A genomic cosmid library of the wide-compatibility-variety rice (Oryza sativa L.Cpslo17) had been generated using vector SuperCos1. The library containing more than 1.0×105 recombinants with an average insert size of approximately 40 kb represented more than 9 times haploid genomic equivalents, but 5% clones did not carry any insert. Using RFLP marker 23D12R linked tightly to S5 as probeto screenlibrary, a new clone R2I19 was isolated and determined.