| Morphogenesis is an important component of animal development. Genetic redundancy has been proposed to be common among morphogenesis genes, posing a challenge to the genetic dissection of morphogenesis mechanisms. Here, we present a screen designed to uncover redundant and partially redundant genes that function in an example of morphogenesis, gastrulation in Caenorhabditis elegans. We performed an RNAi enhancer screen in a gastrulation-sensitized double-mutant background, targeting genes likely to be expressed in gastrulating cells or their neighbors. Secondary screening was used to identify genes with detectable effects on gastrulation in both sensitized and non-sensitized backgrounds. By this method, we identified 16 new genes whose function is required for normal gastrulation in a non-sensitized background. We observed that for most of these genes, their closest known homologs were multiple other C. elegans genes, suggesting that some of these genes may have derived from rounds of relatively recent gene duplication events. We predict that such genes are more likely than single copy genes to comprise redundant or partially redundant gene families. We explored this prediction for one of the new genes. Our results confirmed that this gene and five close relatives do indeed function partially redundantly with each other in gastrulation. Our results implicate new genes in C. elegans gastrulation, and show that an RNAi-based enhancer screen can be used as an efficient means to identify important but redundant or partially redundant developmental genes. |
