Molecular markers - Marker Assisted Selection

To borrow from our previous example , selection of plants in a given generation of backcross generation is done by scoring dozens of markers using DNA from individual plants. Each band on a gel can be scored as comming from one parent (presence of a band) or the other parent (absence of a band). In the figure at right, map locations of markers from the elite culitvar are shown in magenta, and those from the wild parent are shown in green. If we screen enough plants, we can find those plants that maximize the number of markers derived from the elite parent, while retaining the important gene of interest. In this map, a marker located very close to that gene is indicated in red. The majority of the time, if we have the marker, we have the gene.

Advantages of molecular markers in plant breeding:

• Decreased number of breeding generations
• Uniform method for scoring
• No need to use phenotypic scoring until the end
• Tells % of genome from each parent
• Tells WHICH PARTS OF EACH CHROMOSOME come from each parent

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