A pair of invertedly repeated genes in Chlamydomonas reinhardtii encodes a zygote-specific protein whose expression is UV-sensitive

Abstract

Uniparental inheritance of the chloroplast genome has been observed in a wide variety of green plants. In Chlamydomonas this phenomenon, which can be selectively inhibited by UV irradiation of mt ⁺ gametes, has been shown cytologically to be due to the preferential degradation of mt ⁻-derived chloroplast nucleoids in young zygotes. The zygote-specific pair of zys1 genes, zys1A and zys1B, is expressed earliest among five genes isolated from a “10-min” zygote library. We report here that the ZYS1 protein, which is encoded by the invertedly duplicated zys1 gene, accumulates in zygotes and is localized in nuclei. In addition, when mt ⁺ gametes (but not mt ⁻ gametes) are UV-irradiated before mating, only very limited accumulation of ZYS1 protein can be detected in the resulting zygotes.