Do You Know Where Cotton Was First Domesticated And Cultivated

About 200000 years ago, a cotton seed originating from the west coast of Central America drifted westward, took root, germinated and multiplied after landing on Hainan Island, China.

It was not until 2000 to 3000 years ago that the ancestors of Hainan Island discovered its offspring and began domestication and cultivation of tetraploid cotton.

Zhejiang University team in the Journal of Advanced Research (Advanced Research Journal) published a research paper in which the evolution history of allotetraploid cotton over hundreds of thousands of years was restored.

The research team analyzed the upland cotton Hainan native cotton - semi wild cotton variety Pengpeng (G Purpurascens) found that China was one of the first countries to domesticate and cultivate tetraploid cotton.

In 2019, a cotton plant was collected in the field of Yacheng, Hainan, and is planned to be used for parent cross breeding experiment. When other cotton plants are blooming, this plant has not moved yet.

"Why don't they bloom?" Faced with this slightly burly cotton, it 'exposed' that it was really wild cotton. Many wild cotton plants have photoperiod sensitive genes, and the flowering period is constrained by the light time, so they will not blossom once they arrive in the north.

This trait will affect the yield and quality of cotton. Therefore, the current large-scale cultivation of cotton in the world is an artificially bred variety that has eliminated this genetic feature, which is more suitable for large-scale industrial planting and picking.

Wild varieties are inexhaustible treasures. On the one hand, they can help people further understand the history of crop reproduction and domestication on the earth; On the other hand, with the continuous development of breeding technology, various genetic information retained by wild crops will be further explored.

To this end, the cotton research team named this cotton sample HPF17 and sequenced its entire genome.

Based on the existing genome re sequencing data of upland cotton and 11 backbone parent genomes of upland cotton, the study found that the native wild cotton (Hainan Island) represented by HPF17 Cotton, HIC) belongs to the more primitive wild species of Pengpeng cotton in upland cotton.

Allotetraploid upland cotton is native to Central America. Its perennial wild species were domesticated into cultivated upland cotton or American cotton through artificial selection in the southern United States. It was introduced and spread to the world for extensive cultivation after the middle of the 18th century. The early cotton varieties cultivated in China were diploid cotton varieties originated in South Asia, and the tetraploid cotton varieties cultivated on a large scale after 1949 were also brought about by the global spread of American cotton.

However, it is puzzling that, thousands of years ago, the ancestors of Li nationality in Hainan Province of China had mastered the technology of spinning with cotton fiber, using a unique kind of local cotton. When did these local Pengpeng cotton come to China, and its progressive position in the evolution of upland cotton, has not been confirmed by scientific research.

The whole genome sequencing confirmed the ancient "identity" of HIC, which is the "lineal" offspring of allotetraploid upland cotton originated in Central America 200000 years ago. Research shows that it separated from allotetraploid upland cotton which originated in Central America as early as 200000 years ago.

How did it get to Hainan, China?

With the Pacific Ocean current, it gradually moves westward from the west coast of Central America to the islands in the South China Sea (Hainan Island).

Two evidences: First, the distribution of ocean currents. The seeds of Hainan native cotton are small and hard, and the cottonseed with fluff can float in the water for more than half a year. At present, the distribution of the representative wild cotton Pengpeng known on the Pacific islands is highly consistent with the Pacific Ocean currents; Second, it has strong salt resistance and can survive in salt water for more than half a year.

After landing on Hainan Island, is Pengpeng cotton "wild", or does it intersect with human production and life?

What solved the mystery was the hand ginning machine, a machine for removing seeds from cotton. It is very laborious to peel the fiber from the seed with bare hands, which is the first problem encountered in developing the cotton spinning technology of the ancestors.

After studying the fiber degree of different cottonseed, it is further confirmed that only the cotton fiber of puffy cotton needs to be used in the cotton gin. Kapok fiber is very short, so it is impossible to obtain fibers for textile; Island cotton and kapok can easily lose their seeds. From a certain point of view, it is the seed characteristics of Pengpeng cotton that gave birth to the cotton gin.

Around 2000~3000 years ago, Pengpeng cotton was initially domesticated and small-scale cultivated in Hainan Island, and used to spin "Yazhou cloth". This time point was as early as before the Columbus period and the domestication and cultivation of American cotton. Sanya (Yazhou) may be one of the places where upland cotton was first domesticated and cultivated, that is, China is one of the countries where tetraploid cotton was first domesticated and cultivated.