A comparative study between trait selections and marker-assisted selections to improve fiber strength in upland cotton

A determination of efficiency in the use of marker-assisted selection (MAS) for improving cotton (Gossypium hirsutum L.) fiber quality is critical for a successful utilization of MAS in cotton breeding. This study was designed to determine selection responses and realized heritability (h(2)) of fiber strength selected by MAS in comparison with phenotype selections by traditional breeding. Previously identified single-sequence repeats markers, CGR6764 and DPL0852, flanking a fiber strength quantitative trait locus on chromosome A07 were used in MAS. Two genetic populations, MD15/TAM98D-99ne (Pop 1) and TAM98D-99ne/UA48 (Pop 2), were developed. F-2 plants were selected by three methods based on (1) phenotype, (2) combined marker-genotype and phenotype (MAS-1), and (3) marker-genotype alone (MAS-2) in Pop 1 and two methods based on phenotype and MAS-1 in Pop 2. F-3 progeny rows derived from the selected F-2 plants were planted with two replicates in 2019. In Pop 1, the fiber strength mean of the selected F-3 progenies was in an order of MAS-1 > MAS-2 > phenotype selection. In Pop 2, there was no significant difference in strength between F-3 progenies derived from selections by MAS-1 and phenotypic breeding. In Pop 1, h(2) of MAS selections was higher than phenotype selections. In Pop 2, h(2) of MAS selections was similar to the phenotype selections. The results indicate that selection efficiency by MAS for fiber strength is better than or equivalent to phenotype selection.