ABSTRACT
Several DNA constructs targeting a Ceratopteris protoporphyrin IX magnesium chelatase (CrChlI) gene that is required for chlorophyll biosynthesis were each introduced into young gametophytes by biolistic delivery. Their transient expression in individual cells resulted in a colorless cell phenotype that affected most cells of the mature gametophyte, including the meristem and gametangia. The colorless phenotype was associated with a 7-fold decrease in the abundance of the endogenous transcript. While, a construct designed to promote the transient expression of a CrChlI double stranded, potentially hairpin-forming RNA was found to be the most effi cient in systemically silencing the endogenous gene, a plasmid containing the CrChlI cDNA insert alone was suffi cient to induce silencing. Bombarded, colorless hermaphroditic gametophytes produced colorless embryos following self-fertilization, demonstrating that the silencing signal could be transmitted through gametogenesis and fertilization. Bombardment of young gametophytes with constructs targeting the Ceratopteris fi lamentous temperature sensitive (CrFtsZ) and uroporphyrin dehydrogenase (CrUrod) genes also produced the expected mutant phenotypes.
