CONSERVATION OF FINE-SCALE DNA MARKER ORDER IN THE GENOMES OF RICE AND THE TRITICEAE

DNA markers distributed over large chromosomal regions exhibit conserv ation of order (collinearity) in different cereal species, but it is n ot known whether this is maintained on a finer scale, i.e. less than o r equal to 2 cM, To address this, sets of two or more genetically link ed DNA markers were localised to yeast artificial chromosomes containi ng rice DNA inserts. Linkage analysis of these DNA markers in barley r evealed complete correspondence with their genetic order in rice, the distance between linked sequences on rice chromosomes being <1.6 cM or less than or equal to 1 x 10(6) bp (1 Mb), Thus, DNA markers separate d in this range are collinear in rice, barley and, by inference, other members of the Triticeae, These results are discussed with respect to the use of rice as a key system for the isolation of cereal genes.