QTL alleles for improved fiber quality from a wild Hawaiian cotton, Gossypium tomentosum

Seventeen backcross-self families from crosses between two Gossypium hirsutum recurrent parent lines (CA3084, CA3093) and G. tomentosum were used to iden- tify quantitative trait loci (QTLs) controlling Wber quality traits. A total of 28 QTLs for Wber quality traits were identi- Wed (P < 0.001), including four for Wber elongation, eight for Wber Wneness, four for Wber length, four for Wber strength, six for Wber uniformity, one for boll weight, and one for boll number. Three statistically signiWcant marker- trait associations for lint yield were found in a single envi- ronment, but need further validation. Two-way analysis of variance revealed one locus with signiWcant genotype £ family interaction (P < 0.001) for Wber strength and a second locus with signiWcant genotype £ environment interaction (P < 0.001) in the CA3084 background, and two loci with signiWcant genotype £ background interaction (P < 0.001) for the 28 common markers segregating in both of the two recurrent backgrounds. Co-location of many QTLs for Wber quality traits partially explained correlations among these traits. Some G. tomentosum alleles were associated with multiple favorable eVects, oVering the possibility of rapid genetic gain by introgression. Many G. tomentosum alleles were recalcitrant to homozygosity, suggesting that they might be most eVectively deployed in hybrid cottons. DNA markers linked to G. tomentosum QTLs identiWed in the present study promise to assist breeders in transferring and maintaining valuable traits from this exotic source during Upland cotton cultivar development. This study also adds further evidence to prior studies indicating that the majority of genetic variation associated with Wber quality in tetraploid cotton traces to