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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Planta 130 (1976), S. 235-244 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Dry weight analyses and 14CO2 were used to study translocation in leaves of the C3 grass Lolium temulentum L. and the C4 grass Panicum maximum Jacq. and the results related to the distribution and amount of phloem in the lamina. The rate of specific mass transfer rose from the tips to the bases of leaf blades, in both species high rates were recorded. Major veins were responsible for the bulk of longitudinal translocation and minor veins were important in collecting and loading photosynthate. Transverse veins stored 14C-assimilate and may have coordinated the functioning of the longitudinal veins. The bearing of the results on the mechanism of translocation is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Lignification ; Sieve elements ; Translocation of assimilates ; Triticum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Leaves of Triticum aestivum L. were exposed to 14CO2. The 14C activity in lignified sieve elements was not above background levels, whereas it was significnatly higher in normal sieve elements and companion cells.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 10 (1997), S. 351-357 
    ISSN: 1432-2145
    Keywords: Key words Bioassay ; Extracellular matrix ; Nicotiana alata ; Pollen density ; Polyethylene glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A new method for assessing the effects of test compounds on Nicotiana alata pollen tubes in culture is described. Pollen tubes grow from a cluster of grains placed beneath a thin layer of gelled medium in which test substances are incorporated and from which evaporation is prevented by a covering layer of oil. Pollen tubes can grow to 8 mm in length in 24 h, which corresponds to about 25% of the maximum growth rate in styles. Growth is non-destructively measured. The developmental stages reached by cultured tubes are similar to those of tubes growing in styles; growth changes from being reserve-dependent to reserve-independent, callose plugs form, and the nucleus of the generative cell divides. Because culture volumes are small (10–20 μl per replicate), the effects of known concentrations of microgram quantities of compounds on the growth of pollen tubes can be tested.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 10 (1997), S. 27-35 
    ISSN: 1432-2145
    Keywords: Key words Nicotiana alata ; Pollen tube growth ; Stylar graft ; Self-incompatibility ; Cytotoxic model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Style squashes and stylar grafts were used to examine the growth of Nicotiana alata pollen tubes in self-compatible and self-incompatible styles. Compatible tubes typically showed a uniform layer of callose deposition in the walls and in small plugs spaced at regular intervals within the tube. Incompatible tubes were characterised by the variability of callose deposition in the walls and by larger, closer and more irregularly spaced plugs. There was no difference in the growth rate of compatible and incompatible tubes during growth through the stigma, but within the style most compatible tubes grew 20–25 mm day-1 (maximum 30 mm day–1), whereas incompatible tubes grew 1.0–1.5 mm day-1 (maximum 5 mm day–1). Many incompatible tubes continued to grow until flowers senesced, and only a small proportion died as a consequence of tip bursting. Grafting compatibly pollinated styles onto incompatible styles showed that the incompatible reaction could occur in pollen tubes between 2 and 50 mm long, and that inhibition of pollen tube growth occurred in both the upper and lower parts of the transmitting tract. Grafting incompatibly pollinated styles onto compatible styles showed that the incompatible reaction was fully reversible in at least a proportion of the pollen tubes. The findings are not consistent with the cytotoxic model of inhibition of self-pollen tubes in solanaceous plants, which assumes that the incompatible response results from the degradation of a finite amount of rRNA present in the pollen tube. However, if pollen tubes do in fact synthesise rRNA, the findings become consistent with this model.
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  • 5
    ISSN: 1432-2145
    Keywords: Key words LAT52 ; Pollen ; Ovary ; Reporter gene ; Transcription ; Nicotiana alata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The pollen-specific promoter of the LAT52 gene is known to direct expression of marker proteins during the last stages of pollen maturation and in very early pollen tube growth.We have examined the expression of LAT52-GUS during later stages of pollen tube growth in style and ovary of the relatively long-styled species Nicotiana alata. GUS activity was detected histochemically and found to be present in germinating pollen grains of N. alata and in tubes growing through the upper part of the style. No GUS activity was detected in 99% of the pollen tubes growing through the lower part of the style, but activity was present in tubes within the ovary. This finding indicates that the LAT52 promoter is regulated in growing pollen tubes, and is most active during the earliest and latest stages of pollen tube growth. GUS activity was also detected in some ovules, where it presumably marked the release of pollen tube cytoplasm into the ovule. The distribution of ovules with GUS activity within the ovary is not consistent with high-precision pollen tube guidance to the ovule.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 30 (1981), S. 579-587 
    ISSN: 1573-5060
    Keywords: Vigna unguiculata ; cowpea ; origin ; domestication ; evolution ; seed dispersal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Physiological and morphological characteristics of the two wild and three domesticated subspecies of cowpeas are compared. The wild accessions are alike in having small, hard seeds borne in dehiscent pods, but differ in other characteristics. We suggest that the wild subsp. dekindtiana, from the seasonally-arid tropics, is more likely to have been the progenitor of modern cowpeas than the other wild subspecies (subsp. mensensis), but that subsp. dekindtiana was first cultivated in the humid tropics where its pods are slow to dehisce. Domestication has been associated with changes in the structure of pod valves and seed coats which reduce pod dehiscence and seed hardness. Pods and seeds have increased in size, mainly by increases in the rate of dry weight accumulation, and their increase has been only partly paralleled by increase in the area of subtending leaves. There has been no increase in the maximum photosynthetic rate of leaves, but the duration of their photosynthetic activity has increased. Domesticates are less sensitive than are wild plants to some environmental controls, such as in the response of germination to temperature, but in their flowering responses to daylength both wild and cultivated forms retain sensitivity under conditions where this is of adaptive value.
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  • 7
    ISSN: 1573-5028
    Keywords: glycoproteins ; Nicotiana alata ; pollination ; self-incompatibility ; S-locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A summary of recent work on molecular aspects of self-incompatibility in Nicotiana alata is presented. The amino acid sequences of style proteins corresponding to different S-alleles of N. alata have a high level of homology in some regions and are variable in other regions. The regions of homology include N-terminal sequences as well as most of the glycosylation sites and cysteine residues. The glycosyl substituents may consist of a number of ‘glycoforms’. The isolated style S-glycoproteins inhibit in vitro growth of pollen tubes. The S-glycoproteins tested inhibited the growth of pollen of several S-genotypes, and there was some specificity in the interaction. Heat treatment of the isolated S-glycoproteins dramatically increased their activity as inhibitors of pollen tube growth, although the specificity in the interaction was lost. The nature of the S-allele products in pollen is not yet established.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 1990-05-01
    Print ISSN: 0002-1962
    Electronic ISSN: 1435-0645
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 9
    Publication Date: 1991-09-01
    Print ISSN: 0002-1962
    Electronic ISSN: 1435-0645
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 10
    Publication Date: 1979-10-01
    Print ISSN: 0013-0001
    Electronic ISSN: 1874-9364
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Springer
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