–T) and pCUC3:erCFP (U–X) reporters during CaAM formation. Positions are numbered according to the rank of the primordium. Primordium number is indicated. Y–AA, Schemes showing the 3D structures of the apex with the SAM, the cauline leaf primordium and the developing CaAM. Schemes of the expression patterns of CUC3 are shown. The schemes of the optical sections are shown below. Scheme Y corresponds to (U) and (V), scheme Z to (W), scheme AA to (X). Scale bars = 50 µm; clp: cauline leaf primordium; asterisks: AM; lp: leaf primordium formed by the AM, fp: flower primordium formed by the AM. The dotted lines correspond to the outlines of the cauline leaf primordia.