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Development of the pollen in the Antarctic flowering plant Colobanthus quitensis [Kunth] Bartl.

100%

Gielwanowska I., Bochenek A., Szczuka E.

Acta Agrobotanica

2007

tom 60

nr 2

Colobanthus quitensis (Kunth) Bartl, produced two types very small bisexual flowers. In the Antarctic natural conditions chasmogamic and cleistogamic flowers most often form five stamina with short filaments. Two microsporangia with a three-layer wall form in the anther. Microspore mother cells, which develop into microspores after meiosis, form inside the microsporangium. Microsporocytes of Colobanthus quitensis are surrounded with a thick callose layer, the special wall. After meiosis, the callose wall is dissolved and microspores are released from the tetrad. The production of proorbicules, orbicules and peritapetal membrane, and the construction of a complex sporoderm with numerous apertural sites were observed. When microspore and pollen protoplasts underwent necrosis, probably as a result of temperature and osmotic stress, sporoderm layers formed around microspores, and the cell tapetum did not disintegrate. However, woody wall layers did not accumulate in endothecium cells.

Cytological differentiation of the anthers tapetum in the tetraploid cytotype of Ranunculus fluitans Lam

100%

Turala-Szybowska K.

Acta Biologica Cracoviensia. Series Botanica

1992-1993

tom 34-35

The cytological differentiation of the anthers’ tapetum in the tetraploid cytotype of Ranunculus fluitans Lam. (2n = 32) in relation to that in diploid cytotype of this species (Turała-Szybowska 1984) was studied. In the tetraploid plants the first acytokinetic mitosis is obligatory and leads to the formation of binucleate tapetal cells. Two further mitotic divisions do not comprise all cells. Contrary to the diploid cytotype, in the tetraploid these two mitoses most frequently, are not inhibited at prophase but may proceed further. The mitotic disturbances in the tapetal cells, like the bridges between two chromosome groups and the fusion of metaphase or anaphase plates result in the formation of a number of polyploid nuclei of irregular shapes. In the final stage, in different binucleate tapetal cells the nuclei evaluated as diploid, tetraploid or octoploid occur.

Ograniczanie wyników

1 Acta Agrobotanica

1 Acta Biologica Cracoviensia. Series Botanica

1 Bochenek A.

1 Gielwanowska I.

1 Szczuka E.

1 Turala-Szybowska K.

1 2007

1 1993

Wyniki wyszukiwania

Development of the pollen in the Antarctic flowering plant Colobanthus quitensis [Kunth] Bartl.

Cytological differentiation of the anthers tapetum in the tetraploid cytotype of Ranunculus fluitans Lam