A FLORAL 3RD WHORL-SPECIFIC MARKER GENE IN THE DIOECIOUS SPECIES WHITE CAMPION IS DIFFERENTIALLY EXPRESSED IN MUTANTS DEFECTIVE IN STAMEN DEVELOPMENT

The CCLS4 gene of white campion is specifically expressed in anther ep idermis and endothecium from pre-to post-meiotic stages. We report on a detailed in situ analysis of the gene's expression and show that it is a marker of the floral third whorl. The gene is expressed (1) in th e anther (epidermis, parietal cells and the derived endothecium) in no rmally developing stamens and (2) in distinct sub-domains of third-who rl epidermis in mutants exhibiting aberrant states of parietal differe ntiation. Our results suggest that CCLS4 may fulfil different function s during pre-and post-meiotic anther development and reveal the comple x role parietal cells may play during early stamen formation.