Analysis of a cotton introgression population derived through multiple generations of random mating in multiple-parents crosses

Abstract

The genetic base in Upland cotton (Gossypium hirsutum L.) is narrow. Repeated random mating through generations during germplasm development may be an appealing approach to introgress desirable genes from exotic germplasm into Upland cotton. A random mating population, MDRM, was developed to provide a source of germplasm with introgression of novel alleles from other tetraploid species. This population was derived from 48 crosses between four Upland cotton lines/cultivars (MD15, MD52ne, and TAM98D-99ne and FiberMax832) as female parents and twelve exotic germplasm lines as male parents. The male parents include six lines derived from multiple crosses between G. hirsutum and G. barbadense L. and another six lines derived from multiple crosses among five Gossypium tetraploid species. After five generations of random mating followed by six generations of self-pollination, the bulk of RM₅F₇ population was produced, which further led to the development of recombinant inbred lines (RILs) from seed increase of single plants in the bulk. The bulk of RM₅F₇ and its 276 RILs were evaluated along with 134 RM₀F₇ RILs (0 generation of random mating) and 142 RM₁F₇ RILs (1 generation of random mating) and the parents at College Station, TX, Las Cruces, NM, and Stoneville, MS from 2016 to 2022. The bulk of RM₅F₇ has superior fiber quality with acceptable yield as compared with parents. Transgressive segregation was observed in RM₅F₇ RILs for both lint yield and fiber quality. Unfavorable associations between yield and fiber properties of length, strength, and uniformity in RM₅F₇ were reduced compared with RM₀F₇ or RM₁F₇. Therefore, MDRM provides a new breeding stock for cotton breeders to develop germplasm lines with desirable combinations between lint yield and fiber quality and unique combinations of alleles from exotic parents.