Efficient regeneration of Renanthera Tom Thumb 'Qilin' from leaf explants

Age, position and orientation of leaf explants of Renanthera Tom Thumb 'Qilin' and plant growth regulators affected the induction of callus and the formation of protocorm-like bodies (PLBs) and shoots. Calli, PLBs were only induced from the young leaf explants (<= 3.5 cm) of flowering plants, particularly leaf tip and leaf base segments and when placed adaxial side up. PLBs formed in 38.33% of cultures after 120 days culture on Vacin and Went (VW) medium supplemented with 1.0 mg l(-1) thidiazuron (TDZ), 1.0 g l(-1) peptone, and 10% coconut water (CW). PLBs were sub-cultured 12 times on VW medium with 0.5 mg l(-1) N-6-benzylaminopurine (BAP), 1.0 g l(-1) peptone, 100 ml l(-1) CW and 0.5 g l(-1) activated charcoal (AC) over a two-year period with a 2.77- to 3.20-fold increase per subculture. VW medium containing 1.0g l(-1) peptone, 1.0 mg l(-1) alpha-naphthaleneacetic acid (NAA) and 1.0 g l(-1) AC was suitable for plantlet formation and 85.33% of plantlets developed from PLBs within 60 days culture. VW medium containing 100 g l(-1) banana homogenate (BH), 1.0 g l(-1) peptone, 1.0 mg l(-1) NAA, 30 g l(-1) sucrose and 1.5 g l(-1) AC was suitable for plantlet growth and 99.67% of acclimatized plantlets survived. About 50,000 plantlets could be produced successfully within three years, showing no phenotypic variation. This protocol is an efficient means for the large-scale propagation of this Renanthera hybrid. (C) 2011 Elsevier B.V. All rights reserved.