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  • 1
    Electronic Resource
    Electronic Resource
    Genetic differences in seed longevity of various Arabidopsis mutants (2004)
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 121 (2004), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0031-9317.2004.00339.x
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of beta-tubulin during dormancy induction and release in apical and axillary buds of five woody species (1999)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 106 (1999), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cell cycle activity was studied in apical and axillary buds of Norway maple (Acer platanoides L.), apple (Malus‘M9’), pedunculate oak (Quercus robur L.), Scots pine (Pinus sylvestris L.) and rose (Rosa corymbifera‘Laxa’) during dormancy induction and release. Flow cytometric analyses revealed that in dormant buds, cells mainly were quiescent at the G0/G1 phase, while in non-dormant buds, a significantly higher frequency of G2 cells was found in all species. In western blots accumulation of 55 kDa beta-tubulin was found in active growing plant material, whereas in dormant buds the accumulation was much lower or below detection level. It was observed for all species that during dormancy induction the amount of beta-tubulin decreased, while during dormancy release a fast accumulation of beta-tubulin occurred. The dynamics of the beta-tubulin accumulation reflected the dormancy status of tree buds of the five species studied suggesting that the beta-tubulin level might be useful as a marker for the dormancy status in buds of temperate woody species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1999.106214.x
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  • 3
    Electronic Resource
    Electronic Resource
    The role of endogenous gibberellin in seed and fruit development of tomato: Studies with a gibberellin-deficient mutant (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 71 (1987), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of endogenous gibberellin (GA) in seed and fruit development was studied with the use of the GA-deficient ga-1 mutant of tomato (Lycopersicon esculentum Mill. cv. Moneymaker). Flowers of the ga-1 mutant were abnormal and sterile, but parthenocarpic fruit development was observed occasionally on the dwarf plants. A single application of GA4+7 restored the fertility of the mutant flowers and resulted in seed set. Development of GA-producing and GA-deficient seeds in GA-deficient fruits was compared by pollination of ga-1/ga-1 flowers with wild-type or ga-1 pollen, respectively. In ga-1/ga-1 seed dehydration started about 1 week earlier than in Ga-1/ga-1 seeds. Ultimate fresh and dry weights of mature Ga-1/ga-1 seeds were higher than those of ga-1/ga-1 seeds and showed negative correlations with the total number of seeds per fruit. Total content and composition of seed proteins were not influenced by the GA-deficiency. Germination of the mature seeds depended on embryonal GA synthesis and was not influenced by maternal GA production. Final fresh weight of the ga-1/ga-1 fruits was positively correlated with the number of seeds per fruit. In these fruits, the minimum number of seeds for growth above the parthenocarpic level was about 10 or 35 in the presence of Ga-1/ga-1 or ga-1/ga-1 seeds, respectively. Fruits containing GA-producing seeds reached a higher fresh weight than those containing GA-deficient seeds, and their ripening was delayed by one week. It is concluded that gibberellin is indispensable for the development of fertile flowers and for seed germination, but only promoting in later stages of fruit and seed development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1987.tb02865.x
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  • 4
    Electronic Resource
    Electronic Resource
    Strongly reduced levels of endogenous abscisic acid in developing seeds of tomato mutant sitiens do not influence in vivo accumulation of dry matter and storage proteins (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 81 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of endogenous abscisic acid (ABA) in seed development was studied with the use of the ABA-deficient sitw (sitiens) mutant of tomato (Lycopersicon esculentum Mill. cv. Moneymaker). The sitw mutation causes a strong reduction of the endogenous ABA level in the developing seed. Reciprocal crosses of wild-type and the sitw mutant show a dual origin of ABA. The genotype of the mother plant regulates the ABA content present in the testa, which shows a peak half-way through seed development. The genotype of the embryo and endosperm is responsible for a second ABA fraction, present in these tissues. This second fraction reaches its peak during the second half of seed development. The strong reduction of endogenous ABA level in the developing sitw/sitw seed does not change the final fresh and dry weights of the seed nor the accumulation and composition of storage proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb01715.x
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  • 5
