Identification of Robust Microsatellite Markers for Fiber Quality in Gossypium.

Gossypium hirsutum (Upland cotton) accounts for the majority of cotton fiber production world-wide. The global marketplace places value on longer and stronger fibers, mandating that U.S. breeders develop cultivars to meet this demand. One challenge that breeders face concerning the improvement of fiber quality traits is low genetic diversity among elite, agronomically acceptable genotypes of G. hirsutum. The use of marker-assisted selection (MAS) could help breeders access unexploited genetic diversity as well as decrease the cost of phenotyping for fiber quality traits. Linkage (bi-parental) and association mapping studies have led to the discovery of hundreds of quantitative trait loci (QLT) for fiber length and strength, and many of these QTL detected show promise for use in MAS. However, there are few reports of public programs utilizing MAS for the improvement of fiber quality traits. In general, there has been inconsistency among QTL discovered across studies, which has been one of the major obstacles preventing the use of MAS for fiber quality. This inconsistency could be due to QTL being mapped in different genetic backgrounds and environments as well as experimental error. Therefore, the objective of this study was to evaluate previously reported microsatellite markers (SSRs) for fiber length and strength in different genetic backgrounds. Two intra-specific populations (G. hirsutum x G. hirsutum) and one inter-specific population (G. hirsutum x G. tomentosum/G. mustelinum) were selected for the study based on high levels of polymorphism. Within the three selected families, 285 individual F_2:3 plants were genotyped for approximately 250 SSRs, hand harvested, and sent for high volume instrument (HVI) analysis of fiber quality traits. These data were used to evaluate associations between SSRs and fiber length and strength and to identify robust candidate markers for MAS.