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  • 1
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Plant regeneration from callus cultures of Allium trifoliatum subsp. hirsutum fertile accession F-370, was studied as a means for clonal multiplication and germplasm storage of Allium spp. Callus was induced on in votro-cultured basal leaf explants. Best proliferation was obtained on modified BDS medium supplemented with (mg/1): 0.75 picloram, 2.0 benzyl adenine, and 900 casein hydrolysate. Shoot and root organogenesis were obtained in 3 to 5 month old subcultured calli, on BDS or MS medium supplemented with (mg/1): either 0.03 picloram or no auxin, 2 BA or 2-isopentenyladenine, and 900 casein hydrolysate. Direct bulb formation, without shoot elongation, occurred on BDS medium with 10 mg/1 IBA. Under these conditions, callus formation and organogenesis were not obtained with A. trifoliatum subsp. hirsutum var. sterile, a male-sterile genotype. Most regenerants were phenotypically normal, but some abnormal shoots were also observed, i.e. shoots with vitrified or extremely broad leaves. Isozyme polymorphism analysis of seven proteins in the latter regenerants, and in several callus cultures, revealed significant deviation from the original pattern in esterase, 6-phosphogluconate dehydrogenase and superoxide dismutase. No such deviations were detected in normal regenerated plants.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Selection of tomato plants supposedly tolerant to tomato yellow leaf curl virus (TYLCV), based solely on the absence of symptoms in an infested field can be misleading. An inoculation routine was therefore established to avoid escapes and to overcome difficulties associated with the age of the plant at the time of infection. The inoculation routine was applied to a selection of resistant/tolerant individuals generated through a diallel F1 cross and to F2 segregating populations originating from three wild tomato species described as tolerant to TYLCV: Lycopersicon peruvianum EC 104395, Lycopersicon pimpinellifolium Hirsute and Lycopersicon chilense LA 1969. Clear differences were observed between susceptible symptomatic and tolerant symptomless tomato genotypes, indicating that the uncertainty resulting from escapes, from different levels of inoculum, and from the time of inoculation, can be eliminated. The genes involved in tolerance provided different levels of protection; combinations of various tolerant sources and levels in a single genotype gave a higher level of tolerance. Differences in level of protection were found between genes from the same source and between sources; none of the sources tested had complete dominance. The results obtained with the F2 segregating population showed that tolerance from L. pimpinellifolium is controlled by one major gene, that from L. chilense by two genes, and that from L. peruvianum by three genes with no dominant effect. The combination of sources for resistance can thus have positive or negative synergistic effects, or no effect. We suggest that a maximal level of tolerance can be obtained by the additive effect of the partly dominant genes from L. pimpinellifolium and L. chilense.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 48 (1980), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Alcobaca is commonly regarded as an abnormally ripening mutant of the tomato (Lycopersicon esculentum Mill.). Alcobaca fruits were found to be similar to cv. Rutgers fruits in the following characteristics: time between full anthesis and the onset of ripening, response to ethephon, flavor, pH and concentrations of titratable acids, total soluble solids and reducing sugars. The pattern of CO2 and ethylene climacteric are similar in the two plant types, but the peak levels were lower and occurred later in alcobaca than in ‘Rutgers’. The mutant fruits differed from fruits of normal varieties in their greatly prolonged shelf life, their relatively low activity of polygalacturonase (PG) and polymethylgalacturonase (PMG), and their low level of endogenous ethylene. Fruits of the mutant harvested before the onset of ripening failed to reach normal pigmentation and remained yellow. Fruits harvested at the onset of ripening reached an orange color, while fruits ripened while attached to the plant reached almost normal pigmentation. These results suggest that alcobaca is a slow ripening mutant and does not belong to the category of non-ripening mutants.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2048
    Keywords: Chlorella ; Chlorophyta ; Paraquat ; Sulfite ; Superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Growth of Chlorella sorokiniana in the presence of 7.5 mM sulfite, which halved the growth rate while doubling the superoxide dismutase (SOD; EC 1.15.1.1) content per cell, rendered the cells resistant to the toxic effects of 30 μM paraquat. 2. While increasing total SOD content, sulfite increased the relative amount of the H2O2-resistant manganese-containing SOD. 3. It appears that O2 − may be involved in mediating the toxicity of SO2 in this green alga.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Planta 122 (1975), S. 91-97 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The concentration of total xanthophylls in maturing tomato fruit (Lycopersicon esculentum Mill. cv. Moneymaker) passed through a minimum during the period comprising the mature-green and breaker stages. This period marked a rapid decrease in chlorophyll and preceded the accumulation of lycopene and its colorless precursors, phytoene and phytofluene. An epoxide cycle was found to operate in the mature-green fruit, as evidenced by the increase in concentration of zeaxanthin at the expense of violaxanthin upon illumination of the fruit with visible light, whereas in the dark, the reverse process occurred. A second epoxide cycle of lesser amplitude was observed between lutein and lutein monoepoxide.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5028
