In a major scientific breakthrough, a team of academia, government and industry researchers in the US has completed a first draft of the cassava (manihot esculenta) genome. Cassava is a root crop that serves as the primary food source for more than 750 million people in Asia and Africa daily.
“The project is an important first step in accelerating the pace of research on this subsistence crop and addressing some of the limitations that cassava farmers face around the world,” says a press release from Donald Danforth Plant Science Centre, US.
In India, cassava is grown in 24 lakh hectares, mainly in Kerala, Tamil Nadu, Karnataka, Maharashtra and Andhra Pradesh. It is an important substitute for cereals in these States, especially Kerala. It is also a source of alcohol, starch, sago flour, liquid, glucose, vitamin C and is the raw material for many other industrial products and animal feed.
The impetus for the genome sequence began in 2003 with the formation of the Global Cassava Partnership (GCP-21), co-chaired by Claude Fauquet, director of the International Laboratory for Tropical Agriculture Biology (ILTAB) at the Donald Danforth Plant Science Centre (DDPSC) in St Louis, Missouri, US; and Joe Tohme of the International Centre for Tropical Agriculture (CIAT) in Cali, Colombia.
“By 2050, 90% of people will live in developing countries where agriculture is the most important economic activity. Crops grown by small farmers are central to international food security, health, economic growth, energy needs, poverty reduction and social stability,” Fauquet said. “The information contained in the cassava genome will provide tremendous opportunities to improve this important crop, bringing it into the mainstream of plant research, thereby reducing the time and cost of delivering improved cultivars to farmers who need it most,” he added.
“Sequencing of the cassava genome is a major and significant achievement for the research community. The data obtained will accelerate the development of new and more efficient molecular markers to characterise manihot collections and to assist breeding programmes to develop varieties adapted to the needs of the poor in developing countries. It will also strengthen ongoing functional genomics efforts,” said Tohme. Traditional cassava improvement is slow and difficult. The availability of large numbers of markers will help make breeding schemes more efficient. For instance, traits that only show up in mature plants can be identified in seedlings with a cheap DNA test. Since cassava is used for industrial starch production, and has potential as a biofuel source, there are commercial applications of these breeding tools.
However, the most important applications will be to improve lives of those who depend on cassava for their daily calorie intake.
Researchers will use next-generation technologies to sample many varieties of cassava and develop a large database of markers that can be used to identify genes involved in many important traits. The team will collaborate with researchers in Kenya, Uganda and Tanzania in applying these genetic markers towards identifying resistance to cassava brown streak disease.
All the information and tools that the project develops will be available free worldwide.
KA Abraham, head of the crop improvement division, Central Tuber Crop Research Institute, Trivandrum, an ICAR laboratory, told FE that the complete decoding of the cassava genome is an important milestone. “It is an expensive process which no developing country can afford to undertake. Now the cassava genome will be available in the public domain. Scientists doing researches in developing cassava with special traits like disease resistance, higher productivity and enhanced nutrition content now have a readymade short cut, a textbook for guidance and speedy results.”
Abraham said the genome sequence would help find genetic solutions for virus and pests that attack cassava, especially in the Salem belt in Tamil Nadu, where over 800 sago factories produce starch and allied products for the entire country.