Rice cultivar Norin 8 and its mutant Norin 8m harbour bentazon resistance trait and bentazon susceptibility trait respectively. A total of 360 arbitrary 10-mer oligonucleotide primers were screened on the genomic DNA of Norin 8 and Norin 8m with RAPD technique. Among which, five primers produced seven polymorphic RAPD bands between Norin 8 and Norin 8m. Amplified RAPD polymorphic products were cloned and sequenced. The sequences were used to design primers for PCR. Five SCAR markers, SCAR/G18/883, SCAR/G18/890, SCAR/G18/919/948, SCAR/D10/1237 and SCAR/F03/1186, were developed from OPG18/943, OPG18/972, OPD10/1248 and OPF03/1198. F-2 progeny of 320 individuals was analyzed to map SCAR markers in relationship to ben or Ben genes. SCAR markers of SCAR/G18/883, SCAR/G18/890, SCAR/G18/919/948 were shown to cosegregate with ben or Ben genes, and SCAR/D10/1237 to be linked of Ben gene with a distance of (14.8 +/- 2.1) cM. The genetic linkage to ben gene and SCAR markers was identified by a pair of near isogenic lines H121 and Hben121. Southern blotting analysis and segregation ratio of F-2 progeny revealed that OPG18/943 and OPG18/972 were single-copy in genome, and locus of OPG18/943 and OPG18/972 were allelic and sequence tagged sites. It is the first report on molecular markers linked to ben or Ben genes. The markers are useful to marker-assisted selection for the breeding and tag ben gene with map-based cloning.