    Electronic Resource
    Electronic Resource
    Importance of methionine biosynthesis for Arabidopsis seed germination and seedling growth (2002)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 116 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic pathway. This protein was present at low level in dry mature seeds, and its level was increased strongly at 1-day imbibition, prior to radicle emergence. Its level was not increased further at 2-day imbibition, coincident with radicle emergence. However, its level in 1-day imbibed seeds strongly decreased upon subsequent drying of the imbibed seeds back to the original water content of the dry mature seeds. The second enzyme corresponded to S-adenosylmethionine synthetase that catalyses the synthesis of S-adenosylmethionine from methionine and ATP. In this case, this enzyme was detected in the form of two isozymes with different pI and Mr. Both proteins were absent in dry mature seeds and in 1-day imbibed seeds, but specifically accumulated at the moment of radicle protrusion. Arabidopsis seed germination was strongly delayed in the presence of dl-propargylglycine, a specific inhibitor of methionine synthesis. Furthermore, this compound totally inhibited seedling growth. These phenotypic effects were largely alleviated upon methionine supplementation in the germination medium. The results indicated that methionine synthase and S-adenosylmethionine synthetase are fundamental components controlling metabolism in the transition from a quiescent to a highly active state during seed germination. Moreover, the observed temporal patterns of accumulation of these proteins are consistent with an essential role of endogenous ethylene in Arabidopsis only after radicle protrusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1160214.x
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  • 6
    Electronic Resource
    Electronic Resource
    Gibberellin-induced hydrolysis of endosperm cell walls in gibberellin-deficient tomato seeds prior to radicle protrusion (1988)
    Springer
    Planta 174 (1988), S. 500-504 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall hydrolysis ; Endo-β-mannanase ; Endosperm weakening ; α-Galactosidase ; Germination (seed) ; Lycopersicon (mutant, germination) ; Mannosidase ; Mutant (gibberellin deficient)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The weakening of the mechanical restraint of the endosperm layer in tomato (Lycopersicon esculentum Mill.) seeds, a prerequisite for germination, has been studied with the use of seeds of the gibberellin (GA)-deficientgib-1 mutant. Incubation ofgib-1 endosperms, including part of the testa, in 10 μM GA4+7, resulted within 12 h in the release of fructose, glucose, galactose and mannose into the incubation medium. Only small amounts of sugars diffused out of thegib-1 endosperms during incubation in water. Chemical hydrolysis of endosperm cell walls ofgib-1 seeds showed that they are mainly composed of mannose, and smaller quantities of glucose and galactose. Treatment with GA4+7 induced in the endosperms the production of endo-β-mannanase activity that was not detectable during incubation in water, and also increased the activities of mannohydrolase and α-galactosidase as compared with the water controls. No cellulase activity was found. It is concluded that in tomato seeds the weakening of endosperms prior to radicle protrusion is mediated by a GA-induced enzymatic degradation of the mannan-rich cell walls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00634479
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  • 7
    Electronic Resource
    Electronic Resource
    β-Tubulin accumulation and DNA synthesis are sequentially resumed in embryo organs of cucumber (Cucumis sativus L.) seeds during germination (1999)
    Springer
    Protoplasma 208 (1999), S. 230-239 
    Details
    ISSN: 1615-6102
    Keywords: Bromodeoxyuridine incorporation ; Cucumis sativus ; DNA synthesis ; Germination ; Microtubular cytoskeleton ; β-Tubulin accumulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Resumption of DNA synthetic activities and β-tubulin accumulation was studied in embryo organs of germinating cucumber (Cucumis sativus L.) seeds. Flow-cytometric analysis indicated the existence of 2C, 4C, and 8C nuclei in the radicle of mature embryos, whereas in cotyledons most of the cells contained nuclei with 2C DNA content. Upon imbibition of water, nuclear DNA replication was initiated in the radicle within 15 h, subsequently spreading towards the cotyledons. Bromodeoxyuridine incorporation preceded detectable changes in the relative amounts of DNA, implying the occurrence of putative DNA repair. Organellar DNA synthesis occurred independently of the nuclear DNA synthetic cycle. Western blotting and immunohistochemical localization demonstrated that the constitutive level of β-tubulin originated from preserved β-tubulin granules. During imbibition, disappearance of fluorescent tubulin granules, accumulation of β-tubulin, and formation of microtubular cytoskeleton were found in the radicle, but not in the cotyledon areas. Mitosis only occurred after radicle protrusion at 21 h of imbibition. It is concluded that the differences in the initiation and progress of these cellular and molecular events are associated with the discrete behaviors of the radicle and the cotyledons upon imbibition. The formation of cortical microtubular cytoskeleton and the accumulation of tubulins are important features in preparation of radicle protrusion, whereas DNA synthesis may contribute to postgerminative growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279094
