Localization of New Monogerm and Late-bolting Genes in Sugarbeet using RFLP Markers '

A single M-m gene controlling multi-monogerm pheno­ type has been described and mapped into linkage group 2. In this study a second monogerm locus, designated m 2 , was analyzed in a segregating population from a cross between monogerm and multigerm lines of Russian ori­ gin (S22 and No.14, respectivel)'). The 11/ 2 gene was located using RFLP markers previously mapped in the sugarbeet (Beta vulgaris L.) genome. Seventeen RFLP probes were selected and 56 F2 plants examined. Nine RFLP markers were located in all linkage groups except group 2. Segre­ gation patterns of these nine RFLP markers and the monogerm and late-bolting traits indicated independence. The other eight RFLP probes indicated an association between monogerm and late-bolting in linkage group 2. The linear order of the markers considered in this analy­ sis was identical to the order reported by others. How­ ever, the distance between some RFLP markers was not consistent with previous reports. The m 2 gene was mapped in the same linkage group (group 2) as the m gene. The distance between the m 2 and m genes was 32.2 cM. These results confirmed our supposition, based on genetic ex­ periments, that these genes are different from each other. The lb gene from the Russian lines and the late-bolting gene reported in other germplasm appeared to be identi­ cal.