title: Conifer somatic embryogenesis: improvements by supplementation of medium with oxidation-reduction agents.
abstract: A major barrier to the commercialization of somatic embryogenesis technology in loblolly pine (Pinus taeda L.) is recalcitrance of some high-value crosses to initiate embryogenic tissue (ET) and continue early-stage somatic embryo growth. Developing initiation and multiplication media that resemble the seed environment has been shown to decrease this recalcitrance. Glutathione (GSH), glutathione disulfide (GSSG), ascorbic acid and dehydroascorbate analyses were performed weekly throughout the sequence of seed development for female gametophyte and zygotic embryo tissues to determine physiological concentrations. Major differences in stage-specific oxidation-reduction (redox) agents were observed. A simple bioassay was used to evaluate potential growth-promotion of natural and inorganic redox agents added to early-stage somatic embryo growth medium. Compounds showing statistically significant increases in early-stage embryo growth were then tested for the ability to increase initiation of loblolly pine. Low-cost reducing agents sodium dithionite and sodium thiosulfate increased ET initiation for loblolly pine and Douglas fir (Mirb) Franco. Germination medium supplementation with GSSG increased somatic embryo germination. Early-stage somatic embryos grown on medium with or without sodium thiosulfate did not differ in GSH or GSSG content, suggesting that sodium thiosulfate-mediated growth stimulation does not involve GSH or GSSG. We have developed information demonstrating that alteration of the redox environment in vitro can improve ET initiation, early-stage embryo development and somatic embryo germination in loblolly pine.
authors.affiliation: School of Biology, Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA Renewable Bioproducts Institute (RBI), Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA jerry.pullman@ipst.gatech.edu.
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Pullman
authors.affiliation: Renewable Bioproducts Institute (RBI), Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Renewable Bioproducts Institute (RBI), Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA.
authors.forename: Brandi
authors.initials: B
authors.lastname: Copeland-Kamp
authors.affiliation: Renewable Bioproducts Institute (RBI), Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Crockett
authors.affiliation: School of Chemistry and Biochemistry, Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Jacob
authors.initials: J
authors.lastname: Lucrezi
authors.affiliation: School of Chemistry and Biochemistry, Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Sheldon W
authors.initials: SW
authors.lastname: May
authors.affiliation: Renewable Bioproducts Institute (RBI), Georgia Institute of Technology, 500 10th Street N.W., Atlanta, GA 30332-0620, USA.
authors.forename: Kylie
authors.initials: K
authors.lastname: Bucalo
mesh_terms: D001205:Ascorbic Acid / Q000378:metabolism / Q000494:pharmacology; D018525:Germination / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism / Q000494:pharmacology; D019803:Glutathione Disulfide / Q000494:pharmacology*; D056771:Ovule / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010084:Oxidation-Reduction; D028223:Pinus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D058439:Plant Somatic Embryogenesis Techniques / Q000379:methods*; D028224:Pseudotsuga / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D012639:Seeds / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013885:Thiosulfates / Q000494:pharmacology*
chemical_list: D013885:Thiosulfates; D005978:Glutathione; C017717:sodium thiosulfate; D001205:Ascorbic Acid; D019803:Glutathione Disulfide
keywords: Douglas fir; Pinus taeda; Pseudotsuga menziesii; ascorbic acid; embryo development; female gametophyte; glutathione; glutathione disulfide; loblolly pine; redox agents; sodium dithionite; sodium thiosulfate