An efficient regeneration system via somatic embryogenesis in olive

Abstract

Olive is one of the most important oil crops in the Mediterranean area. Biotechnological improvement of this species is hampered by the recalcitrant nature of olive tissue regeneration in vitro. In this investigation, we have developed an efficient regeneration system for juvenile olive explants via somatic embryogenesis. Embryogenic cultures were obtained at a rate of 25% by culturing isolated radicles from mature seeds in a modified olive medium (OMc) containing 2.5 lM 6-(dimethylallylamino) purine (2iP) and 25 lM indole-3-butyric acid (IBA) over 3 weeks and later transferring to the same medium without 2iP and with a lower IBA concentration. Two different basal formulations, OMc and olive cyclic embryogenesis medium (ECO) [1/4 OM macroelements, 1/4 Murashige and Skoog (MS) microelements and 1/2 OM vitamins supplemented with 550 mg l -1 glutamine], were tested for embryogenic callus proliferation and maturation. The growth rate of embryogenic calli was similar in both media. However, the regeneration of mature embryos, achieved by culturing embryogenic masses in the same medium without hormones and supplemented with 1 g l -1 activated charcoal, was significantly higher when embryos were cultured in the ECO basal formulation. Pre-culturing embryogenic masses in liquid medium for up to 4 weeks did not affect subsequent callus proliferation in solid medium. The maturation rate of small globular somatic embryos, 1-3 mm size, obtained after filtering liquid cultures through a 3 9 3 mm mesh, was also similar to control embryos cultured in solid medium. To improve the maturation and germination rates, the effect of culturing globular somatic embryos on semi-permeable cellulose acetate membranes was also tested. Membrane treatments reduced the regeneration of mature embryos from 56.5% in the control treatment to 40.6% when the membrane was applied during the first half of the 8-week maturation phase and to 18% when the membrane was applied during last 4 weeks of the maturation period. However, membrane treatments significantly enhanced the conversion of mature embryos to plants, increasing the embryo conversion rate from 1.5% in the control to an average value of 37.8% in the membrane treatment. Cotyledonary embryos that were matured on the membranes showed lower values of water and solute potential than controls, indicating that this treatment exerted a controlled desiccation rate that enhanced the recovery of plants. Keywords In vitro plant regeneration Á Olea europaea Á Suspension culture Á Semi-permeable membrane Á Somatic embryo Á Water potential Abbreviations 2iP 6-(Dimethylallylamino) purine BA 6-Benzyladenine DKW Driver and Kuniyuki medium ECO Olive cyclic embryogenesis medium IBA Indole-3-butyric acid MS Murashige and Skoog OMc Modified olive medium SE Somatic embryo

The prospect of micropropagating Gonystylus bancanus (Miq.) Kurz, a tropical peat swamp forest timber species through tissue culture technique - Review

“…In another study on Quercus rubra Linnaeus (red oak), Sán-chez et al (2003) reported that sucrose was used as a carbon and energy source, as it enhances somatic embryo maturation by causing osmotic stress when supplied at higher concentrations. Accumulation of food storage, such as sucrose usually converts translucent embryos into white-opaque embryos as reported by Cerezo et al (2011) and Martínez et al (2014). Earlier attempt to initiate somatic embryogenesis in G. bancanus reported a rather interesting outcome as a higher concentration (40.0 mg·l -1 ) of NAA was used with success.…”

Improved secondary embryo production in Quercus alba and Q. rubra by activated charcoal, silver thiosulphate and sucrose: influence of embryogenic explant used for subculture

“…This avoids further damage caused by the laborious separation of individual embryos generated in media without AC, which represents a serious problem for management of SSEs. Examples of embryo histodifferentiation from proembryogenic masses cultured on charcoal-supplemented medium can be found in woody species, such as Passiflora edulis (Pinto et al 2011), olive (Cerezo et al 2011) and grapevine (Dhekney et al 2011;Acanda et al 2013), although in the last two species, these embryogenic aggregates were derived from suspension cultures.…”

Direct adventitious shoot organogenesis and plant regeneration from cotyledon explants in Neolamarckia cadamba

“…(Morimoto et al 2011), leafy shoots of Cryptomeria japonica (Ishii et al 2011), shoot explants of Anacardium occidentale (Thimmappaiah et al 2002) and Eucalyptus (Hajari et al 2006), and radicles of the olive (Cerezo et al 2011), as well as somatic embryogenesis of Olea europea (Shibli et al 2001). In this study, direct adventitious shoot organogenesis and plant regeneration were first established in N. cadamba using cotyledons as explants.…”