The plant activator BTH promotes Ornithogalum dubium and O. thyrsoides differentiation and regeneration in vitro

Abstract

Benzothiadiazole (BTH) is a structural analogue of salicylic acid (SA) which is widely recognized for its role in elicitation of systemic acquired resistance in a broad range of plant species. Here, BTH was applied to cell cultures of the bulbous ornamental plants Ornithogalum dubium and O. thyrsoides, showing a strong effect on rates of differentiation and morphogenesis. Morphogenic cell clusters in liquid Murashige and Skoog (MS) medium containing 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) were used for all treatments. The calluses were washed thoroughly and activated with increasing concentrations of BTH. Following the induction, calli were grown on a solid MS medium without growth regulators (MS) or on a comparable media with NAA and BAP (M-206). The calli treated with BTH displayed a dose dependent increase in formation of meristematic centres followed by enhanced shoot formation compared to controls. Microscopic analyses revealed increased differentiation to cell organelles and a strengthening of the cell wall. A stronger response to BTH was observed in MS than in M-206 medium. A similar effect on calli differentiation was obtained by three weeks darkness followed by light exposure. The dark/light positive effect on differentiation was further augmented by BTH in a synergistic fashion. It is suggested that BTH enhances the rates of morphogenesis in Ornithogalum cultures by triggering a plant regulator-like activity.

Keywords

• benzothiadiazole
• 6-benzylaminopurine
• micropropagation
• morphogenesis
• 1-naphthaleneacetic acid