Researchers, of which most are women, from the Swiss Federal Institute of Technology in Zürich (ETH Zurich), have successfully mapped the genome of African cassava. This breakthrough is a significant milestone and will advance the breeding of new cassava varieties at speed with greater accuracy.
According to Prof Wilhelm Gruissem of the Department of Biology, Institute of Molecular Plant Biology at the Institute and the principal scientist of the research team, the genome has a very high quality and accuracy. The findings had been published in the prestigious Oxford Academics journal GIGA Science Press and will in future serve as the gold standard genome for African cassava and in future will bring massive benefits to breeders and growers.
A vital African food source
Cassava is a vital staple root crop, and almost a billion people worldwide depend on it for food and raw materials. In Africa, the crop is a major source of livelihoods for smallholder farmers and for food security owing to its ability to withstand a wide array of environmental conditions. More than half a billion people in developing countries are dependent on it as a vital food source. Cassava farming is hampered by weeds, pests and viral diseases, breeders are concentrating on developing improved varieties.
A genome is the complete set of genes or genetic material present in any organism, including all hereditary instructions for creating and maintaining life and enabling reproduction. With the population explosion and food scarcity issues on the African continent, this scientific work will ensure shorter crop growth times.
To date, cassava breeders have relied on phenotypic features of mature plants, typical for clonally propagated crops. This is a major drawback as it takes up to six years to produce enough planting material for multi-location trials. The heterozygous nature of the crop and parental lines used to generate new segregating progenies make it difficult to identify parents with good breeding values.
New technologies such as genomic selection (GS) and use of inbred progenitors based on doubled haploids are now being used to accelerate genetic gains in cassava. Despite continuous sequencing efforts using different technologies over the past decade, unresolved gaps and haplotypes persist in all chromosomes of currently available cassava genomes.
This new study has changed the playing field as it generated phased and annotated chromosome pairs allowing a systematic view of the heterozygous diploid genome organisation in cassava with improved accuracy, completeness, and haplotype resolution.
The study may also provide insights into developing cost-effective and efficient strategies for resolving complex genomes with high resolution, accuracy and continuity.