CONSTRUCTION OF AN RFLP MAP IN SORGHUM AND COMPARATIVE MAPPING IN MAIZE

An F-2 population derived from a cross between Sorghum bicolor sap. bi color ('CK60') and Sorghum bicolor ssp. drummondii ('PI229828') was us ed to develop an RFLP genetic linkage map of sorghum. The map consists of 201 loci distributed among 10 linkage groups covering a map distan ce of 1530 cM, with an average 8 cM between adjacent loci. Maize genom ic probes (52), maize cDNA probes (124), and sorghum genomic probes (1 0) were used to define the loci (55, 136, and 10, respectively). Ninet y-five percent of the loci fit expected segregation ratios. The loci w ith distorted segregation ratios were confined almost exclusively to a region of one linkage group. Comparison of sorghum and maize maps ind icated high correspondence between the two genomes in terms of loci or der and genetic distance. Many loci linked in maize (45 of 55) were al so linked in sorghum. Instances of both conserved and rearranged locus orders were detected.