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  • 1
    Electronic Resource
    Electronic Resource
    The mentor pollen phenomenon in poplars: a new concept (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 129-135 
    Details
    ISSN: 1432-2242
    Keywords: Mentor effect ; Interspecific incompatibility ; Populus ; Male-male interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mentor effect has been investigated in poplars. Attempts to overcome interspecific incompatibility are analysed by pollen germination and pollen tube behaviour in situ, both for compatible and incompatible crosses. We have demonstrated that following the mixed pollination, the two pollen sets interact at different levels of the progamic phase. A hypothetical model is proposed which describes mentor effect as the result of interactions of antagonist and cynergic forces applying on compatible pollen and tubes. These forces promote pollen tube growth both on the female partner surface and within the tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299765
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  • 2
    Electronic Resource
    Electronic Resource
    Localization of adenylate cyclase activity in Populus: its relation to pollen-pistil recognition and incompatibility (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 140-149 
    Details
    ISSN: 1432-2145
    Keywords: Interspecific incompatibility ; Stigma-pollen interactions ; Adenylate cyclase ; Cytochemistry ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Adenylate cyclase has been localized cytochemically in female and male parents as well as during the pollen-stigma interaction with an original technique employing strontium as the capture ion and adenyl imidodiphosphate as the specific substrate. The specificity of the reaction was checked by using several controls. No final specific reaction product was detected in unpollinated P. deltoides stigmas or in the P. deltoides or P. alba pollen grains used for compatible and incompatible pollinations. In the compatible cross between P. deltoides × P. deltoides, fine dense precipitates were observed in the dictyosomes and the plasma membrane and exterior to the exine of hydrated pollen grains adhering to the stigma surface. Labeling of the stigmatic pellicle was also observed after pollen adhesion and hydration. This was accompanied by a strong reactivity of the cell wall and plasmalemma of the stigma papillae at the sites of pollen tube germination on the stigma surface and at the sites of penetration of pollen tubes between adjacent papillae. In the incompatible cross between P. deltoides x P. alba, adenylate cyclase activity was still present but reduced at the stigma surface following adhesion, hydration, and germination of P. alba pollen. This activity was completely abolished after the penetration of pollen tubes between stigma papillae. These findings suggest that in Populus, adenylate cyclase activity is correlated to pollen adhesion, hydration, and germination at the stigma surface, and that the abolition of this enzyme activity could be one of the cellular events governing the gametophytic phenotype of incompatibility in the cross between P. deltoides and P. alba.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193744
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  • 3
    Electronic Resource
    Electronic Resource
    Pollen-pistil interactions in Populus: β-galactosidase activity associated with pollen-tube growth in the crosses P. nigra x P. nigra and P. nigra x P. alba (1993)
    Springer
    Sexual plant reproduction 6 (1993), S. 249-256 
    Details
    ISSN: 1432-2145
    Keywords: Incongruity ; Pollen-pistil interactions ; Populus ; Pollen-tube growth ; β-galactosidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to understand the nature of interspecific barriers in Populus, we have explored pollen/pistil interactions in intra- and interspecific crosses Populus nigra x P. nigra and P. nigra x P. alba. The kinetics of pollen-tube growth demonstrated that P. nigra and P. alba pollen tubes have distinct behavioral patterns inside P. nigra pistils. P. alba pollen tubes exhibit an unique S-shaped growth curve and an arrested growth site near the sylodium. P. nigra pollen tubes exhibit two growth phases, in the stigmatic tissues and in the ovarian cavity respectively. P. nigra and P. alba curves diverge 5 h after controlled pollination and could be related to a change in the physiology of the P. nigra pollen tube, which shifts from an autotrophic to a heterotrophic type of nutrition. Protein analysis of pollinated stigmatic extracts (0,6 and 20 h after pollination) revealed qualitative and quantitative differences that are related to the presence of either P. nigra or P. alba pollen tubes inside the stigmatic tissues. Increasing numbers of protein bands were detectable from 0 to 20 h after pollination only in intraspecific cross. Glycoproteins were detected, and the differences observed were dependent of the cross. β-Galactosidase activity was found in pollinated stigmas, but an increase in its activity (one isozyme of pHi 4.2) between 6 h and 20 h after pollination was detected only in the intraspecific cross. This enzyme could play a role in heterotrophic pollen-tube nitrition, and its activity could be the final result of a series of interactions started by the initial pollen-stigma dialog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231902
