Sodom and tomorrow
China was the first country in the world to domesticate mulberry trees for silk production, so it comes as no surprise that the Chinese recently discovered, and are now commercializing, another vegetable fibre. This one is known as Calos. As smooth as silk, as comfortable as cotton and warm as wool, the fibre comes from the seeds of Calotropis gigantea, or the Sodom Apple, a species found in arid regions stretching from China to Africa.
The Sahel also has its own species, C. procera, and in drought-prone regions it is often one of the few plants you will see. A team of scientists led by Jianchu Xu, who manages the World Agroforestry Centre’s office in China, is currently exploring the fibre potential of this species, which has larger fruits than C. gigantea and longer fibres. “We believe that through the domestication and breeding of C. procera, new desert oases and a brand-new ‘silk road’ will be created,” says Xu.
In the past year, a World Agroforestry Centre project team has been overseeing the harvest in Mali, Niger, Benin and Kenya. Local governments and community organizations have worked with the project to organize the community for fruit collection. The community has received training in harvesting techniques from domestication teams in Kenya and Mali. The project has been welcomed by local villagers as they can now earn money from a resource that previously had no use. Once harvested, the fibre is taken for processing research by a Chinese textile company. An important component of the project has involved the genetic analysis of the Calotropis. This was led by Nkatha Murira, a Chinese Academy of Sciences fellow supervised by Aizhong Liu of the Kunming Institute of Botany and Alice Muchugi of the World Agroforestry Centre. Using high-throughput transcriptome and gene functional analysis, they have made great progress identifying the molecular markers related to the species’ drought resistance and high-quality fibre biosynthesis. “This research lays the foundation for selecting superior varieties and genetic improvement,” says Muchugi.
Reference
- Muriira NG, Xu W, Muchugi A, Xu J, Liu A. 2015. De novo sequencing and assembly analysis of transcriptome in the Sodom apple (Calotropis gigantea). BMC Genomics 16(1): 723
