GHOSH, NABARUN*, A. CHATTERJEE, AND DON W. SMITH. Department of Biological Sciences, University of North Texas, Denton, Texas 76203 and CAS, Botany, University of Calcutta, India. - Regeneration of Albizia lebbeck via somatic embryogenesis in suspension culture and study on the karyotype and growth behavior.
Albizia lebbeck Benth. is an economically important woody
legume and can be utilized for biomass production and reforestation
programs. Vegetative methods for mass clonal propagation have not been
available for this tree species. We established callus culture using
leaf explants on modified Murashige and Skoog's medium (1962). The
explants showed various growth behavior in culture with different
combinations and concentrations of growth factors. After several
trials with the addition of 6-BAP, IBA (6/0.25 mg/l) coconut milk
12%(v/v) and casein hydrolysate (70 mg/l) we obtained somatic
embryoids from the cultured tissue. We utilized the original yellow
friable callus to establish suspension culture with Gamborg's B5
liquid medium (without agar). We were also able to induce somatic
embryogenesis in the suspension cultures of this tree species (not
reported previously) using Gamborg's B5 medium that we modified with
kinetin, IBA (4.5/0.05), casein hydrolysate (300 mg/l) and adenine
sulfate(1.5 g/l). We used root tips for karyotypic analysis to confirm
the genetic stability of the regenerants. We followed pre-treatment
with para-dichlorobenzene, fixation with Carnoy’s fluid, staining with
2% aceto-orcein and squashing the root tissue with 45% acetic acid to
study the somatic chromosomes. The regenerated plants maintained the
constant somatic chromosome number for this species which is 2n = 26.
We also studied their growth behavior in the green house by taking
periodical measurements of the developing twigs. The trees exhibited
normal development with a fast growth rate, they reached the apex of
the green house with a height of 20 feet in eight months.
Key words: Albizia lebbeck, growth behavior., karyotype, somatic embryogenesis, suspension culture