Somatic embryogenesis from nucellar callus of cashew.

摘要

Calluses were initiated from bisected ovules with intact nucelli from 3 week-old immature cashew nuts (Anacardium occidentale L. cvs. 'NRCC Sel-2', 'Ullal-1', 'Ullal-3', 'Goa 11/6', 'Vengurla-8' and 'Kanaka') cultured on half-strength Murashige and Skoog (1962) medium (MS) containing 2,4-dichlorophenoxy-acetic acid (2,4-D; at 1.0 or 4.0 micro M) alone, or a combination of 2,4-D (0.5, 1.0 or 4.0 micro M) with 12 micro M kinetin or 10 micro M spermine. Calluses, which became brown after 4-6 weeks, differentiated into somatic embryos on Raj Bhansali medium (RBM) containing 2,4-D (0.01 or 0.5 micro M) and 30 micro M kinetin or 10 micro M spermine. Somatic embryos were initiated in 2.2-27.7% of cultures of cultivars 'Goa 11/6', 'Kanaka' and 'Ullal-3' only. The number of somatic embryos increased more than 5-fold following suspension culture in RBM basal medium. Histological studies on nucellar calluses revealed differentiation of all the developmental stages of somatic embryogenesis: a pro-embryonic mass, and globular and heart-shaped embryos. Somatic embryos matured on half-strength MS medium containing 18.9 micro M abscisic acid, and 60% germinated on liquid medium containing 0.53 micro M alpha -naphthalene acetic acid (NAA) and 4.4 micro M 6-benzylamino purine (BAP) giving plantlets with a well-developed tap-root and a shoot with rudimentary green leaves.