Search

Cassava (Manihot esculenta Crantz) is a staple food for over 800 million people in the tropics. However, its production is constrained by an inadequate supply of clean planting materials. Tissue culture carried out in laboratories is one established method for the mass production of clean planting materials. However, the cost of conventional tissue culture is high and the cassava industry would benefit from an alternative means of propagation. In the current study, a cost-effective protocol for micropropagation of the farmer-preferred cassava landraces ‘Kibandameno’ and ‘Paja la mzee’ in Tanzania was evaluated. Ammonium fertilizer, potassium fertilizer, epsom salt, monopotassium phosphate and calcinit were used as alternative source to conventional Murashige and Skoog (MS) macronutrients, while Stanes Iodized Microfood® was used as alternative to MS micronutrients. Nodal cuttings of the 2 cultivars were initiated in either conventional MS or cost-effective medium supplemented with 20 g/l table sugar and 3 g/L agar. Conventional MS was used as the control in this study. Four parameters namely plant height, number of leaves, number of nodes and number of roots were recorded from the two media and the differences were determined. For all 4 parameters, both cultivars performed better in the cost-effective medium as compared to conventional MS. More than 75% of plantlets acclimatized to greenhouse conditions from both types of media survived. The cost of production of cassava plantlets in both types of media was then calculated and compared. The use of the cost effective medium led to a cost reduction of 93% over conventional MS medium, which makes it a feasible and attractive alternative for growers. Key words: In vitro culture, cassava, cost-effective medium, Tanzania, tissue culture, Murashige and Skoog (MS) medium.

Manihot carthaginensis subsp. glaziovii (Mull.Arg.) Allem., a wild relative of cassava, native to Brazil, is one of the popular agroforestry trees used for hedges and/or boundary plants surrounding homesteads and farms and also harbours cassava mosaic begomoviruses (CMBs) and cassava brown streak ipomoviruses. Sequences of the DNA-A component of East African cassava mosaic virus (EACMV) isolates from M. carthaginensis subsp. glaziovii (Mull.Arg.) Allem., collected from non-cassava growing areas of Tanzania were characterized. Thirteen full length DNA-A sequences were analysed together with 15 already reported EACMV sequences and six CMB species reference genomes. The results show 96 to 100% nucleotide sequence identity with EACMV isolates from Kenya. Phylogenetic analysis revealed that EACMV isolates from M. carthaginensis subsp. glaziovii (Mull.Arg.) Allem, belong to a single cassava mosaic begomovirus species. The EACMV monophyletic clade is distinct from all other CMB species. The presence of Cassava infecting begomoviruses in wild cassava relative growing from traditionally non cassava growing region serve as inoculum sources for cassava-infecting begomoviruses and therefore their eradication is key in the sustainable management of CMBs, especially in the non-cassava growing areas. Key words: Cassava mosaic disease, East African cassava mosaic virus, Manihot carthaginensis subsp. glaziovii (Mull.Arg.) Allem., genetic diversity.