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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 121 (2004), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Seeds gradually lose their viability during dry storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seeds. Although these environmental conditions controlling loss of viability have been investigated frequently, little information is available on the genetics of seed longevity. Using Arabidopsis mutants in defined developmental or biochemical pathways such as those affected in seed coat composition, seed dormancy, hormone function and control of oxidative stress, we tried to gain insight into the genes and mechanisms controlling viability of stored seeds. Mutations like abscisic acid insensitive3 (abi3) as well as abscisic acid deficient1 (aba1) show reduced longevity, which may be partially related to the seed dormancy phenotype of these mutants. Mutants with seed coat alterations, especially aberrant tests shape (ats), showed a stronger reduction in germination percentage after storage, indicating the importance of a ‘functional’ seed coat for seed longevity. A specific emphasis was placed on mutants affected in dealing with Reactive Oxygen Species (ROS). Because several pathways are involved in protection against ROS and because gene redundancy is a common feature in Arabidopsis, ‘double’ mutants were generated. These ‘double’ mutants and the corresponding single mutants were subjected to a controlled deterioration test (CDT) and a germination assay on hydrogen peroxide (H2O2) after prolonged storage at two relative humidities. CDT and germination on H2O2 affected all genotypes, although it appears that other effects like genetic background are more important than the deficiencies in the ROS scavenging pathway. Explanations for this limited effect of mutations affecting ROS scavenging are discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Seed dormancy and germination are complex traits that are controlled by many genes. Four mutants in Arabidopsis thaliana exhibiting a reduced dormancy phenotype, designated rdo1, rdo2, rdo3, and rdo4, have been characterized, both genetically and physiologically. Two of these mutants, rdo1 and rdo2, have been described before, the other two represent novel loci. The mutants mapped on chromosome 1 (rdo3), chromosome 2 (rdo2 and rdo4), and chromosome 3 (rdo1). None of these loci has been related to dormancy before. All four mutants show pleiotropic effects in the adult plant stage, which are different for each mutant. None of the mutants is deficient in ABA. Compared to Ler (wild-type), ABA sensitivity is not altered either, thereby excluding the possibility that ABA is involved in causing the reduced dormancy phenotype. The GA requirement was studied by using the GA biosynthesis inhibitor paclobutrazol, and genetically by generating double mutants with the GA-deficient mutant ga1-3. The results obtained by these two methods were comparable for all but one mutant: rdo1. In a GA-deficient background, rdo1, rdo2 and rdo3, all show sensitivity to GA between that of ga1-3 and ga1-3 aba1. However, when using paclobutrazol rdo1 exhibited the same sensitivity as rdo4 and wild-type. Analysis of double mutants among the rdo mutants revealed a very complex and inconsistent pattern.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effect of daylength on flowering was investigated in the following mutants of Arabidopsis thaliana: phytochrome B deficient (hy3=phyB); phytochrome chromophore deficient (hy2); late-flowering (co, gi. fca and fwa); the hy2 and hy3, late-flowering double mutants and the hy2, hy3, late-flowering triple mutants. The hy mutants flower with fewer rosette leaves than the Landsberg erecta wild type under both long day and short day conditions and express this effect to a different degree in all late-flowering mutant backgrounds and under both daylengths, with the exception of fca under short days. The number of cauline leaves and days to flowering is less affected by the hy genotype. The hy2, hy3 double mutants flower with even fewer rosette leaves than the hy2 and hy3 monogenic mutants, suggesting an inhibitory role for phytochrome B and other stable phytochromes on flowering. The complex interaction between phytochrome, daylength and the effect of the late-flowering genes on the various parameters that describe the transition to flowering in Arabidopsis is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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