Shoot Induction from Megagametophyte of Cycas circinalis L.

Cycas circinalis is one of the surviving remnants of an ancient line of plants of the early Mesozoic period. None of the in vitro studies has been successful in establishing a functional protocol for artificial propagation of cycads. The objective of the present investigation is to explore the possibilities of in vitro plant regeneration from megagametophyte explants of Cycas circinalis � the only species of Cycas naturally seen in Kerala. The basal medium involved major salts of B5 and minor salts of MS media. Glutamine, casein hydrolysate, coconut water and megagametophyte extract were used as supplements. The plant growth regulators - Kn, BAP, 2iP, IAA, NAA and 2,4-D - were incorporated alone and in combinations. Highest percentage of shoot induction and number of shoot buds per culture were observed in PGR combination involving Kn + BAP along with one of the auxins (2,4-D or NAA or IAA). Shoot buds developed did not show continued growth though the cultures were maintained for more than one year. Somatic embryo induction from megagametophyte explant was obtained on B5 + MS medium supplemented with 1 mg/l BAP + 0.5mg/l NAA and 10 % coconut water. Globular embryos turned hard lignified structures and discontinued further growth. Protocol employed in the present investigation with suitable modifications may lead to multiple shoot proliferation and somatic embryogenesis and help in large-scale propagation of Cycas circinalis.