Studies on the Growth in Culture of Plant Cells: VIII. THE PRODUCTION OF ETHYLENE BY SUSPENSION CULTURES OF ACER PSEUDOPLATANUS, L.
TL;DR: Evidence is presented that 2,4-D enhances ethylene production independently of its effects on culture growth, and no evidence was obtained that this ethylene is inhibitory to culture growth or that a critical level of ethane is necessary to initiate cell division in cultures at a critically low cell density.
Abstract: Sycamore cell suspension cultures in a synthetic medium release ethylene; during a 24-day incubation period a single culture (initial volume 70 ml) produces c. 4 p. moles. There is a very sharp peak of ethylene production between day 10 and day 14 of culture; at the peak of pro duction c. 2 nmoles ethylene are released per million cells in 24 h. Evidence is presented that 2,4-D enhances ethylene production independently of its effects on culture growth. Under the standard conditions of culture (250-ml Erlenmeyer flasks closed with aluminium foil and containing 70 ml cell suspension) the concentration of ethylene in the gas phase of the cultures rises above 10 ppm. No evidence was obtained that this ethylene is inhibitory to culture growth or that a critical level of ethylene is necessary to initiate cell division in cultures at a critically low cell density. The low rate of ethylene release by stationary phase cultures is temporarily enhanced by the addition of various solutes and further depressed by dilution with water.
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TL;DR: The development of Robot Scientist “Adam,” which has autonomously generated functional genomics hypotheses about the yeast Saccharomyces cerevisiae and experimentally tested these hypotheses by using laboratory automation, is reported.
Abstract: The basis of science is the hypothetico-deductive method and the recording of experiments in sufficient detail to enable reproducibility. We report the development of Robot Scientist "Adam," which advances the automation of both. Adam has autonomously generated functional genomics hypotheses about the yeast Saccharomyces cerevisiae and experimentally tested these hypotheses by using laboratory automation. We have confirmed Adam's conclusions through manual experiments. To describe Adam's research, we have developed an ontology and logical language. The resulting formalization involves over 10,000 different research units in a nested treelike structure, 10 levels deep, that relates the 6.6 million biomass measurements to their logical description. This formalization describes how a machine contributed to scientific knowledge.
525 citations
TL;DR: It is shown that, on restimulation of suspension-cultured cells, cyclinDelta 3 is rapidly induced by the plant growth regulator cytokinin and cyclin delta 2 is induced by carbon source, suggesting that these plant homologs may mediate growth and phytohormonal signals into the plant cell cycle.
Abstract: A new family of three related cyclins has been identified in Arabidopsis by complementation of a yeast strain deficient in G1 cyclins. Individual members show tissue-specific expression and are conserved in other plant species. They form a distinctive group of plant cyclins, which we named delta-type cyclins to indicate their similarities with mammalian D-type cyclins. The sequence relationships between delta and D cyclins include the N-terminal sequence LXCXE. This motif was originally identified in certain viral oncoproteins and is strongly implicated in binding to the retinoblastoma protein pRb. By analogy to mammalian cyclin D, these plant homologs may mediate growth and phytohormonal signals into the plant cell cycle. In support of this hypothesis, we show that, on restimulation of suspension-cultured cells, cyclin delta 3 is rapidly induced by the plant growth regulator cytokinin and cyclin delta 2 is induced by carbon source.
401 citations
TL;DR: The focus of this review is on embryo development through somatic embryogenesis and especially the factors affecting cell and embryo differentiation.
Abstract: Somatic embryogenesis is the process by which somatic cells, under induction conditions, generate embryogenic cells, which go through a series of morphological and biochemical changes that result in the formation of a somatic embryo. Somatic embryogenesis differs from zygotic embryogenesis in that it is observable, its various culture conditions can be controlled, and a lack of material is not a limiting factor for experimentation. These characteristics have converted somatic embryogenesis into a model system for the study of morphological, physiological, molecular and biochemical events occurring during the onset and development of embryogenesis in higher plants; it also has potential biotechnological applications. The focus of this review is on embryo development through somatic embryogenesis and especially the factors affecting cell and embryo differentiation.
253 citations
TL;DR: It is clear that ethylene has an important influence on many aspects of in vitro regeneration, but it is also clear that it cannot at present describe a specific role or roles for ethylene in tissue culture which can be applied at a general, species-wide level.
Abstract: Ethylene produced by plant tissues grown in vitro may accumulate in large quantities in the culture vessels, particularly from rapidly growing non-differentiated callus or suspension cultures, and hence is likely to influence growth and development in such systems. Research into this aspect of tissue culture has been sparse, although it has grown recently with the increasing importance of in vitro regeneration. This review deals with the measurement and relevance of the accumulated ethylene, and the influence of both exogenous and endogenous ethylene in the different types of tissue culture systems. The relationships between ethylene and other growth regulators in tissue culture growth and development are also discussed. Although in some cases its influence seems negligible, in many types of tissue culture ethylene may act either as a promoter or inhibitor depending on the species used. Thus ethylene has an important influence on many aspects of in vitro regeneration, but it is also clear that we cannot at present describe a specific role or roles for ethylene in tissue culture which can be applied at a general, species-wide level. If its effects are to be enhanced or diminished in order to improve the efficiency and range of plant tissue culture, then more research is needed to clarify what its fundamental role might be in in vitro growth and development.
225 citations
TL;DR: Regulation of maturation would facilitate future efforts to manipulate somatic embryos for large scale propagation in batch cultures, mechanized planting, artificial induction of dormancy, and incorporation into artificial seeds.
Abstract: The ability to control plant somatic embryogenesis is a necessary prelude to its development as an efficient biotechnological tool. The influence of different suspension culture techniques on the maturation of caraway (Carum carvi) somatic embryos and the effect of growth hormones in controlling development were studied. The three types of culture vessels (tumble tubes, test tubes, and Erlenmeyer flasks), each providing contrasting techniques of agitation, generated populations differing significantly in the frequencies of normal and abnormal embryos. Abscisic acid (ABA), at the appropriate concentrations, effectively normalized development in all systems, inhibiting abnormal proliferations and precocious germination and fostering normal maturation. For those cultures where embryos failed to develop on unsupplemented medium, zeatin in combination with ABA fostered growth and normal maturation. Carrot (Daucus carota) somatic embryo development could be similarly controlled. Such regulation of maturation would facilitate future efforts to manipulate somatic embryos for large scale propagation in batch cultures, mechanized planting, artificial induction of dormancy, and incorporation into artificial seeds.
133 citations