Assignment of YAC clones spanning rice chromosomes 10 and 12.

Yeast artificial chromosome (YAC) clones were assigned on rice (Oryza saliva L. cv. Nipponbare) chromosomes 10 and 12 using DNA markers from our high-density linkage map. Out of 1,383 markers localized in this genetic map, 68 and 74 markers were located on chromosomes 10 and 12, respectively. Screening of the YAC genomic library was conducted by colony hybridization and Southern hybridization using restriction fragment length polymorphism (RFLP) markers or by polymerase chain reaction (PCR) using sequence-tagged site (STS) markers. We have completed the screening of 68 markers on chromosomes 10 and 74 markers on chromosome 12. A total of 134 and 103 YACs were assigned to chromosomes 10 and 12, respectively, with an estimated coverage of more than 60% for chromosome 10 and about 47% for chromosome 12. As rice is considered a model plant for genome analysis, the ordered YAC clones on chromosomes 10 and 12 as well as other chromosomes will certainly be helpful for isolation of agronomically and biologically important genes and for understanding the genome structure of these chromosomes.