| dc.description.abstract | An in vitro system for regeneration of Melia volkensii Gurke shoots is described. M. volkensii, a
drought-tolerant tree native to East Africa, has under-utilized potential as a source of botanical
pesticides. Extracts of its fruits and seeds have larvicidal, growth retarding and anti-feedant
effects on mosquito larvae and locusts. The species has been over-exploited for its timber.
Production of adequate planting material for replenishment of declining stock is constrained by
difficulties in propagation via seed and cuttings. The objective of this study was to develop an in
vitro culture protocol for rapid and efficient shoot regeneration in two ecotypes of M. volkensii.
Mature zygotic embryos were aseptically cultured on Gamborg et al’s B5 medium containing the
plant growth regulator Thidiazuron. High frequency callus induction and regeneration were
achieved. Callus subcultured to hormone-free ½ MS or B5 medium formed multiple somatic
embryos which grew into micro shoots. ½ MS was superior to B5 medium for induction of
somatic embryos. Thidiazuron concentration had no significant effect on callus induction but
significant effects were observed on fresh mass of callus and somatic embryo induction (Ftest, p <
0.001). Microshoots elongated well on B5 medium containing 0.1 mg/l Benzylaminopurine plus
5 or 10% (v/v) coconut water. Frequent multiple shoot induction, with 4 to 12 shoots per initial
shoot, was also observed on the elongation medium. This protocol produced phenotypically
normal shoots of height ≥ 5.0 cm in 3.5 months. Further work is in progress to attain rooting of
the shoots. This study offers a simple protocol that could be optimized for exploitation in large
scale in vitro cloning of M. volkensii mother trees with elite genotypes and phenotypes. | en_US |
