Promotion of Lettuce Seed Germination by Gibberellin.

Botany Department, University of California, Los Angeles.
Plant physiology (Impact Factor: 7.39). 06/1960; 35(3):333-9. DOI: 10.1104/pp.35.3.333
Source: PubMed
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    ABSTRACT: Gibberellicacid-induced dark germination of Grand Rapids lettude seed was completely inhibited by 6-azauracil and partly by 2-thiouracil. Other inhibitors of nucleic acid and protein synthesis used were without effect. Inhibition of gibberellic acid-induced dark germination was reversed by uracil but not by thymine, deoxycytidine and orotic acid. The results suggest that gibberellic acid-induced dark germination is dependent on RNA synthesis and not on DNA synthesis.Gibberellic acid-induced lettuce hypocotyl growth was inhibited by all the inhibiters of nucleic acid and protein synthesis used, including actinomycin D, puromycin, chloramphenicol and p-fluorophenylalanine.
    Planta 09/1966; 72(3):284-288. DOI:10.1007/BF00386754 · 3.38 Impact Factor
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    ABSTRACT: Unrolling of etiolated wheat leaf segments is stimulated by short periods of exposure to red light. Both gibberellic acid and kinetin will stimulate unrolling in the dark, whereas abscisic acid (ABA) inhibits the unrolling response to these two hormones and to red light. Exposure to 5 minutes of red light leads to a rapid increase in endogenous gibberellin levels in etiolated wheat leaves, and this increase is followed by a rapid decline. Pre-treatment with ABA inhibits the increase in gibberellin levels in response to red light, but the ihibitory effect of ABA on unrolling cannot be ascribed only to its effect on gibberellin levels. Pre-treatment with red light reduces the lag-phase in chlorophyll development when wheat leaf segments are subsequently exposed to white light; the effect of red light may be replaced by pre-treatment with kinetin, but gibberellic acid is relatively ineffective in this respect.
    Planta 09/1970; 90(3):286-94. DOI:10.1007/BF00387180 · 3.38 Impact Factor
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    ABSTRACT: The phytochrome system is responsible for the photosensitivity of dormant, isolated apple embryos in culture. Maximum photosensitivity occurs on the second day of culture and it is unaffected by gibberellins (GAs) in concentrations below 10(-4)M. Higher concentrations of GA decrease the photosensitivity.The endogenous quantities of GA4 and GA7 were determined in embryos grown at white light, in darkness and in darkness following an exposure to red light. The GA7 level remained unaffected by the light conditions, whereas the amount of GA4 was three times higher in light or red-light-treated cultures than in the dark grown ones.Similar experiments were done using AMO-1618, an inhibitor of GA biosynthesis, which is also a strong inhibitor of apple seed germination. In this case the level of both GA4 and GA7 was light-independent. These experiments suggest that the phytochrome system participates in the regulation of GAs biosynthesis by mediating one of the last steps of GA4 formation.
    Planta 06/1971; 99(2):144-53. DOI:10.1007/BF00388246 · 3.38 Impact Factor


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