Fine mapping of the foliage bitterness gene (Bi) in Cucumis sativus.

A RILs population with 148 individuals derived from a cucumber line 9110 Gt(bibi)and 9930(BiBi)was used to analyze the location of Bi gene.Bi gene was mapped on the linkage group 6,corresponding to chromosome 6 of cucumber.The flanking markers SSR19672 and SSR00004 were linked to the Bi gene with distances of 4.4 and 3.4 cM.An F2 population with 1 815 individuals derived from the same parents was used for screening recombinants for fine mapping of the gene.Recombinant plants were identified by the flanking markers SSR19672 and SSR00004.Based on the whole genome sequence of cucumber,thirty-one SSRs within the region between SSR19672 and SSR00004 were designed and screened for polymorphism between the two parents,which revealed that one of them(SSR02309)was 1.7 cM to Bi gene.The distance between previously identified flanking marker SSR00004 and Bi were 2.2 cM.