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[NAIROBI] Researchers have generated cassavagenomesequence that will enable better understanding of the genetic basis of traits such asdiseaseresistance, food quality and time to maturity.
According to the researchers, cassava boosts food security andnutritionfor more than half a billion people worldwide.
“The study has generated quality cassava genome sequence. It includes 97 per cent of the estimated genes.”
Morag Ferguson, International Institute of Tropical Agriculture (IITA), Kenya
Thestudywhich started in 2012 and its findings was published in the journalNature Biotechnologylast month (18 April) was aimed at increasing the genomic resources for cassava, says Morag Ferguson, a co-author of the study and a molecular geneticist at the International Institute of Tropical Agriculture (IITA), Kenya.
“The study has generated quality cassava genome sequence. It includes 97 per cent of the estimated genes,” Ferguson tellsSciDev.Net. “The large amount of DNA [genetic material] sequence information provides insights into the origin of cassava and resources for the improvement of cassava”.
Ferguson adds that the genome relates to African cassava varieties, particularly those with resistance to cassava brown streak disease (CBSD), a devastating viral disease affecting cassava in southern, eastern and central Africa.
The researchers identified the order of the genetic letters of 53 cultivated and wild cassava plant materials (Manihot esculenta) from Africa, Asia, South America and Oceania — a process called genome sequencing. They also sequenced five cassava-related plants such asM. glazioviiand identified the genetic components of 268 African cassava varieties.
Sequence information, according to Ferguson, revealed that some CBSD-resistant cassava varieties in Tanzania includingNamikongaandMuzege, contain sections of genomes ofM. glaziovii.
Ferguson adds: “Cassava is the mainfood securitycrop of the continent [Africa], providing a [high] yield in poor soils with minimal water, when other crops such as maize will fail.”
The study was conducted by researchers from countries such as Fiji, Kenya, Micronesia, Nigeria, Tanzania and United States.
Paul Kimani, a plant breeder from Kenya’s University of Nairobi says the main contribution of the findings is new information on cassava genome and a clear demonstration of the genetic relationships among the various species, including cultivated cassava, its wild relatives and others in the secondary or even tertiary gene pool.
“What it does not do is link the genes with any economically important traits such as disease resistance, nutritional quality or agronomic traits,” he says.
“The key issue is whether the wild cassava has genes for economically important traits such as resistance to CMD and CBSD, productivity and processing, which can be transferred to commercial varieties,” Kimani tellsSciDev.Net.
This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.
References
Jessen V. Bredeson and othersSequencing wild and cultivated cassava and related species reveals extensive interspecific hybridization and genetic diversity(Nature Biotechnolgy, 18 April 2016)