By Jessica Ryan, Public Affairs Specialist, United States Department of Agriculture

Researchers at the U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS) bred four cotton lines that can be used to make self-extinguishing textiles when exposed to fire and will reduce the need for flame-retardant chemicals to be embedded in consumer products, according to a recent study published in PLOS ONE.

The cotton lines were developed from cultivated cotton varieties and possessed a novel flame-retardant trait. When exposed to an open flame, the fabric from the new cotton lines self-extinguished whereas regular cotton fabric burned entirely in seconds.

“Use of these lines to develop commercial cultivars creates an opportunity to improve the safety of cotton products while reducing the economic and environmental impacts of chemical flame retardants,” said Brian Condon, senior author of the study and retired research leader at the ARS Cotton Chemistry and Utilization Research Unit in New Orleans. “These lines will significantly benefit growers, producers, and consumers.”  

During a standard 45° incline flammability test, regular cotton (seen on the top row) burned instantly when exposed to an open flame. In the same test, the fire-resistant cotton (seen on the bottom row) self-extinguished when exposed to an open flame.

Cotton typically produces flammable fibers and is treated with chemicals to be flame retardant when used for consumer products like clothing, mattresses, upholstery, and carpet. The new cotton lines were created by a multi-parent breeding approach that resulted in new opportunities for natural genes to interact and develop the unexpected trait of flame retardancy.

ARS researchers Johnie Jenkins and Jack C. McCarty, supervisory research geneticists at the ARS Genetics and Sustainable Agriculture Research Unit in Mississippi, bred cotton lines to identify genes that affect agronomic traits such as yield and pest resistance and fiber quality traits such as length, strength, and fineness.

“ARS scientists study every step of cotton production from ‘Dirt to Shirt’ including genetic diversity, field management practices, fiber quality attributes, and end-use textile characteristics,” said Jenkins.  

Although all of the parental cotton lines produced flammable fabric, researchers found that flame retardance did not come from a single gene. Instead, they found that multiple genes created a phenotype for fibers with significantly lower heat release capacities. The new cotton lines also possessed the desired agronomic and fiber quality traits, making the lines sought after for breeding and consumer usage.

“We look at fabric quality and chemical finishes that create permanent press, wrinkle-free, and flame-retardant fabrics. Now we have found lines with a novel and natural genetic mechanism for flame retardance,” said Condon.

According to Gregory Thyssen, Computational Biologist at the ARS Southern Regional Research Center in New Orleans:

Further research about the durability of the flame-resistant property in different types of fabrics, yarn, textiles and after multiple washings, is still ongoing.  This will help us determine what uses of cotton will benefit the most from this novel property.  Further study to identify the metabolite that produces the natural flame retardance is also ongoing, and will help us further clarify the genes involved in its biosynthetic pathway, and therefore the key genes for breeders to incorporate into their new cultivars.  The current paper found that an unexpected combination of genes is likely the cause of the novel [fire resistant] property, but for breeding to be efficient, we will work to narrow the list to the most important ones.

The flame-resistant lines will be released to cotton breeders by Johnie Jenkins and Jack McCarty who developed the MAGIC (multi-parent advanced generation intercross) population. Cotton breeders will be able to use these lines in their breeding programs to combine this new flame-resistant trait with other traits on which they have already been focused, including pest and stress tolerance, fiber quality and geographic optimization.  However, since these lines were derived from already cultivated lines, they already possess many of these other desirable traits.  So, once sufficient seed is available, these lines could be grown for cotton production.  So, likely, two years until growers could grow these lines and [approximately] five years until breeders have incorporated the trait into commercial lines.

Go here to watch a video of fire-resistant cotton versus regular cotton in flammability testing.

Photo Credits: 1) A field of cotton bolls (Kimberly Vardeman via Wikimedia); 2) Cotton flammability testing (Doug Hinchliffe); 3) A roll of cotton cloth (PickPik); 4) Cotton in flower (Christine Moore)

Jessica Ryan is a public affairs specialist with the Agricultural Research Service, Office of Communications, Media Relations ranch of the USDA.