THE DROSOPHILA SEGMENT POLARITY GENE PATCHED INTERACTS WITH DECAPENTAPLEGIC IN WING DEVELOPMENT

The decapentaplegic (dpp) gene of Drosophila melanogaster encodes a po lypeptide of the transforming growth factor-beta family of secreted fa ctors. It is required for the proper development of both embryonic and adult structures, and may act as a morphogen in the embryo. In wing i maginal discs, dpp is expressed and required in a stripe of cells near the anterior-posterior compartment boundary. Here we show that viable mutations in the segment polarity genes patched (ptc) and costal-2 (c os2) cause specific alterations in dpp expression within the anterior compartment of the wing imaginal disc. The interaction between ptc and dpp is particularly interesting; both genes are expressed with simila r patterns at the anterior-posterior compartment boundary of the disc, and mis-expressed in a similar way in segment polarity mutant backgro unds like ptc and cos2. This mis-expression of dpp could be correlated with some of the features of the adult mutant phenotypes. We propose that ptc controls dpp expression in the imaginal discs, and that the r estricted expression of dpp near the anterior-posterior compartment bo undary is essential to maintain the wildtype morphology of the wing di sc.