TDZ-mediated differentiation in commercially valuable Indian mulberry, Morus indica cultivars K2 and DD

Abstract

The effect of various growth regulators, especially of Thidiazuron (TDZ), on seed germination and subsequent differentiation capabilities of hypocotyl, cotyledon, leaf, internode, root and petiole explants was studied in the Indian mulberry, Morus indica cultivars K2 and DD. Of the various hormones tried, thidiazuron at a concentration of 5μM, gave the highest percentage of adventitious bud formation in both the hypocotyl and cotyledon explants obtained from the seedlings germinated on 0.5μM TDZ. The young tissue was more responsive and showed up to 50% regeneration from hypocotyl and 70% from cotyledon explants in M. indica cv. K2 when cultured for 10 days on TDZ containing medium. The leaf explants produced adventitious buds after 30 days of culture on 2.5μM TDZ. The 7-day old leaf explants taken from in vitro cultured axillary buds were more efficient in terms of regeneration percentage than the leaf explants derived from the seedlings or from the plants growing in the experimental field. The regenerated shoots were sub-cultured on to Shoot Elongation Medium (SEM: MS+0.5mgl⁻¹ BAP+0.5mgl⁻¹ GA₃+2mgl⁻¹ AgNO₃) for further growth. Healthy and vigorously growing roots were readily obtained on 1mgl⁻¹ NAA+0.1% activated charcoal (RIM: Root Induction Medium) within three weeks of culture at a rooting percentage of 70-76%. Successfully acclimatized plantlets (95-100%), transferred to the experimental plots, are now well established in the field.