Abstract:
Mass propagation via tissue culture technology could rescue threatened indigenous medicinal, pesticidal and
timber plants. However, its application remains underutilized locally due to high costs of tissue culture
consumables. Local efforts towards reduction of costs have centered on use of cheaper carbon sources such as
table sugar, substitution of Murashige and Skoog and Gamborg’s salts with mixtures of fertilizers and
substitution of conventional gelling agents agar, gelrite and phytogel with cassava starch. However, a gap
exists on the identification of cheaper substitutes of conventional plant growth promoters yet these,
particularly cytokinins, are important cost drivers in tissue culture. Half a gram of plant-cell-culture-tested
Thidiazuron (TDZ) from Sigma-Aldrich costs 2,145 Euros (Ksh 235,500) while 1 g of Zeatin costs 4,220 Euros
(Ksh 463,514). This study sought to determine whether a low-cost agrochemical TDZ that costed only 0.229
USD (Ksh 19.84) per gram and was recently reported by the present authors to support high frequency
regeneration in mature zygotic embryos of M. volkensii, could elicit similar response in other explants.
Cotyledons of mature seeds from wild trees in Kitui were cultured in ½ MS medium containing eight TDZ
concentrations from 0 to 4 mg/l. High frequency (80 to 100 %) direct regeneration of shoots was observed
within 14 days. TDZ treatments had a significant effect (Ftestp < 0.001) on the regeneration response in relation
to the non-morphogenic controls. Shoots were elongated on ½ MS + 0.1 mg/l 6-Benzylaminopurine in
combination with either 0.01 mg/l 1AA or 10% coconut water and rooted in ½ MS + 0.1 mg/l Indole-3-butyric
acid. Low-cost agrochemical TDZ could substitute the exorbitant plant-cell-culture-tested Thidiazuron in tissue
culture of M. volkensii. We recommend testing of this agrochemical on more explants and species.
