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  • 1
    ISSN: 1573-5087
    Keywords: elongation ; gibberellins ; A4, A9, A5 and A3 ; le mutant ; Pisum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5087
    Keywords: elongation ; gibberellin ; hydroxylase ; peas ; seed development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Le gene of pea encodes a gibberellin 3β-hydroxylase. Heterologous expression of the le-2 allele indicated that a truncated protein was produced, confirming that le-2 is a null mutation. The Le expression product was unable to metabolise GA12, but was able to produce a small quantity of GA8 from GA29. The le-2 mutation had no effect on the levels of GA1, GA4 or GA8 in developing seeds. Measurements of mRNA levels indicate that the Le gene is only weakly expressed in young pea seeds. These results explain why mutant alleles at the Le locus have no major impact on seed development, even though 3β-hydroxylated GAs are essential for normal seed development in pea. Rather, a second 3β-hydroxylase, with a different substrate specificity, may be expressed in young seeds, resulting in a different biosynthetic pathway leading to the biologically active GAs.
    Type of Medium: Electronic Resource
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