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Digitale Medien

Abscisic acid, phaseic acid and gibberellin contents associated with dormancy and germination in barley (2002)

Jacobsen, John V. ; Pearce, David W. ; Poole, Andrew T. ; [weitere]

Oxford, UK : Blackwell Science, Ltd

Physiologia plantarum 115 (2002), S. 0

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ISSN: 1399-3054

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Analyses of abscisic acid (ABA), ent-kaurenoids and gibberellins (GAs) showed that there were major changes in the contents of these compounds associated with germination of after-ripened barley (Hordeum vulgare cv. Schooner and cv. Proctor) grain but not in hydrated dormant grain. Embryos from dormant and after-ripened dry grain contained similar amounts of ABA, of ent-kaurenoids and of GAs, determined by gas chromatography-mass spectrometry-selected ion monitoring. In embryos of after-ripened grain, ABA content decreased rapidly after hydration and ABA appeared to be metabolized (inactivated) to phaseic acid (PA) rather than diffusing into the endosperm or the surrounding medium as previously thought. Similar changes in ABA occurred in hydrated dormant grain during germination in darkness. Accumulation of ent-kaurenoids and GAs, including GA1, the first biologically active GA in the early 13-hydroxylation biosynthetic pathway, occurred to a much greater extent in after-ripened than in dormant grain and these changes occurred mainly after 18 h of hydration when ABA had already decreased and germination was occurring. The block in ent-kaurenoid and GA synthesis in dormant grain appeared to occur prior to ent-kaurene in the biosynthetic pathway. These results are consistent with the view that ABA is the primary effector of dormancy and that after-ripening involves the development of the ability to reduce the amount of ABA quickly following hydration. Accumulation of GAs does not appear to be causally related to loss of dormancy but it does appear to be related to germination.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1150313.x

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Digitale Medien

Identification of gibberellin A4 in Pisum sativum L. and the effects of applied gibberellins A9, A4, A5 and A3 on the le mutant (1995)

Poole, Andrew T. ; Ross, John J. ; Lawrence, Naomi L. ; [weitere]

Springer

Plant growth regulation 16 (1995), S. 257-262

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ISSN: 1573-5087

Schlagwort(e): elongation ; gibberellins ; A4, A9, A5 and A3 ; le mutant ; Pisum

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract Gibberellin A4 (GA4) was identified for the first time in the garden pea (Pisum sativum) L.), by gas chromatography-mass spectrometry. However, in wild-type shoots the level of GA4 was only about 6% of the level of GA1, and it is therefore unlikely that GA4 plays a major role per se in the control of pea stem elongation. In shoots of the le mutant, GA4 was not detected, while the level of GA9 was approximately twice that found in the wild-type. The le mutation also markedly reduced the elongation response to applied GA9. It appears, therefore, that in Pisum the le mutation blocks the 3β-hydroxylation of GA9 to GA4, in addition to the 3β-hydroxylation of GA20 to GA1. In contrast, the le mutation did not reduce the response to applied GA5, suggesting the step GA5 to GA3 is not catalysed by the enzyme controlled by the Le gene. The step GA5 to GA3 was confirmed in peas by metabolite analysis after treatment with deuterated GA5.