Shoot Induction, Biochemical Changes During in vitro Rooting in Paeonia lactiflora Pall 'Hortensis'

Abstract

Background: Peony is an ornamental as well as medicinal plant which is difficult to propagate in vitro . Its major problem during in vitro culture is leaching out of phenols in the medium. It causes hindrance in growth and development. Rooting is a complex process and main step for vegetative propagation. The main objective is to propagate this plant and produce multiple copies and understand rooting phenomenon which is usually complicated. Methods: The underground rhizomatous buds of Paeonia lactiflora Pall. ‘Hortensis’ were selected as the explants. In vitro micropropagation was carried out along with biochemical studies during rooting process. Results: Shoot induction, axillary shoot proliferation and rooting were established. The best initial medium for ‘hortensis’ was the half-strength Murashige and Skoog (MS) medium (double-strength Ca ) supplemented with 1 mg L N +2 1 6 benzyl-adenine (BA) and 0.5 mg L Gibberellic Acid (GA ). Shoot induction was 100% with 6.2 shoots per explant. 1 3 Rooting was also observed on the half-strength MS medium supplemented with 1.0 mg L Indole-3-butyric Acid 1 (IBA) and indole-3-acetic acid (IAA). The highest percentage of rooting (15%) was observed when in vitro shoots were dipped in the full-strength liquid MS medium supplemented with 10.0 mg L IBA without agar for five days and then 1 transferred to the quarter strength MS medium without any Plant Growth Regulator (PGR). Conclusion: The cultivar P. lactiflora hortensis is hard to root in vitro. The activities of peroxidase, indole acetic oxidase, polyphenolic oxidase and phenolic content have been estimated prior to and after rooting. These enzyme activities and phenolics have been reported to play a major role in rooting.