pollen tube


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Fig. 255 Pollen tube . Section of grain, showing tube.

pollen tube

a slender structure produced from a POLLEN GRAIN after POLLINATION. The tube protrudes from a pore in the EXINE and grows down through the stigma, style and ovary of the CARPEL, entering the ovule usually by the micropyle. See Fig. 255 . Within the tube, the haploid generative nucleus divides by MITOSIS to give two MALE GAMETE NUCLEI which have an important function in the double FERTILIZATION process of higher plants (see EMBRYO SAC). The growth of the tube appears to be controlled by the tube nucleus and there is some evidence that the tube shows negative AEROTROPISM. The stimulus for the original germination of the pollen grain comes from a sugary fluid secreted by the stigma. Sometimes, however, germination is prevented by SELF-INCOMPATIBILITY factors in the stigma cells and pollen grain, which prevent self-pollination in some plants.
References in periodicals archive ?
Pollen-pollen and pollen-style interaction during pollen tube growth in Erythronium grandiflorum (Liliaceae).
Actin, in this case a kind of scaffold-builder needed to form root hairs and pollen tubes, forms filamentous polymers and is important for many cellular processes in species ranging from yeast to man.
The sum of all pollen tube areas in the subtracted image was divided by the number of pollen grains from the original thresholded image to obtain the average pollen tube area per pollen grain.
Studies on the pollen tube growth in six species of Hibiscus and their crosses in vivo.
Fertility and pollen tube growth in polyploid melons (Cucumis melo L.
Self-pollination at bud stage aims to enable self-fertilization before the glycoproteins reach levels that prevent the development of the pollen tube (ROBERTS et al.
The pollen grain was considered germinated when its pollen tube diameter was equal to or larger than the pollen itself (Chagas et al.
Sucrose has a universal role in Ephedra of also providing a nutrient source for pollen germination and pollen tube growth, regardless of whether the species is insect- or wind-pollinated.
Among their topics are the regulation of cell wall formation by membrane traffic, actin filament dynamics and their role in plant cell expansion, rho of plant signaling and the cytoskeleton in pollen tube growth, phosphoinositide signaling in root hair tip growth, and the transcriptional regulation of the biosynthesis of cell wall components during xylem differentiation.
Recently pollen physiology especially germination and viability has received considerable attention for its application in plant breeding, conservation, adaptation and understanding of physiological behavior of fertilizing pollen grains, there are several reports on pollen germination, viability and tube length from different taxa [33,22,42,2314], but a little research concentrates on pollen tube morphology which is important also to complete fertilization successfully.