A role for post-transcriptional gene silencing in vegetative phase change

Angela G. Peragine, Christine Hunter, Gang Wu and R. Scott Poethig

Department of Biology, University of Pennsylvania, Philadelphia, PA

Genes that regulate the switch from juvenile vegetative to adult vegetative development in Arabidopsis have been identified by screening for mutations that cause this transition to occur precociously. Mutations in three genes have identical and fairly specific effects on this transition. One of these— ZIPPY—corresponds to ARGONAUTE7, a member of the Argonaute protein family. Members of this family have been implicated in the function of both miRNAs and siRNAs. The other mutations we have identified are alleles of SGS2 and SGS3. These genes are required for PTGS and encode, respectively, an RNA-dependant RNA polymerase and a protein of unknown function. Genetic analyses suggest that all three genes act in the same pathway, along with HASTY, the Arabidopsis orthologue of the miRNA export receptor, Exportin 5. These results suggest that miRNAs or endogenous siRNAs play an important role in vegetative phase change.