Scientists unravel domestication history of world's most profitable cotton species

In a significant breakthrough for understanding agricultural history, scientists have unraveled the domestication origins of upland cotton, the world's most dominant nonfood crop. Through meticulous genomic sleuthing, researchers have pinpointed the northwestern part of Mexico's Yucatan peninsula as the cradle of this vital species, Gossypium hirsutum. This ancient domestication event, occurring at least 4,000 and potentially up to 7,000 years ago, predates even the flourishing of the Maya civilization, placing its roots firmly in the era of Stone Age farmers.

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Wild cotton plants are woody, multibranched shrubs or small trees, long-lived, with relatively sparse flowering and smaller flowers, fruits and seeds than under cultivation.

The study, published in the journal Proceedings of the National Academy of Sciences, utilized a comparative genomic approach. By analyzing the genomes of domesticated upland cotton and comparing them with wild cotton species found in the Yucatan, Florida, and Caribbean islands, scientists were able to trace its lineage. The findings strongly suggest that the domesticated variety most closely resembles the wild cotton species native to the Yucatan. This research provides a crucial understanding of how early farmers recognized the potential of wild cotton plants, which were once woody shrubs with sparse flowering, and initiated a gradual process of improvement over millennia.

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Members of some human groups must have taken an interest in the wild forms, setting in motion the process of domestication from which the modern crop form arose over thousands of years of slow and gradual improvement.

As Iowa State University botanist and evolutionary biologist Jonathan Wendel, a co-senior author, explained, early farmers likely saw the potential in the plant's hairy seeds as a source for soft materials. This led to the slow and gradual improvement that transformed the plant into the crop we know today. Similarly, Iowa State University geneticist Corrinne Grover, another co-senior author, highlighted how early weavers could spin the fiber by hand for various uses, including cloth, fishnets, and ropes. The domestication process, involving the selection of desirable traits, ultimately led to the fine, white textile fibers that are a cornerstone of the global textile industry.

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Early farmers saw potential in this sprawling plant with hairy seeds as a source for soft materials. Early weavers could spin fiber by hand and use it for weaving cloth, fish nets, ropes and other goods.

Following the Spanish conquests in the 16th century, upland cotton was introduced to the rest of the world, eventually leading to major production hubs in China, India, the United States, and Brazil. The research also sheds light on the genetic consequences of domestication, noting that the domesticated cotton plant exhibits less genetic diversity compared to its wild counterparts. This reduction in diversity can impact a species' ability to adapt to environmental changes, such as disease exposure. The study underscores the complex genetic symphony that transformed coarse, brownish fibers into the superior textile material we rely on today.

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Research is showing that the process of domestication, of transforming these short, coarse and brownish fibers into the fine, white and superior textile we know today likely involves many genes operating in a complex symphony.