Effect of types and concentrations of auxins on callus induction and primary somatic embryogenesis in low cyanide cassava cultivars ( Manihot esculentum Cranz)

Abstract

Cassava constitutes a greater part of the diet of most Africans south of the Sahara and the demand for the crops has been on a steady increase. Agriculturally, cassava performs very well, but the roots and leaves contain cyanogenic glycosides that are dangerous to human health. As such, cassava cultivars with low cyanide content offer great opportunities for domestic and industrial utilization. However the major constraints to the production of low cyanide cassava cultivar are susceptibility to diseases such as cassava mosaic virus (CMV) and non-availability of disease free planting materials. Application of biotechnology such as plant tissue culture could have a significant impact in the production large amount disease free planting materials. The effects of 2, 4-D and Picloram on callus induction and primary somatic embryogenesis in the low cyanide cassava varieties was evaluated. The result indicated a significant increase in percentage callus induction with increase in the concentration of 2, 4-D with 4mg/L producing the highest callus induction frequency of 72.21%. Similarly on media supplemented with Picloram, 7mg/L produced the highest callus induction frequency (73.11%) and frequency decreases with corresponding decrease in Picloram concentration. For the formation of somatic embryos, the result indicated a significant increase in number of primary embryos with increase in the concentrations of 2, 4-D or Picloram. This protocol presents a reproducible system for generation totipotent culture that could be used in genetic improvement of cassava and mass production of disease-free planting materials.Keywords: Cassava, Auxin, Callogenesis, Somatic embryogenesis