A method for generating virus-free cassava plants to combat viral disease epidemics in Africa

Abstract

Here, we report a method to clean cassava plants from viral infections that cause cassava mosaic and brown streak diseases in Africa. Infected plants of resistant or tolerant varieties from Malawi, Mozambique, Kenya, Tanzania and Uganda were cleaned in the UK using a combination of tissue culture, chemotherapy and thermotherapy. In the first cycle of our virus-indexing procedure, we successfully cleaned 27 of the 31 varieties (87%), and after an additional three cleaning cycles, all plants were virus-free. Virus-free tissue-cultured plants were shipped back to Africa for distribution to farmers. This first cross-boundary effort provides important lessons for mitigating the two-major cassava viral diseases.

In vitro propagation of three mosaic disease resistant cassava cultivars

“…During the current study, exposing the nodal explants to 20% Jik (3.85% NaOCl) for 15 min gave the highest (90%) clean explants. These results concur with those of Maruthi et al [28] who reported high percent (80-90%) clean explants when a commercial bleach (5% pure sodium hypochlorite) was used on some cassava cultivars. It also corroborates with the results of Waweru et al [29] who reported that the highest proportion (92%) of clean explants was obtained when the Cyphomandra betacea nodal explants were exposed to 15% Jik for 20 min.…”

Nanoparticles as Potential Antivirals in Agriculture

“…In comparison, the advanced methods consist of RNA silencing, cross-protection, transgenic plants, gene pyramiding, and protein-protein interaction [15]. In the latter, the virus can be eliminated in plant tissues (as opposed to simply avoiding or delaying the infection), though this process does interfere with the vectors, use of attenuated strains and resistant or tolerant varieties, and is very expensive [24][25][26]. Chemotherapy consists of the use of antivirals that treat some diseases in animals and is also useful for the treatment of viruses in plant tissue cultures [27].…”

The metabotyping of an East African cassava diversity panel: A core collection for developing biotic stress tolerance in cassava

“…The clean and virus-free plant material used in this study originated from the 5CP project [14]. Plants were grown in a mixture of soil and compost (John Innes No.2; Fargo Ltd., Arundel, UK) in an insect-free quarantine glasshouse at 25 ± 5˚C, 50-60% relative humidity and L14:D10 (light:dark) hours for three months.…”

“…Since the raise and spread of African cassava whitefly superabundant populations, the development of improved cassava varieties possessing virus and whitefly resistance has constituted one of the core milestones of national breeding programs in Sub-Saharan African countries and international consortiums [8,11,12]. Efforts in finding natural sources of African whitefly (Bemisia tabaci) resistance have been focused on collections of local landraces and advanced lines originally developed for virus resistance [13][14][15][16][17] with the intention of pyramiding both disease and vector resistance into farmer-preferred varieties adapted to local agroecosystems.…”

“…In the present article we have used metabolomics as a phenotyping tool (metabotyping), in conjunction with genotyping by sequencing to characterise elite and pre-breeding materials found among cassava varieties presently used in East Africa. These materials are commonly referred to as the "5CP" material due to their assembly in the 5CP project [14]. Despite their importance as core resources for the development of new cassava varieties, very little detail is known on their genetic pedigree or chemical composition.…”