Physical location of rice Gm-6, Pi-5(t) genes in O-officinalis with BAC-FISH

A fluorescence ill situ hybridization (FISH) procedure was adopted to physi cally map two rice BAC clones 24E21 and 4F22 linked to Gm-6 and Pi-5(t) in O. officinalis. FISH results showed that the two BAC clones were located at 4L, The percentage distance from the centromere to the hybridization sites was 72 +/-2.62 for 24E21 and 54 +/-5.43 for 4F22, the detection rates were 52.70% and 61.2%. The results obtained from the BAC and plasmid clones, RG 214 and RZ565 of cultivated rice and O. officinalis were the same, This sug gested that the markers, RG214 and RZ565 of cultivated rice and O. officina lis were in the same BAC clones. The homologous sequences of Gm-6 and Pi-5( t) in O, officinalis were positions that signals existed on the 4L, Many si gnals were observed when no Cot-l DNA blocked, This also showed that repeti tive sequences were some homolgous between cultivated rice and O. officinal is, The identification of chromosome 4 of O, officinalis is based on Jena e t al. (1994). In our study, we discussed the possibility of physical map in O. officinalis with rice BAC clones.