GHOSH, NABARUN1*, A. CHATTERJEE2, and DON W. SMITH3. 1Department of Life Earth and Environmental Sciences, West Texas A & M University, Canyon, Texas 79016-0001 USA; 2CAS, Department of Botany, University of Calcutta, Calcutta-19, India; 3Department of Biological Sciences, University of North Texas, Denton, Texas 7 6203, USA. - Albizia lebbeck Benth.: In Vitro Regeneration via Embryogenesis, Karyotypic Analysis and SEM studies.
Albizia lebbeck Benth. is known as the East Indian Walnut in
Europe. A. lebbeck plantations are found in Hawaii and
different parts of Florida in the United States. It is an erect
deciduous tree of Mimosaceae with umbrella shaped crown and is
preferred as a timber yielding ornamental tree. Large -scale
plantation forestry and afforestation of degraded forestlands are the
solution to ensure future sufficiency in biomass. Tissue culture is a
very useful and reproducible technique for mass clonal propagation. We
used leaf explants on modified MS (Murashige and Skoog 1962) medium to
establish in vitro culture. On MS medium modified with 6, BAP
(0.4 mg/l), Kinetin (0.25 mg/l) and coconut milk 12% (v/v) the leaflet
explants produced callus from the cut end of the explants. We used
0.5% PVP to reduce and dissolve the polyphenol exudation from the
explant. The calli could be classified into 4 major types: friable
white callus, friable white and green mixed callus, compact green
callus and very compact green callus. We found friable white and green
mixed callus as the most suitable one for establishing the suspension
culture in the liquid medium. We tried different concentrations and
combinations of growth regulators ( 6, BAP, Kinetin, 2,4-D, IAA, NAA)
and growth supplements (coconut milk, casein hydrolysate) to induce
morphogenesis in the suspension culture. MS medium with 6, BAP (8
mg/l), IAA (0.25 mg/l) and coconut milk 8% (v/v) produced embryoids.
The embryos followed rhizogenesis and cauliogenesis on agarified
medium. We fixed the tissue in 4% Glutaraldehyde and observe the
regeneration with SEM after Critical Point Drying and gold plating.
Karyotyping was done from well scattered metaphase plate from root tip
squash. A pre exposure of the plantlets to the Knop's medium increased
the survival efficiency. 66% of the transferred plantlets survived in
the greenhouse. The regenerated plants showed normal fast growth and
reach the roof of the greenhouse (20 ft.) within 6 months.
Key words: Albizia lebbeck Benth., Karyotyping, SEM studies, Tissue culture