Fig. 4. Reduction of SAM size by CLV3 overproduction. (A-D) In situ hybridizations to inflorescences of wild type (A,C) and CLV3::(CLV3)₅-expressing plants (B,D). Control hybridizations using corresponding sense riboprobes did not produce any specific staining (not shown). (A) In the wild-type inflorescence meristem CLV3 expression is restricted to the presumed stem cells in the centre of the three outermost cell layers (arrow). (B) In inflorescence meristems of CLV3::(CLV3)₅-expressing plants strong hybridization signal with the CLV3 antisense riboprobe is detected in the presumed stem cells, similar to wild type (arrow). However, weak staining is also observed in lateral and basal stem cell daughters (arrowhead). (C,D) WUS is expressed in the centre of wild-type (C) and CLV3::(CLV3)₅-expressing (D) inflorescence meristems underneath the presumed stem cells. However, the width of the expression domain appears to be reduced in D compared with C. (E,F) Scanning electron micrographs of CLV3::GUS- (E) and CLV3::(CLV3)₅-expressing (F) plants. Young flower primordia are numbered successively 1 to 5, and the distance measured for determining meristem size is indicated by double-headed arrows. Scale bars: 50 µm (in A for A-D and E for E,F).

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