Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/20/2009
Publication Date: 6/1/2009
Citation: Zeng, L., Meredith Jr, W.R., Gutierrez, O.A., Boykin, D.L. 2009. Identification of Association Between SSR Markers and Fiber Related Traits in Exotic Germplasm Derived from Multiple Crosses among Gossypium Tetraploid Species. Theoretical and Applied Genetics. 119:93-103 Interpretive Summary: It is a great challenge to continue improving fiber quality while maintaining high yield in cotton breeding. Molecular markers (fragments of DNA closely associated with an important trait) can help breeders select for both yield and fiber quality. Thirty-two molecular markers were identified associated with 10 fiber related traits; twenty-two of these markers were confirmed to be reliable. Use of these molecular markers associated with fiber traits can help cotton breeders develop cultivars with improved fiber quality and better yield.
Technical Abstract: Identification of molecular markers associated with fiber related traits can facilitate selection and improve our understanding of the genetic mechanisms underlying the interactions among fiber related traits. This study was designed to evaluate an exotic germplasm population, Species Polycross (SP), derived from multiple crosses among Gossypium tetraploid species and screen the population for associations between SSR markers and fiber related traits. The SP population underwent 11 generations of mixed random mating and selfing followed by12 generations of selfing. Two hundred and sixty lines were evaluated at two locations with two replicates each in 2005. Variance components of genotype for yield components and fiber properties were at least two times greater than that of genotype and location interactions. Broad-sense heritability was high for all traits except short fiber content. Thirty-two SSR markers were found to have a significant (p<0.01) association with 10 traits. The lines grouped into three groups, Group1, Group2 and Group3 consisting of 28, 35 and 101 lines, respectively, based on analysis using Structure. The identified population substructure was significantly associated with boll weight, seeds per boll, and micronaire. Genetic differentiation was significant among the substructures. Wright’s genetic differentiation index, Fst, reduced to 0.04 after exclusion of the 63 lines in Group 1 and Group 2. The exclusion of these lines did not change the number of markers significantly (p<0.01) associated with seed weight and lint per seed, but reduced the number of markers associated with boll weight, seeds per boll, micronaire, and span length (2.5%) to at least half.