Location: Crop Genetics ResearchTitle: A comparative study between trait selections and marker-assisted selections to improve fiber strength in upland cotton
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2022
Publication Date: 3/22/2023
Citation: Zeng, L., Fang, D.D., Li, P., Delhom, C.D. 2023. A comparative study between trait selections and marker-assisted selections to improve fiber strength in upland cotton. Crop Science. 63:1092-1101. https://doi.org/10.1002/csc2.20881.
Interpretive Summary: In traditional crop breeding, selections for genetic improvement of quantitative traits such as most fiber quality traits in cotton are based on observable traits. In recent decades, selection with aid of molecular markers has emerged as a new breeding approach. However, there are lack of reports on the efficiency of this new approach in crop breeding, especially in cotton. It is unknown whether the breeding with aid of molecular markers is advantageous over the breeding based on observable traits in terms of efficiency and breeding values. This study was designed to investigate the efficiency and fiber quality of molecular markers assisted cotton breeding in comparisons with the breeding based on observable traits in two breeding populations. Results were different in different breeding populations. In one breeding population, the breeding assisted by molecular markers was more efficient than the breeding based on observable traits, while in another breeding population results were reversed. However, results showed that fiber quality of molecular marker assisted breeding was better than breeding based on observables with highly efficient marker assisted selections. Therefore, molecular assisted breeding has advantages over breeding based on observable traits in breeding populations when highly efficient molecular marker assisted selections are applied.
Technical Abstract: A determination of efficiency in the use of marker assisted selection (MAS) for improving fiber quality is critical for a successful utilization of MAS in cotton breeding. This study was designed to determine selection responses and realized heritability (h2) of fiber strength selected by MAS in comparison to selections by traditional breeding. Previously identified SSR markers, CGR6764 and DPL0852, flanking fiber strength QTL on chromosome A07, were used in MAS. Two genetic populations, MD15/TAM98D-99ne (Pop 1) and TAM98D-99ne/UA48 (Pop 2), were developed. F2 plants were selected by three methods based on (1) phenotype in traditional breeding, (2) combined marker-genotype and phenotype (MAS-1), and (3) marker-genotype alone (MAS-2) in Pop1 and two methods based on phenotype in traditional breeding and MAS-1 in Pop2. F3 progeny rows derived from the selected F2 plants were planted with two replicates in 2019. In Pop1, fiber strength of the selected F3 progenies was in an order of MAS-1 > MAS-2 > traditional breeding. In Pop2, there was no significant difference of strength in F3 progenies derived selections by MAS-1 and traditional breeding. In Pop 1, h2 of MAS selections was higher than traditional breeding. In contrast, in Pop 2, h2 of MAS selections was lower than traditional breeding. Results indicate selection efficiency by MAS is different in different genetic backgrounds. However, when highly efficient MAS selection is applied in cotton breeding, selections by MAS with combined marker-genotype and phenotype will be superior to traditional breeding.