Conservation of the Cedrus libani populations in Lebanon: history, current status and experimental application of somatic embryogenesis
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Published source details
Khuri S., Shmoury M.R., Baalbaki R., Maunder M. & Talhouk S.N. (2000) Conservation of the Cedrus libani populations in Lebanon: history, current status and experimental application of somatic embryogenesis. Biodiversity and Conservation, 9, 1261-1273.
Published source details Khuri S., Shmoury M.R., Baalbaki R., Maunder M. & Talhouk S.N. (2000) Conservation of the Cedrus libani populations in Lebanon: history, current status and experimental application of somatic embryogenesis. Biodiversity and Conservation, 9, 1261-1273.
Summary
The cedar of Lebanon Cedrus libani is a threatened conifer native to the Levant region of the East Mediterranean. Deforestation has led to fragmentation and degradation of extant Lebanese cedar populations. Two protected areas have recently been established in Lebanon which contain two of the more important remaining forests. A number of other populations are protected by ministerial decrees but there is a need for management of all remaining cedar populations to ensure long-term survival. The application of in vitro techniques such as somatic embryogenesis (whereby somatic cells give rise to embryos which are able to mature and regenerate into plants), as summarised here, may assist in the conservation of this conifer.
Plant material: C.libani cones were collected from a natural population in Bmohrai (35º43'E, 33º45'N), Lebanon. Collections were made every two weeks from 1 May to 1 December 1996, and 10 March and 1 April in1997. Cones were surface sterilised in a 2% bleach solution for 5 min and rinsed in distilled water. Intact megagametophytes (female gametophyte that arises from a megaspore of a heterosporous plant) of varying developmental stages were removed and placed in culture.
Effect of developmental stage of immature zygotic embryos: Thirty explants from each collection date were cultured on a half strength Murashige and Skoog medium (MS) supplemented with 1% lactose and growth regulators(10 µM 2,4-D + 5 µM BA), or 1% lactose only. Cultures were kept at 25ºC in the dark.
Effect of different concentrations and ratios of growth regulatorsThe MS medium was supplemented with various concentrations of 2,4-dichlorophenoxy acetic acid (2,4-D) and 6-benzylamino purine (BAP), and effects assessed.
Initiation of somatic embryos from C. libani in this study was found to be optimal when the explants used are immature zygotic embryos taken from cones collected in the autumn months. With the half-strength MS medium used, the most suitable combination of growth regulators was 10µM 2,4-D + 5µM BAP. These findings form the basis for future studies.
The application of somatic embryogenesis in terms of conservation of the Lebanese cedar population would be to propagate and preserve selected genotypes for use in restoration projects.
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