A BETTER WAY TO CONSTRUCT RECOMBINANT CHROMOSOME LINES AND THEIR CONTROLS

Previous procedures to construct chromosome monosomic, substitution, recombinant chromosome lines and their controls underestimated cultivar heterogeneity, which can increase background effects. Modifications are proposed to increase background homogeneity and to eliminate interference of genetic or structural heterogeneity of the target chromosomes in parental populations. To achieve this goal, a single plant or plants of single-seed descendants of disomic, monosomic, and substitution lines should be used as the parents to construct recombinant chromosome lines and the controls (i.e., the recreated disomic recurrent parent and the recreated disomic substitution line). Intracultivar variations can thus be avoided. The mating plan is carefully designed so that the resultant recombinant chromosome lines and their controls will have a similar genetic background. All the resultant lines will share the same cytoplasm and the same target chromosomes or chromosome segments that came from the parent plant(s). Therefore, we are able to largely reduce the heterogeneity in the genetic background, eliminate the potential intracultivar cytoplasm variations, and be free from the structural or genetic heterogeneity of the target chromosome. In addition, the background heterogeneity, if it exists, could be measured by comparing individual control lines.