Concept of Graphical Genotypes for Analysing Introgressed Cotton Populations
Feb 6, 2019
Cotton breeders have utilized genes from Gossypium barbadense to enhance fiber properties of Acala cotton G. hirsutum. This has been achieved only after many decades of careful selection and breeding. Extensive problems with interspecific hybrid population have frustrated breeders and prevented targeted introgression of genes for important fiber quality traits. Genomic maps, utilizing DNA markers, permit dissection of each linkage group into its parental pedigree origin. This is very interesting in G. hirsutum x G. barbadense segregating populations, since species-specific chromosome regions can be identified and followed in breeding. Some of these large regions correspond to locations of quantitative trait loci (QTL) for fiber span length, fiber strength and fineness. Two genetic mapping populations involving extensive G. hirsutum x G. barbadense introgression have been studied with Simple Sequence Repeat (SSR) and RAPD markers. Due to limited intra-specific DNA polymorphisms, species-specific DNA markers have been catalogued and scored on these two mapping populations. These markers have also been utilized to create graphical genotypes of genetically stable homozygous lines that demonstrate various levels of introgression. This graphical genotype can be associated with phenotype but more importantly compared with QTL analysis for fiber quality. These QTLs can provide a foundation for introgressive breeding to enhance fiber traits, as well as, improve genetic diversity in G. hirsutum.