Flame resistant cotton lines generated by synergistic epistasis in a MAGIC population

Authors: Thyssen, Gregory; Condon, Brian; Hinchliffe, Doug; Zeng, Linghe; Naoumkina, Marina; Jenkins, Johnie; McCarty, Jack; Sui, Ruixiu; Madison, Crista; Li, Ping; Fang, David

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/23/2022
Publication Date: 1/18/2023
Citation: Thyssen, G.N., Condon, B.D., Hinchliffe, D.J., Zeng, L., Naoumkina, M., Jenkins, J.N., Mccarty,J.C., Sui, R., Madison, C., Li, P., Fang, D.D. Flame resistant cotton lines generated by synergistic epistasis in a MAGIC population. PLOS ONE. 18:e0278696.2023. https://doi.org/10.1371/journal.pone.0278696.
DOI: https://doi.org/10.1371/journal.pone.0278696

Interpretive Summary: Breeding programs that combine multiple parents can create new combinations of variants of genes that results in traits that are superior to those of any of the parents. A screen of cotton lines for naturally enhanced flame retardance (FR) from a multi-parent advanced generation intercross (MAGIC) population was conducted. All eleven parents, like other conventional white fiber cotton cultivars, produce flammable fabrics. Found among the new cotton lines generated, were lines that produced textiles with the novel characteristic of inherent flame resistance. When exposed to open flame by standard flammability testing procedures, textiles made from these lines self-extinguished. Linkage, epistatic, transcriptomic and multi-locus genome wide association studies (GWAS) were conducted with Big Data from multiple locations and years with the collaboration of USDA chemists, biologists and cotton breeders. Together, these data provide insight that has the potential to greatly reduce the costs and impacts of flame-retardant chemicals through the breeding of inherently flame-resistant white cotton varieties.

Technical Abstract: Textiles made from cotton fibers are flammable and thus often include flame retardant additives for consumer safety. Transgressive segregation in multi-parent populations facilitates new combinations of alleles of genes and can result in traits that are superior to those of any of the parents. A screen of 257 recombinant inbred lines from a multi-parent advanced generation intercross (MAGIC) population for naturally enhance flame retardance (FR) was conducted. All eleven parents, like all conventional white fiber cotton cultivars produce flammable fabric. MAGIC recombinant inbred lines (RILs) that produced fibers with significantly lower heat release capacities (HRC) as measured by microscale combustion calorimetry (MCC) were identified and the stability of the phenotypes of the outliers were confirmed when the RILs were grown at an additional location. Of the textiles fabricated from the five superior RILs, four exhibited the novel characteristic of inherent flame resistance. When exposed to open flame by standard 45° incline flammability testing, these four fabrics self-extinguished. To determine the genetic architecture of this novel trait, linkage, epistatic and multi-locus genome wide association studies (GWAS) were conducted with 473k SNPs identified by whole genome sequencing (WGS). Transcriptomes of developing fiber cells from select RILs were sequenced (RNAseq). Together, these data provide insight into the genetic mechanism of the unexpected emergence of flame-resistant cotton by transgressive segregation in a breeding program. The incorporation of this trait into global cotton germplasm by breeding has the potential to greatly reduce the costs and impacts of flame-retardant chemicals.