GENE TRAP TAGGING OF PROLIFERA, AN ESSENTIAL MCM2-3-5-LIKE GENE IN ARABIDOPSIS

Gene trap transposon mutagenesis can identify essential genes whose fu nctions in later development are obscured by an early lethal phenotype . In higher plants, many genes are required for haploid gametophyte vi ability, so that the phenotypic effects of their disruption cannot be readily observed in the diploid plant body. The PROLIFERA (PRL) gene, identified by gene trap transposon mutagenesis in Arabidopsis, is requ ired for megagametophyte and embryo development. Reporter gene express ion patterns revealed that PRL was expressed in dividing cells through out the plant. PRL is related to the MCM2-3-5 family of yeast genes th at are required for the initiation of DNA replication.