A 120 KILOBASE RESOLUTION CONTIG MAP OF THE RICE GENOME

92% of the rice genome (4.3 x 10(8) bp, 2n = 24) was covered by 631 co ntigs of various length, which were generated by fingerprinting from a representative and genetically stable bacterial artificial chromosome (BAC) library of the Guang Lu Ai 4 (a O. Sativa variety) genome with the average insert of 120 kb in length. To form the contig map, 565 mo lecular markers of RFLP, STS, cDNA and anchor set derived from two O. Sativa varieties were by colony hybridization mapped to the contigs, w hich were then assigned to and ordered along the particular chromosome s according to the marker colinearity. Being highly conserved DNA sequ ences shared among the genomes of rice, barley, wheat, oat, maize, sor ghum and sugar cane, 89 anchor markers mapped help to identify the ric e genes through the information provided by the maps of relative genom es, and vice versa. Numerous repeated DNA sequences of various length were identified and mapped to the chromosomes. Physical distances have been determined for hundreds pairs of adjacent markers, which would f acilitate the identification by map-based cloning the rice genes of in terest. The accuracy of clone overlaps in contigs was further confirme d by the existence in contigs of well fit stacks of marker-lodged clon es independently identified by hybridization. Large scale DNA sequenci ng of individual chromosomes could now be initiated simply by selectin g and sequencing the minimally overlapped BAC clones of the contigs.