An Improved Micropropagation Protocol for Bael-A Vulnerable Medicinal Tree

Abstract

An efficient and rapid in vitro clonal propagation of the endangered medicinal tree Aegle marmelos (L.) Corr. (Rutaceae) by enhanced axillary shoot proliferation from mature single node was designed. The explants showed marked seasonal variation in their response under in vitro conditions. Explants collected in October (72.8%) and November (78.6%) showed maximum response. Multiple shoots were formed on Murashige and Skoog (MS) medium supplemented with 0.5 mg L-1 6-Benzyladenine (BA). An average of 6.2 shoots/explant could be obtained after 45 days of culture. The number of shoots was increased at the third subculture with an average of 16.3 shoots per explant. The effect of subsequent subcultures (upto 20 cycles) on shoot formation was also studied. Subculturing was carried out every 45 days on fresh shoot multiplication medium. Continuous culture in the same medium resulted in distorted and vitrified shoots. Transfer of cultures to half strength MS medium devoid of ammonium ions and cytokinin (BA) for a single cycle before going to the shoot multiplication medium could solve this problem. In vitro rooting was inconsistent in medium with different auxins (Indole 3-butyric acid-IBA, Indole 3-acetic acid-IAA and α-naphthalene acetic acid-NAA) at varying concentration and combinations. But in vitro raised shoots could be rooted ex vitro by pulse treatment with naphthoxy acetic acid (NOA) and IBA and then in chlorogenic acid followed by planting in moist sand. This treatment resulted in 83.9% survival of plantlets. The method standardised could be used for large scale planting material production and conservation of this important endangered medicinal tree.