Tunicamycin-inhibited carrot somatic embryogenesis can be restored by secreted cationic peroxidase isoenzymes

Cordewener, J.H.G.; Booij, H.; Zandt, Hans van der; Engelen, F.A. van; Kammen, A. van; Vries, S.C. de

doi:10.1007/bf00197895

Cited by 128 publications

(67 citation statements)

References 28 publications

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“…As part of our ongoing research effort to investigate the role of secreted proteins in carrot somatic embryogenesis (De Vries et al, 1988a, 1988bLoSchiavo et al, 1990;Cordewener et al, 1991), we set out to clone genes encoding secreted proteins ; this work; P. Sterk and S.C. De Vries, unpublished observations), employing expression screening of an embryo cDNA library. Among the secreted proteins, we identified a plant lipid transfer protein, EP2, present in cell walls of somatic embryos as well as in the conditioned medium of embryo cultures.…”

Section: Dlscusslonmentioning

confidence: 99%

Cell-specific expression of the carrot EP2 lipid transfer protein gene.

et al. 1991

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A cDNA corresponding to a 10-kD protein, designated extracellular protein 2 (EP2), that is secreted by embryogenic cell cultures of carrot was obtained by expression screening. The derived protein sequence and antisera against heterologous plant lipid transfer proteins identified the EP2 protein as a lipid transfer protein. Protein gel blot analysis showed that the EP2 protein is present in cell walls and conditioned medium of cell cultures. RNA gel blot analysis revealed that the EP2 gene is expressed in embryogenic cell cultures, the shoot apex of seedlings, developing flowers, and maturing seeds. In situ hybridization showed expression of the EP2 gene in protoderm cells of somatic and zygotic embryos and transient expression in epidermis cells of leaf primordia and all flower organs. In the shoot apical meristem, expression is found in the tunica and lateral zone. In maturing seeds, the EP2 gene is expressed in the outer epidermis of the integument, the seed coat, and the pericarp epidermis, as well as transiently in between both mericarps. Based on the extracellular location of the EP2 protein and the expression pattern of the encoding gene, we propose a role for plant lipid transfer proteins in the transport of cutin monomers through the extracellular matrix to sites of cutin synthesis.

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Section: Dlscusslonmentioning

confidence: 99%

Cell-specific expression of the carrot EP2 lipid transfer protein gene.

et al. 1991

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“…At this stage it is essential that the cells remain small and isodiametric (fail to elongate) for embryogenesis to proceed (Cordewener et al, 1991). After 6 d, globular embryoids developed into heart, torpedo, and cotyledonary stages, during which there is a requirement for localized cell elongation and expansion (Schiavone and Cooke, 1985) and therefore presumably wall loosening.…”

Section: Dlscusslonmentioning

confidence: 99%

“…Vol. 103, 1993 adhering so as to initiate globular embryoids successfully (Cordewener et al, 1991). However, at the heart and torpedo stages of embryogenesis, localized cell elongation resumes.…”

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confidence: 99%

Xyloglucan Endotransglycosylase Activity in Carrot Cell Suspensions during cell Elongation and Somatic Embryogenesis

Hetherington

Fry

1993

Plant Physiol.

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Xyloglucan endotransglycosylase (XET) has been proposed to contribute to cell elongation through wall loosening. To explore this relationship further, we assayed this enzyme activity in suspensions of carrot (Daucus carota L.) cells exhibiting various rates of cell elongation. In one cell line, elongation was induced by dilution into dichlorophenoxyacetic acid (2,4-D)-free medium. During this elongation, 93% of the XET activity was found in the culture medium; in nonelongating controls, by contrast, 68% was found i n the cell extracts even though the specific activity of these extracts was lower than in the elongating cells. By far the highest rates of XET secretion per cell were in the elongating cells. A second cell line was induced to undergo somatic embryogenesis by dilution into 2,4-D-free medium. During the first 6 d, numerous globular embryoids composed of small, isodiametric cells were formed i n the absence of cell elongation; extracellular XET activity was almost undetectable, and intracellular specific activity markedly declined.After 6 d, heart, torpedo, and cotyledonary embryoids began to appear (i.e. cell elongation resumed); the intracellular specific activity of XET rose rapidly and >80% of the XET activity accumulated i n the medium. Thus, nonexpanding cell suspensions (whether or not they were rapidly dividing) produced and secreted less XET activity than did expanding cells. We propose that a XET molecule has an ephemeral wall-loosening role while it passes through the load-bearing layer of the wall on its way from the protoplast into the culture medium.

