MAPPING AND SEQUENCING RICE TELOMERES

¹ Arizona Genomics Institute, 303 Forbes Building, The University of Arizona, Tucson, AZ85721, USA

² Laboratory of Genetics, Wageningen University, the Netherlands

³ Clemson University Genomics Institute, Clemson University, Clemson, SC29634, USA

The International Rice Genome Sequencing Project (IRGSP) is a collective effort directed to sequence the rice genome. Most of the telomeric regions have not been characterized even though almost complete BAC, PAC, and YAC-based physical maps have been constructed. The telomeric and subtelomeric regions are important for maintaining the integrity of chromosomes and are known to contain a high density of genes. We have isolated eight clones harboring telomeric regions from two whole genome 10kb libraries, OSJNPb (HaeIII library 166,752 clones) and OSJNPc (Sau3AI 138,960 clones). These clones include 17 to 100 copies of the telomeric repeats (CCCTAAA)n at one end and unique sequences at the other region. Three clones and one sub clone among them were positioned on four chromosome ends (Tel-1 on 10s; Tel-5 on 3q; Tel-7 on 7q; Tel7-2u on 7p) by STS mapping using BIL (backcross inbred lines, BC₁F₅, of Nipponbare and Kasalath) population of RGP. We are trying to find some more telomere specific clones and map them on specific chromosome by STS and FISH. Furthermore, BAC and PAC clones are expected to be useful to close the subtelomeric physical gaps by chromosome walking, using these telomere specific clones. These telomere specific sequences might be a valuable resource to complete the rice genome sequencing and to more fully understand the function of these specific chromosomal regions.