Tomato genome sequencing: deciphering the euchromatin region of the chromosome 8

Abstract

As a member of the Solanaceae Genomics Network International Tomato Sequencing Project, we launched on sequencing of the chromosome 8. Our task is to sequence the euchromatin region of the chromosome, the estimated size of which is 17 megabases. BAC-by-BAC strategy is adopted for sequencing. We initially received BAC clone candidates anchored to overgo probes developed from 33 markers mapped on chromosome 8. For confirmation of the BAC candidates, we analyzed the sequence of PCR product amplified from the BAC DNA with primers designed on the marker sequence. Twenty-five BAC clones were verified and subjected to shotgun sequencing. As of Nov. 2006, we finished 40 clones to Phase 3 (total non-redundant length 4,429,168 bases) of 25 are seed and 15 are extended clones. In order to find additional seed points, we performed PCR screening of markers against 3D DNA-pool of LE-HBa, SL-MboI and SL-EcoRI BAC libraries, and succeeded in obtaining 9 new seeds. We report the current status of our project and future perspectives toward the final goal, which include development of new microsatellite markers from tomato EST sequences and Selected BAC Mixture shotgun sequencing for the gap filling.