    Keywords: agroinfection ; geminivirus ; leaf disc ; Lycopersicon spp. ; tomato ; TYLCV ; whitefly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The leaf disc agroinoculation system was applied to study tomato yellow leaf curl virus (TYLCV) replication in explants from susceptible and resistant tomato genotypes. This system was also evaluated as a potential selection tool in breeding programmes for TYLCV resistance. Leaf discs were incubated with a head-to-tail dimer of the TYLCV genome cloned into the Ti plasmid ofAgrobacterium tumefaciens. In leaf discs from susceptible cultivars (Lycopersicon esculentum) TYLCV single-stranded genomic DNA and its double-stranded DNA forms appeared within 2–5 days after inoculation. Whiteflies (Bemisia tabaci) efficiently transmitted the TYLCV disease to tomato test plants following acquisition feeding on agroinoculated tomato leaf discs. This indicates that infective viral particles have been produced and have reached the phloem cells of the explant where they can be acquired by the insects. Plants regenerated from agroinfected leaf discs of sensitive tomato cultivars exhibited disease symptoms and contained TYLCV DNA concentrations similar to those present in field-infected tomato plants, indicating that TYLCV can move out from the leaf disc into the regenerating plant. Leaf discs from accessions of the wild tomato species immune to whitefly-mediated inoculation,L. chilense LA1969 andL. hirsutum LA1777, did not support TYLCV DNA replication. Leaf discs from plants tolerant to TYLCV issued from breeding programmes behaved like leaf discs from susceptible cultivars.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 49 (1977), S. 35-42 
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The experiment described in this paper was designed to measure some of the genotype-environment interactions in Antirrhinum majus and the emphasis has been upon characters which are of economic importance. — Seven F1 hybrids were grown in 27 different environmental conditions, consisting of 3 levels of nitrogen and 9 sowing dates. Analysis of variance followed by regression analysis and the partitioning of the variation into its genetic, environmental and interacting components were employed. — The practical applications of these methods by the grower and plant breeder, are discussed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2242
    Keywords: Lycopersicon ; Tomato yellow leaf curl virus ; Gemini-virus ; Tolerance ; RFLP-assisted selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The whitefly-transmitted tomato yellow-leaf curl gemini-virus (TYLCV) is a major pathogen of tomatoes. The wild tomato species Lycopersicon chilense, which is resistant to the virus, was crossed to the cultivated tomato, L. esculentum. The backcross-1 selfed (BC1S1) generation was inoculated and a symptomless plant was selected. This plant was analyzed using 61 molecular markers, which span the tomato genome, to determine which L. chilense chromosome segments were introgressed. A BC2S1 population was cage-inoculated with viroliferous whiteflies (Bemisia tabaci), the natural insect vector of the virus, and subjected to RFLP analysis. Markers on chromosomes 3 and 6 were significantly associated with the level of tolerance; the association of chromosome-6 markers was further substantiated in two additional BC2S1 populations. A tolerant BC2S1 plant which was homozygous for L. chilense introgressions in chromosomes 3, 6 and 7 was crossed to generate a BC3S1 population which was planted in an infested field. A TYLCV-tolerance gene with partial dominance, TY-1, was mapped to chromosome 6; two modifier genes were mapped to chromosomes 3 and 7. Field and whitefly-mediated cage inoculations of nearly-isogenic lines in BC3S3 supported our conclusion that TY-1 is the major TYLCV-tolerance locus.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5060
    Keywords: Lycopersicon esculentum ; tomato ; preferential fertilization ; microgametogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Preferential fertilization of ovules by male gametes carrying the dominant I allele for Fusarium resistance occurred when heterozygous Ii plants served as male parent. Pollination with a mechanical l:l mixture of I and i pollen gave the normally expected Mendelian ratio. No significant differences were found in vivo in growth rate or in final length of pollen tubes of genotypes I and i. The experiments indicated that preferential fertilization was mainly caused by prepollination events leading to production of unequal amounts of fertile pollen grains of the two types.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 34 (1985), S. 385-391 
    ISSN: 1573-5060
    Keywords: Allium cepa ; onion ; Allium fistulosum ; Pyrenochaeta terrestris ; Pink root ; assay for resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An assay for resistance of onion to pink root Pyrenochaeta terrestris was developed, employing infested vermiculite medium with an adequate inoculum concentration of the fungus to minimize escapes of susceptible plants. Plant material other than seed was used. Either root-excised 6–8 week-old seedlings or onion sets were planted in infested vermiculite, and kept for two successive 2-week periods of growth differing in light and temperature regimes. During the first phase a short-day regime of 10 h and 17±1°C was kept, under which a vigorous root system was obtained. For an additional 12–14 days under 26±1°C and 12 h light the prolific roots were then exposed to the optimal temperature for disease development. This technique enables one to distinguish easily between susceptible Allium cepa material and a resistant line of A. fistulosum.
    Type of Medium: Electronic Resource
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