In vitro regeneration of silktree (Albizzia julibrissin) from excised roots

Abstract

Root segments (1 cm long) were excised from 15–20 day old seedlings of silktree (Albizzia julibrissin) grown on B5 medium. About 50% of the control (no growth regulators added) root explants formed shoot buds within 15 days after placement on the culture medium. After 30 days, there were about 4 shoots per control explant. Addition of low levels of various auxins (0.5 μM) did not influence the formation of shoot buds from the explants. Higher concentrations (5μM), however, decreased shoot regeneration. Kinetin and 2iP did not influence shoot regeneration at the concentrations tested (1 & 10 μM). Addition of benzyladenine, Zeatin, or thidiazuron to the culture medium increased both the percentage of explants that formed shoots and the number of shoots per explant. Thidiazuron was highly effective in stimulating shoot formation at low concentrations (<1 μM). At 0.05 μM thidiazuron, 95% of the explants produced shoots and about 10 shoots were formed per explant. Compared to TDZ, higher concentrations (10 μM) of benzyladenine and Zeatin were required to enhance shoot formation. Upon excision and transfer to B5 medium, regenerated shoots developed into normal rooted plantlets.