Somatic Embryogenesis in Woody Plants

Dunstan, David I.; Tautorus, T. E.; Thorpe, Trevor A.

doi:10.1007/978-94-011-0485-2_12

Cited by 69 publications

(38 citation statements)

References 371 publications

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“…This phenomenon was Wrst reported in the late 1940s by Levine (1947) using carrot cells, and subsequently extended to a variety of plant species (see Dunstan et al 1995;Thorpe and Stasolla 2001). Despite the improvement in tissue culture conditions achieved for many species in the last decades, a recurrent problem encountered during in vitro embryogenesis is the low conversion rate of the embryos into seedlings.…”

Section: Introductionmentioning

confidence: 69%

Buthionine sulfoximine (BSO)-mediated improvement in cultured embryo quality in vitro entails changes in ascorbate metabolism, meristem development and embryo maturation

Stasolla

Belmonte

Tahir

et al. 2008

Planta

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Applications of buthionine sulfoximine (BSO), an inhibitor of GSH (reduced glutathione), which switches the cellular glutathione pool towards the oxidized form GSSG, positively inXuences embryo quality by improving the structure of the shoot apical meristem and promoting embryo maturation, both of which improve the post-embryonic performance of the embryos. To investigate the mechanisms underlying BSO-mediated improvement in embryo quality the transcript proWles of developing Brassica napus microspore-derived embryos cultured in the absence (control) or presence of BSO were analyzed using a 15,000-element B. napus oligo microarray. BSO applications induced major changes in transcript accumulation patterns, especially during the late phases of embryogenesis. BSO aVected the transcription and activities of key enzymes involved in ascorbate metabolism, which resulted in major Xuctuations in cellular ascorbate levels. These changes were related to morphological characteristics of the embryos and their postembryonic performance. BSO applications also activated many genes controlling meristem formation and function, including ZWILLE, SHOOTMERISTEMLESS, and ARG-ONAUTE 1. Increased expression of these genes may contribute to the improved structural quality of the shoot poles observed in the presence of BSO. Compared to their control counterparts, middle-and late-stage BSO-treated embryos also showed increased accumulation of transcripts associated with the maturation phase of zygotic embryo development, including genes encoding ABA-responsive proteins and storage-and late-embryogenic abundant (LEA) proteins. Overall these transcriptional changes support the observation that the BSO-induced oxidized glutathione redox state allows cultured embryos to reach both morphological and physiological maturity, which in turn guarantees successful regeneration and enhanced post-embryonic growth.

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Section: Introductionmentioning

confidence: 69%

Buthionine sulfoximine (BSO)-mediated improvement in cultured embryo quality in vitro entails changes in ascorbate metabolism, meristem development and embryo maturation

Stasolla

Belmonte

Tahir

et al. 2008

Planta

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“…2,4-D is commonly used to initiate tissue cultures of carrot (Daucus carota) (Ammirato, 1985) and other species (Dunstan et al, 1995). The presence of 2,4-D in the growth medium often results in undifferentiated callus proliferation.…”

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confidence: 99%

The Effects of Exogenous Auxins on Endogenous Indole-3-Acetic Acid Metabolism (The Implications for Carrot Somatic Embryogenesis)

et al. 1996

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(D.M.R., N.I., T.J.C.)l h e effect of auxin application on auxin metabolism was investigated in excised hypocotyl cultures of carrot (Daucus carota). Concentrations of both free and conjugated indole-3-acetic acid (IAA), [2H,]IAA, 2,4-dichlorophenoxyacetic acid, and naphthaleneacetic acid (NAA) were measured by mass spectroscopy using stable-isotope-labeled interna1 standards.[l3C1]NAA was synthesized for this purpose, thus extending the range of auxins that can be assayed by stable-isotope techniques. 2,4-Dichlorophenoxyacetic acid promoted callus proliferation of the excised hypocotyls, accumulated as the free form in large quantities, and had minor effects on endogenous IAA concentrations. NAA promoted callus proliferation and the resulting callus became organogenic, producing both roots and shoots. NAA was found mostly in the conjugated form and had minor effects on endogenous IAA concentrations. [ZH,lIAA had no visible effect on the growth pattern of cultured hypocotyls, possibly because it was rapidly metabolized to form inactive conjugates or possibly because it mediated a decrease in endogenous IAA concentrations by an apparent feedback mechanism. l h e presente of exogenous auxins did not affect tryptophan labeling of either the endogenous tryptophan or IAA pools. This suggested that exogenous auxins did not alter the IAA biosynthetic pathway, but that synthetic auxins did appear to be necessary to induce callus proliferation, which was essential for excised hypocotyls to gain the competence to form somatic embryos.Since the 1940s (Thimann, 1974), exogenous auxins have been used frequently as experimental tools for studying their effects in developing structures (Schiavone and Cooke, 1987); for screening for mutants impaired in the uptake, metabolism, and physiology of endogenous auxins (Timpte et al., 1994); and even to find potential IAA receptors (Jones and Venis, 1989; LoSchiavo et al., 1991). One important use for the application of exogenous auxin is as a growth regulator for maintaining plant-cell-and tissue-

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“…Conifer somatic embryo development undergoes similar morphological changes to those in zygotic embryo development, although somatic embryogenesis relies upon changes in culture conditions during induction of embryogenic tissues, stimulation of embryo maturation, desiccation and subsequent germination. Somatic embryogenesis in conifers is being used for the large-scale multiplication of a small number of diverse species (Gupta et al, 1993;Dunstan et al, 1995). Somatic embryos are also used as the target materials for plant transformation, e.g., via particle microprojectile (Bommineni et aI., 1993;Charest et aI., 1996;Ellis et al, 1993).…”

Section: Introductionmentioning

confidence: 98%