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1

Study of ovule and megagametophyte development in four species of subtribe Phaseolinae [Leguminosae]

100%
Soverna A. F., Galati B., Hoc P.
Acta Biologica Cracoviensia. Series Botanica
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2003
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tom 45
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nr 2
Ovule development, megasporogenesis and megagametogenesis were studied in Macroptilium bracteatum, Phaseolus augusti, P. vulgaris var. aborigineus and Vigna adenantha to elucidate their taxonomic position. The ovule is anacampylotropous, bitegmic and crassinucellate. Megaspore tetrads are linear in M. bracteatum and T-shaped in the other three species. In all species the chalazal megaspore produces an embryo sac of Polygonum type. The results are discussed in relation to the current taxonomic classification. Our findings support the position of Macroptilium as a separate genus and the inclusion of V. adenantha in the genus Phaseolus. This is the first report of the use of embryological characters to solve intergeneric relationships of the Phaseolus-Vigna-Macroptilium neotropical complex, pointing out the method’s usefulness.
2
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Cytoembryology of infertile segregants of the hybrid Lupinus varius L. x L. digitatus Forsk

100%
Kazimierska E. M., Kazimierski T.
Journal of Applied Genetics
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1995
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tom 36
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nr 3
In F₂, F₃ and F₄ generations of one hybrid line of Lupinus varius × L. digitatus, segregation into infertile and fertile plants in the ratio 3:1 was observed. Cytoembryological analyses showed that sterility was caused by irregularities in megasporocyte formation, in megasporogenesis and megagametogenesis. The following abnormalities lead to female sterility: no megasporogenic cells separated in nucelluses; in other nucelluses with megaspore mother cells, these cells underwent vacuolation and died before reduction division. In the megaspore mother cells, in which probably meiosis occurs, the megasporocyte division is irregular; a restitution nucleus is frequently formed after reduction division and such megasporocyte develops into an embryo sac. In 8-nucleate embryo sacs a change in the nucellus polarization was observed, while in rarely encountered embryo sacs the embryo cells underwent vacuolation and then died. Female sterility in the studied segregants is determined genetically, whereas sterilization of reproduction cells is a developing process throughout the period of sporocyte and female gametophyte formation.
3

Apomixis in Brachiaria decumbens Stapf.: gametophytic development and reproductive calendar

100%
Dusi D. M. A., Willemse M. T. M.
Acta Biologica Cracoviensia. Series Botanica
|
1999
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tom 41
Brachiaria decumbens is a forage grass widely cultivated in tropical areas. This apomictic species reproduces mainly by facultative apospory. A comparison of male and female gamete development between the diploid sexual ecotype and the tetraploid apomictic B. decumbens was made. Aspects of sporophytic and gametophytic development such as developmental stage, several morphological variations, and callose deposition during meiosis are compiled in a real-time reproductive calendar which can be used to select plants as well as reproductive stages. Based on this calendar, part of the differences observed may be related to tetraploidy. Apomictic embryo sacs are formed earlier than the sexual ones, and callose deposition during meiosis follows a different pattern in sexual and apomictic plants. Effects of apomixis are expressed during both male and female development.
4
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Rapid assessment of early embryo development in some wide crosses of cereals

88%
Slusarkiewicz-Jarzina A., Ponitka A., Wojciechowska B., Wozna J.
Journal of Applied Genetics
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2000
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tom 41
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nr 2
5

In vitro pollination of excised ovaries

88%
Zenkteler M.
Acta Biologica Cracoviensia. Series Botanica
|
1999
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tom 41
In vitro placental pollination can be employed to overcome barriers of self-incompatibility and cross-incompatibility. Pollen grains of self-incompatible plants are capable of germinating directly on ovules, and the whole process of sexual reproduction can be accomplished. In some combinations of crosses, direct pollination of ovules enables prezygotic incompatibility barriers to be overcome. As a result, hybrid embryos or even hybrid plants can develop, depending on the partners crossed. Pollen grains germinate abundantly on immature ovules irrespective of the stage of megasporogenesis or megagametogenesis, and their tubes can penetrate the integuments and the nucellus cells. Preliminary investigations revealed that pollen grains of seven selected species of gymnosperms germinated on ovules of various species of Angiospermae. Embryological analysis of ovules of Melandrium album fixed 3 days after pollination with pollen of Pinus wallihiana revealed the presence of remnants of pollen tubes and 2-celled embryos in the embryo sacs. Those preliminary observations have not been described heretofore.
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