MSc

A study was taken up in the Department of plantation Crops and Spices, College of Horticulture, Vellanikkara, During 1991-93, to standardize the in vitro technique for multiplying Gymnema sylvestre R. Br. Which is locally known as ‘Gurmar’. This being the first attempt of micropropagation in this crop , the methodology was to be standardized, from the initial stage itself . Nodal segments, leaf segments as well as stem segments collected from mature vines maintained in the college of horticulture were used as explants in the present study.
Different routes like enhance release of axillary buds, organogenesis and embryogenesis were attempted for the plant. The main limitation in establishing in vitro cultures of Gymnema sylvestre was identified to be microbial interference, which was mainly due to the fungus collectotrichum sp. Great seasonal variation was observed for the fungal interference and the period from January to April was identified as the best season for establishing the cultures of Gymnema sylvestre was identified to be microbial interference, which was mainely due to the fungus Collectotrichum sp. Great seasonal variation was observed for the fungal interference and the period from January to April was identified as the best season for establishing the cultures of Gymnema sylvestre. Mercuric chloride at 0.1 per cent level was identified as the best surface sterilant , with the survival rate being 82 to 94 percent according to the explant material used. Basal medium MS supported the cultures of leaf segments while the inorganic salts were to be reduced to half level for supporting the cultures of stem segments. Out of the various growth regulator combinations tried for bud break and healthy shoot elongation in Gymnema, kinetin and IAA could support bud break and healthy shoot production . Coconut water and adenine sulphate when supplemented in the medium favoured healthy shoot induction . Survival rate of newly formed shoots were very poor due to leaf abscission. Higher levels of MgSo4 in the medium helped leaf retention to the extent of 10 per cent . None of the treatments tried could induce roots in the in vitro shoots.
Profuse callusing could be induced from leaf and stem segments in MS basal medium supplemented with growth regulators BA+2,4-D, with a callus index ranging from 280 to 360. The calli did not respond to organogenesis. Callus mass consisted of uniform cells without any vascular differentiation . The morphology and growth rate varied according to the growth regulator combinations tried. Stray instances of embryogenesis (6 to 20%) were observed when cultured in growth regulator combinations of BA+NAA, BA+IAA and Kin+2, 4-D. The embryoids developed up to torpedo stage and failed to grow further. They exhibited a strong callusing tendancy and got reverted to the callus stage within 5 days.
The results of the study would be a pioneering report that unravels the in vitro response of ‘Gurmar’ for micro propagation. Since the plant exhibited a relatively recalcitrant nature at various stages of in vitro culture , much more concerted efforts are to be made for standardizing the protocol for micropropagation of Gymnema sylve estre.