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  • 4
    Electronic Resource
    Electronic Resource
    Organization of the early post-fertilization megagametophyte ofPopulus deltoides (1990)
    Springer
    Protoplasma 155 (1990), S. 153-165 
    Details
    ISSN: 1615-6102
    Keywords: Cytoplasmic inheritance ; Female germ unit ; Fertilization ; Gametic fusion mechanisms ; Male gamete ; Populus ; Synergid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gynoecia ofPopulus deltoides, 48 to 60 h after pollination, were examined using transmission electron microscopy. The mature megagametophyte contains two synergids, an egg cell, a central cell with two unfused polar nuclei and three antipodals. Pollen tube passage between cells in the styloid, on the placenta and through the micropyle does not induce degeneration of surrounding cells. Pollen tube entry into the megagametophyte occurs through the degenerated synergid immediately adjacent to the filiform apparatus. The tube grows the length of the filiform apparatus 20–30 μm into the synergid, and then discharges its contents-two sperm cells, the vegetative nucleus, and pollen tube cytoplasm. Sperm cells appear progressively hypertrophied during their passage in the pollen tube. In the degenerate synergid, the sperm nucleus is located at one end of the cell and the remaining cytoplasm is diffuse, containing a large vacuole. Following transmission of sperm nuclei into the egg and central cell, one male nucleus fuses with the egg and the other fuses with the micropylar polar nucleus. Enucleate cytoplasmic bodies of apparent sperm origin were observed within the degenerated synergid. The gametic fusion mechanism in this plant appears to involve: (1) eccentric positioning of the nucleus within the sperm cell, (2) separation of cytoplasmic and nuclear portions of the sperm cell, and (3) fusion of the nuclear portion with the egg cell. This represents a previously undescribed mechanism by which male cytoplasmic organelles are eliminated from sperm cells prior to fusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322625
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  • 5
    Electronic Resource
    Electronic Resource
    Interspecific incompatibility in Populus: inhibition of tube growth and behaviour of the male germ unit inP. deltoides×P. alba cross (1992)
    Springer
    Protoplasma 168 (1992), S. 107-110 
    Details
    ISSN: 1615-6102
    Keywords: Callose ; Interspecific incompatibility ; Male germ unit ; Pollen tube ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to better understand the cellular events controlling interspecific incompatibility in the genus Populus, the incompatible cross betweenP. deltoides andP. alba has been investigated both at the light and electron microscopic levels. Stained in decolourized aniline blue and observed by epifluorescence microscopy, most incompatible pollen grains are seen to germinate at the stigma surface. Numerous incompatible pollen tubes reach the base of the style where they are arrested 19 h after pollination. Ultrastructural observations on in vivo growing incompatible pollen tubes confirm these data. Very few cytoplasmic modifications are seen within living pollen tubes reaching the lower end of the style or within arrested ones, except the presence of polymorphic plastids. In this predominantly tricellular system, the male germ unit (MGU) is apparently initiated at pollen maturity as an association between the vegetative nucleus and sperm cells. It is maintained during pollen tube growth within the style and persists within arrested incompatible pollen tubes. The unique observation of an association between a dividing generative cell at metaphase and the vegetative nucleus is also reported. Arrested pollen tubes are characterized by apical deformations and accumulation of callose within their thickened cell walls. These cytological data provide additional information on the cellular events associated with interspecific incompatibility in Populus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666256
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