The
glp-1 gene functions in two inductive cellular interactions and in development of the embryonic hypodermis of C. elegans. We have isolated six mutations as recessive suppressors of temperature-sensitive (ts) mutations of
glp-1. By mapping and complementation tests, we found that these suppressors are mutations of known dumpy (dpy) genes; dpy genes are required for development of normal body shape. Based on this result, we asked whether mutations previously isolated in screens for mutants defective in body shape could also suppress
glp-1(ts). From these tests, we learned that unselected mutations of eight genes required for normal C. elegans morphogenesis, including the four already identified, suppress
glp-1(ts). All of these suppressors rescue all three mutant phenotypes of
glp-1(ts) (defects in embryonic induction of pharyngeal tissue, in embryonic hypodermis development, and in induction of germline proliferation). However, they do not rescue putative
glp-1 null mutants and therefore do not bypass the requirement for
glp-1 in development. In the light of current ideas about the molecular nature of the
glp-1 and suppressor gene products, we propose an interaction between the
glp-1 protein and components of the extracellular matrix and speculate that this interaction may impose spatial constraints on the decision between mitosis and meiosis in the germline.