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  • 8
    Electronic Resource
    Electronic Resource
    Regulation of UFGT activity in the bz-m4 allele of Zea mays: A possible case of gene fusion (1983)
    Springer
    Molecular genetics and genomics 190 (1983), S. 1-4 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Revertant derivates (bz-m4 to Bz′ 1 and Bz′ 7) of the bz-m4 sh mutant allele were investigated for their UDP-Glucose: flavonoid 3-O-glucosyltransferase (UFGT) activity in the subaleurone endosperm layer of developing kernels. The UFGT activity profile during development in Bz′ 1 subaleurone endosperm is partly the same as that of the bz-m4 mutant. This result is interpreted as supportive evidence for the occurence of gene fusion in the original bz-m4 sh mutant allele, causing the alteration in time and place of activity of the structurally unaltered UFGT in bz-m4 kernels. The possibility that regulating sequences of the sh gene are fused with the structural sequences of the Bz gene is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330316
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  • 9
    Electronic Resource
    Electronic Resource
    Search for novel genes for resistance to powdery mildew (Sphaerotheca fuliginae) in cucumber (Cucumis sativus) (1992)
    Springer
    Euphytica 64 (1992), S. 31-37 
    Details
    ISSN: 1573-5060
    Keywords: Cucumis sativus ; cucumber ; Spaerotheca fuliginea ; Erysiphe chichoracaerum ; powdery mildew ; leaf chlorosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The current powdery mildew (Sphaerotheca fuligninea) resistant cucumber varieties suffer from leaf chlorosis during autumn, winter and early spring cultivation in the Netherlands. Therefore screening was carried out for novel powdery mildew resistance genes. From 177 accessions, derived from different sources, 108 accessions proved to be partially resistant to S. fuliginea. Crosses were made with 53 resistant accessions to distinguish the presence of novel genes. It is likely that the accessions C. sativus 2145, C. sativus LV 41, PI 188807, Vladivostokij, White and Yellow 1 have one or more recessive powdery mildew resistance genes, different from powdery mildew resistance genes of the line NPI, which was used for variety breeding. Powdery mildew resistance tests with S. fuliginea give similar results in different regions of the world.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023535
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  • 10
    Electronic Resource
    Electronic Resource
    Increase of endogenous zeatin riboside by introduction of the ipt gene in wild type and the lateral suppressor mutant of tomato (1995)
    Springer
    Plant growth regulation 16 (1995), S. 27-36 
    Details
    ISSN: 1573-5087
    Keywords: axillary meristem ; cytokinin ; ipt gene ; ls mutant ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied axillary meristem formation of the lateral suppressor (ls) mutant of tomato after elevating the endogenous cytokinin levels through introduction of the isopentenyltransferase (ipt) gene from Agrobacterium tumefaciens. Growth and development of several transformants were examined during in vitro culture. Transformants exhibited phenotypes varying in severity and were divided into four classes. A number of the ipt transformants had a normal phenotype, as non-transformed plants. Others showed a mild to severe ‘cytokinin-like’ phenotype. Transformants with a mild phenotype exhibited reduced internode length and reduced root development. Transformants with a severe phenotype showed even shorter internodes, loss of apical dominance, reduction of leaf size, production of callus at the basis of the shoots and absence of root development or development of green non-branching roots. The severity of the phenotype correlated well with the level of ipt gene expression, as measured by northern analysis. Transformants with a severe phenotype also exhibited increased levels of zeatin riboside, but zeatin levels were not elevated. The increase in endogenous zeatin riboside levels in the ls mutant did not restore axillary meristem formation, but sometimes bulbous structures were formed in the initially ‘empty’ leaf axils. Several adventitious meristems and shoots developed from below the surface of these structures. It is concluded that a reduced level of cytokinins in the ls mutant shoots is not responsible for the absence of axillary meristem formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040504
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