Researchers develop longer, stronger cotton fiber

The research, funded primarily by the U.S. Department of Agriculture Office of International Research Programs, is published in the most recent edition of the journal Nature Communications.

“This technology allows improvement of fiber quality in upland cotton, which is widely grown everywhere,” said Alan Pepper, an associate professor in the Texas A&M Department of Biology and senior author of the paper that was led by a former Texas A&M graduate student now in Uzbekistan. “This will increase the competitiveness of natural cotton fibers versus synthetic fibers, which have been snagging an increasing amount of the market share every year.”

The overwhelming majority of cotton harvested in the U.S. and worldwide is upland cotton, or Gossypium hirsutum, with more than 6.5 million acres planted in 2012 in Texas alone, according to the USDA. A higher-end cotton called Gossypium barbadense is more desirable because of greater fiber length and strength but is late-maturing, low-yielding and more difficult to grow because it requires dry climates with significant irrigation and is less resistant to pathogens and pests.

“For a long time cotton breeders have been trying to develop upland cotton with the fiber qualities of barbadense cotton,” Pepper said. “Globally, everybody’s trying to do it. Economically, it’s a huge deal, because every millimeter you add to fiber length adds that much to the price of cotton when the farmer sells it.”

The researchers’ method increased the length of the fiber by at least 5 millimeters, or 17 percent, compared to the control plants in their experiment.

Pepper, a plant biologist at Texas A&M since 1995, acknowledges that the cotton plants developed in the project technically are genetically modified organisms (GMOs), a controversial subject. But he makes a key distinction: A major criticism of GMOs, Pepper notes, focuses on cases where genes from other species — even bacterial ones — have been added to an organism to achieve a desired trait. For instance, the agricultural giant Monsanto adds a gene to cotton that makes it resistant to Roundup® and then sells both the seeds and the weed killer to farmers.

“What we’re doing is a little different,” Pepper said. “We’re not actually adding in a gene from another species. Rather, we’re knocking down the effect of one of the genes that’s already in the plant.”

Like human and animal eyes, plants also have photoreceptors that pick up information about the environment. Pepper’s interest is in a type of photoreceptor called a phytochrome, which is mainly responsive to different wavelengths of red light. The phytochromes regulate many plant traits, including the length of leaves and stems and flowering time. The researchers found literature from the 1990s that suggested the amount of red light also influenced fiber length in cotton plants.

Using a genetic cross between a long-fiber plant and a short-fiber plant, then zeroed in on a region of the genome that sat directly on top of one the phytochrome genes. They then used a technique called RNA interference to “knock down” or interfere with expression of that gene, Pepper said.

“This was pure basic science, seeking to understand the biological function of a gene,” Pepper said. “And sure enough, the phytochrome ‘knock-down’ plants had all these phenotypic changes associated with it, and one of them was longer fiber.”

The discovery was especially important to Ibrokhim Abdurakhmonov, the lead author of the study who received his master’s degree in plant breeding from Texas A&M in 2001 and is now a professor in his native Uzbekistan. The landlocked agricultural nation that borders Afghanistan historically has relied heavily on cotton to strengthen its rapidly diversifying economy. Once used by the former Soviet Union as a base for its cotton production, Uzbekistan currently accounts for around 10 percent of world cotton fiber exports.

“Sustainability and biosecurity of cotton production is pivotal for the Uzbekistan economy because agriculture accounts for 24-to-28 percent of the country’s gross domestic product,” said Abdurakhmonov, who also serves as director of the Center of Genomics and Bioinformatics at the Academy of Sciences of Uzbekistan, which is located in the capital, Tashkent, and part of the Ministry of Agriculture and Water Resources.

“The increased value of longer and stronger lint, at 10 cents per pound, would be at least $100 per acre more income from the lint for each new cultivar using this technology. New markets for longer, finer, stronger and more uniform cotton lint fiber, as well as early maturity and increased yield potential could further increase estimated economic value. Our anticipation of possible improvement of resistance to abiotic stresses via phytochrome RNA interference further adds to its commercial potential.”