Construction of a Saccharum Consensus Genetic Map from Two Interspecific Crosses

A consensus map of homologous DNA linkage groups from two genotypes in each of two Saccharum species was aligned with the compact diploid genome of Sorghum bicolor (L.) Moench. A set of 439 DNA probes from different Poaceae (grasses) detected 2523 loci in two segregating populations derived from the crosses Saccharum officinarum L.'Green German' × S. spontaneum L. ‘IND 81‐146’, and S. spontaneum ‘PIN 84‐1’ × S. officinarum ‘Muntok Java’. Genetic maps of the four Saccharum genotypes, including a total of 289 linkage groups (LGs), were assembled into 13 homologous groups (HGs) on the basis of parallel arrangements of duplicated loci. The consensus map of HGs consisted of 232 probes and 982 mapped loci/alleles in four sugarcane linkage maps. Of the 982 loci/alleles on the consensus map, 845 (86%) of them correspond to a single linkage group of Sorghum, indicating the highly conserved genome structure between these two closely related genera. At least six basic chromosomes, LGs A, D, F, H, I, and J, showed close correspondence to each other in Saccharum and Sorghum Two possible chromosome fusion events were found in S. spontaneum corresponding to sorghum LG B fused with LG E, and LG B fused with LG G. This consensus map illustrates how the high‐density sorghum linkage map can be used to facilitate the mapping and understanding of the complex sugarcane genome.