Studies on in Vitro Propagation of Aegle Marmelos. Corr.

Abstract

The aun of the present investigation was to standardize in vitro culture techniques for plant regeneration and root induction from the different explants such as, embryo, cotyledon. hypocotyl, leaf and nucellar tissue of the different 5 trees of Aegle marmelos. The morphogenic competence of these explants and trees were not same. Among these explants the morphogenic potentiality of the embryo explant was the highest and the leaf explant was the lowest. The morphogenic competency of Tree 5 was found to be higher than other trees. The embryo explant produced large number of adventitious buds when cultured in MS medium containing 1.0 mgl"1 BA+ 0.5 mgl"1 GA3 without intermediate callus formation. The cytokinins BA, Kn or 2ip alone was less effective. Lower concentrations of auxins or GA3 incombination with cytokinins increased direct shoot proliferation but supported callus growth. Occasional shoot proliferation was observed from root tip and leaf while they were attached with parent shoot. The morphogenic potentiality of the immature embryo was higher than the mature embryo. Higher concentrations of auxins (5.0 mgr1) incombination with lower concentrations of cytokinins (1.0-2.0 mgl"1) suppressed adventitious bud induction butinfluenced callus proliferation from embryo explant. The cotyledon explant induced multiple shoot formation directly or by passing callus stage when incubated in MS medium containing 1.0 mgl"1 BA+ 0.5 mg1"1 GA3• BA, Kn or 2ip with higher concentrations of auxins promoted callusing rather than direct shoot proliferation. Kn 2.0 mgl"1 + 2,4-D ~LO mg1"1 was the optimum growth regulator supplement for callusing from the cotyledon explant. Adventitious shoot regeneration directly or through organogenesis from the callus was obtained from the hypocotyl explant after culturing onto MS medium supplemented with different growth regulations formulations. Among the various growth regulators formulations, 2.0 mg1"1 BA + 0.2 mgl"1 NAA + 1.0 mg1"1 1.0 was found more effective Abstract combination for direct shoot regeneration and 2.0 mgl"1 BA+ 0.5 mgr1 GA3 was found to be the best for shoots induction from hypocotyl callus. Growth regulator combination 2.0 mgr1 Kn+ 5.0 mgr1 2,4-D was proved to be the best for long term maintenance of callus culture. The leaves of in vitro grown shoots showed potentiality to regenerate shoot BA 2.0 mgl"1 + NAA 0.2 rngl"1 and BA 0.2 mgr1 + IAA 0.2 mg1"1 were the optimum growth regulator supplements for direct shoot regeneration. Frequent shoot regeneration was obsetved from primary callus of the leaf explant. The morphogenic potentiality of more recently formed leaves was higher than the older ones. The nucellus of A. marmelos showed potentiality to regenerate shoots. BA 1.0 mgl"1 + NAA 0.1 mgl"1 was the optimum growth regulator supplement for the induction of direct shoot regeneration from the nucellar tissue. On the other hand, the nucellar explant induced to develop callus in 5.0 mgl"1 NAA + 2.0 mg1"1 Kn. Multiple shoot regeneration from the callus was obtained after the subsequent subculture onto 1.0 mgr1 BA+ 0.5 mgl"1 GA3 supplemented medium. The rooting potentiality of the microcuttings varied greatly with their sources of explant and different other factors. IBA 30 mgr1 in MS medium showed more effective media formulation for the maximum frequency of root initiation and root growth. Among the different agar, sucrose, and pH levels in the rooting medium 7.5 gl"1 , 30 gl"1 and 7.0 respectively, the best for root initiation and root length. In general, the rooting potentiality of rnicrocuttings derived juvenile tissues was higher than those derived from nucellar tissues. Rooted microcuttings were successfully acclimatized in non-sterile natural environment.