RFLP Mapping of Plant Nuclear Genomes: Planning of Experiments, Linkage Map Construction, and QTL Mapping

Abstract

Mapping of plant genomes began soon after the development of genetic mapping in Drosophila in the early 1900s. These efforts were driven in part by the recognition that genetic maps could facilitate indirect selection based on associations between desired traits and more easily determined characters. As early as the 1930s, genetic linkage groups were presented for tomato (MacArthur 1934) and maize (Emerson et al. 1935). These linkage groups consisted entirely of loci that caused discrete and visible changes in morphological characteristics, and until the 1970s genetic mapping was restricted to these types of markers. Because the number of morphological markers segregating within one cross is generally limited, combination of segregation data from multiple crosses was required to construct one complete linkage map (that is, a map covering an entire genome; e.g. Rick 1980). The development of biochemical markers in the form of isozymes and other polymorphic proteins significantly increased the number of markers which could be followed in a single segregating population (Tanksley 1983). Unfortunately, biochemical markers suffer some of the same inherent limitations as genes for morphological characters.