Nairobi, Kenya: 5th July, 2021– In a bid to improve cassava varieties in Kenya, researchers at the Kenya Agricultural and Livestock Research Organization (KALRO) working in partnership with others from Nigeria, Uganda, Rwanda and the United States have developed disease resistant cassava varieties.
Speaking during an Africa Science Media Centre (AfriSMC) press briefing on the new cassava variety, Dr. Catherine Taracha, Director KALRO Biotechnology Centre, said the Cassava Mosaic disease (CMD) and Cassava Brown Streak disease (CBSD) are the most important viral cassava diseases that may cause up to 100 percent loss in cassava production in Kenya.
CBSD in cassava is characterized by brown streaks or rot and malformed roots whereas CMD is characterized by yellow mosaic on affected areas coupled with distortion of leaves and stunting. These diseases transmitted by white flies and sharing of cuttings by farmers have posed a great challenge to cassava farmers and breeders in Africa.
The new cassava varieties include an improved variety that is resistant to CBSD and another one that is resistant to both CMD and CBSD. “Apart from the disease resistance, the improved varieties are not different from the conventional variety”, she said.
Dr. Taracha observed that evidence from planting the CBSD resistant variety event 4046 in Uganda and Kenya demonstrated that there was sustained resistance across multiple generations and different locations.
In addition, she said that the evaluation of the variety was based on International Food, Feed and Environmental Safety guidelines.
“There were three things we looked at. Cassava plant characteristic remained the same. The nutrition composition was not altered and no negative effect on the environment was observed during the trials,” Dr. Taracha explained.
The technology used to produce virus resistant crops such as papaya, plum, beans and squash which have been approved for commercialization in other parts of the world, was the same used to develop the CBSD resistant variety.
“A part of the DNA of the virus is integrated into plant genome. The plant defenses are activated to recognize, target and degrade the virus pathogen,” she explained.
However, conventional crossbreeding was done to develop the dual disease resistant variety which is resistant to both CMD and CBSD.
“We took our improved cassava with resistant cassava brown streak disease and crossed it with farmer-preferred variety that had latent cassava mosaic disease resistance. This was done several times and the seed germinated into seedlings which were taken through various evaluation to ensure both disease resistant were in the plant,” she explained.
Dr. Taracha noted that evaluations were carried out on the progenies in Kenya and Uganda for trait selection. Some of the things considered include: harvest index, marketable roots, non-marketable roots and biomass.
The Kenya National Biosafety Authority approved the variety for environmental release. This means it will now be put under the national performance trials (NPTs). The NPTs involve testing the Distinctness, Uniformity and Stability (DUS) of the new cassava variety. This will be done for a period of two seasons or two years since each season will take between 9-12 months.
Some of the areas that KALRO has mapped for the NPTs include Alupe, Kakamega, Kibos, Homabay and Oyani in the western part of the country while in the coastal region which also grows a significant amount of cassava, Mpeketoni, Mtwapa, Matuga, Kikoneni and Msabaha have also been listed. However, only three locations will be selected from per region.
After the NPTs have been carried out within the two years (two seasons), the report will be sent to the National Variety Release Committee (NVRC) of the ministry of Agriculture. The Committee, which will determine whether or not the variety should be commercialized, is comprised of the Kenya Plant Health Inspectorate Services (KEPHIS) and cassava breeders, among other value chain players.
Dr. Taracha said that if approved, the new cassava variety, will be distributed to smallholder farmers by KALRO free of charge because there will be no technology fee applied to it since the variety will be wholly owned KALRO.
“Those who sell cutting as a business, will sell but from KALRO (seed units) it will be absolutely free because there is no intellectual property issue involved,” she reiterated.
With the average production annually of cassava in Kenya resting at 970,000 tonnes, she notes that cassava has a lot of potential making the new varieties very marketable not just because of food security but also for production of other items such as making biodegradable bags, sanitizers, animal feeds, industrial starch among others.
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