The perception and response of pollen tubes to the female guidance signals are crucial for directional pollen tube growth inside female tissues, which leads to successful reproduction. In pursuing the mechanisms underlying this biological process, we identified the Arabidopsis (Arabidopsis thaliana) abnormal pollen tube guidance1 (aptg1) mutant, whose pollen tubes showed compromised micropylar ...

Pollen tube elongation depends on the secretion of large amounts of membrane and cell wall materials at the pollen tube tip to sustain rapid growth. A large family of RAS-related small GTPases, Rabs or Ypts, is known to regulate both anterograde and retrograde trafficking of transport vesicles between different endomembrane compartments and the plasma membrane in mammalian and yeast cells. Stud...

Polarized growth in pollen tubes results from exocytosis at the tip and is associated with conspicuous polarization of Ca(2+), H(+), K(+), and Cl(-) -fluxes. Here, we show that cell polarity in Nicotiana tabacum pollen is associated with the exclusion of a novel pollen-specific H(+)-ATPase, Nt AHA, from the growing apex. Nt AHA colocalizes with extracellular H(+) effluxes, which revert to influ...

Cytoplasmic calcium concentration ([Ca2+]i) and extracellular calcium (Ca2+o) influx has been studied in pollen tubes of Lilium longliflorum in which the processes of cell elongation and exocytosis have been uncoupled by use of Yariv phenylglycoside ((beta-D-Glc)3). Growing pollen tubes were pressure injected with the ratio dye fura-2 dextran and imaged after application of (beta-D-Glc)3, which...

Pollen hydration is usually tightly regulated and occurs in vivo only when desiccated pollen grains acquire water from the female, thus enabling pollen tube growth. Pollen tubes are easily visualized by staining with decolorized aniline blue, a stain specific for callose. We identified a mutant, raring-to-go, in which pollen grains stained for callose before anther dehiscence. When raring-to-go...

Genes directly involved in male/female and host/parasite interactions are believed to be under positive selection. The flowering plant Arabidopsis thaliana has more than 300 defensin-like (DEFL) genes, which are likely to be involved in both natural immunity and cell-to-cell communication including pollen-pistil interactions. However, little is known of the relationship between the molecular ev...

Myosin, detected by immunofluorescence using an antibody to bovine skeletal and smooth muscle myosin, has been localised on individual identifiable organelles from the grasses Alopecurus pratensis and Secale cereale, and on the surfaces of vegetative nuclei and generative cells from pollen and pollen tubes of Hyacinthus orientalis and Helleborus foetidus. Taken in conjunction with recent eviden...

Pollen tubes of Tradescantia growing on media containing 10(-3) M-Ca2+ and 10(-2)M-Ca2+ exhibit growth rates of 28 micrometers min-1 and 7 micrometers min-1, respectively. The rates of vesicle production by the dictyosomes in these tubes were determined from the rates at which vesicles accumulated in the cytoplasm after treatment with cytochalasin D. Although the vesicle requirements for these ...

The male gametophytes of gymnosperms are characterized by the diversities in pollen morphology, cellular composition and pattern of cell division, pollen tube morphology, sperm delivery, growth pattern through the ovule and nucellus, and pollen tube wall composition both within and among the four living orders, i.e., Cycadales, Ginkgoales, Coniferales, and Gnetales. At dehiscence, gymnosperm po...

Flowering plants possess specialized extracellular matrices in the female organs of the flower that support pollen tube growth and sperm cell transfer along the transmitting tract of the gynoecium. Transport of the pollen tube cell and the sperm cells involves a cell adhesion and migration event in species such as lily that possess a transmitting tract epidermis in the stigma, style, and ovary....