Development and Characterization of Chromosome Segment Substitution Lines (LT)

Cultivated cotton has limited genetic variability; introgression of wild species can increase the breadth of usable germplasm available for breeders. If wild germplasm will be beneficial, it would be so in small portions. Consequently, Chromosome Segment Substitution Lines (CSSLs) can be a powerful tool for introgression and characterization of wild germplasm.

Chromosome Segment Substitution Lines were developed through the introgression of Gossypium mustelinum, a wild Brazilian cotton species, into Gossypium hirustum (TM-1). Each CSSL has a small piece of G. mustelinum introgressed into a nearly isogenic TM-1 background. All CSSLs collectively represent the entire genome of G. mustelinum. Marker-assisted backcrossing selection with interspecific marker assays allowed efficient recovery of introgressed segments.

CSSLs allow the possibility for more robust characterization compared to Chromosome Substitution Lines or similar large introgression populations. Small segments create the opportunity to see effects caused by epistasis, and the ability to increase correlation between phenotype and genotype.