A MATING-TYPE LINKED GENE-CLUSTER EXPRESSED IN CHLAMYDOMONAS ZYGOTES PARTICIPATES IN THE UNIPARENTAL INHERITANCE OF THE CHLOROPLAST GENOME

A characteristic feature of early zygote development in Chlamydomonas is the selective degradation of chloroplast DNA from the mating type m inus parent. The zygote-specific gene cluster ezy-1 is linked to the m ating type locus and is transcribed almost immediately upon zygote for mation. We show here that the acidic Ezy-1 polypeptide is rapidly tran sported to both the plus and minus chloroplasts, where it interacts wi th each chloroplast nucleoid. Expression of ezy-1 is selectively inhib ited when pius, but not minus, gametes are briefly ultraviolet irradia ted just prior to mating, a treatment known to disrupt the uniparental inheritance of chloroplast traits. We propose that the Ezy-1 polypept ide participates in the destruction of the minus chloroplast DNA in zy gotes and thus the uniparental inheritance of chloroplast traits. The ezy-1 gene represents a valuable molecular probe for dissecting mechan isms underlying organelle inheritance.