‘Genes to jeans’: Scientists discover DNA that boost cotton’s drought defense

Cotton, the soft, versatile fiber that clothes billions, is facing a growing challenge of severe and frequent drought.

Cotton growers are battling to keep output consistent as the planet warms. This may seriously jeopardize the multibillion-dollar global cotton industry.

But, new research from the Boyce Thompson Institute (BTI) suggests the possibility of creating drought-resistant cotton with high yields.

Examining 22 cotton varieties

For this study, the researchers planted 22 types of upland cotton ( Gossypium hirsutum L. ) in Arizona’s desert — subjecting half to drought stress.

​​Scientists gain valuable insights on how to adapt crops to shifting climates by studying different cotton varieties.

The team then delved into the genetic makeup and physical traits of 22 cotton varieties, and compared their responses to drought.

They discovered a fascinating pattern of cotton’s drought-coping mechanisms. Cotton plants require two important genes, GhHSFA6B-D and GhDREB2A-A, to tolerate drought and maintain fiber production.

Interestingly, the team found that these regulatory genes “act like orchestra conductors.”  This suggests that the master genes control the expression of hundreds of genes involved in drought resistance and fiber formation.

“We were excited to discover this direct link between stress tolerance and fiber yield maintenance,” said Andrew Nelson, an Assistant Professor, and co-corresponding author from BTI.

Nelson added: “It appears that over time, cotton plants have evolved this regulatory mechanism to help them cope with dry conditions while still producing the fibers that are so economically important.”

High fiber yield gene

The researchers also found new insights about the gene GhIPS1-A. Interestingly, it produces an enzyme crucial for creating compounds that protect plants from drought.

“The researchers found that only one copy of this gene, inherited from the cotton plant’s African ancestors, responds to GhHSFA6B-D. This suggests that cotton’s ability to cope with drought has ancient roots predating its domestication,” the press release noted.

Moreover, they found a tiny genetic tweak near the GhIPS1-A gene linked to higher fiber yield in drought conditions. This discovery could be a game-changer for breeding more resilient cotton varieties.

“This single DNA letter change was associated with higher fiber production in drought-stressed plants. Such small genetic differences could be valuable targets for breeders looking to develop more resilient cotton varieties,” said Duke Pauli, co-corresponding author and an Associate Professor at the University of Arizona.

Cotton thrives in warm, sunny climates with specific soil conditions. The primary cotton-growing regions are spread across various parts of the globe – with the United States, India, China, and Egypt being just a few examples.

Currently, most of the traditional cotton-growing regions are impacted by cascading climate change. That’s why, there’s a growing trend towards producing genetically modified (GM) cotton varieties for increased yield and pest resistance.

Among them, BT cotton is the most widely known genetically modified cotton variety. It’s engineered to produce a natural insecticide derived from the Bacillus thuringiensis (Bt) bacteria. This helps protect the crop against bollworms and other pests and reduces the need for chemical pesticides.

However, GM cotton varieties are not widely grown currently due to various reasons including regulatory approvals, and farmer preferences.

To address the growing water scarcity in cotton cultivation, creating drought-resistant varieties is imperative. This research provides a roadmap for developing such cotton strains.

The study has been published in the Plant Biotechnology Journal.