Two rice DMC1 genes are differentially expressed during meiosis and during haploid and diploid mitosis

Abstract.

We have cloned two rice homologues of yeast DMC1, a meiosis-specific gene required for recombination between homologous chromosomes. We show that rice DMC1A and DMC1B were produced by a gene duplication event that occurred after rice separated from the common ancestor of the cereals. The predicted proteins contain 344 amino acids, of which all but 7 are conserved between the two homologues. Between bases –1 and –245, the two promoters share six invariant blocks of sequence of 10–28 bp, interspersed in variable sequences. Both DMC1A and DMC1B are expressed in pollen mother cells coincident with meiosis, and in diploid non-meiotic tissues such as calli and root tips. DMC1B is also expressed in haploid male gametophytes during pollen maturation and in diploid zygotic embryos and endosperm after pollination. These data suggest that DMC1B, either alone or in combination with DMC1A, contributes to recombination during meiosis and during haploid and diploid mitosis.