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“…Surprisingly, EP3 rescue of ts11 embryos at the restrictive temperature is mimicked by the addition of a Rhizobium nodulation (Nod) factor, an A/-acetylglucosamine-containing lipooligosaccharide; these results suggest that the endochitinase may generate plant analogs of Nod factors (De Jong et al, 1993b). Another enzyme secreted into the medium, a cationic peroxidase, can restore globular embryo development in carrot cultures in which somatic embryogenesis is impaired by tunicamycin (Cordewener et al, 1991). These genes, like others reviewed elsewhere, will serve as important tools to further probe developmental events in the early embryo.…”

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confidence: 92%

Gene expression during plant embryogenesis and germination: an overview.

Thomas

1993

Plant Cell

229

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INTRODUCTIONSeed development represents a unique transition state in the life cycle of higher plants, providing the physical link between parenta1 and progeny sporophytic generations. During embrye genesis, the root and shoot apical meristems are specified, thus establishing the basic architecture of the seedling, and differentiation of vegetative tissue and organ systems occurs. Maturation events prepare the seed for germination and subsequent development of the mature plant. During maturation, the developing seed increases dramatically in volume and mass due to significant cell expansion and the concomitant accumulation and storage of protein and lipid to be used as nitrogen and carbon sources during germination. Early during the maturation phase, abscisic acid (ABA) levels reach a maximum, suppressing precocious germination and modulating gene expression. Desiccation ensures seed dormancy even in the absence of ABA and serves as the boundary between seed maturation and germination. Following imbibition, germination and seedling growth ensue, driven metabolically by the hydrolysis of protein and lipid stored during maturation.This review will provide an eclectic overview of gene expression in angiosperm embryogenesis and germination. I will focus primarily on dicot plants and will address only a small number of the more than 3 x 104 different genes expressed in embryos and seedlings. First, gene expression in early embryogenesis will be reviewed, focusing on selected results obtained with carrot somatic embryos. Control of gene expression during seed maturation will then be discussed, with an emphasis on cis-and tfans-acting factors involved in regulating maturation phase genes. A brief description of gene expression during germination and the relationship of embryonic and vegetative gene expression programs will follow. The review will conclude with a prospectus for the study of global gene expression patterns in early embryos. GENE EXPRESSION IN EARLY EMBRYOSAlthough most of the major discernible morphogenetic events in plants occur after germination, the overall architectural pattern of the mature plant is established during embryogenesis (see West and Harada, 1993, this issue). Following fertilization, an asymmetric division of the zygote of many dicots yields a basal cell that will produce the suspensor and an apical cellthe first embryonic cell. Ensuing cleavages of the apical cell yield a radially symmetric globular embryo with a differentiated protoderm, or dermatogen. Further cell divisions and subsequent morphogenesis break radial symmetry, yielding the bilaterally symmetric, heart stage embryo with root and shoot apices, incipient cotyledons, and provascular tissue (for recent reviews, se8 Meinke, 1991;Van Engelen and De Vries, 1992;De Jong et al., 1993a;West and Harada, 1993, this issue). So far, few genes have been identified that are expressed specifically during early embryogenesis, primarily because of technical difficulties associated with the mass ratios of the embryo and the surrounding mate...

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Tunicamycin-inhibited carrot somatic embryogenesis can be restored by secreted cationic peroxidase isoenzymes

Cited by 128 publications

References 28 publications

Cell-specific expression of the carrot EP2 lipid transfer protein gene.

Cell-specific expression of the carrot EP2 lipid transfer protein gene.

Xyloglucan Endotransglycosylase Activity in Carrot Cell Suspensions during cell Elongation and Somatic Embryogenesis

Gene expression during plant embryogenesis and germination: an overview.

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