Influence of gelling agents on culture medium gel strength, water availability, tissue water potential, and maturation response in embryogenic cultures of Pinus strobus L.

Abstract

Maturation of somatic embryos of Pinus strobus L. was evaluated on media containing various types (agars and gellan gum), brands and concentrations of gelling agents in the presence of 80 mM ABA and 0.09 M sucrose. The media were characterized with respect to gel strength, water potential and water availability. Embryogenic tissue and somatic embryos cultured on medium with various concentrations of gellan gum were used to determine their water potential (C). Regardless of the type of gelling agent used, gel strength increased with gelling agent concentration and was critical to the maturation response. High gel strength was associated with reduced water availability from the medium to the cultures. The water potential of gelled maturation medium remained constant between 0.4 and 1.0% gellan gum. It is concluded that the embryogenic tissue was exposed to varying amounts of water at the onset of and during the culture period, and that the amount of water in the culture environment in turn influenced the maturation response. Cotyledonary somatic embryos derived from gellan gum medium of high gel strength had a lower C than somatic embryos matured on medium of lower gel strength. Once somatic embryos developed to the cotyledonary stage on the maturation medium, they were transferred to the germination medium. The germination frequency and the number of morphologically normal germinants were higher for somatic embryos matured on medium of high gel strength. Raising the concentration of the gelling agent in the maturation medium may be an alternative to the use of solutes to restrict water available to the embryogenic cultures.

Somatic embryogenesis and plant regeneration from callus cultures of Cleome rosea Vahl

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Conifer somatic embryogenesis – an efficient plant regeneration system for theoretical studies and mass propagation

“…The adverse effect of PEG has also been demonstrated in Picea abies (Bozkhov and von Arnold 1998). Somatic embryo maturation is also stimulated by high concentration of gellan gum (1%) in the presence of ABA (Klimaszewska et al 2000).…”

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“…Huang et al (2012) highlighted that endogenous auxin stimulate shoot regeneration in rice calli. Abscisic acid (ABA) supplemented medium produces high quality somatic embryos by decreased osmotic water potential compared to the maintenance medium (Klimaszewska et al, 2000;Pérez et al, 2015). Osmotic water potential depends on types of media, carbon sources and gelleting agent concentrations (Hadeler et al, 1995;Klimaszewska et al, 1997;Laine et al, 2000;Triqui et al, 2008).…”