A 291-bp DNA fragment (Zi35) was cloned by PCR amplification using partial degenerate primers from genomic DNA of Zizania latifolia(Griseb.), a wild species related to rice. Southern analysis shows that Zi35 occurs, by a dispersed pattern, in the haploid genome of Z. latifoliaat a copy number of ca. 400, whereas, it is completely absent from the rice genome. It is also absent from other four major cereal species. The utility of this sequence in identifying somatic hybrids between rice and Z. latifoliawas demonstrated. The sequence however did not hybridize to one of the somatic hybrids and all four rice lines known to contain small pieces of introgressed DNA fragments from Z. latifolia, suggesting that Zi35 is probably not distributed on all chromosomes of the Z. latifoliagenome. Sequence analysis shows that Zi35 is most probably non-coding, and has no significant homology to known-function sequences in the databases.