Fig. 1. CLV3-GFP protein localization. (A-C) Photographs of live inflorescences. Arrows indicate the inflorescence meristem. (A) Wild-type inflorescence. (B) CLV3::CLV3-GFP-expressing clv3-1 mutant. The meristem is only slightly larger than in A. (C) Non-transgenic clv3-1 mutant. The meristem is grossly enlarged. (D-F,G,J) In situ hybridizations with WUS (D-F) and GFP (G,J) antisense probes. Control hybridizations using corresponding sense riboprobes did not produce any specific staining (not shown). (H,I,K,L) CLSM images. GFP fluorescence is shown in green, chlorophyll autofluorescence is in red. (D-F) WUS expression in CLV3::CLV3-GFP-expressing clv3-1 mutant plants is restricted to a small group of cells underneath the presumed stem cells (E), as it is in wild type (D). By contrast, the expression domain is greatly enlarged in non-transgenic clv3-1 mutants (F). (G,H) In CLV3::mGFP5-ER-expressing wild-type background, strong GFP fluorescence is restricted to the apical stem cells (H) that also show GFP mRNA expression (G). (I) Non-transgenic clv3-1 mutant inflorescence imaged under the same conditions as K does not show any fluorescence in the GFP channel. (J-L) In CLV3::CLV3-GFP-expressing clv3-1 mutant plants, GFP fluorescence (K,L) is detectable outside the domain of GFP mRNA expression (J), extending towards the meristem periphery. Arrows in J and K indicate the boundary between the inflorescence meristem and comparable young flower meristems. (L) Same apex as in K showing only GFP fluorescence. Note the spread of the signal laterally, but not into deeper regions of the SAM. IM, inflorescence meristem; FM, floral meristem. Scale bars: 100 µm in A (for A-C), 50 µm in D-L.