Putrescine and polyamine inhibitors in culture medium alter in vitro rooting response of Decalepis hamiltonii Wight & Arn.

Abstract

The influence of polyamine putrescine (PUT), and polyamine inhibitors were tested for in vitro rooting response from micro shoots that initially established on Murashige and Skoog (MS) medium comprising 2.7 µM α-Naphthaleneacetic acid (NAA) and 8.9 µM 6-Benzylaminopurine (BA) by using nodal explants of Decalepis hamiltonii. Incorporation of putrescine alone in rooting medium devoid of auxins supported the best response for in vitro rooting qualitatively and quantitatively. Incorporation of putrescine at 50 µM able to induce 8.62 ± 1.93 roots with a maximum root length of 9.10 ± 1.65 cm wherein, the root fresh weight was also found to be high compared to all other treatments (5.248 ± 1.71 g). Addition of putrescine inhibitor cyclohexylamine (CHA) in medium curtailed rooting response from microshoots. Among the three polyamine inhibitors, CHA in presence of 9.8 µM Indole-3-butyric acid (IBA) outperformed α-DL-difluromethylarginine (DFMA) and α-DL-difluoromethylornithine (DFMO) combination with 9.8 µM IBA. The least response for root number (1.55 ± 0.72), root length (1.96 ± 0.45 cm), and root weight (1.94 ± 0.35 g) was found for IBA + PUT + DFMA and the best response was noted for IBA + PUT + CHA (2.6 ± 1.1, 2.92 ± 0.73 cm, 3.03 ± 0.75 g) respectively. Endogenous content of putrescine, spermidine and spermine supported the rooting response from in vitro shoots. These results have clearly demonstrated that putrescine plays a crucial role in rooting of D. hamiltonii. Plantlets were transferred to micro-pots for a short acclimatization stage in greenhouse where they survived at 90 %. This highly reproducible procedure can be adopted for large scale swallow root propagation. Overall, supplementing putrescine in the rooting medium enhances the quantity and quality of roots in D. hamiltonii, thus confirming its role.