Pyramiding of New QTL LOCI into a Single Genotype in Cotton

The goal of this research was to pyramid QTLs, which control cotton fiber quality traits using MAS technique. The commercial Uzbek cotton cultivar “Andijan-35” was used as a recipient parent, “L-141” and “Saenr Pena85” lines as donor genotypes. “Andijan-35” is an elite cultivar that has high yield, but poor fiber quality. “Andijan-35” was crossed with “L-141” (possessing marker locus BNL1604 associated with fiber length and strength) and “Saenr Pena85” (having marker locus BNL3650 associated with fiber elongation) donor lines. Resulting two different F1 hybrids were crossed with each other in order to combine two different QTLs of fiber length, strength and elongation. Subsequently, complex F1 hybrids have been backcrossed with the recipient genotype for the next four generations. In addition, twice self-pollinations were conducted in obtained BC4F1 hybrids, which combining two QTL loci in BC4F3 hybrids were resulted in with improved fiber quality properties. Backcross hybrids were PCR screened in each generations using DNA markers of target. The fiber quality characteristics of them were tested using HVI. The results of fiber quality analysis of the homozygous plants in BC4F3 generation showed the mean fiber length – 1.20 inches, strength – 35.2 g/tex and fiber elongation – 8.8 %. These parameters are significantly lower in the recipient genotype, in which fiber length is 1.12 inches, strength – 31.5 g/tex and fiber elongation – 7.0 %. “L-141” line is one of the donor genotypes of BC4F3 generation that has a mean fiber length and strength of 1.27 inches and 40.7 g/tex and fiber elongation 7.6%. The second donor, “Saenr Pena 85” has a mean fiber elongation – 9.0 %. Results of fiber quality analysis of BC4F3 hybrids revealed that QTLs, which were stacked into a new cotton lines, had a significant impact on improving the fiber quality traits of BC4F3 hybrids.